THE FABRICATION AND PROPERTIES OF PARTICLE-REINFORCED CAST METAL-MATRIX COMPOSITES

Cast aluminium alloy and zinc alloy matrix composites reinforced by ce ramic particles and graphite flakes were fabricated by centrifugal cas ting and sqeeze casting, and their conventional mechanical as well as tribological properties investigated, Both ZL-109 alloy and ZA-27 allo y were chosen as the matrices of the composites, and the reinforcement s were the particles of SiC, Si3N4, B4C, Al2O3 and the graphite flakes without coating. After being pretreated, the particles were added int o the melt and vigorously agitated mechanically to activate the interf aces between the melt and particles, and hence to form an uniform mixe d slurry. A metal matrix composite component was then made directly by squeeze casting or centrifugal casting. Metallography of the composit es showed that conventional mechanical properties, while slightly decr eased ar compared ra those or the matrix alloys, still remained at a r elative high level for a particular value of particle fraction. The pa rticle reinforced composites showed excellent tribological properties. with the In addition, the linear expansion coefficent of the composit es decreased with increase in the particle fraction.