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Towards interoperability: Digital representation of a material specific characterization method
(2023)
Certain metallic materials gain better mechanical properties through controlled heat treatments. In age-hardenable aluminum alloys, the strengthening mechanism is based on the controlled formation of nanometer sized precipitates, which hinder dislocation movement. Analysis of the microstructure and especially the precipitates by transmission electron microscopy allows identification of precipitate types and orientations. Dark-field imaging is often used to image the precipitates and quantify their relevant dimensions.
The present work aims at the digital representation of this material-specific characterization method. Instead of a time-consuming, manual image analysis, a digital approach is demonstrated. The integration of an exemplary digital workflow for quantitative precipitation analysis into a data pipeline concept is presented. Here ontologies enable linking of contextual information to the resulting output data in a triplestore. Publishing digital workflow and ontologies ensures the reproducibility of the data. The semantic structure enables data sharing and reuse for other applications and purposes, demonstrating interoperability.
Packaging containers for dangerous goods that include aggressive liquids require that any packaging material that is based on high-density polyethylene has a high degree of stability and durability. This work is focused on testing the environmental stress cracking of the high-density polyethylenes used for such containers in contact with crop protection formulations, in particular, two model liquids established in Germany as standardized test media representatives for crop protection formulations containing the various admixtures typical for such products. One of the liquids is water-based and contains mostly surface-active ingredients, while the other is solvent-based and includes some emulsifiers. Originally established for pin impression tests, these model liquids and their individual components were here used for the first time as environmental media in the Full Notch Creep Test, which addresses the resistance against environmental stress cracking. The Full Notch Creep Test was carried out on five high-density polyethylene types with both model liquids, and also on one selected material with its components. The evaluation was focused on the fracture surface structures, which were visualized by a scanning electron microscope and by optical in situ imaging of the notch opening. While the water-based model liquid and its surface-active individual components induced environmental stress cracking with the characteristic pattern for a craze-crack mechanism and so-called brittle fracture on the surface, the solvent-based model liquid and its soluble ingredients exhibited rather ductile failure behavior, caused by the plasticizing effect on the polymer that reduced the yield stress of the high-density polyethylene.
For both cases, fracture surface analysis, together with side views of the crack opening, showed a clear relation between surface pattern, notch deformation (e.g., by blunting), or crack opening due to crack growth with time to failure and the solubility of the liquids in high-density polyethylene.
This dataset consists of indentation data measured with a conospherical tip in a Hysitron-Bruker TI980 Nanoindenter on the surface of a <100> Silicon wafer and a polished cross-sectional cut of a Zr65Cu25Al10 bulk metallic glass.
It is associated with the following publication:
Birte Riechers, Catherine Ott, Saurabh Mohan Das, Christian H. Liebscher, Konrad Samwer, Peter M. Derlet and Robert Maass "On the elastic microstructure of bulk metallic glasses" Materials and Design xxx, (2023) 111929. https://doi.org/10.1016/j.matdes.2023.111929
All experimental information can be found in this paper and in the accompanying supplementary information.
This electronic version of the data was published on the "Zenodo Data repository" found at http://zenodo.org/deposit in the community "Bundesanstalt fuer Materialforschung und -pruefung (BAM)".
The authors have copyright to these data. You are welcome to use the data for further analysis, but are requested to cite the original publication whenever use is made of the data in publications, presentations, etc.
Any questions regarding the data can be addressed to birte.riechers@bam.de who would also appreciate a note if you find the data useful.
The elastic properties (Young's modulus, shear modulus) of austenitic stainless steel AISI 316L were investigated between room temperature and 900 °C in an additively manufactured variant (laser powder bed fusion, PBF‑LB/M) and from a conventional process route (hot rolled sheet). The moduli were determined using the dynamic resonance method. The data set includes information on processing parameters, heat treatments, grain size, specimen dimensions and weight, Young’s and shear modulus as well as their measurement uncertainty.
The dataset was generated in an accredited testing lab using calibrated measuring equipment. The calibrations meet the requirements of the test procedure and are metrologically traceable. The dataset was audited as BAM reference data.
The elastic properties (Young's modulus, shear modulus) of Ni-based alloy Inconel IN718 were investigated between room temperature and 800 °C in an additively manufactured variant (laser powder bed fusion, PBF‑LB/M) and from a conventional process route (hot rolled bar). The moduli were determined using the dynamic resonance method. The data set includes information on processing parameters, heat treatments, grain size, specimen dimensions and weight, Young’s and shear modulus as well as their measurement uncertainty.
