Papers by Keyword: SiC/Al Composite

Abstract: The machining characteristics of SiC/Al composite using wire electro discharge machining (WEDM) were investigated in this study. Material cutting speed and surface roughness value were adopted to evaluate the machinability. Peak current, pulse on time, pulse duration and working voltage were selected as the input variables to investigate the machining performance. Effects of input variables on the cutting speed and surface roughness were experimentally tested. Peak current, pulse on time and working voltage were confirmed to have positive effects on cutting speed and surface roughness value. Whereas the cutting speed and surface roughness value decrease with the increase of pulse duration.

Abstract: SiC/Al composites with high reinforcement content were fabricated by pressure infiltration of aluminum alloy into porous SiC preform obtained by powder injection molding using a bimodal powder mixture. The influence of powder loading and particle size on the thermo-physical properties of the prepared composites was investigated. The results indicate that the thermal conductivities (TC) increases and coefficients of thermal expansion (CTE) decreases with increasing powder loading and particle size of the coarse powders in the bimodal powder system. The TCs are below the estimated value based on Hasselman-Johnson model, mainly due to the residual pores and the irregular particle shape. The CTEs of the composites increase with increasing temperature from 100°C to 400°C, and the increasing rates vary at different temperature ranges. Deep cooling in liquid nitrogen is effective to bring dislocations in the matrix and thus reduces the CTEs.

Abstract: SiC/Al composites with high volume fraction of SiC were prepared at 1150°C by pressureless infiltration. The volume fraction of SiC was increased by decreasing the amount of starch in the green body. Both the microstructure and the strength of the composites were investigated. The results showed that the strength decreased with the increasing of the particle size and volume fraction of SiC. It was suggested that the interface between the SiC particles, which were not sintered, make of the defects in the composites. The defects led to the decreasing of the strength with increasing of the volume fraction of SiC.

Abstract: Copper and 2024 aluminum alloy were melt-infiltrated into porous β-SiC to form SiC/Cu and SiC/Al composites. The porous β-SiC was prepared using Moso bamboo as the bio-template and had structural characteristics of bamboo. The Cu infiltration occurred as low as 1100°C and became significant at 1200°C. After infiltration at 1300°C for 4 h, there was still ~5 % of residual porosity. For the composites with low degree of metal infiltration, the samples fractured like the bamboo-structured porous SiC. For the composites with high degree of infiltration, the sample behaved like monolithic copper. In the infiltration of Al alloy, infiltration occurred at 900°C. Higher Infiltration temperatures would result in significant formation of Al4C3, which gradually decomposed in air.

Abstract: High volume fraction (63vol.%) SiCp/Al composite for electronic packaging fabricated by pressureless infiltration was characterized by microscopy, physical and mechanical tests. Microscopy observations and XRD analysis indicated that the composite appeared to be free of porosity and macroscopically homogeneous, SiC-Al interface was atomic bonding interface with low thermal resistivity and electrical resistivity, no interfacial reaction products was detected. Examination of the fracture surfaces of the composites revealed that the cracks passed through the SiC particles and Al matrix, no debonding of SiC-Al interface was observed. The fracture mode indicated that the bonding between SiC-Al was sufficient strong. The properties of the composite were noted for its ultrahigh thermal conductivity of 235W/m·K and specific modulus (79.9×105m), low coefficient of thermal expansion (7.2×10-6/K) and density of 2.99g/cm3. The advantages of the composite over traditional materials used as the electronic packages for aerospace applications were analyzed.