Increased high temperature strength and oxidation resistance of Al4SiC4 ceramics

Al4SiC4 bulk ceramics were synthesized by reaction hot-pressing using Al, graphite powders and polycarbosilane (PCS) as starting materials. The present work confirmed that this process was an effective method for the preparation of Al4SiC4 ceramics having high relative density and well-developed plate-like grains. The mechanical, thermal properties and oxidation behaviors of the Al4SiC4 ceramics were also investigated. The flexural strength, fracture toughness (KIC) and Vickers hardness at room temperature were 297.1 ± 22 MPa, 3.98 ± 0.05 MPa m1/2, 10.6 ± 1.8 GPa, respectively. The high-temperature bending strength showed an increasing trend with increasing test temperatures, with the value of 449.7 ± 26 MPa at 1300 °C. The thermal expansion coefficient was 6.2 × 10−6 °C−1 in the temperature range from 200 °C to 1450 °C. The isothermal oxidation of Al4SiC4 ceramics at 1200–1600 °C for 10–20 h revealed that it had excellent oxidation resistance.