The dataset was generated in an accredited testing lab using calibrated measuring equipment. The calibrations meet the requirements of the test procedure and are metrologically traceable. The dataset was audited as BAM reference data.
The elastic properties (Young's modulus, shear modulus) of titanium alloy Ti-6Al-4V were investigated between room temperature and 400 °C in an additively manufactured variant (laser-based directed energy deposition with powder as feedstock, DED-LB/M) and from a conventional process route (hot rolled bar). The moduli were determined using the dynamic resonance method. The data set includes information on processing parameters, heat treatments, microstructure, grain size, specimen dimensions and weight, Young’s and shear modulus as well as their measurement uncertainty.
The dataset was generated in an accredited testing lab using calibrated measuring equipment. The calibrations meet the requirements of the test procedure and are metrologically traceable. The dataset was audited as BAM reference data.
Oxide thermoelectric semiconducting materials like p-type calcium cobaltite Ca3Co4O9 are investigated as oxidation- and temperature-resistant thermoelectric materials for thermoelectric generators (TEGs). To realize TEGs in planar film technology, the powder aerosol deposition (PAD) method is emerging recently. PAD is a method to obtain dense ceramic films directly from the synthesized starting powders without a subsequent high temperature step.
In the present work, Ca3Co4O9 (CCO) powders are processed by PAD to ceramic films at room temperature. The thermoelectric properties of the films (film thickness 10 – 20 µm) are characterized from room temperature to 900°C. Additionally, the layer morphology and texture of the films will be investigated.
As result, the Seebeck coefficient of the CCO-PAD film is comparable to pressed and sintered CCO-bulk materials during the 1st heating cycle to 900°C. The morphology of the films after the thermal treatment shows strong aligned crystallites resulting in a strong texture of the films. The electrical conductivity increases strongly during the 1st heating cycle to 900°C and stays almost constant afterwards. Compared to CCO-bulks, the films provide higher electrical conductivity which could be explained by the oriented crystal growth in-plane direction of the film.
The relationship between thermoelectric properties and layer morphology as a function of thermal annealing parameters will be further investigated.
Self-healing agents have the potential to restore mechanical properties and extend service life of composite materials. Thermoplastic healing agents have been extensively investigated for this purpose in epoxy matrix composites due to their strong adhesion to epoxy and their ability to fill in microcracks. One of the most
investigated thermoplastic additives for this purpose is poly(ethylene-co-methacrylic acid) (EMAA). Despite the ability of thermoplastic healing agents to restore mechanical properties, it is important to assess how the addition of thermoplastic healing agents affect properties of the original epoxy material. In this work, EMAA was added to epoxy resin and the effect of the additive on fracture toughness of epoxy was evaluated. Results indicate that although added in low concentrations, EMAA can affect fracture toughness.
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.
Destructive and non-destructive 3D-characterization of inner metal structures in ceramic packages
(2023)
Ceramic multilayer packages provide successful solutions for manifold
applications in telecommunication, microsystem, and sensor technology. In such packages, three-dimensional circuitry is generated by combination of structured and metallized ceramic layers by means of tape casting and multilayer technology. During development and for quality assurance in manufacturing, characterization of integrity, deformation, and positioning of the inner metal features is necessary.
Visualization with high resolution and material contrast is needed.
Robot-assisted 3D-materialography is a useful technique to characterize such multimaterial structures. In that, many sections of the specimen are polished and imaged automatically. A three-dimensional representation of the structure is created by digital combination of the image stack. A quasi non-destructive approach is to perform X-ray computer tomography (CT) with different beam energies. The energies are chosen to achieve a good imaging of either the metal features, or the ceramic matrix of the structure. The combination of the respective tomograms results in a high contrast representation of the entire structure. Both methods were tested to characterize Ag and Ag/Pd conductors in a ceramic multilayer package. The results were compared in terms of information content, effort, and applicability of the methods.
The increasing importance of resource availability and closed-loop material cycles are driving materials research to reduce alloying content in conventional materials or even substitute them with more sustainable alternatives. Intermetallic iron aluminide alloys (FeAl) present a potential alternative. Many alloy concepts for improved high-temperature properties or ductility have already been successfully implemented in casting technologies on a laboratory scale. However, successful testing of FeAl alloys on an industrial scale was still pending at the beginning of the project.
