Abstract
Magnesium matrix composites are considered a desired solution for lightweight applications. As an attractive thermal management material, diamond particle-reinforced Mg matrix (Mg/diamond) composites generally exhibit thermal conductivities lower than expected. To exploit the potential of heat conduction, a combination of Cr coating on diamond particles and squeeze casting was used to prepare Mg/diamond (Cr) composites. The thickness of the Cr coating under different coating processes (950 °C/30 min, 950 °C/60 min, 950 °C/90 min, 1000 °C/30 min, and 1050 °C/30 min) was measured by FIB-SEM to be 1.09–2.95 μm. The thermal conductivity (TC) of the Mg/diamond composites firstly increased and then decreased, while the coefficient of thermal expansion (CTE) of Mg/diamond (Cr) composite firstly decreased and then increased with the increase in Cr coating thickness. The composite exhibited the maximum TC of 202.42 W/(m·K) with a 1.20 μm Cr coating layer, while a minimum CTE of 5.82 × 10−6/K was recorded with a coating thickness of 2.50 μm. The results clearly manifest the effect of Cr layer thickness on the TC and CTE of Mg/diamond composites.
Highlights
The rapid development of the electronic field urgently requires the development of thermal management materials with high performance [1,2]
The development of diamond-reinforced magnesium matrix composites with high thermal conductivity (TC) and low coefficient of thermal expansion (CTE) can further broaden the applications of magnesium alloys [7,8]
When the coating temperature reached 950 ◦C, the Cr coating successfully adhered to the diamond surface, and the thickness increased with holding time
Summary
The rapid development of the electronic field urgently requires the development of thermal management materials with high performance [1,2]. Carbon materials, including carbon fibers, graphite, diamond, carbon foams, carbon nanotubes, graphene, and reinforced metal matrix composites (MMCs) with high TC and low CTE, are the possible solution for electronic packaging applications [3,4]. In the context of diamond-reinforced MMCs with high TC, magnesium and its alloys have long been neglected because of their intrinsic thermal conductivity being lower than that of Al and Cu. it still needs to be pointed out that the density of magnesium is much lower than that of aluminum and copper. The development of diamond-reinforced magnesium matrix composites with high TC and low CTE can further broaden the applications of magnesium alloys [7,8]
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