Study on mechanical properties of hot pressing sintered mullite-ZrO2 composites with finite element method

In this study, mullite–zirconia (ZrO₂) composites were fabricated by hot pressing sintering method. The effects of sintering temperature and holding time on the microstructures, phase compositions and mechanical properties of the composites were investigated. The results indicated that the size of t-ZrO₂ grain varies with sintering temperature and holding time, and the maximum flexural strength of 674.05?MPa and fracture toughness of 12.08?MPam^1/2 are obtained when the sintering temperature is 1500?°C with holding times of 20 and 60?min, respectively. Finite element method was employed to analyze the relationship between grain size and mechanical properties of mullite–ZrO₂ composites for the first time. The results showed that the maximum stress on mullite–ZrO₂ interface increases with the growth of t-ZrO₂ grain size, which enhances the generation and propagation of cracks on grain boundaries significantly and degrades the flexural strength and fracture toughness of the mullite–ZrO₂ composite ceramics.