Effect of Al-Si alloy powder on properties of corundum-mullite composites

By means of transient plastic phase process, the corundum-mullite composites were produced using tabular corundum, fused mullite, SiO2 micro powder and Al-Si alloy powder as raw material. The effect of Al-Si alloy powder addition on the sintering, mechanical strength, thermal shock resistance, phase composition and microstructure of the specimens treated at 1550 degrees C for 3 h in an air atmosphere were studied by XRD and SEM analyses. The results indicate that Al-Si alloy powder can lead to plastic shaping in corundum-mullite materials. At the same time, additive of Al-Si alloy powder can greatly improve the sintering, mechanical strength and thermal shock resistance of corundum-mullite composites. This is because that Al-Si alloy powder can melt, oxidize in sintering. The new oxide can react with the matrix to mullite and the in-situ mullite crystals are needle-like that can interleave with others.