Consolidation induced microstructural inhomogeneities in Al2O3-ZrO2 composites prepared by centrifugal slip casting

Centrifugal slip casting was applied to the fabrication of an Al2O3-5 vol%ZrO2 (3Y-TZP) composite and the effect of solid contents in the slurry was investigated on various kinds of inhomogeneities and segregations. When a relatively thick slurry (40 or 45 vol%) was used, mutually hindered settling occurred quite effectively and thus essentially no segregations were observed in the distribution of grain sizes and the dispersion of the two phases. Even the zirconia aggregates contained in the starting powders were found distributed over the entire body of a sample. On the other hand, when a slurry of moderate thickness (30 vol%) was used, the Al2O3 and ZrO2 particles were still uniformly distributed but the zirconia aggregates were found accumulated in the thin layer of the bottom section. The results were discussed with a model calculation and shown to be in general agreement with the theoretical prediction.