Effect of Sintering Temperature on the Interfacial and Mechanical Properties of SiC Fiber Reinforced Mullite Matrix Composites

In the present work, SiC fiber reinforced mullite matrix composites (SiCf/Mu composite) were prepared through a sol-gel process. The effect of sintering temperature on the interfacial and mechanical properties of the SiCf/Mu composite was studied comprehensively and deeply. The experimental results indicated that the micro-mechanical properties of mullite matrix and fiber/matrix interface were closely related to the sintering temperature. When sintering temperature reached 800 and 1000 degrees C, the matrix was composed of the gamma-Al2O3 and amorphous SiO2. As the sintering temperature rise to 1200 degrees C, mullite phase was formed via the chemical reaction between gamma-Al2O3 and amorphous SiO2, leading to significantly increased Young's modulus and hardness of mullite matrix. It was also found that the interfacial shear strength was enhanced remarkably with sintering temperature due to the interfacial interaction between fiber and matrix. The interface controlled macro-mechanical properties of SiCf/Mu composites were sharply depressed at sintering temperature of 1000 degrees C, exhibiting a ductile-to-brittle fracture behavior transition.