Thermal properties of tungsten/tungsten carbide-coated double-size diamond/copper composite

Abstract

Diamond‑copper composites with high thermal properties and low density show huge potential applications in thermal management. Solving the interface between diamond and copper and increasing the volume fraction of diamond in the composite are crucial for its thermal conductivity. In this work, tungsten/tungsten carbide (W/WC) was used as an interface and fabricated on diamond surface by the molten salt method. Well-coating with higher than 95 % of coverage was obtained at the mass ratio of diamond and W of 3:3, which owns a 200 nm ± 10 nm thickness of W/WC layer. Meanwhile, double-size diamonds with 200 μm and 40 μm were compounded with the copper matrix to increase the volume fraction of the diamond. Theoretical calculation displays only 14.5 % of porosity in the bimodal diamond composite when 74.2 vol% of the large-size diamond is in the total volume fraction of the diamond. Microstructure characterization displays that the interfacial bonding was enhanced by the W/WC interface and morphology was improved by using the double-size diamonds even at 70 % of the volume fraction. Compared with single-size diamond/copper composite, the thermal conductivity was also increased and obtained the highest value of 640 Wm−1 K−1 for the double-size diamonds/copper composites. Finite element analysis and testing of actual scenarios further confirm the excellent thermal performance of double-size diamonds/copper composite, which meets the requirements of thermal management in high-power devices.