高强低导热莫来石-刚玉轻质砖的制备

以高铝矾土、硅灰、聚苯乙烯球作原料,用凝胶注模工艺制备高强轻质莫来石-刚玉材料,确定最佳pH值和分散剂用量,并研究了烧成后样品的强度、气孔率、热导率、物相组成和微观结构.结果表明:最佳pH值为9,分散剂加入量为0.33%,当球料比为4:1 (mL·g~(-1))时,1550 ℃烧结出的样品密度为0.37 g/cm~3,气孔率达87.37%,热导率仅0.22 W/(m·K),强度高达2.17 MPa;材料主晶相为莫来石,并含有少量刚玉相,晶粒细小,气孔分布均匀,孔壁薄而完整并有封闭小气孔.

Preparation of Lightweight Mullite-Corundum Materials with High-Strength and Low Thermal-Conductivity

Lightweight mullite-corundum materials were prepared by a gel-casting method, using bauxite, silica fume and polystyrene ball as starting materials. The effects of pH values and dispersant contents on the properties of slurry and the strength, porosity, thermal conductivity, phase composition and microstructure of the sintered materials were investigated. The results showed that the optimum pH value for slurry was 9, and the optimum dispersant content was 0.33%. The mullite-corundum materials sintered at 1550 ℃ were of good properties: bulk density of 0.37 g/cm~3, porosity of 87.37%, thermal conductivity of 0.22 W/(m·K) and strength of 2.17 MPa. The main crystal phase of the material is mullite, with a few corundum. The crystal size was small, vacancies were distributed uniformly, and some small closed vacancies were found in the thin hole walls.