ZrW 2O 8/ZrO 2 composites by in situ synthesis of ZrO 2 + WO 3: Processing, coefficient of thermal expansion, and theoretical model prediction

Abstract

The in situ synthesis of WO 3 and ZrO 2 in a particular mass ratio enables us to produce ZrW 2O 8, a material with negative coefficient of thermal expansion (CTE). By increasing the proportion of ZrO 2, the products were made into a wide variety of ZrW 2O 8/ZrO 2 composites. The temperature dependences of the CTEs of those materials were measured and the experimental data were compared with the predictions from several models. The Levin model yielded the predictive values most close to the experimental CTEs. This was the first time the micromechanics models were applied to predict the CTEs of composite materials containing a negative thermal expansion material. A ZrW 2O 8/ZrO 2 composite with a designed CTE can be fabricated and utilized to meet a special thermal requirement in many industrial applications.