Characterization of Graphite-Reinforced LM30-Aluminium Matrix Composite Processed through Gravity and Vertical Centrifugal Casting Processes

摘要

This paper discusses the fabrication of graphite-reinforced aluminium LM30 (A390) matrix composite through gravity die casting and vertical centrifugal casting processes (VCC). The microstructures and the hardness of the cast specimen were characterized and presented here. The functionally graded composite (FGCs) processed through VCC showed the gradual transition of graphite and primary silicon from outer region to core region in microstructures. This was based on the gravity difference amongst the reinforcement and matrix during centrifugal casting. FGC is one of the potential engineering materials and has many applications in engineering industry. The microstructure of the gravity cast sample showed no gradual transitions but showed the uniform distribution of graphite reinforcement. The hardness of gravity cast samples showed a maximum of 130 HB. The hardness of FGC was measured from the outer periphery to the inner periphery. The results showed that the inner periphery had low hardness than that of inner periphery. Graphite particles reduced the hardness and increased the lubricating property of the composite. Gravity cast specimen showed greater hardness than that of VCC processed FGCs. Graphite particles had associated mostly with the primary silicon particles. Though the primary silicon particles are at inner, the graphite particles reduced the hardness.