Fabrication and cyclic oxidation behavior of Al₄SiC₄–SiC composite carbides on carbothermal reduction of kaolinite

Abstract

Al₄SiC₄–SiC composite carbides are expected as a high-temperature structural material because Al₄SiC₄ and SiC have high melting points. Synthesis, its densification and its oxidation behavior of Al₄SiC₄–SiC composite carbides have been investigated in this paper. Al₄SiC₄–SiC composite carbides were synthesized from the mixtures of Al₄C₃, C and kaolin powder by carbothermal reduction heating at 1550 °C for 12 h in vacuum. The dense sintered Al₄SiC₄–SiC composite carbide with above 97.6 % relative density is obtained by heating at 1700 °C for 1 h under 50 MPa by hot-pressing (HP). Oxidation of the sintered Al₄SiC₄–SiC composite carbides doesn’t almost progress even at 1500 °C, because of the formation of an oxide protective layer near the surface.