摘要
To maintain the volume stability of lightweight magnesia-silica castables during heating,lightweight spherical forsterite aggregates(8-5,5-3,3-1 and 1-0 mm),pre-synthesized forsterite fine powder(≤0.074 and≤0.044 mm),natural silica powder(≤0.074 mm),middle grade magnesia fine powder(≤0.074 and≤0.044 mm)and silica fume were used as the raw materials to prepare lightweight magnesia-silica castables,and the magnesia fine powder and natural silica powder were gradually replaced by pre-synthesized forsterite fine powder(10%,20%,30%and 40%,by mass).The properties of the castables were tested and the microstructure was analyzed.The influence of the pre-synthesized forsterite fine powder addition on their properties was researched.The results show that:with the increase of the pre-synthesized forsterite fine powder addition in the matrix,the workability of the castables is almost the same.After being heated at 1450℃for 3 h,the bulk density of the castables increases,the apparent porosity decreases,the permanent linear change changes from expansion to shrinkage,the cold strengths increase firstly and then decrease,and the thermal conductivity at different temperatures increases.Generally,the optimal pre-synthesized forsterite fine powder addition is 20%.
