A single step laser activation strategy for high-integrity electroless Ni-P plating on binderless WC

The exceptional hardness and poor machinability of binderless tungsten carbide (WC) present significant challenges in fabricating high-performance molds for precision glass molding (PGM). While electroless nickel-phosphorus (Ni-P) plating is often applied as a machinable interface, the intrinsic chemical inertness and poor catalytic activity of binderless WC hinder direct deposition. This study introduces a novel, single-step laser induced activation technique as a green and superior alternative for electroless Ni-P deposition on binderless WC. A hierarchical micro-nano structured surface, comprising periodic microgrooves and laser induced periodic surface structures (LIPSS), was generated using a picosecond Nd: YAG laser. The resulting Ni-P plating exhibited remarkable improvements in microstructure and surface characteristics: the as-deposited plating demonstrated significantly reduced roughness (Ra ≈ 175 nm) compared to its palladium (Pd) activated counterpart, while maintaining a dense, continuous, and defect-free structure. Following chemical mechanical polishing (CMP), the laser activated plating achieved an ultra-smooth, uniform finish (Ra ≈ 22 nm) and exhibited excellent interfacial adhesion, withstanding critical loads exceeding 15 N in scratch tests without delamination. This work establishes picosecond laser surface activation as an advanced route for developing high quality mold materials for PGM.