Preparation of Ni-coated W powder by electroless plating

The effects of W powder particle size, complexing agent, W powder loading on the electroless Ni plating on the surface of W powder are analyzed, and the morphology of coated particle, utilization rate of Ni and deposition rate are investigated. The controllable electroless Ni plating process parameters are optimized. The Ni-coated W powders are mixed with Cu powders, and then the mixed powders are sintered to prepare 67W-25Cu-8Ni alloy by using spark plasma sintering (SPS) technique. 67W-25Cu-8Ni alloy is analyzed by scanning electric microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). Results show that, when W powder particle size is in range from 4 μm to 6 μm, the complexing agent of sodium pyrophosphate is 60 g/L, triethanolamine is 100 g/L, and trisodium citrate is 8 g/L. The Ni layer is uniform and complete, and the weight percent of Ni in W-Ni powder can be controlled by adjusting the W powder loading. Metallurgical bonding is achieved at the W/Ni/Cu interface. Compared with W-Cu alloy, the sintering density of 67W-25Cu-8Ni alloy prepared by SPS is greatly increased, reaching to 97%.