The Effect Of Annealing Temperature On Micro-structure And Mechanical Properties Of C/sic Composites

摘要

In this paper, the rare-earth-oxide La_2O_3 combined with Al_2O_3 served as sintering additives and low-cost α-SiC powder were exploited successfully to prepare dense short carbon fiber reinforced SiC composites by hot-pressing (HP) sintering. The results of the experiments proved that the combination of Al_2O_3 and La_2O_3 sintering additives system was effective to promote densification of the hot-pressed C_f/SiC composites. The influence of the annealed temperature on the micro-structure and mechanical properties of the C_f/SiC composites was investigated in details. The proper annealed condition is favorable to improve the room temperature mechanical properties. The most interesting phenomenon was observed that silicon carbide nano-whisker structure was formed in the material which was annealed at 1750 ℃ for 1 h. It is undoubted that nano-whisker structure would promote fracture toughness. The combination of grain bridging, crack deflection and nano-fiber debonding can improve fracture toughness.