Influence of Kyanite Content on the Microstructures and Properties of Castables Containing Spherical Lightweight Mullite Aggregates

摘要

Five lightweight mullite castables were prepared using the lightweight mullite aggregate (M45A) with narrow particle size distribution and spherical shape,mullite powder (M45P), kyanite powder, microsilica and Secar 71 cement as raw materials.After the specimens sintered at 1100 ℃,1200 ℃ and 1300 ℃ for 3 h, the effect of kyanite contents (8wt.％, 10wt.％ 12wt.％, 14wt.％, 16wt.％) on the physical properties,phase compositions and microstructures was investigated through x-ray diffractometer (XRD),scanning election microscopy (SEM) and a microscopy measurement method, etc.The results showed that, for the specimens sintered at 1300 ℃ with the kyanite content increased from 8wt.％ to 16wt.％, the bulk densities and apparent porosities changed little, but the flexural strengths and the crushing strengths decreased significantly, and the linear change rates increased from-0.87％ to 0.64％.The most apposite mode is the sample containing 12wt.％ kyanite sintered at 1300 ℃, which has a high crushing strength of 29.3MPa, a low linear change of 0.18％, an apparent porosity of 36.8％ and a bulk density of 1.73g/cm3.