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ORIGINAL ARTICLE

Squeeze Infiltration Processing and Structural Characteristics of Lightweight Aluminum‑Carbon Metal Matrix Composites M. G. Akhil1,2 · A. G. Arsha1,2 · Vishak Manoj1 · R. L. Vishnu1 · T. P. D. Rajan1,2 · B. C. Pai1 Received: 29 June 2020 / Accepted: 31 August 2020 © Indian National Academy of Engineering 2020

Abstract Natural Graphite flakes are attractive carbon-based reinforcements due to its layered structure providing self-lubrication, thermal properties, cost and ease of machinability. The present study focuses on the processing of high volume fraction graphite-reinforced composites by liquid metal squeeze infiltration technique using various volume fractions of graphite. The interface between the matrix and reinforcement plays a vital role in determining the properties of metal matrix composites (MMC). The presence of oxide layer on the surface of molten metal and the adsorbed contaminant on the reinforcement surface generally leads to non-wetting of the reinforcement with molten metal. To avoid interfacial reactions and improper wetting between Graphite reinforcement and the matrix, the graphite particles were properly surface treated and coated with copper. The graphite particles were coated with copper by cementation technique and characterization has been done. Porous graphite preforms of varying volume fractions and pore densities were prepared through cold pressing followed by vacuum sintering. The sintered porous graphite preforms are infiltrated with liquid aluminum alloy (A356) at 760 °C under squeeze infiltration pressure of 40 MPa. The microstructural characteristics and thermal conductivity measurements were carried out for the infiltrated composites. Keywords  Graphite/Aluminum composite · Copper coating · Porous graphite preforms · Squeeze infiltration · Thermal conductivity

Introduction The fabrication of graphite particle reinforced metal matrix composites (MMCs) with low density, increased thermal conductivity (TC), and tailorable coefficient of thermal expansion (CTE) is of vital importance owing to the increasing requirement imposed on thermal management materials’ microelectronics and semi- conductors (Mallik et al. 2011; Qu et al. 2011). At present, a number of techniques have been developed to prepare graphite -metal composites including stir casting, powder metallurgy, spray deposition, and so on (Shalu et al. 2009). Liquid metal infiltration is * M. G. Akhil [email protected] * T. P. D. Rajan [email protected] 1



CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, India



Academy of Scientific and Innovative Research (AcSIR), New Delhi, India

2

regarded as an efficient method for fabricating carbon fiber reinforced MMCs due to its significant potential at low costs (Qi et al. 2012; Mizumoto et al. 2005). Liquid metal infiltration consists of two steps: preparing porous preform and infiltrating the preform with liquid metal. Preform fabrication is the most important step for the liquid metal infiltration technique since a high