LAUSR

Abstract Castables have been widely used in repairing furnace linings owing to their numerous verified benefits. Al2O3 coated Al powders (ACAPs) were prepared to prevent their hydration during castable preparing. The effect of ACAPs on the properties of cement-bonded Al2O3–SiO2 refractory castables under simulated coke drying quenching (CDQ) conditions was investigated. The results show AlN plate in situ formed at 800 °C and grew into whiskers and fibers at 1000 °C because metal Al melted and expanded which resulted to the cracks of Al2O3 shell, Al liquid flew out and directly reacted with N2. The strength and thermal shock resistance of castable samples were greatly improved by adding ACAPs while keeping minor expansion. The toughness of castables was greatly enhanced after fired at 1000 °C owe to AlN whiskers and fibers in situ synthesized in the castable matrix. The optimum amount of ACAPs is 9 wt % which provides higher strength and excellent toughness.