尖晶石含量对轻量化方镁石-尖晶石浇注料显微结构和性能的影响

Inf luence of Spinel Content on the Microstructure and Properties of Lightweight Periclase-MA Spinel Refractory Castables

以多孔方镁石-尖晶石陶瓷为骨料,以97烧结镁砂、刚玉和70尖晶石等细粉为基质,通过改变浇注料中预合成尖晶石的质量分数(分别为0wt.%、8.5wt.%、16.3wt.%和26.5wt.%),制备了四组轻量化方镁石-尖晶石浇注料。采用急冷法测试样的抗热震性能,借助弹性模量测量仪检测试样热震前后的弹性模量,并使用SEM、EDS和Fact Sage?热化学软件研究了尖晶石含量对轻量化方镁石-尖晶石浇注料显微结构和性能的影响。研究发现:试样的力学性能受骨料/基质界面结构及基质的物相组成双重的影响,随着尖晶石含量增大,基质的中位孔径逐渐减小,耐压强度呈现先增大后减小的趋势;由于方镁石与尖晶石相的热膨胀系数差异使各物相间存在一些"微裂纹",此微裂纹和材料中微孔可以吸收裂纹扩展能,以阻碍裂纹的进一步扩展,当尖晶石含量由8.5wt.%增大到26.5wt.%时,热震试验后试样的弹性模量及弹性模量保持率均逐渐增大;当尖晶石含量为26.5wt.%时,轻量化方镁石-尖晶石浇注料热震后弹性模量保持率最高,抗热震性能最佳。

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 conmdtttn 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 microstruetures and properties of lightweight periclase-MA spinel refractories were investigated through SEM, EDS and FactSage~ soil-ware, 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.