TY - CONF A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Stargardt, Patrick A1 - Töpfer, Jörg A1 - Moos, Ralf A1 - Rabe, Torsten T1 - Development of textured multilayer thermoelectric generators based on calcium cobaltite N2 - Thermoelectric generators can be used as energy harvesters for sensor applications. Multilayer thermoelectric generators (ML-TEGs) are a promising alternative to conventional π-type generators due to their high filling factor, high capability of automated production and the texturing potential during the production process. Calcium cobaltite is a promising thermoelectric oxide (p-type) with highly anisotropic properties. The following study shows the development of a textured unileg ML-TEG using ceramic multilayer technology. Tape-casting and pressure assisted sintering are applied to fabricate textured calcium cobaltite. Compared to conventional sintering, pressure assisted sintering increases the strength by the factor 10. Thermoelectric properties can be tuned either towards maximum power factor or towards maximum figure of merit depending on the pressure level. As electrical insulation material, a screen-printable glass-ceramic with high resistivity and adapted coefficient of thermal expansion is developed. From various commercial pastes a metallization with low contact resistance is chosen. The unileg ML-TEG is co-fired in one single step. The demonstrators reach 80% of the simulated output power and the power output is highly reproducible between the different demonstrators (99%). These results provide the first proof-of-concept for fabricating co-fired multilayer generators based on textured calcium cobaltite with high power factor, high density, and high strength. T2 - Virtual Conference on Thermoelectrics 2021 (VCT) CY - Online meeting DA - 20.07.2021 KW - Thermoelectrics KW - Multilayertechnik KW - Screen printing PY - 2021 AN - OPUS4-52993 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Höhne, Patrick A1 - Mieller, Björn A1 - Koppert, Ralf A1 - Rabe, Torsten T1 - Commercial LTCC for thin film deposition N2 - Low-temperature co-fired ceramics (LTCC) are used to fabricate multilayer circuits which are robust in harsh environments. Thick-film technology is well established for the metallization of circuit boards and microsystems. For specific sensor applications, the combination of LTCC and thin-film technology is advantageous to reach higher structure resolutions. Due to the high roughness of as-fired LTCC surfaces compared with silicon-wafers, the deposition of low-defect- films with narrowly specified properties is challenging. There is spare literature about thin films on commercial LTCC comparing different material systems or sintering techniques. For developing thin film sensors on multilayer circuits it is crucial to identify thin-film-compatible commercial LTCC material as well as the crucial surface properties. In this work we evaluate the thin-film capability of different LTCC surfaces. The as-fired surfaces of free-sintered, constrained-sintered (sacrificial tape), and pressure-assisted sintered commercial LTCCs (DP951, CT708, CT800), as well as respective polished surfaces, were analyzed by tactile and optical roughness measurements and scanning electron microscopy. The thin-film capability of the LTCC surfaces was assessed by sheet resistance and temperature coefficient of resistance (TCR) of deposited Ni thin-film layers. Contrary to the expectations, no correlation between roughness and thin-film capability was found. Ni thin films on constrained sintered DP951 show the lowest sheet resistance and highest TCR within the experimental framework of the as-fired surfaces. The influence of surface morphology on the film properties is discussed. T2 - KERAMIK 2022 / 97. DKG-Jahrestagung CY - Online meeting DA - 7.3.2022 KW - Roughness KW - Hydrogen sensor KW - LTCC PY - 2022 AN - OPUS4-54436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Stargardt, Patrick A1 - Mieller, Björn A1 - Moos, Ralf A1 - Rabe, Torsten T1 - Material development for oxide multilayer generators N2 - Thermoelectric generators can be used for energy harvesting by directly transforming a temperature gradient into a voltage. Multilayer generators based on low-temperature co-fired ceramics technology (LTCC) are an interesting alternative to conventional π-type generators. They exhibit several advantages like high filling factor, possibility of texturing, co-firing of all materials in one single-step, and reduction of production costs due to the high possible degree of automation. Pressure-assisted sintering enables the theoretical possibility of co-firing two promising oxide thermoelectric materials: Ca3Co4O9 (p-type) and CaMnO3 (n-type). Due to the large difference in sintering temperature (300 K) the process is very challenging. In this work we show the material development of Ca3Co4O9, CaMnO3, insulation and metallization for multilayer generators co-fired under pressure at 900 °C. The materials are tailored regarding their sintering behavior, electrical performance and coefficients of thermal expansion. Different generator designs (unileg and pn-type) were fabricated and analyzed regarding crack formation, interaction layers and thermoelectric performance. Simulated stresses during cooling in the multilayers are compared with actual crack formation for different sintering conditions. This study shows that a lower pressure level and a lower level of complexity are beneficial for co-firing and performance. T2 - 45th International Conference and Expo on Advanced Ceramics and Composites (ICACC 2021 Virtual) CY - Online meeting DA - 08.02.2021 KW - Thermoelectrics KW - Multilayer PY - 2021 AN - OPUS4-52462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Moos, Ralf A1 - Rabe, Torsten T1 - Improved thermoelectric properties of CaMnO3 and Ca3Co4O9 by increasing the driving force for sintering N2 - Thermoelectric materials can convert waste heat directly into electrical power by utilizing the Seebeck effect. Calcium cobaltite (Ca3Co4O9, p-type) and calcium manganate (CaMnO3, n-type) are two of the most promising oxide thermoelectric materials. The performance of these materials is evaluated by the power factor PF = S²∙σ and the figure of merit ZT = (PF ∙ T) / κ, demanding high Seebeck coefficient S, high electrical conductivity σ and low thermal conductivity κ. The latter two are increasing with increasing relative sinter density. According to theory, the relative density of ceramics can be improved by increasing the driving force for sintering. This study investigates different approaches to increase the driving force for sintering of Ca3Co4O9 and CaMnO3 to improve densities and thermoelectric properties. The following approaches were applied: minimizing the energy input during powder synthesis by calcination, fine milling of the powder, using reaction-sintering without a powder synthesis step, and adding a transient liquid phase by sinter additives. All different approaches led to an increased densification and thus higher electrical conductivity and higher PF. Thermal conductivity increased as well but not to the same extent. E.g. reaction-sintering increased the densification of Ca3Co4O9 (p-type) and CaMnO3 (n-type). Consequently, the electrical conductivities improved by about 100 % for both oxides leading to superior power factors (PF = 230 µW/mK² for CaMnO3). Although the thermal conductivity increased as well by 8 %, the figures of merit (ZT) were significantly higher compared to conventionally sintered bars. The addition of 4 wt% CuO as a sinter additive to CaMnO3 lowers the sinter temperature from above 1250 °C to below 1100 °C and increases the relative density. Due to the increased density, both electrical conductivity and PF increased by more than 200 % even though the sintering temperature was 150 K lower. T2 - Electroceramics XVII CY - Online meeting DA - 24.08.2020 KW - Thermoelectrics KW - Reaction sintering KW - Sintering additives PY - 2020 AN - OPUS4-51163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Höhne, Patrick A1 - Lindemann, Franziska A1 - Koppert, Ralf A1 - Mieller, Björn T1 - Chemical resistance of commercial LTCC against thin film etching media N2 - Low-temperature co-fired ceramics (LTCC) are used to fabricate robust multilayer circuits. Typically, thick-film technology is applied for metallization. For specific sensor applications, thin films are deposited directly on the as-fired LTCC-surface. These deposited thin films are structured either by lift-off or by etching. The latter is less error-prone and thus preferred in industry provided the selected materials allow it. 200 nm Ni-thin films were deposited on three different commercial constrained-sintered LTCC (CT708, CT800 and DP951) by electron beam physical vapour deposition. The thin-films were structured by covering corresponding sections with a UV-curable photo resisn and subsequent etching of the uncovered surface, leaving behind the desired structure. The etched Ni-thin film showed high difference in failure rate and sheet resistance regarding the used LTCC-material. DP951 had the lowest sheet resistance and no failure, whereas the CT800 had a failure rate of 40 %. The LTCC with high failure rate showed a strong chemical attack by the used etching medium. To address this phenomenon, the chemical resistance of the three different commercial LTCC (CT708, CT800 and DP951) against four different commonly used etching media (sulphuric acid, phosphoric acid, aqua regia, and hydrofluoric acid) is investigated. The dissolved ions are analyzed by ICP-OES to correlate the LTCC-composition and its chemical resistance. T2 - KERAMIK 2023 / 98. DKG-Jahrestagung CY - Jena, Germany DA - 27.03.2023 KW - Glass-ceramics KW - Hydrogen sensors KW - Acids PY - 2023 AN - OPUS4-57273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Reimann, T. A1 - Moos, R. A1 - Rabe, Torsten T1 - Texturing of calcium cobaltite for thermoelectric applications by pressure assisted sintering N2 - Thermoelectric materials can convert waste heat directly into electrical power by using the Seebeck effect. Calcium cobaltite (CCO) is considered as a promising thermoelectric p-type oxide for energy harvesting applications at temperatures above 500 °C. The properties and morphology of single-crystal CCO are strongly anisotropic because of its crystal structure of alternating layers of CoO2 and Ca2CoO3. By aligning the plate-like grains, the anisotropic properties of the grains can be assigned to the poly-crystalline parts. In this study, the combination of tape casting and pressure-assisted sintering is used to texture and densify large scale components (50 cm²). Thereby, the influence of powder preparation and applied pressure during sintering on texturing and thermoelectric properties is investigated. The analysis of XRD pole figures revealed that tape casting already leads to highly textured CCO. By pressure variation during sintering, the microstructure of CCO can be tailored either toward maximum power factor as required for energy harvesting or toward maximum figure of merit as required for energy recovery. Low pressure lead to a porous microstructure and maximum figure of merit and higher pressure to full densification and maximum power