Impacts of interface modification by Ni coating on the property of Cu matrix composites reinforced by β-Si3N4 whiskers

Abstract

β-Si3N4 whiskers were applied as the reinforcements to prepare Cu matrix composites (SCMMCs) by powder metallurgy method. In order to optimize the Cu/Si3N4 interfacial structure, Ni-coating was deposited on the surface of β-Si3N4 whiskers by means of chemical plating. Mechanical property tests indicated that the tensile strength and bending strength of Cu matrix composites reinforced by Ni coated β-Si3N4 whiskers (NSCMMCs) were both improved compared to that of Cu matrix composites reinforced by uncoated β-Si3N4 whiskers (USCMMCs), and the maximum value reached up to 222 MPa and 271 MPa, respectively. A notable improvement was found in the thermal conductivity. Thermal conductivity at 25 °C reached up to 218 W m−1•K−1, which was 43 W m−1•K−1 higher than that of USCMMCs. Microstructure observation proved that the Cu/Si3N4 interfacial structure was converted into the firm Cu/Ni/Si3N4 sandwich structure, and the Si diffusion from Si3N4 into Cu matrix was inhibited by Ni coating to ensure the purity of Cu. Meanwhile, the aggregation of whiskers was alleviated. Ni coating on β-Si3N4 whiskers was proved to be an effective way to enhance the mechanical and thermal property of SCMMCs.