Effect of the cooling ways on the properties and microstructure of ZrO₂/ZrW₂O₈ ceramic composites

ZrO₂ has been widely used due to its good physical and chemical properties and the ZrO₂/ZrW₂O₈ ceramic composites with adjustable thermal expansion coefficient can be prepared by mixing and sintering the ZrO₂ and ZrW₂O₈ powders. In this paper, the ZrO₂/ZrW₂O₈ ceramic composites have been prepared by mixing, cold isostatic pressing and atmospheric sintering, and then being cooled in air or in water. We focus on the effect of the cooling ways on the properties and microstructure of the ZrO₂/ZrW₂O₈ ceramic composites. The results show that the relative density of all samples is more than 98%. For the in-situ method, the density and flexural strength of the samples cooled in air and in water are 98.1% and 98.4%, 112.96MPa and 45.23MPa, respectively. The ZrW₂O₈ content and thermal expansion coefficient of the samples cooled in the air are less and higher than those in the water, respectively. For the direct mixture method, the density and flexural strength of the samples cooled in air and in water are 98.9% and 99.3%, 195.99MPa and 58.71MPa, respectively. For the four groups of the composite samples, they behave better mechanical properties after cooled in air, and lower thermal expansion coefficients after cooled in water.