Micro-Porosity and Properties of Light-Weight Insulation Refractories Based on Calcined Flint Clay

ABSTRACTIn this study, light-weight insulation materials were prepared with calcined flint clay as the main material and sawdust was infused by sols as a pore forming agent. Micro-porosity and properties of the prepared insulation materials were investigated and were found to have better comprehensive properties. Apparent porosity, bulk density and cold crushing strength of the compositions containing 40 wt% calcined flint clay, fired at 1400°C for 3 h, were found to be 71%, 0.85 g.cm–3and 2.65 MPa, respectively. Thermal conductivity of the material was 0.133 W.m–1.K –1at 300°C. When sawdust was soaked by 0 wt% sol, microstructure of the materials showed irregular pores. When sawdust was infused with 7 wt% alumina sol, the micropores were wrapped with larger pore. Meanwhile, the original pore was refined, and cold crushing strength and thermal conductivity were also optimized. When the sawdust was soaked in alumina sol, the cold crushing strength increased to 3.3 MPa and the thermal conductivity decreased to 0.116 W.m–1·K–1at 300°C. Grey correlation method indicated that the pore size of <2 µm, 2-6 µm and 18-26 µm had more significant influence on cold crushing strength and thermal conductivity.