IMPROVEMENT OF SiC-TiC COMPOSITES BY HOT ISOSTATIC PRESSING
She Jihong, Jiang Dongliang, Tan Shouhong, Guo Jingkun(Shanghai Institute of Ceramics,Academia Sinica,Shanghai 200050,China)
Hot-pressed SiC—TiC composites with different densities were hot isostatically pressed in N_2. The possibility of that open pores can be closed was analyzed theoretically and confirmed experimentally. Moreover, the effect of post-HIPping on physical and mechanical properties such as density, strength and fracture toughness was investigated. The results showed that SiC and TiC can be transformed respectively into Si_3N_4 and TiN under high pressure N_2 and high temperature. For the SiC—TiC composites with a density of about 95％ by presintering under hot-pressing condition and after nitridation by HIPping under 200MPa in N_2 at 1850℃ for 1 h,the room-temperature strength was increased from 345 MPa to 686 MPa,the fracture toughness was up to 7.9 MPa·m~(1/2)and the oxidation resistance was also obviously improved.