Research on Microstructure Characteristic and Thermo-physical Properties of Diamond/Cu-Ni

The diamond/copper matrix composites have the advantages of low density, high thermal conductivity and adjustable thermal expansion coefficient, but poor wettability and high thermal resistance at the interface between diamond and copper lead to low thermal conductivity of the composites. In this paper diamond/Cu-Ni composites are prepared by spark plasma sintering and using Cu-Ni alloy as the matrix. The effects of Ni content and powder mixing methods on the microstructure and thermo-physical properties of diamond /Cu-Ni composites are studied. The results show that the thermal conductivity of the diamond /Cu-Ni composite first increases and then decreases as increase of Ni content. When the mass fraction of Ni is 0.5%, the thermal conductivity reaches the maximum of 210.63 W/( m•K). The diamond particles disperse evenly in the Cu matrix and the interface between diamond and copper is closely combined. All these demonstrate that Ni element can obviously improve the wettability between diamond and copper, while the content of Ni had little impact on the mechanical properties of the composites. Among the different process of mixing powder, the maximum thermal conductivity of the sample is 244.91 W/( m•K) for ordinary mixing powder with grinding ball, and the hardness of the sample can reach 200 for mixing powder without grinding ball and for mixing powder with heat treatment after grinding ball, which is 32.5% higher than that of ordinary mixing powder with grinding ball.