轻质氧化镁含量对方镁石-镁铝尖晶石砖性能的影响

Effect of Lightweight Magnesia Content on Properties of Periclase-Magnesium-Aluminate Spinel Bricks

以不同粒径的烧结镁砂、电熔镁铝尖晶石、镁铝尖晶石空心球为起始原料,采用固相烧结法制备了方镁石-镁铝尖晶石砖。通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)表征试样的物相组成和微观结构,利用阿基米德排水法测试试样的体积密度和显气孔率,研究轻质氧化镁含量和烧结温度对方镁石-镁铝尖晶石砖性能的影响。结果表明,随轻质氧化镁含量的增加,方镁石-镁铝尖晶石砖显气孔率呈增加趋势,而体积密度变化不明显,试样表现出优异的力学性能。当轻质氧化镁含量为25%(质量分数)时,方镁石-镁铝尖晶石砖的抗折强度最大为9.56 MPa,热导率最低为1.92 W·m^(-1)·K^(-1)。显微结构表明骨料和基质结合良好,并能形成微孔状通道。利用其特殊的微孔结构,提高了试样的力学性能和耐腐蚀性,进一步保护方镁石-镁铝尖晶石砖免受碱侵蚀。

Periclase-magnesium-aluminate spinel bricks were fabricated by solid-state sintering method using sintered magnesia,fused magnesia-aluminate spinel and magnesium-aluminate spinel hollow spheres with different particle sizes as raw materials.The phase composition of samples was examined by X-ray diffractometer(XRD),the microstructure of samples was characterized by scanning electron microscopy(SEM),and the bulk density and apparent porosity of samples were measured according to the Archimedes principle method.The effects of lightweight magnesia content and sintering temperature on the properties of periclase-magnesium-aluminate spinel bricks were investigated.The results show that with the increase of lightweight magnesia content,the apparent porosity of periclase-magnesium-aluminate spinel bricks increases,and the bulk density has little change,so it has good mechanical properties.When the lightweight magnesia mass fraction is 25%,the maximum flexural strength of periclase-magnesium-aluminate spinel bricks is 9.56 MPa,and the lowest thermal conductivity is 1.92 W·m^(-1)·K^(-1).The microstructure shows that the aggregate and matrix are well combined and formed microporous channels.Periclase-magnesium-aluminate spinel bricks have good mechanical properties and alkali corrosion resistance because of their unique microporous structure,which further protect samples from alkali corrosion.