Fabrication of High Strength a-SiAION/BN Composition Ceramics by Hot Pressing

摘要

Dense Y~(3+)-dopted a-SiAION/BN composition ceramics were fabricated by hot pressing sintering at 1900 °C holding for 1 h, then flexural strength was investigated through three-point bending test at room and 1000 °C. The results show that h-BN contributes to the densification of the powder, but which has little affect on the key temperature region of sintering densification of α-SiAlON ceramics. When content of BN is lower, which don't affect on the phase transformation of α-SiAlON, but when content of BN is higher, besides of major phase α-SiAlON, a little of β-SiAlON were also formed. For the α-SiAlON/BN composite ceramics content of 20 wt.% h-BN, the higher flexural strength (room-temperature and 1000 °C) is obtained, the formation of β-SiAlON should be an important reason for the higher strength, more important is , whose flexural strength at 1000 °C was higher 50 MPa than at room temperature, the difference of thermal properties between SiAlON and BN should contribute to the improve of high-temperature flexural strength.