factor. The electrical and thermal conductivity of CCO seem depending on both texture and sinter density. T2 - KERAMIK 2021 / CERAMICS 2021 CY - Online meeting DA - 19.04.2021 KW - Thermoelectrics KW - Hot pressing KW - Pole figures PY - 2021 AN - OPUS4-52490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Moos, Ralf A1 - Rabe, Torsten T1 - Reaction sintering and sintering additives for cost-effective production of thermoelectric oxides N2 - Thermoelectric oxides attract much interest recently. Although their thermoelectric properties are inferior to non-oxides, they exhibit distinct advantages. Thermoelectric oxides are stable in air at higher temperatures, their raw materials are less toxic, and more abundant. To enhance attractivity of these materials for industrial applications, production costs need to be reduced. Conventionally, the legs of thermoelectric generators are sintered from green bodies of previously synthesized powder. Reaction-sintering is a fabrication method without a powder synthesis step, as the final phase is formed during the sintering from a raw material mixture. Moreover, the reduction of chemical potential during reaction-sintering is effective as an additional driving force for sintering. We show that reaction-sintering increases the densification of CaMnO3 (n-type, Sm doped). Consequently, the electrical conductivities improved by about 100 % leading to superior power factors (PF = 230 µW/mK² for CaMnO3). Another approach to reduce the production costs is to lower the sintering temperature by adding sinter additives. The addition of 4 wt% CuO to CaMnO3 lowers the sinter temperature from 1250 °C to 1050 °C. The achieved power factor PF = 264 µW/mK is more than two times higher as reported in literature for the same dopant. T2 - Virtual Conference on Thermoelectrics (VCT) CY - Online meeting DA - 21.07.2020 KW - Thermoelectrics KW - Reaction sintering KW - Sintering additives KW - Calcium manganate KW - Calcium cobaltite PY - 2020 AN - OPUS4-51070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Schönauer-Kamin, D. A1 - Moos, R. A1 - Giovanelli, F. A1 - Rabe, Torsten T1 - Influence of pressure assisted sintering and reaction sintering on microstructure and thermoelectric properties of bi-doped and undoped calcium cobaltite N2 - Calcium cobaltite (Ca3Co4O9) is considered as one of the most promising thermoelectric p-type oxides for energy harvesting applications at temperatures above 500 °C. It is challenging to sinter this material as its stability is limited to 920 °C. To facilitate a practicable and scalable production of Ca3Co4O9 for multilayer generators, a systematic study of the influence of powder calcination, Bi-doping, reaction sintering, and pressure-assisted sintering (PAS) on microstructure and thermoelectric properties is presented. Batches of doped, undoped, calcined, and not calcined powders were prepared, tape-cast, and sintered with and without uniaxial pressure at 900 °C. The resulting phase compositions, microstructures and thermoelectric properties were analysed. It is shown that the beneficial effect of Bi-doping observed on pressureless sintered samples cannot be transferred to PAS. Liquid phase formation induces distortions and abnormal grain growth. Although the Seebeck coefficient is increased to 139 µV/K by Bi-doping, the power factor is low due to poor electrical conductivity. The best results were achieved by PAS of calcined powder. The dense and textured microstructure exhibits a high power factor of 326 µW/mK² at 800 °C but adversely high thermal conductivity in the relevant direction. The figure of merit is higher than 0.08 at 700 °C. KW - Ceramics KW - Calcium cobaltite KW - Thermoelectric properties KW - Calcination KW - Pressure-assisted sintering PY - 2019 DO - https://doi.org/10.1063/1.5107476 SN - 0021-8979 VL - 126 IS - 7 SP - 075102-1 EP - 075102-11 PB - AIP Publishing CY - Melville AN - OPUS4-48708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Delorme, F. A1 - Chen, C. A1 - Bektas, M. A1 - Moos, R. A1 - Rabe, Torsten T1 - Influence of Reaction-Sintering and Calcination Conditions on Thermoelectric Properties of Sm-doped Calcium Manganate CaMnO3 N2 - A wide range of solid-state synthesis routes for calcium manganate is reported in the literature, but there is no systematic study about the influence of the solid-state synthesis conditions on thermoelectric properties. Therefore, this study examined the influence of calcination temperature and calcination cycles on the Seebeck coefficient, electrical conductivity, and thermal conductivity. Higher calcination temperatures and repeated calcination cycles minimized the driving force for sintering of the synthesized powder, leading to smaller shrinkage and lower densities of the sintered specimens. As the electrical conductivity increased monotonously with increasing density, a higher energy input during calcination caused deterioration of electrical conductivity. Phase composition and Seebeck coefficient of sintered calcium manganate were not influenced by the calcination procedure. The highest thermoelectric properties with the highest power factors and figures of merit were obtained by means of reaction-sintering of uncalcined powder. KW - Thermoelectric oxides KW - Calcination KW - Solid-state-synthesis KW - Power factor KW - Reaction-sintering PY - 2018 DO - https://doi.org/10.4416/JCST2018-00017 SN - 2190-9385 VL - 9 IS - 3 SP - 289 EP - 300 PB - Göller Verlag AN - OPUS4-46224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiel, Erik A1 - Ziegler, Mathias A1 - Ahmadi, Samim A1 - Portella, Pedro Dolabella T1 - Structured heating in active thermography by using laser arrays N2 - Lock-in- and flash thermography are standard methods in active thermography. They are widely used in industrial inspection tasks e.g. for the detection of delaminations, cracks or pores. The requirements for the light sources of these two methods are substantially different. While lock-in thermography requires sources that can be easily and above all fast modulated, the use of flash thermography requires sources that release a very high optical energy in the very short time. By introducing high-power vertical cavity surface emitting lasers (VCSELs) arrays to the field of thermography a source is now available that covers these two areas. VCSEL arrays combine the fast temporal behavior of a diode laser with the high optical irradiance and the wide illumination range of flash lamps or LEDs and can thus potentially replace all conventional light sources of thermography. However, the main advantage of this laser technology lies in the independent control of individual array areas. It is therefore possible to heat not only in terms of time, but also in terms of space. This new degree of freedom allows the development of new NDT methods. We demonstrate this approach using a test problem that can only be solved to a limited extent in active thermography, namely the detection of very thin, hidden defects in metallic materials that are aligned vertically to the surface. For this purpose, we generate destructively interfering thermal wave fields, which make it possible to detect defects within the range of the thermal wave field high sensitivity. This is done without pre-treatment of the surface and without using a reference area to depths beyond the usual thermographic rule of thumb. T2 - ConaEnd&Iev 2018 CY - Sao Paulo, Brazil DA - 27.08.2018 KW - VCSEL KW - Active thermography KW - Laser KW - Structured heating KW - Subsurface defects PY - 2018 AN - OPUS4-45851 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eddah, Mustapha A1 - Markötter, Henning A1 - Mieller, Björn A1 - Beckmann, Jörg A1 - Bruno, Giovanni T1 - Synchrotron Multi-energy HDR tomography for LTCC systems N2 - LTCCs (Low-temperature co-fired ceramics) consist of three-dimensionally distributed, hermetically bonded ceramic and metallic components with structure sizes within [10; 100] µm. A non-destructive imaging technique is needed that provides 3D, sharp, high-contrast resolution of these structures, as well as porosity and defect analysis, which is made difficult by the very different X-ray absorption coefficients of the individual components of the microstructure. A HDR method is being developed that allows a combination of different tomograms, each with X-ray energies adapted to individual materials. T2 - Bessy II User Meeting CY - Berlin, Germany DA - 22.06.2023 KW - LTCC KW - Synchrotron tomography KW - Data fusion KW - In-situ tomography PY - 2023 AN - OPUS4-57795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hajian, A. A1 - Konegger, T. A1 - Bielecki, K. A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Schwarz, S. A1 - Zellner, C. A1 - Schmid, U. T1 - Wet chemical porosification with phosphate buffer solutions for permittivity reduction of LTCC substrates N2 - The wireless high-frequency technology requires a robust, cost-effective, and highly integrated substrate technology offering the capability for areas of tailored permittivity. The wet-chemical porosification of low temperature co-fired ceramics (LTCC) substrates offers such an approach by locally embedding air. Porosification of LTCC in both extremely acidic and alkaline media has been investigated in previous works. However, for improving the available knowledge on the porosification of LTCC with H3PO4 as a standard and a widely used etching solution, the impact of solution concentration was systematically investigated and a substantial improvement in the etching performance was achieved. Moreover, in the present study, for the first time, the intermediate pH values, and the impact of pH as a key parameter on the etching process have been investigated. For this purpose, the applicability of phosphate buffer solution (PBS) as a prospective novel etchant mixture for the porosification of a commercially available LTCC tape (Ceramtape GC) was explored. Valuable information about surface morphology, crystalline composition, and the pore structure of the etched LTCCs was gathered employing scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and mercury porosimetry measurements. Based on these findings, the performance of PBS-based etchant systems towards the generation of porous LTCCs combining high depths of porosification with acceptable surface characteristics for subsequent metallization is demonstrated. Based on the obtained results, by application of a 0.2 mol L−1 solution of PBS, the effective relative permittivity of test samples with a thickness of approximately 600 µm and a porosification depth of 186 µm from each side, could be reduced up to 10% of its initial “as fired” value. Also, based on the measurement results and by measuring the depth of porosification, the permittivity of the etched layer was estimated to show a reduction of up to 22% compared to the initial “as fired” value. KW - LTCC KW - Porosification KW - Wet chemical etching KW - Permittivity reduction PY - 2020 DO - https://doi.org/10.1016/j.jallcom.2020.158059 SN - 0925-8388 VL - 863 SP - 158059 PB - Elsevier B.V. AN - OPUS4-51800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Making materials (digital) - Keramik N2 - Der Vortrag gibt einen Überblick über die Materialklasse Keramik, insbesondere