Atmospheric plasma activation enhanced electroless Ni-P plating on binderless WC

Precision glass molding (PGM) requires high-performance binderless tungsten carbide (WC) molds, but its extreme hardness and poor machinability hinders direct precision structuring. Introducing a Ni-P plating layer as a machinable and protective interface offers a feasible solution. This study investigates the efficacy of atmospheric pressure (AP) plasma activation for improving the uniformity, surface quality, corrosion resistance, and adhesion of electroless Ni-P plating on binderless WC substrate. Compared to traditional Pd activation method, AP plasma activation significantly increases the surface energy of the binderless WC substrate, promoting uniform Ni-P nucleation and growth. The resulting Ni-P plating exhibits improved thickness (up to 98 μm, a 145 % increase over Pd-activation), high homogeneity (with surface roughness Ra reduced to ∼20 nm post-plating, compared to ∼2.2 μm for Pd-activation), and formation of Ni₂P and Ni₃P strengthening phases confirmed via XRD. Scratch tests demonstrate excellent adhesion between the Ni-P plating and the plasma-treated substrate, with no delamination or cracking under a progressive 15 N load, unlike Pd-activated substrate which suffers severe failure due to hydrogen embrittlement. This study advances the understanding of electroless Ni-P plating on AP plasma activated binderless WC, which will further facilitate its integration into PGM mold production for improved molding performance and durability.