Processing of mullite–zirconia grains for slip cast ceramics

Dense composites were prepared by slip casting and sintering at 1600 °C from a commercially available mullite–zirconia powder which was finely ground in an attrition mill. Submicron alumina and a mixture of alumina and zircon were used as sintering aids. The effects of amount of dispersant and pH on colloid stability of diluted suspensions were determined to obtain the optimum conditions for suspension stabilization. The influence of powder composition and solid content on flow behavior of concentrated suspensions and on density of green cast were analyzed. Dried compacts achieved a relative density nearly to 60% theoretical density (TD) for fused zirconia mullite powder with and without 10 wt.% of sintering aids. Density, microstructure and crystalline phase content of sintered compacts such as were determined and analyzed in relation to the previous processing.