WANG Tingting, MA Sanbao, LIN Xiaoli, ZHENG Kai, LENG Panpan, ZHU Yi, YAN Wen
(Wuhan University of Science and Technology, The State Key Laboratory of Refractories and Metallurgy, Wuhan 430081, Hubei, China)

Abstract: Four lightweight periclase-MA spinel refractories were fabricated using porous periclase-MA spinel ceramics as aggregates, 97 sintered magnesia, per-synthesized spinel (0wt%, 8.5wt.%, 16.3wt.%, and 26.5wt.% in mass, respectively), and corundum powder as matrices. The thermal shock resistances of lightweight periclase-MA spinel castables containing different spinel content were investigated using the cold thermal shock test. The elastic moduli were measured with an elastic modulus measuring instrument. The effects of spinel content on the microstructures and properties of lightweight periclase-MA spinel refractories were investigated through SEM, EDS and FactSage® software, etc. It is found that the mechanical properties of the castables were strongly affected by the microstructure of the aggregate/matrix interface and the phase composition of the matrices.With the increase of the spinel content, the median pore sizes of the matrices of castables gradually decreased, and the compressive strengths firstly increased and then decreased. Some microcracks existed in the interface between the spinel and the periclase phases because of the mismatch of their thermal expansion coefficients. Micropores and microcracks of the castables could absorb energies of crack propagation, and then prevented the crack propagation caused by thermal shock. With the spinel content increasing from 8.5wt.% to 26.5wt.%, the elastic modulus and the retention rate of the elastic modulus of the castables after thermal shock tests gradually increased. When the spinel content was 26.5wt.%, the castable had the highest thermal shock resistance.

Key words: lightweight periclase-MA spinel castable; spinel content; microstructure; property