A dense and fine-grained SiC/Ti_3Si(Al)C_2 composite and its high-temperature oxidation behavior

摘要

A dense SiC/Ti_3Si(Al)C_2 composite was synthesized by in situ hot pressing powders of Si, TiC and Al as a sintering additive at 1500 °C for 2h under 30 MPa in Ar atmosphere. This composite has a fine-grained and homogeneous microstructure with grain sizes of 5 ìm for Ti_3Si(Al)C_2 and of 1 ìm for SiC. The SiC/Ti_3Si(Al)C_2 composite possesses an improved oxidation resistance, with parabolic rate constants of 4.57 × 10~(-8) kg~2/m~4/s at 1200 °C and 1.31 × 10~(-7) kg~2/m~4/s at 1300 °C. This study provides an experimental evidence to confirm the formation of amorphous phases in the oxide scale of the SiC/Ti_3Si(Al)C_2 composite. Microstructure and phase composition of the SiC/Ti_3Si(Al)C_2 composite and oxide scales were identified by X-ray diffractometry and scanning electron microscopy. The mechanism for the enhanced oxidation resistance has been discussed.