첨가제 SiC의 함량과 열처리 방법에 따른 Al2O3 세라믹스의 강도특성

Abstract

In this study, crack healing effect and residual stress of Al2O3 ceramics were investigated by changing the sintering temperature and heat treatment conditions. It was also investigated that the influence of nano-sized SiC particle content and cyclic indentation-heat treatment on the crack healing behavior of Al2O3 ceramics. The strength of these samples were tested by three point bending method. The morphological changes were studied by FE-SEM and EDS. The test results indicated that the Al2O3 with nano-sized SiC sintered at 1800 ℃ were showed the highest density. In case of samples sintered at 1800 ℃, the bending strength of Al2O3 showed about 42% increment by heat treatment in air atmosphere than that of no heat treatment specimens. The cracked specimens can be also healed slightly by heat treatment in 1×10-4 torr of vacuum atmosphere. Al2O3 with 30 wt% of SiC have indicated higher crack healing ability than that of with 15 wt% of SiC. After cyclic process of indentation and heat treatment, the bending strength of Al2O3 ceramics with 15 wt% of SiC were decreased. However, Al2O3 ceramics with 30 wt% of SiC showed high bending strength in the cyclic indentation-heat treatment process. The FE-SEM images showed that the median cracks and pores were disappeared after heat treatment in air. Furthermore, fractured surface was changed roughly by cyclic indentation and heat treatment.