Technische Keramik. Nach einem kurzen Überblick über typische Anwendungen und Werkstoffe wird die keramische Prozesskette erläutert. Am Beispiel von Festigkeit wird der für Keramik typische, enge Zusammenhang zwischen Technologie, Mikrostruktur und Eigenschaften herausgearbeitet. Daraus werden Anforderungen für eine erfolgreiche Digitalisierung abgeleitet. T2 - Workshop "STREAM" - Semantische Repräsentation, Vernetzung und Kuratierung von qualitätsgesicherten Materialdaten CY - Darmstadt, Germany DA - 26.09.2022 KW - Keramik KW - Festigkeit KW - Überblick PY - 2022 AN - OPUS4-55859 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Herstellung und Charakterisierung keramischer Federn N2 - Aufgrund ihres spezifischen Eigenschaftsprofils sind keramische Federn attraktiv für Spezialanwendungen in Maschinenanlagen, Metrologie und Sensortechnik. Durch Hartbearbeitung keramischer Hohlzylinder können Spiralfedern mit rechteckigem Windungsquerschnitt präzise gefertigt werden. Dabei kann durch gezielte Auslegung der Federgeometrie die Federkonstante über mehrere Größenordnungen variiert werden. Der Vortrag gibt einen Überblick über den Herstellungsprozess, verschiedene Eigenschaften keramischer Federn und Anwendungsbeispiele. T2 - Industrieller Arbeitskreis Keramikbearbeitung CY - Online meeting DA - 08.04.2022 KW - Keramik KW - Hartbearbeitung KW - Federkonstante PY - 2022 AN - OPUS4-54623 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhne, Patrick A1 - Mieller, Björn A1 - Rabe, Torsten T1 - Slurry development for spray granulation of ceramic multicomponent batches N2 - The granules commonly yielded by spray drying procedures exhibit a hard shell and an irregular, dimpled shape, which is often described as donut-like morphology. Sintered parts produced from such granules suffer from microstructural defects and reduced mechanical properties resulting from these disadvantageous granule properties. Using the example of alumina, zirconia and zirconia-toughened alumina (ZTA) batches, this paper shows that the morphology of the granules can be tuned by adjusting slurry stability. High zeta potential is essential to optimally disperse the particles. But to achieve spherical and soft granules the electrostatic repulsion forces between the particles should be reduced before spray granulation. Electrostatic repulsion forces were changed with the addition of nitric acid. Measurements of zeta potential and viscosity, as well as sedimentation investigations with an optical centrifuge were used for precise slurry assessment as a major precondition for optimal and reproducible adjustment of slurries before spray drying. Sedimentation analysis using an optical centrifuge was performed to investigate different influences like that of additive composition, solids content or pH-value on the sedimentation behavior. Adequately flocculated slurries lead to homogeneous, soft granules that can be easily deformed and pressed. The fraction of donut-shaped particles and the rigidity of granules were reduced. Consequently, the sintered parts produced from these granulates show improvements regarding porosity, pore size distribution, sintered density and biaxial strength. KW - Slurry optimization KW - Optical centrifugation KW - Destabilization KW - Spray drying KW - Biaxial strength PY - 2018 DO - https://doi.org/10.4416/JCST2018-00022 SN - 2190-9385 VL - 9 IS - 3 SP - 327 EP - 336 PB - Göller Verlag AN - OPUS4-46225 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kang, M. A1 - Czasny, M. A1 - Kober, D. A1 - Reschetnikow, A. A1 - Stargardt, Patrick A1 - Mieller, Björn A1 - Gurlo, A. T1 - Influence of mica particle content in composites for high voltage applications produced by additive manufacturing and mold casting N2 - The insulation system of high voltage electrical devices like generators and electrical motors has to withstand thermal, electrical, ambient and mechanical influences (TEAM) during operation. Especially the dielectric properties have to satisfy the requirements also under elevated temperatures and extreme environments. To provide this high quality, the conventional fabrication process uses partly manually applied insulation tapes combined with a cost-intensive and under safety concerns at least problematic vacuum pressure impregnation step (VPI). In order to reduce process costs by increasing the degree of automation and avoiding the VPI process, additively manufactured (AM) insulations were studied. This study focuses on the fabrication of ceramic/polymer compounds via AM technique. The AM technology used a rotating screw extrusion print head with air pressure to supply the paste. Plate-like samples with dimensions of 55 mm x 55 mm x1mm thickness were produced. This work focuses on the homogeneously high viscous paste with 12.5 to 50 volume % ratio of filler particles. Three types of mica powders as ceramic filler materials with different particle sizes from micro to mm scale were evaluated. The controlled volume % ratio of particles affects the paste viscosity which enables stacking of paste layers with a viscosity close to clay pastes. The mixed pastes were cured by heating and UV light to increase mechanical properties. A TG/DTA was performed, and electrical properties were investigated. First experiments with respect to the dielectric properties such as volume resistance, permittivity and dielectric strength revealed promising results and the possibility to use AM techniques for the fabrication of high voltage insulations for electrical machines. T2 - MaterialsWeek 2021 CY - Online meeting DA - 07.09.2021 KW - HV-Insulation KW - Polymer-Ceramic-Composite KW - Additive manufacturing PY - 2021 AN - OPUS4-54368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Schulz, Bärbel A1 - Rabe, Torsten T1 - Tailoring the spring constant of ceramic helical compression springs N2 - Ceramic springs combine attractive properties for applications in machinery, metrology, and sensor technology. They are electrically insulating, non-magnetic, provide a linear stress-strain behavior, and are stable at high temperatures and in corrosive environments. Generally, the precise dimensioning of a ceramic spring with respect to the spring constant is challenging. Different models are described, but many of these calculations do not match the actual spring properties. We demonstrate a reliable approach for the dimensioning and manufacturing of helical compression springs with a rectangular winding cross-section. Based on the German standard DIN 2090, which is referring to metallic springs, the spring constant can be calculated based on shear modulus, diameter, height, widths, and number of windings. Different ceramic springs were produced by milling of sintered hollow cylinders of zirconia, alumina and silicon nitride. The experimental spring constants are in very good agreement with the calculated values. Spring constants of zirconia springs were varied over three orders of magnitude between 0.02 N/mm and 5 N/mm by purposeful adaption of the spring geometry. The combination of dimensioning based on DIN 2090 and precise hard machining offers a reliable technology for the fabrication of tailored ceramic springs for special applications. T2 - 45th International Conference and Exhibition on Advanced Ceramics and Composites (ICACC 2021) CY - Online meeting DA - 08.02.2021 KW - Ceramics KW - Hard machining KW - Spring constant PY - 2021 AN - OPUS4-52136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Patrick A1 - Mieller, Björn A1 - Rabe, Torsten T1 - Small batch preparation of ready-to-press powder for systematic studies N2 - Efficient studies of scarce or expensive materials require material saving processes. Therefore, a high yield concept for small batch preparation of ready-to-press powder is exemplarily presented for yttria stabilized nano-zirconia (d50 < 50 nm). The concept involves small batch preparation in an ultrasound resonator, dispersant selection based on zeta potential measurements, evaluation of slurry stability using an analytical centrifuge, and preparation of ready-to-press powder by freeze drying. Freeze drying offers key advantages. Process efficiency and high yield above 95 % are independent of sample size. The dried product does not require further mechanical treatment like milling or grinding. Side effects like migration of additives are avoided. An optimized freeze drying process tolerates slurries with moderate stability. Thus, efforts for slurry development can be reduced. Generally, identifying a suitable dispersing agent requires only 3-5 zeta potential measurements. Slurry stability is rechecked using an analytical centrifuge, which also accounts for steric stabilization. An ultrasound resonator is used to disperse the powder without contamination, which becomes critical for small batches. The described route is exemplarily presented for the development of an additive recipe for nano-sized zirconia powder, targeting for good pressing behavior and high green density. Therefore, a variety of binding and lubricating agents were tested. Following the presented route, 80 g zirconia powder were sufficient to conduct a study including slurry development and five sample sets with varying composition, each set comprising five discs (d = 20 mm and h = 2 mm). T2 - 94. DKG Jahrestagung CY - Leoben, Austria DA - 05.05.2019 KW - Fine Powder KW - Slurry KW - Freeze Drying PY - 2019 AN - OPUS4-48293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Markötter, Henning A1 - Dayani, Shahabeddin A1 - Mishurova, Tatiana A1 - Eddah, Mustapha A1 - Mieller, Björn A1 - Böttcher, Nils A1 - Bruno, Giovanni T1 - Tomographic Imaging Capabilities with hard X-Rays at BAMline (Bessy II) N2 - The BAMline at the synchrotron X-ray source BESSY II (Berlin, Germany) is supporting researchers especially in materials science. As a non-destructive characterization method, synchrotron X-ray imaging, especially tomography with hard X-Rays, plays an important role in structural 3D characterization. The imaging capabilities allow for in-situ and operando experiments. In this presentation the equipment, data handling pipeline as well as various examples from material science are presented. T2 - Correlative Materials Characterization Workshop 2023 CY - Brno, Czech Republic DA - 09.11.2023 KW - Tomography KW - X-ray imaging KW - Li-ion battery PY - 2023 AN - OPUS4-58958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Electric field distribution on ceramic samples during dielectric strength testing N2 - The dielectric breakdown strength of ceramics strongly depends on the test conditions. Thus, standardized test procedures and thorough documentation are indispensable. However, during dielectric strength testing the breakdown often occurs near the electrode edge or even outside the specified electrode area. This behavior is similarly observed for printed and cylindrical electrodes. The aim of the presented study was to calculate the electric field strength distribution in a ball-on-plate testing setup for metallized samples and to correlate the field distribution with the observed breakdown locations. Small misalignments in the test setup were also considered in the simulations. Furthermore, the field strength at the breakdown Location should be