Therefore, the aim of the project was to develop simulation based casting concepts for industrial casting processes using the base alloy Fe-26Al-4Mo-0.5Ti-1B and to narrow down process limits by means of hot cracking tests. Findings were transferred into practice-oriented guidelines for casting of iron aluminides, which is accessible to future applicants in SMEs. The focus was placed on centrifugal casting combined with investment casting or die casting. In addition to numerous design and casting process parameters, heat treatments and alloying additions (Al, Mo, B) were varied to determine the influence of alloying elements on castability, microstructure and mechanical properties. Data from microstructure analyses (microscopic imaging, determination of grain sizes as well as phase compositions and volume fractions, fractography), mechanical tests (hardness measurements, compression tests, ambient and high-temperature tensile tests, creep tests) as well as measurements of thermophysical properties could be generated on the base alloy. Correlations of materials data with process variables allowed conclusions to be drawn on strengthening mechanisms and ductility of the alloy and how they can be controlled in terms of processing and component design. Successful casting of highly complex components with thin wall thicknesses and optimised alloy compositions points out prospects for new fields of application.
3D printing or additive manufacturing in space is of great value for long-term human spaceflight missions and space stations, conveniently offering access to a ‘virtual warehouse’ of tools and spare parts on the push of a button. The process only needs one type of feedstock such as powder or filament and only as much material as the final part requires, giving it a huge weight benefit over traditional subtractive methods.
While 3D printers are already operational on the ISS since 2014, the utilized processes are only capable of manufacturing relatively low strength parts from polymers not suitable for many tools or critical components. To gain access to high quality metal prints, a modified Laser Powder Bed Fusion (LPBF) process was developed to stabilize the critical powder bed in microgravity through a gas flow [2]. This setup was able to generate a (miniature) steel wrench during parabolic flights, but a reliable layer deposition has raised challenges due to the combination of gas flow parameters with microgravity conditions. Furthermore, the quality and density of the powder bed, which is critical for the process, cannot be examined afterward on the ground. This is due to hyper gravity phases during the flight that are influencing the properties of the powder bed.
In this paper, the challenges of the layer deposition are revised, and the subsequent evolution of the recoating system explained. Later, the challenges of an in-situ quality control, evaluation, and quantification of the properties of the powder bed are examined. As a solution, a high-resolution line-scanner is proposed and its implementation int the compact LPBF system demonstrated. Its ability to measure common defects such as ridges in the deposited layer is shown in experiments at normal gravity. As an illustration, Figure 1 shows an extreme case of the formation of ridges.
The increasing importance of resource availability and closed-loop material cycles are driving materials research to reduce alloying content in conventional materials or even substitute them with more sustainable alternatives. Intermetallic iron aluminide alloys (FeAl) present a potential alternative. Many alloy concepts for improved high-temperature properties or ductility have already been successfully implemented in casting technologies on a laboratory scale. However, successful testing of FeAl alloys on an industrial scale was still pending at the beginning of the project.
Therefore, the aim of the project was to develop simulation-based casting concepts for industrial casting processes using the base alloy Fe-26Al-4Mo-0.5Ti-1B and to narrow down process limits by means of hot cracking tests. Findings were transferred into practice-oriented guidelines for casting of iron aluminides, which is accessible to future applicants in SMEs. The focus was placed on centrifugal casting combined with investment casting or die casting. In addition to numerous design and casting process parameters, heat treatments and alloying additions (Al, Mo, B) were varied to determine the influence of alloying elements on castability, microstructure and mechanical properties. Data from microstructure analyses (microscopic imaging, determination of grain sizes as well as phase compositions and volume fractions, fractography), mechanical tests (hardness measurements, compression tests, ambient and high-temperature tensile tests, creep tests) as well as measurements of thermophysical properties could be generated on the base alloy. Correlations of materials data with process variables allowed conclusions to be drawn on strengthening mechanisms and ductility of the alloy and how they can be controlled in terms of processing and component design. Successful casting of highly complex components with thin wall thicknesses and optimised alloy compositions points out prospects for new fields of application.
The aim of the task area Materials Data Infrastructure (TA-MDI) of the consortium Materials Science and Engineering (MatWerk) of National Research Data Infrastructure (NFDI) is to shape scientific datasets obtained through the Participant Projects (PPs) from a data management perspective conforming to the FAIR principles, making use of the FAIR Digital Object (FAIR DO) concept, including structured metadata and storage solutions. As an example, they apply PP18 (BAM) as a use case to demonstrate the proposed technical workflow.
