Effect of SiO2 micro powder on properties of corundum-mullite composites

In this paper corundum-mullite composites were prepared used tabular corundum as coarse clinker, ultra-fine tabular alumina, fused mullite powder, SiO2 micro powder and white clay as host material, dextrin as binder. Under the condition of the same content of SiO2 micro powder and white clay, the effect of SiO2 micro powder addition on the sintering, mechanical strength, thermal shock resistance, phase composition and microstructure of the specimens treated at 1600 degrees C for 3 h in an air atmosphere were studied by XRD and SEM analyses. The results indicate that the bulk density, mechanical strength decrease and there are apparent amount of porosities, thermal shock resistance increases with increasing the content of SiO2 micro powder. This is because that the in-situ mullite content of sample after sintering increases with increasing the content of SiO2 micro powder. At the same time. It is found that there are some needle-like secondary mullite in the sample after thermal shock recycling five times.