compared to the experimentally determined dielectric strength. Therefore, Finite Element Models of several test conditions with varying printed electrode areas and sample thicknesses were created and electrostatic calculations of the electric field Distribution were performed. The simulation results were compared to experimental data. Alumina (96 %) was used as test material. The calculations show that the electric field strength maxima match the experimentally observed locations of breakdown. Without any fitting of the model, the maximum calculated field strength is in reasonable agreement with the experimental dielectric strength. The FE analysis is a helpful tool to understand the observations in experimental dielectric strength testing. T2 - CERAMICS 2021 / 96th DKG Annual Meeting CY - Online Meeting DA - 19.04.2021 KW - Dielectric breakdown KW - Dielectric strength KW - Electric field strength KW - Ceramics PY - 2021 AN - OPUS4-52512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Practical breakdown voltage calculations using dielectric breakdown strength reference values N2 - Dielectric breakdown is a catastrophic failure of ceramic substrates and insulators. The use of dielectric breakdown strength (DBS) reference values for the dimensioning of such components is not straightforward, as the DBS depends on sample thickness and electrode area. This fact also hampers a valid comparison of data taken from different literature sources. Based on the empirically confirmed proportionality of DBS to the reciprocal square root of sample thickness and an approach to account for the influence of electrode area on the failure probability, a practical equation is derived to calculate the breakdown voltage for arbitrary sample thickness and electrode area from one set of DBS reference data. To validate the equation, the AC DBS of commercial alumina substrates with thicknesses ranging from 0.3 mm to 1.0 mm was performed using different printed electrodes with varying areas. The breakdown voltages comprise a range from 18 kV for thick samples to 8.5 kV for thin samples, resulting in DBS values from 17 kV/mm for 1.0 mm thick samples to 29 kV/mm for 0.3 mm thin samples, all made from the same material. The influence of electrode area is comparatively smaller. The results calculated with the proposed equation are in reasonable accordance with the measured data. Thus, the equation can be applied for a proper comparison of literature DBS data measured in different setups and for a reasonable estimation of breakdown voltages in DBS tests and applications based on reference data. T2 - Electroceramics Conference XVII CY - Online meeting DA - 24.08.2020 KW - Ceramics KW - Dielectric breakdown KW - Weibull distribution PY - 2020 AN - OPUS4-51151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Junge, P. A1 - Greinacher, M. A1 - Kober, D. A1 - Mieller, Björn T1 - Bulk vs thermal sprayed alumina for insulation applications: A comparison of electrical and dielectrical properties N2 - Additive manufacturing (AM) processes are opening new design possibilities for large scale electrical devices such as power generators. Conventional manufacturing methods use copper rods which are wrapped, vacuum impregnated, bend and welded. These processes are labor-intensive and time-consuming. The introduction of AM methods for manufacturing the copper conductor and electrical insulation can reduce the size of the generator head, the most complex part of the generator. In this study, the electrical and dielectrical properties of additively deposited ceramic layers are investigated and compared with the properties of conventionally fabricated bulk ceramics. The ceramic layers are thermally deposited by atmospheric plasma spraying of a commercially available alumina powder. Bulk ceramics are fabricated by dry pressing and sintering of the same powder. Microstructure and porosity were analyzed by scanning electron microscopy (SEM). Electrical and dielectrical properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards. The microstructures of sprayed and sintered alumina show significant differences with respect to grain form and porosity. The density of the bulk ceramic is lower than the density of the sprayed layer due to the coarse particle size (d50 = 33 μm). Therefore, data from dense samples of the same chemical composition but lower particle size alumina powder were used for comparison. T2 - Keramik 2022 CY - Online meeting DA - 07.03.2022 KW - High Voltage Insulation KW - Thermal Spray KW - Dielectric Spectroscopy KW - Atmospheric Plasma Spraying PY - 2022 AN - OPUS4-54446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geyler, Paul A1 - Rabe, Torsten A1 - Mieller, Björn A1 - Léonard, Fabien T1 - Machine learning assisted evaluation of the shape of VIAs in a LTCC multilayer N2 - The introduction of the 5G technology and automotive radar applications moving into higher frequency ranges trigger further miniaturization of LTCC technology (low temperature co-fired ceramics). To assess dimensional tolerances of inner metal structures of an industrially produced LTCC multilayer, computer tomography (CT) scans were evaluated by machine learning segmentation. The tested multilayer consists of several layers of a glass ceramic substrate with low resistance silver-based vertical interconnect access (VIA). The VIAs are punched into the LTCC green tape and then filled with silver-based pastes before stacking and sintering. These geometries must abide by strict tolerance requirements to ensure the high frequency properties. This poster presents a method to extract shape and size specific data from these VIAs. For this purpose, 4 measurements, each containing 3 to 4 samples, were segmented using the trainable WEKA segmentation, a non-commercial machine learning tool. The dimensional stability of the VIA can be evaluated regarding the edge-displacement as well as the cross-sectional area. Deviation from the ideal tubular shape is best measured by aspect ratio of each individual layer. The herein described method allows for a fast and semi-automatic analysis of considerable amount of structural data. This data can then be quantified by shape descriptors to illustrate 3-dimensional information in a concise manner. Inter alia, a 45 % periodical change of cross-sectional area is demonstrated. T2 - DKG Jahrestagung 2019 CY - Leoben, Austria DA - 06.05.2019 KW - Machine Learning KW - LTCC multilayer KW - 5G PY - 2019 AN - OPUS4-48289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Bresch, Sophie A1 - Mieller, Björn A1 - Rabe, Torsten T1 - Analysis of reaction layers and cooling simulations of co-fired thermoelectric multilayers N2 - Ceramic multilayer technology is an attractive approach for the cost-effective fabrication of thermoelectric generators. Therefore, efforts are being made to co-sinter two promising thermoelectric oxides, namely calcium cobaltite and calcium manganate. In this study, calcium cobaltite, calcium manganate and release tapes were pressure assisted sintered. A major challenge here is the cracking of calcium manganate during cooling. A relationship between the properties of the release tape used in pressure-assisted sintering and the cracking behavior was observed experimentally. To understand the origin of failure, formed reaction layers in the multilayer were analyzed by EDX and grazing incident XRD. Based on this analysis, bulk samples were prepared, and thermal expansion and Young's modulus and were determined thereon, if they were not known from the literature. The biaxial strength of the thermoelectric oxides was determined by the ball on three ball method. The thermal stresses during cooling of different multilayer designs were estimated by finite element simulations. The stresses caused by the reaction layers turned out to be negligible. The FEM study indicated further, and a validation experiment proved, that the thickness of the release tape has the main effect on thermal stresses during cooling in single material. For best performance, the design of a thermoelectric multilayer generator needs to consider thermoelectric performance and thermal stresses during cooling. T2 - Virtual Conference on Thermoelectrics CY - Online meeting DA - 20.07.2021 KW - Ceramic multilayer KW - Cooling simulations KW - Thermal stress KW - Thermoelectric PY - 2021 AN - OPUS4-52994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Stargardt, Patrick A1 - Greinacher, M. T1 - Numerical study of electric field distribution in breakdown strength testing of ceramics N2 - Dielectric breakdown of insulators is a combined electrical, thermal, and mechanical failure. The exact breakdown mechanism in ceramics and the formulation of useful models are still subject of investigation. Recent studies highlighted that several experimental aspects of dielectric breakdown strength testing affect the test results, and thus impede the recognition of fundamental principles. Excess field strength near the electrode can lead to premature breakdown in the insulating liquid. This would cause superficial damage to the test specimen and thus falsify the measurement results. The field strength distribution is influenced by the ratio of permittivity of the sample and the surrounding insulating liquid. Premature breakdown depends on the breakdown strength of the liquid and the actual test voltage. The test voltage again depends on the specimen thickness. To systematically investigate these relations, a numerical simulation study (FEM) of the electric field distribution in a typical testing rig with cylindrical electrodes was performed. The permittivity of the sample and the insulating liquid was parameterized, as well as the sample thickness. The electric field distribution was calculated for increasing test voltage. Field strength maxima are compared to experimental breakdown strength of typical insulating liquids and experimental breakdown locations on alumina. Strategies are discussed to adjust the insulation liquid and the sample thickness to reduce the influence of the testing setup on the dielectric breakdown strength results. T2 - Ceramics in Europe 2022 CY - Krakow, Poland DA - 10.07.2022 KW - Ceramics KW - Dielectric breakdown strength KW - Electric field distribution KW - Alumina PY - 2022 AN - OPUS4-55325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Bestimmung der elektrischen Durchschlagfestigkeit keramischer Werkstoffe - Einfluss von Messverfahren und -umgebung N2 - Als elektrische Durchschlagfestigkeit bezeichnet man die elektrische Feldstärke, bei der es zur Entladung durch ein isolierendes Medium kommt. Im Falle von Festkörpern ist dies ein zerstörender Prozess. Bei der messtechnischen Bestimmung der Durchschlagfestigkeit haben neben den verwendeten Messgeräten auch die eingesetzten Elektroden, die Form des Prüfkörpers und das Isoliermedium, in dem die Prüfung stattfindet, einen signifikanten Einfluss auf die ermittelten Messwerte. Im Vortrag werden die Einflüsse erläutert und anhand von Messreihen aus der Literatur und der eigenen Forschung quantifiziert. Aufgrund der vorgestellten Effekte wird klar, dass es sich bei elektrischer Durchschlagfestigkeit nicht um absolute Materialkennwerte handelt, sondern vielmehr um systemabhängige Größen. T2 - 