Reference datasets in the MSE domain represent specific material properties, e.g., structural, mechanical, … characteristics. A reference dataset must fulfill high-quality standards, not only in precision of measurement but also in a comprehensive documentation of material, processing, and testing history (metadata). This Infrastructure Use Case (IUC) of the consortium Materials Science and Engineering (MatWerk) of National Research Data Infrastructure (NFDI) aims to develop, together with BAM and other Participant Projects (PP), a framework for generating reference material datasets using creep data of a single crystal Ni-based superalloy as a best practice example. In a community-driven process, we aim to encourage the discussion and establish a framework for identifying reference material datasets. In this poster presentation, we highlight our current vision and activities and intend to stimulate the discussion about the topic reference datasets and future collaborations and work.
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.
The KupferDigital project aims to develop digital methods, tools, and data space infrastructures for digitalizing the entire life cycle of copper materials. The mechanical testing process is one of the main chains of such life cycles which generates lots of important testing data about the mechanical properties of the materials and their related materials and testing metadata. To train the digitalization of the mechanical testing process, different kinds of copper alloys were provided for this project, and their mechanical properties were measured by typical methods like Brinell and Vickers hardness and tensile testing. The primary raw testing data as well as the secondary datasets of these tests are provided. The detailed materials specifications, the utilized mechanical testing methods, and provided datasets are described in the content file. The test data files of heterogeneous structures are processed by the KupferDigital digital tools to be converted to standardized machine-readable data files.
Due to their unique physico-chemical properties, nanoparticles are well established in research and industrial applications. A reliable characterization of their size, shape, and size distribution is not only mandatory to fully understand and exploit their potential and develop reproducible syntheses, but also to manage environmental and health risks related to their exposure and for regulatory requirements. To validate and standardize methods for the accurate and reliable particle size determination nanoscale reference materials (nanoRMs) are necessary. However, there is only a very small number of nanoRMs for particle size offered by key distributors such as the National Institute of Standards and Technology (NIST) and the Joint Research Centre (JRC) and, moreover, few provide certified values. In addition, these materials are currently restricted to polymers, silica, titanium dioxide, gold and silver, which have a spherical shape except for titania nanorods. To expand this list with other relevant nanomaterials of different shapes and elemental composition, that can be used for more than one sizing technique, we are currently building up a platform of novel nanoRMs relying on iron oxide nanoparticles of different shape, size and surface chemistry. Iron oxide was chosen as a core material because of its relevance for the material and life sciences.
A new patented dynamic mechanical analysis (DMA) is presented, where the tensile, bending- or torsional stiffness of a media can be characterized in-situ during the phase transition from liquid to solid. An epoxy system, e.g. Hexion L285/H287, is filled into an elastomer container, such as a silicone tube. This can be mounted into a conventional OMA and, based on a linear viscoelastic approach, the storage modulus (E';G'), the loss modulus (E'';G'') and the loss angle tan(δ) can be measured at constant temperature as a function of time in order to investigate the liquid to sol-gel to solid transition. With this new method, the stiffness increase as a result of the cure process can be directly measured more precisely than with a rheometer in a shear plate set-up, because using an elastomer container gives a defined cross section for calculating the Young's modulus.
Lithium-ion batteries (LIBs) are one technology to overcome the challenges of climate and energy crisis. They are widely used in electric vehicles, consumer electronics, or as storage for renewable energy sources. However, despite innovations in batteries' components like cathode and anode materials, separators, and electrolytes, the aging mechanism related to metallic aluminum current collector degradation causes a significant drop in their performance and prevents the durable use of LIBs.[1] Glow-discharge optical emission spectroscopy (GD-OES) is a powerful method for depth-profiling of batteries' electrode materials. This work investigates aging-induced aluminum deposition on commercial lithium cobalt oxide (LCO) batteries' cathodes. The results illustrate the depth-resolved elemental distribution from the cathode surface to the current collector. An accumulation of aluminum is found on the cathode surface by GD-OES, consistent with results from energy-dispersive X-ray spectroscopy (EDX) combined with focused ion beam (FIB) cutting. In comparison to FIB-EDX, GD-OES allows a fast and manageable depth-profiling. Results from different positions on an aged cathode indicate an inhomogeneous aluminum film growth on the surface. The conclusions from these experiments can lead to a better understanding of the degradation of the aluminum current collector, thus leading to higher lifetimes of LIBs.