Characterization of Graphite-Reinforced LM30-Aluminium Matrix Composite Processed through Gravity and Vertical Centrifug
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ORIGINAL CONTRIBUTION
Characterization of Graphite-Reinforced LM30-Aluminium Matrix Composite Processed through Gravity and Vertical Centrifugal Casting Processes S. Senthil Murugan1
. T. P. D. Rajan2
Received: 11 January 2018 / Accepted: 5 November 2020 Ó The Institution of Engineers (India) 2020
Abstract This paper discusses the fabrication of graphitereinforced 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.
& S. Senthil Murugan [email protected] 1
Department of Mechanical Engineering, Mepco Schlenk Engineering College, Sivakasi, Tamil Nadu 626005, India
2
Materials Science and Technology Division, NIIST-CSIR, Thiruvananthapuram, Kerala 695 019, India
Keywords Vertical centrifugal casting LM30 alloy Reinforcement Composite Graphite Functionally graded material (FGM)
Introduction Composite materials are being developed using stir casting process as it enhances the dispersal of reinforcement into the metal matrix [1, 2]. The properties of the composites and the microstructures can be varied by the processing parameters and the different processing routes. Generally, the composites were synthesized by the stir casting process and shaped through the various casting processes [3] like gravity die casting, centrifugal casting, squeeze casting, etc. In composite processing, mechanical stirrer with blades creates a vortex flow at certain rpm in the fully liquid matrix and mixes the reinforcement particles. In the gravity die casting the liquid metal composite is poured into mould uniformly with the help of gravitational force. The application of composites especially functionally graded materials (FGMs) is crucial in aerospace industries. Centrifugal casting is one of the methods for the production of FGMs [4]. In centrifugal casting, the centrifu
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