Mechanical properties and oxidation resistance of Ti3SiC2/SiC composite synthesized by in situ displacement reaction of Si and TiC

Ti3SiC2/SiC composite has been synthesized by in situ displacement reaction of Si and TiC powders. Its relative density is >98%, Its Vickers hardness was measured to be 8.7 GPa. Its flexural strength and the fracture toughness were 505 MPa and 5.3 MPa.m(1/2) respectively. Scanning electron micrograph (SEM) and transmission electron micrograph (TEM) were used to observe the microstructure of the composite. Mechanisms for its high flexural strength and fracture toughness were discussed, respectively. The composite shows a better oxidation resistance than monolithic Ti3SiC2 at high temperatures. The oxidation layers were comprised of an outer layer with coarse TiO2 grains and an inner layer with a mixture of fine-grained SiO2 and TiO2. Its weight gain is only about 7.9 mg/cm(2) at 1200 degreesC in air for 21 h. However, that of Ti3SiC2 is 30 mg/cm(2). The results suggested that the in situ formation of SiC improved its oxidation resistance. (C) 2002 Elsevier Science B.V. All rights reserved.