Synthesis mechanism and properties of lightweight mullite-corundum refractories obtained through high temperature liquid-assisted micrometer-scale Kirkendall effect

Abstract At high temperature, the lightweight mullite-corundum refractory was prepared by the micrometer-scale Kirkendall effect using quartz, bauxite, and corundum as the main raw materials. In this paper, the preparation mechanism of the mentioned effect has been discussed. The results prove that the silicon-rich phase produced during high-temperature firing forms mullite by reacting with the corundum powder in the matrix. Due to the diffusion of the silicon-rich liquid phase to the matrix and the dissolution of the Al2O3 to the silicon-rich liquid phase, the cristobalite continuously dissolves into the silicon-rich liquid phase and leaves holes in the original position, thereby meeting the needs of the mullitization. The lightweight mullite-corundum refractory with high compressive strength (85.0 MPa), high refractoriness under load (1636 °C), and low thermal conductivity (1.55 W (m K)−1) were obtained by controlling the quartz particle size, addition of content, and firing temperature.