Synthesis of BaAl₂Si₂O₈ glass-ceramic by a sol-gel method and the fabrication of SiC_pl/ BaAl₂Si₂O₈ composites

BaAl₂Si₂O₈ glass ceramics were synthesized by sol-gel using partial alkoxides. The crystallization behavior of BaAl₂Si₂O₈ gel was characterized by XRD, DTA and TGA techniques. Barium aluminosilicate glass ceramic matrix composites reinforced with SiC platelets were fabricated by hot pressing method. The microstructure, mechanical properties and fracture behavior of the composites were investigated by X-ray diffraction, scanning and transimision electron microcopies, and three point bending tests. The results show that the flexural strength and the fracture toughness of the SiC_pl/BAS composites increases with increasing SiC platelet content. By incorporation of 30 vol.% SiC_pl, the flexural strength and the fracture toughness of the composites increase 80% and 114% compared to the pure BAS matrix, respectively. The main toughening mechanism is crack deflection.