|About this Abstract
||2015 TMS Annual Meeting & Exhibition
||Novel Synthesis and Consolidation of Powder Materials
||Structure, Microstructure and Electrical Properties of ZnO Based Varistors Obtained by Spark Plasma Sintering
||Yannick Beynet, Sophie Guillemet-Fritsch, Vincent Bley, Thomas Pérel, Frederic Malpièce, Jonathan Morel, Claude Estournès
|On-Site Speaker (Planned)
Varistor ceramics were prepared by spark plasma sintering (SPS) using two doped zinc oxide powders. Firstly, the sintering cycle (870°C, 100 MPa) was optimized on a commercial powder to obtain dense parts (RD>99%) containing mainly ZnO grains (average size: 1μm with hexagonal structure) and additional Bi2O3 and Zn7Sb2O12 oxides. Secondly, to reduce the grains size, improve the dopants and the grains size distributions, zinc oxide powder with the same formulation was synthesised by coprecipitation. Due to the highly reactivity of such powder and the use non graphitic tools (ie WC-Co), fully dense parts were obtained under air atmosphere at a temperature as low as 400°C leading to limited ZnO grain growth (grain size ~ 0,3-0,6μm). We show that, for a given formulation, the electrical properties of the varistors greatly depend on the grain size and grain boundaries property variables induced by the microstructure of the powder and SPS sintering conditions.
||Planned: A print-only volume