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Journal of Ceramic Science and Technology 1/2020
Vol. 11, No. 1 · May 2020
Contacting Methods for C12A7 Electride Ceramic
K. Waetzig, A. Rost, J. Schilm, M. Tajmar, A. Michaelis
Pages 11-16 · DOI: 10.4416/JCST2019-00032
C12A7:e- ([Ca24Al28O64]4+4e-) ceramic is a material with high electrical conductivity and low work function, so that this ceramic is suitable as an electron-emitting material. Although the bulk material indicates these extraordinary properties, the surface of the ceramic is insulating. Therefore, a metallization film is needed to realize an electrical contact with low ohmic losses for the application of the material. In this study, we investigated three different metal pastes (Pt, Au and Cusil-ABA®) for contacting the surface and measured the reduction of the resistance during the firing proce …
Electric Field-Assisted Sintering of Gadolinium-Doped Ceria: Sintering and Grain Growth Kinetics
S. K. Sistla, T. Mishra, Y. Deng, A. Kaletsch, M. Bram, C. Broeckmann
Pages 17-26 · DOI: 10.4416/JCST2019-00045
The densification and grain growth kinetics during field-assisted sintering of gadolinium-doped (10 mol%) ceria (GDC10) were analyzed by conducting isothermal sintering experiments. The model parameters, namely, a stress exponent of ∼ 2 and apparent activation energy of ∼ 260 kJ/mol for the densification have been determined experimentally. Subsequently, the grain growth has been described by a power law with an exponent of 2 and an activation energy of ∼ 200 kJ/mol. Such values suggest that the dominating densification mechanism combines both diffusion and dislocation motion. A numerical mode …
Fabrication and Dielectric Properties of LiTaO3 Matrix Ceramics with Added Manganese Dioxide
Y. Yao, Y. Zhang
Pages 27-35 · DOI: 10.4416/JCST2019-00053
Polycrystalline LiTaO3 ceramics are beset with difficulties with regard to fabrication by means of conventional pressureless sintering because of their own refractory character. In this study, composite ceramics of LiTaO3 with added manganese dioxide were obtained by sintering at 1 250 °C. The sinterability, microstructure and dielectric properties of the LiTaO3 composite ceramics were then investigated. The relative densities of the LiTaO3 composite ceramics were significantly improved by the addition of MnO2 powder. The LiTaO3 composite ceramics achieved the highest relative density (93.1 %) …
(K0.5Na0.5)NbO3-Ba(Zn1/3Nb2/3)O3 Lead-Free Ceramics: Transmittance and Microstructure
Chenwei Li, Xin Xu, Zhenlin Lu
Pages 36-43 · DOI: 10.4416/JCST2019-00063
Lead-free transmittance electro-optic ceramics (1 –x)(K0.5Na0.5)NbO3-xBa(Zn1/3Nb2/3)O3 (x = 0.03, 0.05, 0.07, 0.08, 0.09 and 0.11) (KNN-BZN) were prepared with the solid-state reaction technique. The effects of Ba(Zn1/3Nb2/3)O3 dopant content on the microstructure, phase transition, optical property, and electrical properties were studied systematically. The X-ray-diffraction and Raman spectroscopy results indicated that for KNN-BZN ceramics with increasing BZN content, the crystal structure transforms from the orthorhombic phase into the pseudo-cubic phase and finally to the tetragonal phase. …
Circuit-Board-Integrated TransformersDesign and Manufacture
R. Matz, T. Rabe, J. Töpfer, S. Ziesche
Pages 44-61 · DOI: 10.4416/JCST2019-00071
Transformers couple two sections of a circuit by electromagnetic induction. They are widely used to either transform alternating voltage levels or to transmit power or signals across galvanic isolation. Both of these functions are essential for the operation of sensors and controllers. Covering all aspects from idea to circuit performance and from design to manufacture, this paper presents the first comprehensive description of the making of miniaturized, rugged, up-to-100 W transformers for embedding into multilayer circuit boards. For circular coils, the well-manageable Ampere-Laplace law is …
Preparation and Characterization of Reticulated Porous Mullite Coated with Radar-Absorbing Material
S. Lee, S. Lee, J.-H. Ha, J. Lee, I.-H. Song, B. Park, S. B. Lee, S.-H. Kwon
Pages 62-72 · DOI: 10.4416/JCST2019-00076
Porous ceramics have received much attention because they have excellent thermal and chemical properties. Among the porous ceramics, reticulated porous ceramics (RPCs) have been fabricated for many years. However, as far as the authors know, knowledge of the radar-absorbing properties of RPCs remains insufficient. The authors discussed the feasibility of RPCs, prepared using mullite, as a potential platform that could be coated with a radar-absorbing material (RAM). The results of the experiments in this study were used to determine (1) whether RAM-coated reticulated porous mullite (RPM) could …
Investigation of Chemically Modified ICIE16 Bioactive Glass, Part II
F.J. Hmood, F. Schmidt, O. Goerke, J. Günster
Pages 1-10 · DOI: 10.4416/JCST2019-00031
Chemically modified bioactive glasses based on ICIE16 were prepared with the melt-quenching method using water as a quenching medium. The sinterability of these bioactive glasses was investigated and is discussed in this article. The sintering experiments were conducted with different sintering temperatures, sintering times and heating rates. Those parameters are crucial for dense glass with an amorphous structure. The particle size (d50) of the starting glass powder was determined at 88 µm and kept constant. The pre-pressed glass pellets were cold-isostatically pressed at 300 MPa to a green d …
