LI Shaofeng

(Ningbo Donglian Seals Co., LTD., Ningbo 315191, Zhejiang, China)

Abstract: Silicon carbide ceramic composites were prepared by using hot pressing sintering. Phase composition and microstructure of the ceramics were characterized by using X-ray diffractometer (XRD) and scanning electron microscopy (SEM)respectively. Mechanical properties and oxidation mechanism of the sintered bodies were studied. The mechanical strength was enhanced gradually with increasing content of TiC. Optimal mechanical properties were achieved in the composite with 9 wt.%,with a fracture toughness of 5.07 MPa.m^1/2, a bending strength of 552 MPa and relative density of 99.3%. The toughening mechanism is mainly crack deflection and pinning effect, because the TiC particles are dispersed in the SiC matrix. A relatively compact protective oxide-layer was formed on surface of the ceramics, which protected the matrix under the condition of static oxidation in air at 1200 ℃ for 2 h.

Key words: silicon carbide; titanium carbide; composites; hot pressing sintering; antioxidant behavior