Sintering of High Purity ZrSiO4 Powder

Abstract

By measuring shrinkage and bulk density of the specimens at 900°-1700°C, sintering of three kinds of high purity ZrSiO4 powders prepared from 0.2-0.8M ZrOCl2 and colloidal silica was studied. The flexural strength of their sintered bodies at room temperature to 1400°C was also evaluated to investigate the effect of sintering conditions. In the initial stage of sintering of high purity ZrSiO4 powders with an average particle size of 0.5μm, grain boundary diffusion was a dominant factor. The apparent activation energy for sintering in the initial stage was 81kJ/mol. On the other hand, when the average diameter of the particles is greater than 0.7μm, the bulk diffusion seemed to be overwhelming, and the apparent activation energy for sintering was higher than 130kJ/mol. In the intermediate and final stages of sintering, the powders with relatively large sizes have resulted in high bulk density. However, the strength of the specimen obtained using powders with large grain sizes was low since the grain growth proceeded significantly. The sintered bodies of high-purity ZrSiO4 with excellent flexural strength at high temperature were obtained by sintering the powder with the average particle size of less than 0.5μm up to more than 98% of theoretical density.