Improvements on the wear resistance of high thermal conductivity Cu alloys using an electroless Ni–P coating prior to PVD deposition

An attempt to improve the load support for hard PVD coatings on soft Cu alloys has been made by using a medium phosphorous content electroless Ni–P coating prior to PVD deposition, envisaging the application of these coating/substrate systems in plastic injection moulding. Several PVD coatings, including TiN, CrN, CrAlN, multilayered CrAlN, WC–C, multilayered CrAlN/WC–C were deposited onto an Ampcoloy 940 Cu alloy in two conditions: ‘standard’ and electroless Ni–P plated. The effect of the electroless Ni–P coating on the coating/substrate performance was evaluated by pin-on-disc wear and impact tests. Ultra-microhardness and surface roughness measurements were also used to characterise the resulting coating/substrate systems. The electroless Ni–P coating reduced the wear rates of the PVD-coated Cu alloys and increased the impact wear resistance. Among the PVD coatings trialled, CrN, CrAlN and multilayered CrAlN coatings on electroless Ni–P provided the lowest wear rates.