SYNTHESIS AND TRIBOLOGICAL CHARACTERIZATION OF ALUMINIUM BASE COMPOSITES

Abstract

Particle reinforced metal matrix composites are attractive to industries for a number of reasons. For a given application, the composites may be designed to possess the required spectrum of properties which are not available either in the matrix or the reinforcements alone. The reinforcements may have different size, shape and orientation and the particles , if used as reinforcements, result in isotropic composites which are convenient to the designers. In addition, the particles are cheaper compared to fibres and are relatively easy to incorporate in metals and alloys by a cheaper route of solidification synthesis. Weight saving to reduce the weight of a vehicle is a prime motive for application of composites in space, aerospace and automobile industries. However, the quantum of accumulated savings per vehicle limits the choice of materials and technologies available for the purpose of weight saving. Composites based on aluminium and aluminium alloys are lightweight and by dispersing reinforcement in it, a significant improvement in specific strength and stiffness may be attained. Fibre or whisker reinforced composites processed by relatively costlier processing routes of powder metallurgy or high pressure infiltration of preforms result in superior and more reliable products which are within the reach of space or aerospace industries but outside the reach of automobile industries which has a much lower quantum of accumulated savings. Therefore, the automobile industries are engaged in developing relatively cheaper particle reinforced metal matrix composites synthesised by solidification processing using the existing infrastructure of conventional foundries.