Fabrication, thermal stability and microhardness of sputtered Ni–P–W coating

Ternary Ni–P–W alloy coating was fabricated by the RF magnetron sputtering technique with dual targets of electroless nickel alloy and tungsten metal. The composition of both the alloy deposited and the sputtered targets were evaluated by electron probe microanalysis. The homogeneity of Ni–P targets fabricated by electroless nickel plating on copper plates was revealed from cross-sectional line profile analysis. Transitions in microstructure, in terms of the tungsten content in the as-deposited alloy deposit, were discussed using X-ray diffraction analysis. Results of microhardness tests showed that the surface hardness could be engineered by controlling the composition and microstructure in the Ni–P–W coating. A relatively high microhardness of approximately 1900 HK was observed for the ternary coating with high tungsten contents of 65 wt.%. The thermal stability could be enhanced by addition of tungsten into the deposit compared to the binary Ni–P sputtered coating.