Simultaneously enhancing heat transfer ability, thermal expansion matching and thermal stability of diamond-reinforced Cu matrix composites through multi-level interface layer design

Abstract

Although diamond-reinforced Cu matrix (diamond/Cu) composites can achieve high thermal conductivity (TC) via interface modification, the significant mismatch in the coefficient of thermal expansion (CTE) between these composites and semiconductors, along with the degradation of heat transfer performance during long-term service, severely impedes their engineering applications. In this work, inspired by the concept of elemental interdiffusion, a novel interface design strategy combined with the control of the interface layer thickness was put forward to achieve the goal of simultaneously enhancing the heat transfer ability, thermal expansion matching, and thermal stability of the diamond/Cu composites. The results reveal that, when adjusting the sputtering time to 45 min, the designed diamond/Cu composites exhibit an excellent TC of 743 W∙m⁻¹∙K⁻¹, a low CTE of 4.5 × 10⁻⁶ K⁻¹ at 323K and a faster thermal response. After undergoing 100 thermal cycles in an atmospheric environment, the composites maintain a high thermal diffusion coefficient up to 244.9 mm²∙s⁻¹, with only a 20.7 % decrease. It has been confirmed that introducing the WC-(Zr,W)C multi-level interface layer is conducive to improving the interfacial bonding strength and phonon matching between diamond and matrix. In addition, there are uniformly distributed diamond particles, a high relative density, and isolated pores in the diamond/Cu composites post-thermal shock, ensuring the distinguished heat transfer ability. This work not only tackles the engineering application challenges of diamond/Cu composites and elucidates in-depth understanding of the enhancement mechanisms, but also offers a fresh perspective for interface layer design in thermal management composites.