Study On The Preparation Andproperties Of Al/SiC Ceramics Composites

With the rapid development of new technology and industries,such as automobile, aerospace, military industry and atomic energy, materials with high strength and low density are in badly need by people. Metal can not meet the upper requirements. SiC honeycomb ceramics with low density, high strength hasits unique advantages in industrial applications, but the brittleness limits its application. The texture of Al and its alloys has good ductility. Al/SiC composites inheriting the excellent performance of both materials are in great desire to be prepared. While the SiC honeycomb is difficult to extrude for its poor plasticity. In addition, the weak wet-ability of Al and SiC in the preparation work of Al/SiC composites made it focuse in the experiment.Firstly, SiC honeycomb ceramics were successfully extruded, and then sintered by micro oxidation sintering, pressureless sintering and reaction bonded sintering technique, respectively.It showd: the way oxidation affecting the properties of SiC honeycomb is by the generation of SiO2 on the surface. At the experimental temperature, the phase of SiC honeycomb ceramics had not change bystuding the effect of sinteringtemperature and the amount of Al2O3/Y2O3 added in pressureless sintering process. It’s clined to be crystallized to YAG at 1750℃(near the eutectic pointof YAG). With the increasing of sintering temperature, the shrinkage increases. With the sintering temperature changing, the change of bulk density and the compression strength are almost at the same trend, and their maximum value appeared at 1750℃and was 1.8g/cm3 and 14.09 MPa, respectively. The results of SiC ceramics by reaction sintering showed that it can provide the channel for the infiltrationof molten silicon by buring out the binder among the particles with a wide range size distribution during the sintering process, besides, the organic binder via the high temperature pyrolysis can provide the C source needed for reaction sintering process. By studying the function of B4 C added in reaction-bonded silicon carbide, it revealed that B4 C can promote the sintering of SiC ceramics during reaction sintering process, and with the addition of B4 C the density of SiC ceramics decreased while its mechanical properties improved.Secondly, SiC honeycomb ceramics was used as reinforcement to prepare the Al/SiC ceramics composites through pressureless infiltration, low pressure casting and squeeze casting methods. It came to be that SiC aluminum honeycomb ceramics were difficult to be filled with aluminium alloywithout outer force, which can force the liquid metal flow into the holes through honeycomb ceramics and promote the mutual infiltration of SiC and Al through the interface. The component of the alloy was studied to explore the interfacial wettability of Al/SiC ceramics composites. It revealed thatalloy element influencing the properties of Al/SiC composites by decreasing the viscosity and enhancing the interfacial reaction between the two materials.