骨料浸渍硅溶胶对矾土基耐火材料性能的影响

为了改善矾土基耐火材料的力学性能和抗热震性能,分别以SiO2含量(w)为15%和30%的硅溶胶对3~1 mm的矾土熟料粗颗粒进行浸渍处理,再与≤1 mm的矾土熟料颗粒、≤0.074 mm的矾土熟料细粉、α-Al2O3微粉、≤0.074 mm的红柱石细粉、≤0.074 mm的广西白泥、纸浆废液等经配料、成型、干燥、烧成(1400、1450和1500℃保温3 h),制得矾土基耐火材料,同时制备了使用未浸渍3~1 mm矾土熟料的空白试样。结果表明:1)随着烧成温度的升高,试样的常温抗折强度和常温耐压强度呈先升高后降低的变化趋势,其最佳烧成温度为1450℃。2)随着浸渍用硅溶胶浓度的提高,试样的烧后线变化增大,体积密度、常温抗折强度和常温耐压强度降低,高温抗折强度、荷重软化温度和抗热震性能提高,这是由骨料表面硅溶胶层中的SiO2与骨料及周围基质中的Al2O3反应生成了莫来石所致。3)当浸渍用硅溶胶中SiO2含量(w)为15%时,材料的综合性能最优。

Effect of silica sol impregnated aggregates on properties of bauxite-based refractories

This work aims at improving the mechanical properties and thermal shock resistance of bauxite-based refractories.Coarse bauxite clinker particles(3-1 mm)were impregnated in different silica sols(SiO2 contents of 15 mass%and 30 mass%).Then the impregnated coarse bauxite clinker particles,bauxite clinker particles(≤1 mm),bauxite clinker powder(≤0.074 mm),α-Al2O3 micropowder,andalusite(≤0.074 mm),Guangxi white clay(≤0.074 mm),and sulphite waste liquor were batched,shaped,dried and fired at different temperatures(1400,1450,and 1500℃ for 3 h)to prepare bauxite-based refractories.Meanwhile,blank specimens were prepared by the unimpregnated coarse bauxite clinker particles with the same route.The results show that:(1)the cold modulus of rupture and cold crushing strength of the specimens increase initially and then decrease with the rising temperature,and the optimum firing temperature is 1450℃;(2)with the increase of the SiO2 content in the impregnation silica sol,the linear change on heating of the specimens increases,but the bulk density,the cold modulus of rupture and the cold crushing strength of the specimens decrease,and the hot modulus of rupture,the refractoriness under load and the thermal shock resistance of specimens improve,which are caused by the reaction of SiO2 in the silica sol layer on the aggregate surface with Al2O3 in the surrounding aggregates and matrix to form mullite;(3)when the SiO2 content in the silica sol for impregnation is 15 mass%,the comprehensive properties of the material is optimum.