The effect of mechanical activation on the microstructural properties of ZnO-Bi2O3-TiO2-Cr2O3 ceramic system

In the present study, effect was invetigated Cr2O3 on the microstructural and electrical properties of the ZnO-Bi2O3-TiO2 varistor system produced by mixing in aqueous media, one of the chemical methods, was investigated. ZnO, Bi2O3, TiO2 and Cr2O3 were added as starting chemicals. The chemicals mixed in the aqueous medium were dried at 1000 C for 1 day. Some of the dried powders were mechanically activated. It is ensured that powder sizes are smaller and more homogeneous in the mechanical activation process.The powders were pelletized. After pelletization, sintering was carried out at distinct sintering temperatures and sintering times. Diverse characterization analyzes were performed on the pellets obtained and their electrical properties were tested. In order to optimize the electrical properties of ZnO varistors, control of grain size and grain size distribution during production is very important.Microstructure control is necessary for practical application of all high-tech ceramics. ZnO grain size; many factors such as initial powder shape, additives, impurities, surface structure of starting powders and sintering conditions. For this reason, all these factors need to be well defined and controlled to control the microstructure.