Structural, Fatigue Behavior, and Mechanical Properties of Zirconium Tungstate-Reinforced Casted A356 Aluminum Alloy

The aim of this study is to investigate the structure–property relationship of the zirconium tungstate-reinforced casted A356 aluminum alloy. The reinforcement ceramic used was zirconium tungstate of the negative thermal coefficient type, which assists in the weldment of crack growth and enhances the fatigue life. The specimens used in this study were casted by stir casting method and prepared according to Compact Tension standard E-399, and microstructural, fatigue behavior, and mechanical properties were investigated systematically. Microstructural analysis showed reduction in porosity by the addition of ZrW2O8 particles. Fatigue results depict the increase in the fatigue life of aluminum reinforced ceramic as compared to the casted base aluminum alloy. Brinell hardness of ZrW2O8 reinforced alloy samples increased 7% as compared to the base aluminum alloy hardness value. Tensile strength also significantly improved from 176 MPa for the base A356 alloy to 198 MPa for the ZrW2O8 reinforced composite. Furthermore, addition of ZrW2O8 ceramic powder increased the fatigue life more than 50% of the base alloy. These results suggest that the ZrW2O8 reinforced A356 composites may be potential candidates for aerospace industry, military, transportation and in structural sites.

High Temperature Stability of Zirconium Tungstate

In this paper, zirconium tungstate ceramic with negative thermal expansion coefficients was prepared from zirconium oxide and tungstic acid by solid phase synthesis and high temperature quenching technique with a sintering temperature of 1200 °C. The phase structure of the material was determined by X ray and the thermal expansion coefficient was measured by dilatometer, while the TG-DTA analysis of the prepared material was also carried out. The results showed that zirconium tungstate with high purity could be obtained by rapid chilled while fired at 1200 °C. The coefficient of thermal expansion at 300 °C was minus 8.5413 × 10-6K-1, which is identical with the theoretical value. The thermal expansion coefficient of the material was negative fired lower than 750 °C, while it was positive fired higher than 750 °C, and this indicates that the decomposition temperature of zirconium tungstate is about 750 °C.