硅溶胶对莫来石结合刚玉质耐火材料力学性能的影响

EFFECT OF SILICA SOL ON MECHANICAL PROPERTIES OF MULLITE BONDED CORUNDUM REFRACTORY

以板状刚玉为骨料,莫来石为结合相,采用反应烧结工艺制备莫来石结合刚玉质耐火材料。以SiO2微粉作为合成莫来石的硅源,并尝试引入硅溶胶,以其部分取代SiO2微粉,旨在提高复相耐火材料的力学性能。结果表明:引入硅溶胶能促进莫来石合成,使显微结构更均匀致密,显著提高了材料强度和高温抗蠕变性。1550℃烧成时,以硅溶胶取代4%(质量分数,下同)SiO2微粉作硅源制备的样品比以SiO2微粉作硅源制备的样品,其常温和高温抗弯强度分别提高40.16%和29.92%;1650℃烧成时,前者比后者高温抗蠕变率降低71%。载荷-变形测试结果显示:莫来石结合刚玉质耐火材料常温断裂过程为渐进式,引入硅溶胶,在一定程度上提高了材料常温断裂韧性。

Mullite bonded corundum refractory was synthesized by the reaction sintering technique and using tabular corundum as the aggregate and mullite as the bonding phase, and silica powders and silica sol were used as the SiO2 sources. The results show that the microstructure and properties of the refractory prepared using silica sol to partially substitute for silica powders as the SiO2-containing raw material can be improved; for example, the formation of mullite is accelerated, the uniformity and density are enhanced, and the strength and the high temperature creep resistance are improved. Compared with the sample using silica powders as the raw material, the room temperature and high temperature flexural strengths of the sample sintered at 1 550℃ using silica sol to replace 4% （in mass） silica powders are 40.16% and 29.92% higher, respectively, and the high temperature creep rate of the sample is 71% lower for the sample sintered at 1 650 ℃. The load-flexivity curves of the samples show that the fracture behavior of mullite bonded corundum refractory at room temperature is gradual, and adding silica sol can improve the fracture toughness of the refractory.