7. Sitzung des Fachausschusses 6 - Material- und Prozessdiagnostik der Deutschen Keramischen Gesellschaft (DKG) CY - Online meeting DA - 16.02.2023 KW - Keramik KW - Hochspannungsprüfung KW - Durchschlagfestigkeit PY - 2023 AN - OPUS4-57015 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Electrode area dependence of dielectric breakdown strength N2 - Dielectric breakdown of ceramics is widely believed to originate from microstructural defects. Still, there is no commonly accepted model for the origin and process of dielectric failure that covers all observed phenomena and dependencies. In analogy to mechanical strength, the Weibull distribution is commonly used to evaluate dielectric strength data. This works well for a given group of specimens with constant geometry. But unlike mechanical strength, dielectric strength scales with the inverse square root of sample thickness. This cannot be explained by the classic Weibull concept. The Griffith type energy release rate model of dielectric breakdown proposed by Schneider is based on space charge injection and conducting filaments from the sample surface. This model incorporates the distinct thickness dependence and the pronounced influence of surface defects. Based on this model and the classic Weibull probability of failure, Schneider’s group theoretically derived a probability of breakdown that predicts an increase of failure probability with increasing electrode area. In our study we tested this model with dielectric strength data measured on dense alumina samples using different electrode areas. Weibull modulus and characteristic dielectric strength (scale parameter) were determined for a set of measurements using small electrodes. These values were used to calculate the failure probability under large electrodes according to the model. The calculated data excellently fits the measured values. Thus, our experiments substantiate the assumptions made in the breakdown model and the significance of surface defects for dielectric failure. T2 - 94. DKG Jahrestagung CY - Leoben, Austria DA - 05.05.2019 KW - Dielectric strength KW - Breakdown strength KW - Ceramics PY - 2019 AN - OPUS4-48015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzer, Marco A1 - Waurischk, Tina A1 - George, Janine A1 - Maaß, Robert A1 - Müller, Ralf T1 - Glass fracture surface energy calculated from crystal structure and bond-energy data N2 - Enhancing the fracture toughness is still one of the major challenges in the field of oxide glasses. To screen different glass systems for promising candidates, a theoretical expression for the fracture surface energy, G, linked to the fracture toughness, KIc, is thus of interest. Extending our earlier work on nucleation and surface energies [1], we present a simple approach for predicting the fracture surface energy of oxide glasses, G using readily available crystallographic structure data and diatomic bond energies. The proposed method assumes that G of glass equals the surface fracture energy of the weakest fracture (cleavage) plane of the isochemical crystal. For non-isochemically crystallizing glasses, an average G is calculated from the weighed fracture energy data of the constitutional crystal phases according to Conradt [2]. Our predictions yield good agreement with the glass density- and chemical bond energy-based prediction model of Rouxel [3] and with experimentally obtained G values known at present. [1] C. Tielemann, S. Reinsch, R. Maass, J. Deubener, R. Müller, J. Non-Cryst. Solids 2022, 14, 100093 [2] R. Conradt, J. Non-Cryst. Solids 2004, 345-346, 16 [3] R., Tanguy, Scripta Materialia 2017, 109-13, 137 T2 - DPG Spring Meeting of the Condensed Matter Section CY - Dresden, Germany DA - 26.03.2023 KW - Fracture Toughness KW - Oxide Glasses KW - Surface Energy PY - 2023 AN - OPUS4-58414 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - 4th International Symposium on Negative Thermal Expansion and Related Materials (ISNTE-4) CY - Padua, Italy DA - 04.07.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Mieller, Björn ED - Kollenberg, W. T1 - Sintern N2 - Unter Sintern versteht man allgemein die Überführung eines aus Pulver geformten Rohlings in ein Formteil mit angestrebter Mikrostruktur bzw. gewünschten Gebrauchseigenschaften durch thermische Prozesse. In diesem Kapitel werden die Grundlagen zu Triebkräften und Kinetik sowie die prinzipiellen Mechanismen für Stofftransport und Verdichtung vorgestellt. Die verschiedenen Sintermechanismen Festphasensintern, Flüssigphasensintern und Reaktionssintern werden erläutert und mit einem Überblick über Drucksinterverfahren ergänzt. Abschließend wird ein Überblick über technologische Einflussfaktoren auf die Sinterung gegeben. KW - Technische Keramik KW - Sintermechanismen PY - 2018 SN - 978-3-8027-2986-7 SN - 978-3-8027-3081-8 SP - Kap. 4.6, 510 EP - 525 PB - Vulkan Verlag GmbH CY - Essen ET - 3 AN - OPUS4-43656 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, T. A1 - Reimann, T. A1 - Bochmann, A. A1 - Vogel, A. A1 - Capraro, B. A1 - Mieller, Björn A1 - Teichert, S. A1 - Töpfer, J. T1 - Sintering behavior, microstructure and thermoelectric properties of calcium cobaltite thickfilms for transversal thermoelectric multilayer generators N2 - The sintering behavior and the thermoelectric performance of Ca3Co4O9 multilayer laminates were studied, and a multilayer thermoelectric generator was fabricated. Compacts and multilayer samples with anisotropic microstructure and residual porosity were obtained after conventional sintering at 920 °C, whereas dense and isotropic multilayer samples were prepared by firing at 1200 °C and reoxidation at 900 °C. A hot-pressed sample has a dense and anisotropic microstructure. Samples sintered at 920 °C exhibit low electrical conductivity due to the low density, whereas the Seebeck coefficient is not sensitive to preparation conditions. However, thermal conductivity of multilayers is very low, and, hence acceptable ZT values are obtained. A ransversal multilayer thermoelectric generator (TMLTEG) was fabricated by stacking layers of Ca3Co4O9 green tapes, AgPd conductor printing, and co-firing at 920 °C. The TMLTEG has a power output of 3 mW at ΔT =200 K in the temperature interval of 25 °C to 300 °C. KW - Thermoelectric oxide KW - Calcium cobaltite KW - Pressure-assisted sintering KW - Multilayer PY - 2018 DO - https://doi.org/10.1016/j.jeurceramsoc.2017.11.017 SN - 0955-2219 SN - 1873-619X VL - 38 IS - 4 SP - 1600 EP - 1607 PB - Elsevier Ltd. AN - OPUS4-43983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Markötter, Henning T1 - Machine learning assisted characterization of a Low Temperature Co-fired Ceramic (LTCC) module measured by synchrotron computed tomography. N2 - The 5G technology promises real time data transmission for industrial processes, autonomous driving, virtual and augmented reality, E-health applications and many more. The Low Temperature Co-fired Ceramics (LTCC) technology is well suited for the manufacturing of microelectronic components for such applications. Still, improvement of the technology such as further miniaturization is required. This study focuses on the characterization of inner metallization of LTCC multilayer modules, especially on the vertical interconnect access (VIA). Critical considerations for this characterization are delamination, pore clustering in and at the edge of the VIA, deformation, and stacking offset. A LTCC multilayer consisting of a glassy crystalline matrix with silver based VIAs was investigated by synchrotron x-ray tomography (CT). The aim of this study is to propose a multitude of structural characteristic values to maximize the information gained from the available dataset. Data analysis has been done with the open source software ImageJ as well as several additional plugins. The high-resolution CT data was evaluated through 2D slices for accessibility reasons. The segmentation of all 2000 slices to assess the different regions e.g. pores, silver and glass ceramic was done by a supervised machine learning algorithm. A quantitative evaluation of shape, deformation, and porosity of the VIA with respect to its dimensions is presented and the suitability of the characterization approach is assessed. T2 - 54. Metallographie Tagung CY - Online meeting DA - 16.09.2020 KW - Machine Learning KW - LTCC KW - Synchrotron Tomography PY - 2020 AN - OPUS4-51299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Bresch, Sophie A1 - Marucha, P. A1 - Moos, R. A1 - Rabe, Torsten T1 - Sintering and interconnecting thermoelectric oxides for energy applications N2 - Today, more than 12% of the primary energy is lost in the form of waste heat. Thermoelectric generators (TEGs) can convert waste heat directly into electrical power by utilizing the Seebeck effect. The performance of such a generator is defined by a dimensionless figure of merit ZT of the thermoelectric pairs and the resistance R of the metallic contacts between these pairs. The figure of merit of thermoelectric oxides is considerably smaller compared to semiconductors. Still, thermoelectric oxides like calcium cobaltite (Ca3Co4O9) are attractive for applications at elevated temperatures in air. In contrast to the established π-type architecture of common TEGs, tape casting and multilayer technology may be applied for cost-effective manufacturing of oxide TEGs. Promising demonstrations of multilayer TEGs have been published in the last years. Still, the development of reliable and scalable manufacturing processes and proper material combinations is necessary. The aim of our project is to evaluate the feasibility of low temperature co-fired ceramics (LTCC) technology for a practical manufacturing of oxide multilayer TEGs of Ca3Co4O9 (p-type) and calcium manganate (CaMnO3, n-type). Ca3Co4O9 exhibits an undesired phase decomposition at 926 °C. Because of that, the application of sintering strategies and interconnect concepts well known from LTCC technology is a promising approach. We present results of pressure-assisted sintering of Ca3Co4O9 multilayer at 900 °C and axial pressures of up to 7.5 MPa. Ca3Co4O9 was produced by solid state reaction of CaCO3 and cobalt(II,III)oxide at 900 °C. Green tapes were prepared by a doctor-blade process, manually stacked and laminated by uniaxial thermocompression. Sintering was conducted in a LTCC sintering press between SiC setter plates. The thickness shrinkage was recorded by an in-situ technique. After sintering under 7.5 MPa, the microstructure of the single phase material shows a high density of 95 % and an advantageous alignment of the platelet grains. This results in good electrical conductivity and a comparatively high ZT of 0.018 at room temperature. However, the lowering of CaMnO3 sintering temperature from above 1200 °C to below 920 °C remains a challenge. To select a proper metal paste for interconnections of an oxide TEG, several pastes have been investigated regarding contact resistance of internal and external (soldered) connections in a preliminary study. Commercial pastes containing Ag, Au, Au/Pt, Ag/Pd, and Ag/Pd/Bi were manually applied and post-fired on sintered test bars of Ca3Co4O9 and CaMnO3 at 900 °C for 2 h. All tested pastes formed mechanically stable metallization after firing. For