Microhardness of sputtered ternary Ni–P–W coating with extra-high phosphorous content from improved deposition rate-derived electroplated NiP targets

The ternary Ni–P–W alloy coating was fabricated by RF magnetron sputtering technique with dual targets of Ni–P/Cu and pure W. Electroplating Ni–P process was introduced to obtain the NiP compound target with extra-high phosphorous contents around 21 at.%. The deposition rate achieved as high as 20 μm/h after modification of the processing parameters. The Ni–P–W coating with a high P/Ni ratio of 0.25 was successfully derived by electroplating with a high P content Ni–P/Cu target. After heat treatment, the coating was strengthened by the precipitation of Ni–P compounds and solutioning of W in the crystallized Ni matrix. The Ni–P–W coating exhibited a relatively higher hardness with higher P codeposited after annealing at elevated temperature. The advantage of the composite target was also discussed by comparing with the ternary deposit fabricated by the electroless process.