Enhanced thermal conductivity of Cu matrix composites reinforced with Ag-coated β-Si3N4 whiskers

•The Cu/Si3N4 interfacial structure was modified by Ag coating.•The highest thermal conductivity was 273 W m−1 K−1 at 25 °C.•Enhanced thermal conductivity was benefit from high densification, uniform whisker distribution.

Cu matrix composites reinforced with 10 vol.% Ag-coated β-Si3N4 whiskers (ASCMMCs) were prepared by powder metallurgy method. With the aim of improving the thermal conductivity of the composites, a quite thin Ag layer was deposited on the surface of β-Si3N4 whiskers. The results indicated that thermal conductivity of ASCMMCs with 0.30 vol.% Ag (0.30ASCMMCs) reached up to 273 W m−1 K−1 at 25 °C, which was 98 W m−1 K−1 higher than that of Cu matrix composites reinforced with uncoated β-Si3N4 whiskers (USCMMCs). The Ag coating could promote the densification of composites, reduce the aggregation of β-Si3N4 whiskers and enhance the Cu/Si3N4 interfacial bonding, therefore it could efficiently enhance the thermal conductivity of Cu matrix composites reinforced with β-Si3N4 whiskers (SCMMCs).