resistance measurement, 4-wire method and a custom-made probe head were used. The contacts on Ca3Co4O9 exhibit significantly (2-sample t-test, α = 5%) higher resistance compared to contacts on CaMnO3. Pure silver paste exhibits the lowest resistance for internal contacts on both materials, lower than 5 mΩ on CaMnO3. Ag/Pd/Bi paste resulted in conspicuously high variance of resistance. EDX analyses clarified an enrichment of Bi in the thermoelectric material near the interface and thereby the formation of an oxide layer with probably high electrical resistance. The thickness of that layer varies with the thickness of metallization. In conclusion, the use of Bi containing pastes is not advisable. Pure Ag paste shows the best results regarding resistance and solderability. T2 - CICMT 2018 CY - Aveiro, Portugal DA - 18.04.2018 KW - Thermoelectric oxide KW - Thermoelectric generator KW - Multilayer technology KW - Pressure-assisted sintering PY - 2018 AN - OPUS4-44740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn T1 - Evaluation of a multi-purpose measurement cell for standardized volume resistivity measurements at high temperatures N2 - The ProboStat is a multi-purpose measurement cell suitable for various electrical and physical measurements under different atmospheres and at high temperatures. Disc and bar shaped samples are sandwiched between platinum electrodes at the top of the tubular cell. The gas tight assembly can be inserted into a furnace. Different gases can be flushed through the tube. For this study, a ProboStat was adapted to measure volume resistivity of ceramic insulators at high temperatures according to standards. The standardized measurement of volume resistivity of ceramic insulators requires the consideration of many specifications including sample diameter, thickness, electrode design, and the proportion of these characteristics. Measurements are ideally performed in a state of dielectric equilibrium. The time-related slope of resistivity of a specific sample follows a power function. Thus, care must be taken when choosing a charge time or defining the duration of a measurement. As fringing of the guarded electrode occurs under high voltage, the effective electrode area for evaluation of the results should be corrected with respect to sample thickness and electrode design. The demands of effective standards on sample geometry and electrode design are stricter for room temperature measurements than for high temperature measurements. To perform high temperature measurements on ceramic samples that also fulfill the demands on room temperature measurements, a ProboStat was equipped with a dedicated large sample setup for discs with diameters of up to 60 mm. The volume resistivity of different alumina samples was first measured at room temperature in a standard test fixture and then compared to results obtained with the ProboStat. All measurements were performed for at least 100 min using a 26 mm guarded electrode. High temperature measurements at 500 °C were performed using the same samples. Room temperature values obtained with the standard test fixture are in the order of 10^17 Ohm·cm. The quantitative effect of electrode area correction is presented. Practical issues related to the use of the multi-purpose cell are addressed. These include electrode material selection, application of electrodes, and compensation of leakage currents. High temperature results of volume resistivity of the different alumina samples are presented. The validity is discussed with respect to the suitability of the multi-purpose cell for such measurements. T2 - XVI Conference and Exhibition of the European Ceramic Society (ECerS 2019) CY - Torino, Italy DA - 16.06.2019 KW - ceramics KW - alumina KW - volume resistivity PY - 2019 AN - OPUS4-48270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pavasarytė, Lina A1 - Azevedo do Nascimento, Allana A1 - Cysne Barbosa, Ana Paula A1 - Trappe, Volker A1 - Melo, Daniel T1 - Effects of particle size and particle concentration of poly (ethylene-co-methacrylic acid) on properties of epoxy resin N2 - Self-healing polymers have been developed to improve durability and reduce costs associated with maintenance during service. The addition of thermoplastics to thermosets to produce mendable polymers appears as a promising selfhealing technique. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was added to epoxy resin and the effects of EMAA addition on epoxy properties were evaluated. Specimens with two different contents of thermoplastic and particles sizes were manufactured. A two-level full factorial experimental design was used to evaluate the effect of particle size and particle content on properties of epoxy modified with addition of EMAA. Tensile tests and dynamic mechanical analysis (DMA) were used and the evaluated responses were tensile strength, modulus of elasticity, and glass transition temperature (Tg). X-ray computed tomography (XCT) was used to investigate particle size and concentration after manufacturing. It was found that the particle concentration has greater effects on stress–strain behavior of epoxy while Tg was not significantly affected by neither of the analyzed entrance variables. KW - Fracture KW - Self-healing KW - Epoxy KW - Thermoplastic PY - 2024 DO - https://doi.org/10.1002/app.55677 SN - 0021-8995 SP - 1 EP - 14 PB - Wiley online library AN - OPUS4-60205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Waurischk, Tina A1 - Müller, Ralf A1 - Arendt, F. A1 - Sierka, M. A1 - Diegeler, A. T1 - A new robot-assisted compositional screening method N2 - The system Na2O.B2O3-SiO2 (NBS) is the basis of many industrial glass applications and therefore one of the most studied systems at all. Glass formation is possible over a wide compositional range, but the system also contains ranges of pronounced phase separation and crystallization tendency. Despite its importance, experimental data are limited to few compositional areas. The general understanding and modelling of glass formation, phase separation, and crystallization in this system would therefore be easier if small step melt series could be studied. The efficient melting of such glass series is now possible with the new robotic glass melting system at the Federal Institute for Materials Research and Testing (BAM, Division Glasses). Using three exemplary joins within this NBS system, the small step changes of glass transition temperature (Tg), crystallization behavior as well as glass density (Roh) was studied. Additionally, experimental Tg and Roh data were compared with their modeled counterparts using SciGlass and a newly developed DFT model, respectively. T2 - Annual meeting of the French Union for Science and Glass Technology (USTV) and the 96th Annual Meeting of the German Society of Glass Technology - USTV-DGG joint meeting. CY - Orléans, France DA - 22.05.2023 KW - Robot-assisted galss melting KW - Sodiumborosilicate glasses KW - Density KW - Glass transformation temperature KW - Property simulation PY - 2023 AN - OPUS4-58724 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Schottner, G. A1 - Wondraczek, L. A1 - Sierka, M. A1 - Deubener, J. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Contreras, A. A1 - Diegeler, A. A1 - Kilo, M. A1 - Pan, Z.-W. A1 - Arendt, F. A1 - Chen, Y.-F. A1 - Gogula, S. A1 - Bornhöft, H. T1 - GlasDigital: Data-driven workflow for accelerated glass development N2 - Glasses stand out by their wide and continuously tunable chemical composition and large variety of unique shaping techniques making them a key component of modern high technologies. Glass development, however, is still often too cost-, time- and energy-intensive. The use of robotic melting systems embedded in an ontology-based digital environment is intended to overcome these problems in future. As part of the German research initiative MaterialDigital, the joint project GlasDigital takes first steps in this direction. The project consortium involves the Fraunhofer ISC in Würzburg, the Friedrich Schiller University Jena (OSIM), the Clausthal University of Technology (INW), and the Federal Institute for Materials Research and Testing (BAM, Division Glasses) and aims to combine all main basic components required for accelerated data driven glass development. For this purpose, a robotic high throughput glass melting system is equipped with novel inline sensors for process monitoring, machine learning (ML)-based, adaptive algorithms for process monitoring and optimization, novel tools for high throughput glass analysis and ML-based algorithms for glass design, including software tools for data mining as well as property and process modelling. The talk gives an overview how all these tools are interconnected and illustrates their usability with some examples. T2 - USTV-DGG joint meeting CY - Orleans, France DA - 22.05.2023 KW - Glass KW - Ontology KW - Data Space KW - Workflow KW - Robotic melting PY - 2023 AN - OPUS4-60372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bayerlein, Bernd A1 - Schilling, Markus A1 - Waitelonis, Jörg A1 - v. Hartrott, Phillip A1 - Hanke, Thomas A1 - Birkholz, Henk A1 - Lau, June A1 - Skrotzki, Birgit T1 - Adapting FAIR Practices in Materials Science: Digital Representation of Material-Specific Characterization Methods N2 - Age-hardenable aluminum alloys undergo precise heat treatments to yield nanometer-sized precipitates that increase their strength and durability by hindering the dislocation mobility. Tensile tests provide mechanical properties, while microstructure evaluation relies on transmission electron microscopy (TEM), specifically the use of dark-field TEM images for precise dimensional analysis of the precipitates. However, this manual process is time consuming, skill dependent, and prone to errors and reproducibility issues. Our primary goal is to digitally represent these processes while adhering to FAIR principles. Ontologies play a critical role in facilitating semantic annotation of (meta)data and form the basis for advanced data management. Publishing raw data, digital workflows, and ontologies ensures reproducibility. This work introduces innovative solutions to traditional bottlenecks and offers new perspectives on digitalization challenges in materials science. We support advanced data management by leveraging knowledge graphs and foster collaborative and open data ecosystems that potentially revolutionize materials research and discovery. T2 - TMS - Specialty Congress 2024 CY - Cleveland, Ohio, US DA - 16.06.2024 KW - FAIR KW - Research Data Management KW - Semantic Interoperability KW - Ontologies KW - Materials and Processes Data Reusability PY - 2024 AN - OPUS4-60375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Portella, P. A1 - Müller, Ralf T1 - The contribution of the Platform MaterialDigital (PMD) in building up a Materials Data Space - Application to glass design and manufacturing N2 - Suitable material solutions are of key importance in designing and producing components for engineering systems – either for functional or structural applications. Materials data are generated, transferred, and introduced at each step along the complete life cycle of a component. A reliable materials data space is therefore crucial in the digital