Synthesis and characterization of stir casted Cu-ZrO 2 -Graphite hybrid metal matrix composites for thermal management structures

The present study aims at investigating the properties of copper matrix-based hybrid metal matrix composites (MMCs) reinforced with ZrO₂ and Graphite. The MMCs were prepared using stir casting technique. The composite material was developed for its application in thermal management structures. The properties of the prepared MMCs were found to be dependent on the reinforcements content present in the MMCs. ZrO₂ and Graphite reinforcements were added (0.5–0.5, 1.0–1.0, 1.5–1.5 and 2.0–2.0 wt %) in the four composite samples prepared via stir casting. Amongst several available techniques, stir casting was chosen to prepare the samples due to its simplicity and economic viability. The phase identification was done by using X-ray diffraction (XRD) and the microstructure was observed using Scanning Electron Microscopy (SEM). No intermediate phase was observed from the XRD results. The reinforcement phase was found to be dispersed in a uniform manner as observed through the SEM micrographs. The density of the samples was found to decrease with an increase in the reinforcements content. The density of the composite sample containing 2 wt. % of each reinforcement was found to be 8.01 g/cm³ which was 10% lesser than pure copper. Hardness of pure copper sample was found to be 35.71 BHN; however, the hardness of composite sample containing 4 wt. % of each of the reinforcements was found to be 70.14 BHN which indicates an increase of around 100%. Wear rate of pure copper and composite sample containing 5 wt. % of each of the reinforcements was found to be 0.3788 mm³/Km and 0.3603 mm³/Km, respectively, at 20 N load. However, the composite samples consisting of 4 wt. % of each of the reinforcements exhibited wear rate of 0.3001 mm³/Km which was 20% lesser than that of pure copper at the same load. The compressive strength of composite sample containing 2.0 wt. % ZrO₂ and graphite was found to be 674.57 MPa which was around 1.25% higher than the composite sample containing 0.5 wt. % reinforcements. The specific heat of the samples was found to increase marginally with an increase in reinforcement content. It is expected that the hybrid composites developed will be suitable for use in structural applications pertaining to thermal management.