Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-56439 Zeitschriftenartikel Junge, P.; Greinacher, M.; Kober, D.; Stargardt, Patrick; Rupprecht, C. Metastable Phase Formation, Microstructure, and Dielectric Properties in Plasma-Sprayed Alumina Ceramic Coatings The need for new solutions for electrical insulation is growing due to the increased electrification in numerous industrial sectors, opening the door for innovation. Plasma spraying is a fast and efficient way to deposit various ceramics as electrical insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed ceramics in the coating industry since it exhibits good dielectric properties, high hardness, and high melting point, while still being cost-effective. Various parameters (e.g., feedstock type, spray distance, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, and metastable phase formation. Consequently, these parameters need to be investigated to estimate the impact on the dielectric properties of plasma-sprayed alumina coatings. In this work, alumina coatings with different spray distances have been prepared via atmospheric plasma spray (APS) on copper substrates. The microstructure, porosity, and corresponding phase formation have been analyzed with optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Moreover, we present an in-depth analysis of the fundamental dielectric properties e.g., direct current (DC) resistance, breakdown strength, dielectric loss tangent, and permittivity. Our results show that decreasing spray distance reduces the resistivity from 6.31 × 109 Ωm (130 mm) to 6.33 × 108 Ωm (70 mm), while at the same time enhances the formation of the metastable δ-Al2O3 phase. Furthermore, space charge polarization is determined as the main polarization mechanism at low frequencies. Basel MDPI 2022 Coatings 12 1 15 urn:nbn:de:kobv:b43-564394 10.3390/coatings12121847 https://creativecommons.org/licenses/by/4.0/deed.de 2022-12-01 OPUS4-55821 Beitrag zu einem Tagungsband Junge, P.; Stargardt, Patrick; Kober, D.; Greinacher, M.; Rupprecht, C. Thermally Sprayed Al2O3 Ceramic Coatings for Electrical Insulation Applications Thermal spraying enables a fast and propelling way to additively deposit various ceramics as electric insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed materials in the coating industry since it exhibits good dielectric properties, high hardness, high melting point while still being cost-effective. Various parameters (e.g. feedstock type, plasma gas mixture, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, crystallinity, and degree of un-or molten particles. As a consequence, these parameters need to be investigated to estimate the impact on the electrical insulating properties of thermally sprayed alumina. This study focuses on the development of a novel electric insulation coating from Al2O3 feedstock powders deposited via atmospheric plasma spray (APS). The microstructure, porosity, and corresponding crystallographic phases have been analyzed with optical microscopy, XRD, and SEM images. To achieve an understanding of the parameters influencing the electrical insulation performance of the manufactured coatings, an in-depth analysis of the fundamental dielectric parameters e.g., DC resistance, breakdown strength, dielectric loss tangent, permittivity is presented. 2022 Proceedings of International Thermal Spray Conference and Exposition 2022 International Thermal Spray Conference and Exposition 2022 Vienna, Austria 04.05.2022 06.05.2022 1 8 2022-09-28 OPUS4-48861 Zeitschriftenartikel Gili, A.; Bischoff, B.; Simon, U.; Schmidt, Franziska; Kober, D.; Görke, O.; Bekheet, M.; Gurlo, A. Ceria-based dual-phase membranes for high-temperature Carbon dioxide separation: Effect of iron doping and pore generation with MgO template Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane's ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system. MDPI 2019 Membranes 9 9 108, 1 15 urn:nbn:de:kobv:b43-488612 10.3390/membranes9090108 https://creativecommons.org/licenses/by/4.0/deed.de 2019-09-05 OPUS4-47519 Zeitschriftenartikel Lüchtenborg, Jörg; Kober, D.; Weber, A. P.; Melcher, J.; Günster, Jens Textured dense zinc oxide layers for active noise canceling windows Dense ZnO films with a strong c-axis texture have been deposited on transparent conductive oxide glass, glass, and Si wafers, respectively, with a two-step pressureless wet chemical method using zinc acetate dihydrate as Zn-precursor. The crystallographic structure of the films has been studied with XRD and scanning electron microscopy. Optical measurements reveal a high transparency of the ZnO films with a thickness of up to 10 μm. This new cost-effective route for ZnO film deposition does not require expensive sophisticated equipment and is easily upscaled. Wiley American Ceramic Society 2019 Journal of the American Ceramic Society 102 3 988 996 10.1111/jace.15928 2019-03-12