关键词: Ti₃SiC₂-64vol%SiC复相陶瓷, 氧化机制, 扩散机理, 热等静压

Abstract: Full dense Ti₃SiC₂-64vol%SiC ceramics were successfully fabricated by in situ synthesis under hot isostatic pressing (HIP). The high temperature oxidation behaviors and mechanisms of the ceramics were studied by thermogravimetry tests (TG) at 1100-1450℃ in air. Testing results indicate the curves of isothermal kinetics of the ceramics obey parabolic oxidized law or paraboliclinear oxidized law. The addition of SiC (64vol%) efficiently improves the oxidation resistance of Ti₃SiC₂-SiC ceramics. According to XRD and SEM-EDS results, the oxidized layers are composed of an outer layer of TiO₂ (rutile) and SiO₂ (glass)，and a transition layer of mixture of TiO₂ and SiO₂. At high temperature (1400℃), the growth morphology of TiO₂ layer can be influenced by the formation of glassy SiO₂. The continuous and dense TiO₂ films which can efficiently prevent the diffusion of oxygen are formed. The parabolic rate constants decrease about one order of being oxidized at 1400℃ for long time compared with that oxidized at 1200℃. The oxidation resistance of Ti₃SiC₂-64vol% SiC ceramics at 1400℃ is better than that oxidized at 1200℃.

Key words: Ti₃SiC₂-64vol%SiC ceramics, oxidation mechanism, diffusion-control mechanism, hot isostatic pressing(HIP)