Study On The SiC(Cu)/Al Ceramic-metal Composites

SiC/Al composites show superior properties such as low density, high inflexibility , high strength, etc. They can be widely used in many industrial fields, e.g. the aerospace vehicles, cars, sports, architecture, and electron devices. Recently, SiCp reinforced 6061 Al alloy was widely investigated. However the interfacial behavior between SiC and Al is not yet very clear until now.In this study, coated SiC/Cu composite particles were used to improve the interfacial properties and the bonding strength in the SiC reinforced Al composites. The heterogeneous deposition method was used to coat Cu on SiC particles. The coating process was investigated. The influence of original particle size distribution of SiC particles, temperature, and the concentration of initial CuSO4 solution on the coating process were investigated. The combined DSC-TG technique was carried out to detect the thermo-dynamic behavior of the coated SiC/Cu powders. Then, PM method was employed to measure the density and SiC(Cu)/Al composite. XRD, SEM techniques were used to characterize the samples. The SiC-Cu(Al) interface and the influential aspects were analyzed. The hardness and density were measured. The solidification process and the grain growth mechanism of Al grain and SiC(Cu)/Al interface reaction were investigated.It was found that the heterogeneous-deposition method was the desired way to achieve the coated SiC/Cu composite particles. SiC and Cu dispersed homogeneously within the composite powders. Small and spherical SiC particles facilitated the coating process. Different phases were detected in the coated composite particles at different temperature. Cu2O content decreased with the increasing temperature. The concentration of initial CuSO4 solution has no obvious influence on the structure and phase distribution of the composite powder. The DSC-TG profiles showed that the optimized sintering temperature was at 700 - 750 C. Changes in the microstructure were observed in the sintered composites at different temperatures. No reaction was detected at the interface between Al-SiC below 650C, the melting point for Al. The coating structure did not change either at such low temperatures. As the temperatureincreased, the interface reaction occurred. SiC clusters to separate from the Al matrix appeared at high temperatures. Rough crack surface was observed with the crack propagated along the surface of the SiC particles. The density of SiC(Cu)/Al composite was about 2.70g/cm3. The hardness increased with the increasing Alcontent. La2O3 was helpful to increase the density. The hardness increased at first and then reduced and the increased as the increasing temperature. The maximum hardness was 79.67 Hv. During the pressureless sintering process, the densification of the SiC/Al composites proceeded through the spheroid growth of the coated particles. Al2O3, CuAl2 were detected in the samples sintered at high temperatures because of the interface reaction.