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.