transformation of an industrial branch. A great challenge in establishing a materials data space lies in the complexity and diversity of materials science and engineering. It must be able to handle data from different knowledge areas over several magnitudes of length scale. The Platform MaterialDigital (PMD) is expected to network a large number of repositories of materials data, allowing the direct contact of different stakeholders as materials producers, testing labs, designers and end users. Following the FAIR principles, it will promote the semantic interoperability across the frontiers of materials classes. In the frame of a large joint initiative, PMD works intensively together with currently near 20 research consortia in promoting this exchange (www.material-digital.de). In this presentation we will describe the status of our Platform MaterialDigital. We will also present in more detail the activities of GlasDigital, one of the joint projects mentioned above dealing with the digitalization of glass design and manufacturing. (https://www.bam.de/Content/EN/Projects/GlasDigital/glasdigital.html) T2 - OntoCommons Workshop CY - Berlin, Germany DA - 04.04.2023 KW - Ontology KW - Materials Data Space KW - PMD KW - Glass PY - 2023 AN - OPUS4-60371 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kilo, M. A1 - Contreras, A. A1 - Diegeler, A. A1 - Niebergall, R. A1 - Müller, Ralf A1 - Waurischk, Tina A1 - Reinsch, Stefan T1 - New Approaches for the Preparation and Characterisation of New Glasses N2 - The new robot-assisted glass melting device at BAM is presented by the manufacturing team within the joint project GlasDigital together with an automatic thermo-optical measurement technique. T2 - USTV-DGG joint meeting CY - Orleans, France DA - 22.05.2023 KW - Glass KW - Robotic melting PY - 2023 AN - OPUS4-60374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Diegeler, A. A1 - Schottner, G. A1 - Niebergall, R. A1 - Kilo, M. A1 - Arendt, F. A1 - Chen, Y.-F. A1 - Sierka, M. A1 - Limbach, R. A1 - Pan, Z. A1 - Wondraczek, L. A1 - Gogula, S. A1 - Bornhöft, H. A1 - Deubener, J. A1 - Waurischk, Tina A1 - Reinsch, Stefan T1 - GlassDigital: Digital Infrastructure for Data-Driven High-Throughput Glass Development N2 - Gläser zeichnen sich durch eine breite und kontinuierlich abstimmbare chemische Zusammensetzung sowie einzigartige Formgebungstechniken aus, was sie oft zur Schlüsselkomponente moderner Hochtechnologien macht. Die Glasentwicklung ist jedoch oft noch zu kosten-, zeit- und energieintensiv. Der Einsatz von robotergestützten Schmelzsystemen, eingebettet in eine Ontologie-basierte digitale Umgebung, soll diese Probleme in Zukunft überwinden. Im Rahmen der BMBF Forschungsinitiative MaterialDigital unternimmt das Verbundprojekt GlasDigital „Datengetriebener Workflow für die beschleunigte Entwicklung von Glas“ erste Schritte in diese Richtung. Das Projektkonsortium, an dem das Fraunhofer ISC in Würzburg, die Friedrich-Schiller-Universität Jena (OSIM), die Technische Universität Clausthal (INW) und die Bundesanstalt für Materialforschung und -prüfung (BAM, Fachgruppe Glas) beteiligt sind, will alle wesentlichen Basiskomponenten für eine beschleunigte datengetriebene Glasentwicklung zusammenführen. Zu diesem Zweck wird ein robotergestütztes Hochdurchsatz-Glasschmelzsystem mit neuartigen Inline-Sensoren zur Prozessüberwachung, auf maschinellem Lernen (ML) basierenden adaptiven Algorithmen zur Prozessüberwachung und -optimierung, neuartigen Werkzeugen für die Hochdurchsatz-Glasanalyse sowie ML-basierten Algorithmen zum Glasdesign, Data Mining sowie Eigenschafts- und Prozessmodellierung ausgestattet. Der Vortrag gibt einen Überblick darüber, wie all diese Komponenten miteinander verzahnt sind, und veranschaulicht ihre Nutzbarkeit anhand einiger Beispiele. T2 - HVG-Fortbildungskurs CY - Offenbach, Germany DA - 27.11.2023 KW - Glas KW - Ontology KW - Workflow KW - Simulation KW - Robotic melting PY - 2023 AN - OPUS4-60386 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Niebergall, R. A1 - Schottner, G. A1 - Wondraczek, L. A1 - Sierka, M. A1 - Deubener, J. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Contreras, A. A1 - Diegeler, A. A1 - Kilo, M. A1 - Puppe, F. A1 - Limbach, R. A1 - Pan, Z. A1 - Arendt, F. A1 - Chen, Y.-F. A1 - Gogula, S. A1 - Bornhöft, H. T1 - GlasDigital: Data-driven workflow for accelerated glass development N2 - lasses stand out by their wide and continuously tunable chemical composition and large variety of unique shaping techniques making them a key component of modern high technologies. Glass development, however, is still often too cost-, time- and energy-intensive. The use of robotic melting systems embedded in an ontology-based digital environment is intended to overcome these problems in future. As part of the German research initiative MaterialDigital, the joint project GlasDigital takes first steps in this direction. The project consortium involves the Fraunhofer ISC in Würzburg, the Friedrich Schiller University Jena (OSIM), the Clausthal University of Technology (INW), and the Federal Institute for Materials Research and Testing (BAM, Division Glasses) and aims to combine all main basic components required for accelerated data driven glass development. For this purpose, a robotic high throughput glass melting system is equipped with novel inline sensors for process monitoring, machine learning (ML)-based, adaptive algorithms for process monitoring and optimization, novel tools for high throughput glass analysis and ML-based algorithms for glass design, including software tools for data mining as well as property and process modelling. The talk gives an overview how all these tools are interconnected and illustrates their usability with some examples. T2 - HVG-DGG Fachausschuss I CY - Jena, Germany DA - 03.11.2023 KW - Glass KW - Robotic melting KW - Ontologie KW - Simulation KW - Workflow KW - Data Space PY - 2023 AN - OPUS4-60383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bayerlein, Bernd A1 - Schilling, Markus A1 - Birkholz, Henk T1 - Digital Transformation in Materials Science: Insights From the Platform MaterialDigital (PMD) N2 - The digital era has led to a significant increase in innovation in scientific research across diverse fields and sectors. Evolution of data-driven methodologies lead to a number of paradigm shifts how data, information, and knowledge is produced, understood, and analyzed. High profile paradigm shifts in the field of materials science (MS) include exploitative usage of computational tools, machine learning algorithms, and high-performance computing, which unlock novel avenues for investigating materials. In these presentations, we highlight prototype solutions developed in the context of the Platform MaterialDigital (PMD) project that addresses digitalization challenges. As part of the Material Digital Initiative, the PMD supports the establishment of a virtual materials data space and a systematic handling of hierarchical processes and materials data using a developed ontological framework as high priority work items. In particular, the mid-level ontology PMDco and its augmentation through application-specific ontologies are illustrated. As part of the conclusion, a discussion encompasses the evolutionary path of the ontological framework, taking into account standardization efforts and the integration of modern AI methodologies such as natural language processing (NLP). Moreover, demonstrators illustrated in these presentations highlight: The integration and interconnection of tools, such as digital workflows and ontologies, Semantic integration of diverse data as proof of concept for semantic interoperability, Improved reproducibility in image processing and analysis, and Seamless data acquisition pipelines supported by an ontological framework. In this context, concepts regarding the application of modern research data management tools, such as electronic laboratory notebooks (ELN) and laboratory information management systems (LIMS), are presented and elaborated on. Furthermore, the growing relevance of a standardized adoption of such technologies in the future landscape of digital initiatives is addressed. This is supposed to provide an additional basis for discussion with respect to possible collaborations. T2 - NIST Seminar on Digital Transformation CY - Gaithersburg, MD, USA DA - 11.06.2024 KW - Digital Transformation KW - Research Data Management KW - Ontology KW - Reusability KW - FAIR PY - 2024 AN - OPUS4-60381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bayerlein, Bernd A1 - Schilling, Markus A1 - Birkholz, Henk A1 - Jung, Matthias A1 - Waitelonis, Jörg A1 - Mädler, Lutz A1 - Sack, Harald T1 - PMD core ontology: Building Bridges at the Mid-Level – A Community Effort for Achieving Semantic Interoperability in Materials Science N2 - Knowledge representation in the materials science and engineering (MSE) domain is a vast and multi-faceted challenge: Overlap, ambiguity, and inconsistency in terminology are common. Invariant and variant knowledge are difficult to align cross-domain. Generic top-level semantic terminology often is too abstract, while MSE domain terminology often is too specific. This poster presents an approach to create and maintain a comprehensive and intuitive MSE-centric terminology by developing a mid-level ontology–the PMD core ontology (PMDco)–via MSE community-based curation procedures. The PMDco is designed in direct support of the FAIR principles to address immediate needs of the global experts community and their requirements. The illustrated findings show how the PMDco bridges semantic gaps between high-level, MSE-specific, and other science domain semantics, how the PMDco lowers development and integration thresholds, and how to fuel it from real-world data sources ranging from manually conducted experiments and simulations as well as continuously automated industrial applications. T2 - TMS - Specialty Congress 2024 CY - Cleveland, Ohio, US DA - 16.06.2024 KW - Interoperability KW - Semantic Interoperability KW - Digtial Representation KW - Knowledge graph and ontologies PY - 2024 AN - OPUS4-60378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus A1 - Bayerlein, Bernd A1 - Bruns, S. A1 - Birkholz, H. A1 - von Hartrott, P. A1 - Waitelonis, J. A1 - Lau, J. W. A1 - Skrotzki, Birgit T1 - Transforming Materials Science with ontologies, ELN, and LIMS: Semantic Web Solutions for Digitalization and Data Excellence N2 - Following the new paradigm of materials development, design and optimization, digitalization is the main goal in materials sciences (MS) which imposes a huge challenge. In this respect, the quality assurance of processes and output data as well as the interoperability between applications following FAIR (findability, accessibility, interoperability, reusability) principles are to be ensured. For storage, processing, and querying of data in contextualized form, Semantic Web Technologies (SWT) are used since they allow for machine-understandable and human-readable knowledge representations needed for data management, retrieval, and (re)use. The project ‘platform MaterialDigital’ (PMD) is part of an initiative that aims to bring together and support interested parties from both industrial and