The Investigation On The Preparation And Properties Of Ceramic Matrix Composites With Multi-phase Vague Interface

The effect and growth mechanism of the dopant were contrasting investigated by ZnO, MgO and SiO2 dopants of the in-Situ Oxidation of Molten Aluminum. On the base of the study, A new preparation technique of Al2O3/SiC/Ni/Al-Si multi-phase ceramic matrix composites was developed by oxidative infiltration of Al-5Zn-10Si alloy melt into SiC/Ni performs made by slip casting at high temperature. The phase composition, microstructure and the interface characteristic were all analyzed through XRD, SEM, optical microscope, EDS, etc. The results are listed as follows:The growth mechanism of Al-5Zn-10Si alloy is that molten aluminum keep a continuous oxidation and growth in the way of cell-shape through the micro-channels which transfer the molten aluminum to the reaction front. The dopants of ZnO,MgO,SiO2 coated on the surface of Al-5Zn-10Si alloy can shorten the incubation period of Al-5Zn-10Si alloy directed oxidation process markedly, and keep the micro-channels homogeneous and unblocked, thereby redound to uniformly growing of the A12O3/ Al composite, and increase the its relative density.The main phase of the Al2O3/SiC/Ni/AI-Si multi-phase ceramic matrix composites include A12O3 and SiC,Al (Si) compound oxide, NiAl2O4 , Ni and Al-Si alloy phase exist in the interface of A12O3 phases or SiC phases. The composition in different phase interface is continuous variety, consequently formation the multi-phase composites with vague interfacewas formed.The thermal shock resistance experiments of the Al2O3/SiC/Ni/Al-Si composites and the A12O3/A1 composites were comparatively studied. The results show that the thermal shock resistance of the Al2O3/SiC/Ni/Al-Si composites are preferable to that of the A12O3/A1 composites obviously. It indicated that the vague interface was favorable to improve the thermal shock resistance of materials.