Fabrication of CaAl₁₂O₁₉–CaTiO₃ composites and their potential usage for TiAl alloy smelting

CaAl₁₂O₁₉–CaTiO₃ (CA₆–CT) materials are fabricated using a solid sintering method to investigate the effects of TiO₂ content on the phase composition, properties, and microstructure of the materials. With increasing TiO₂ content, the preferential replacement of Al³⁺ by Ti⁴⁺ in the CA₆ crystal increases the concentration of vacancy defects, thereby promoting ion diffusion and mass transfer, which improves the sintering reaction activity. However, as more TiO₂ is added, the CaTiO₃ phase formed increases the thermal conductivity and mean expansion coefficient of the material at high temperatures, which degrades its thermal shock stability. The CA₆–CT refractory showed good corrosion resistance to the Ti₆Al₄V melt. Except for a slight penetration of iron element, no obvious corrosion occurred at the reaction interface.