PREPARATION AND PROPERTIES OF ALUMINUM MATRIX COMPOSITES WITH SIC PARTICULATE BY A NOVEL METHOD

Abstract

Processing of metal matrix composites (MMC) with ceramic particulate reinforcements through the casting route is associated with problems because of poor wet ability. The major difficulty is getting a uniform distribution of reinforcement especially in higher volume fractions. An innovative method of producing cast composites is tried in present study to overcome this problem. The method involves multi axis random rotation of liquid aluminum and silicon carbide particulates encapsulated in a steel pipe. Up to 65 % volume
fraction of SiC could be incorporated in aluminum by this technique. Properties like hardness, micro hardness, densities and microstructures have been studied. The distribution of particles as well the mechanical properties are better as compared to that of stir cast composites with similar volume fraction of silicon carbide reinforcement. The composite with 65-volume percentage of silicon carbide of particulates showed a Rockwell Hardness value of 67Rb.In some locations the microstructure showed a non-uniform distribution of particles. There were segregation of silicon carbide particles at a particular location and the hardness obtained in this zone was much higher. The particle distribution is a result of the combined influence of random mixing of particles and liquid aluminum and the solidification pattern obtained.