academic sectors in a sustainable manner in solving digitalization tasks and implementing digital solutions. Therefore, the establishment of a virtual material data space and the systematization of the handling of hierarchical, process-dependent material data are focused. Core points to be dealt with are the development of agreements on data structures and interfaces implemented in distinct software tools and to offer users specific added values in their projects. Furthermore, the platform contributes to a standardized description of data processing methods in materials research. In this respect, selected MSE methods are ontologically represented which are supposed to serve as best practice examples with respect to knowledge representation and the creation of knowledge graphs used for material data. Accordingly, this presentation shows the efforts taken within the PMD project to store data in accordance with a testing standard compliant ontological representation of a tensile test of metals at room temperature (ISO 6892-1:2019-11). This includes the path from developing an ontology in accordance with the respective standard up to connecting the ontology and data. The semantic connection of the ontology and data leads to interoperability and an enhanced ability of querying. For further enhanced reusability of data and knowledge from synthesis, production, and characterization of materials, the PMD core ontology (PMDco) was developed as mid-level ontology in the field of MSE. The semantic connection of the tensile test ontology (TTO) to the PMDco leads to enhanced expressivity and interoperability. Moreover, as a best practice example, generation and acquisition of test data semantically connected to the ontology (data mapping) was realized by applying an electronic laboratory notebook (ELN). Corresponding tensile tests were performed by materials science students at university. This enabled a fully digitally integrated experimental procedure that can be transferred to other test series and experiments. In addition to facilitating the acquisition, analysis, processing, and (re)usability of data, this also raises the awareness of students with respect to data structuring and semantic technologies in the sense of education and training. The entire data pipeline is further seamlessly integrable in a laboratory information management system (LIMS). More specifically, the integration of semantic conceptualization and knowledge graphs may become essential parts in LIMS as this would be very beneficial. Therefore, some first approaches of SWT integration in LIMS will also be presented briefly. T2 - TMS Specialty Congress 2024 CY - Cleveland, OH, USA DA - 16.06.2024 KW - Semantic Data KW - Plattform Material Digital KW - Tensile Test Ontology KW - Electronic Lab Notebook KW - Material Life Cycle PY - 2024 AN - OPUS4-60394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus A1 - Bayerlein, Bernd A1 - Birkholz, H. T1 - Digital Transformation in Materials Science: Insights from Platform MaterialDigital (PMD), Tensile Test Ontology (TTO), Electronic Lab Notebooks (ELN) N2 - The digital era has led to a significant increase in innovation in scientific research across diverse fields and sectors. Evolution of data-driven methodologies lead to a number of paradigm shifts how data, information, and knowledge is produced, understood, and analyzed. High profile paradigm shifts in the field of materials science (MS) include exploitative usage of computational tools, machine learning algorithms, and high-performance computing, which unlock novel avenues for investigating materials. In these presentations, we highlight prototype solutions developed in the context of the Platform MaterialDigital (PMD) project that addresses digitalization challenges. As part of the Material Digital Initiative, the PMD supports the establishment of a virtual materials data space and a systematic handling of hierarchical processes and materials data using a developed ontological framework as high priority work items. In particular, the mid-level ontology PMDco and its augmentation through application-specific ontologies are illustrated. As part of the conclusion, a discussion encompasses the evolutionary path of the ontological framework, taking into account standardization efforts and the integration of modern AI methodologies such as natural language processing (NLP). Moreover, demonstrators illustrated in these presentations highlight: The integration and interconnection of tools, such as digital workflows and ontologies, Semantic integration of diverse data as proof of concept for semantic interoperability, Improved reproducibility in image processing and analysis, and Seamless data acquisition pipelines supported by an ontological framework. In this context, concepts regarding the application of modern research data management tools, such as electronic laboratory notebooks (ELN) and laboratory information management systems (LIMS), are presented and elaborated on. Furthermore, the growing relevance of a standardized adoption of such technologies in the future landscape of digital initiatives is addressed. This is supposed to provide an additional basis for discussion with respect to possible collaborations. T2 - NIST Seminar Series CY - Gaithersburg, MD, USA DA - 11.06.2024 KW - Semantic Data KW - Plattform Material Digital KW - Digitalization KW - Data Interoperability KW - NIST KW - Tensile Test Ontology KW - Elctronic Lab Notebook PY - 2024 AN - OPUS4-60392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - INPR A1 - Pauw, Brian Richard A1 - Smales, Glen Jacob A1 - Anker, A. S. A1 - Balazs, D. M. A1 - Beyer, F. L. A1 - Bienert, Ralf A1 - Bouwman, W. G. A1 - Breßler, Ingo A1 - Breternitz, J. A1 - Brok, E. S. A1 - Bryant, G. A1 - Clulow, A. J. A1 - Crater, E. R. A1 - De Geuser, F. A1 - Giudice, A. D. A1 - Deumer, J. A1 - Disch, S. A1 - Dutt, S. A1 - Frank, K. A1 - Fratini, E. A1 - Gilbert, E. P. A1 - Hahn, Marc Benjamin A1 - Hallett, J. A1 - Hohenschutz, Max A1 - Hollamby, M. J. A1 - Huband, S. A1 - Ilavsky, J. A1 - Jochum, J. K. A1 - Juelsholt, M. A1 - Mansel, B. W. A1 - Penttilä, P. A1 - Pittkowski, R. K. A1 - Portale, G. A1 - Pozzo, L. D. A1 - Ricardo de Abreu Furtado Garcia, P. A1 - Rochels, L. A1 - Rosalie, Julian M. A1 - Saloga, P. E. J. A1 - Seibt, S. A1 - Smith, A. J. A1 - Smith, G. N. A1 - Annadurai, V. A1 - Spiering, G. A. A1 - Stawski, Tomasz A1 - Taché, O. A1 - Thünemann, Andreas A1 - Toth, K. A1 - Whitten, A. E. A1 - Wuttke, J. T1 - The human factor - Results of a small-angle scattering data analysis round robin N2 - A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5 % and half of the population width entries within 40 %, respectively. Due to the added complexity of the structure factor, much fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44 % and 86 % respectively. This Round Robin experiment highlights several causes for the discrepancies, for which solutions are proposed. KW - Round robin KW - Sall-angle scattering KW - Nanostructure quantification KW - Nanostructure KW - SAXS KW - MOUSE KW - X-ray scattering KW - Size distribution KW - Nanoparticles PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571342 DO - https://doi.org/10.48550/arXiv.2303.03772 SP - 1 EP - 23 PB - Cornell University CY - Ithaca, NY AN - OPUS4-57134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauw, Brian Richard A1 - Smales, Glen Jacob A1 - Anker, A. S. A1 - Annadurai, V. A1 - Balazs, D. M. A1 - Bienert, Ralf A1 - Bouwman, W. G. A1 - Breßler, Ingo A1 - Breternitz, J. A1 - Brok, E. S. A1 - Bryant, G. A1 - Clulow, A. J. A1 - Crater, E. R. A1 - De Geuser, F. A1 - Del Giudice, A. A1 - Deumer, J. A1 - Disch, S. A1 - Dutt, S. A1 - Frank, K. A1 - Fratini, E. A1 - Garcia, P. R. A. F. A1 - Gilbert, E. P. A1 - Hahn, Marc Benjamin A1 - Hallett, J. A1 - Hohenschutz, M. A1 - Hollamby, M. A1 - Huband, S. A1 - Ilavsky, J. A1 - Jochum, J. K. A1 - Juelsholt, M. A1 - Mansel, B. W. A1 - Penttilä, P. A1 - Pittkowski, R. K. A1 - Portale, G. A1 - Pozzo, L. D. A1 - Rochels, L. A1 - Rosalie, Julian M. A1 - Saloga, Patrick E. J. A1 - Seibt, S. A1 - Smith, A. J. A1 - Smith, G. N. A1 - Spiering, G. A. A1 - Stawski, Tomasz M. A1 - Taché, O. A1 - Thünemann, Andreas A1 - Toth, K. A1 - Whitten, A. E. A1 - Wuttke, J. T1 - The human factor - Results of a small-angle scattering data analysis round robin N2 - A round-robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5% and half of the population width entries within 40%. Due to the added complexity of the structure factor, far fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44 and 86%, respectively. This round-robin experiment highlights several causes for the discrepancies, for which solutions are proposed. KW - Round Robin KW - Data analysis KW - Small-angle scattering KW - Nanomaterials KW - Interlaboratory comparability KW - Nanostructure quantification KW - Methodology KW - MOUSE PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-587091 DO - https://doi.org/10.1107/S1600576723008324 SN - 1600-5767 VL - 56 IS - 6 SP - 1618 EP - 1629 PB - Wiley-Blackwell CY - Oxford AN - OPUS4-58709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mieller, Björn A1 - Schulz, Bärbel A1 - Mrkwitschka, Paul A1 - Rabe, Torsten T1 - Influence of surface treatment on the strength of a dental zirconia for implants N2 - Roughening of zirconia dental implants is a common clinical practice to improve ingrowth behavior. It depends on the manufacturer of the implant at which stage of the manufacturing process and by which method the surface is roughened. Systematic studies on this topic are rarely found in the literature. Therefore, the influence of surface treatment on the strength of a dental zirconia was investigated as part of a research project on the development of ceramic implants. The material under test was a commercial zirconia consisting of a Y-TZP matrix and Ce-TZP inclusions in the sintered state. This material is characterized by a slightly higher fracture toughness and slightly reduced strength compared to typical 3Y-TZP. Sets of samples were sandblasted in the white-fired or sintered condition. The ball-on-three-ball-strength of these samples was measured and compared to the strength of as-fired samples and polished samples. The complete study was performed two times for validation of the results. It is found that the average strength of TZP ceramics differs by almost 500 MPa depending on the surface treatment. Conventionally sintered specimens with as-fired surface exhibit a strength of 880 MPa. Sandblasting in the white fired state reduces the strength to 690 MPa. Both polishing and sandblasting in the sintered condition result in an increase in strength to about 1180 MPa. Comparative microstructural investigations, roughness measurements and X-ray phase analyses were carried out to determine the causes of these huge differences in strength. These findings may challenge the practice of white body surface treatment and give reason for further investigations on other commercial dental TZP materials. T2 - 97th DKG Annual Meeting - CERAMICS 2022 CY - Online meeting DA - 07.03.2022 KW - Ceramics KW - Implants KW - Biaxial strength PY - 2022 AN - OPUS4-54453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -