Enhancing the thermal conductivity of Mg/diamond composites prepared by gas pressure infiltration through Zr coating and heat treatment

Abstract

In the booming electronic information technology field, diamond-reinforced magnesium matrix composites (Mg/diamond composites) have attracted attention in the pursuit of high-performance thermal management materials. However, Mg/diamond composites suffer from low thermal conductivity. This is due to the fact that the interfacial reaction products between the diamond reinforcement and the Mg matrix are easily decomposed and Mg is highly reactive. In this study, we first coated a 150 nm Zr layer on diamond particles through a magnetron sputtering method. Subsequently, the Zr-coated diamond particles were heat-treated at different temperatures. Finally, the Mg/diamond-Zr composites were prepared through a gas pressure infiltration method. Furthermore, we analyzed the surface morphology of the Zr-coated diamond particles, as well as the microstructure and interfacial morphology of the composites using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The results show that in the unheat-treated Mg/diamond-Zr composites, the interfacial bonding between the diamond reinforcement and the Mg matrix is weak. Through heat treatment, ZrC is formed at the Mg/diamond interface, strengthening the interfacial bonding. It was also found that the thickness of the ZrC layer increases with the heat-treatment temperature, and a suitable ZrC layer can enhance the thermal conductivity by bridging the acoustic impedance gap. Moreover, the thermal conductivity of the pristine Mg/diamond composites is only 67 W/mK. When there is a Zr coating on the diamond particles' surface, it increases to 159 W/mK, and it continues to rise with the heat treatment of the Zr-coated diamond particles. The thermal conductivity of the composites reaches a maximum value of 430 W/mK at 1150°C. These results will provide theoretical support for the application of Mg/diamond composites.