Preparation of the Ni/Ti-coated diamond micro-powder for electroplated diamond wire saws using vacuum slow evaporation technology combined with the palladium-free electroless plating

The electroplated diamond wire saw is a crucial tool for cutting semiconductor materials such as silicon ingots and sapphire. The nickel (Ni)-coated diamond serves as an essential abrasive in the production of electroplated wire saws. Nevertheless, producing Ni-coated diamonds necessitates the use of the precious metal palladium as a catalyst. Moreover, Ni-coated diamonds are prone to detachment from the wire saw during cutting, since no chemical bond is formed between Ni and the diamond. To address these issues, we proposed the production of electroplated diamond wire saws using Ni/titanium (Ti)-coated diamonds. The vacuum slow evaporation technology had been used to apply a uniform Ti coating on the diamond micro-powder (8 μm), which firmly bonded to the diamond through the interfacial product TiC. The Ti-coated diamonds exhibited surface activity, allowing direct electroless plating of the Ni coating without palladium. At an overpotential of −0.7 V, the current densities in the composite electroplating bath were − 0.026 A/cm2 (Ni/Ti-coated diamond) and − 0.018 A/cm2 (Ni-coated diamond). Additionally, electrochemical impedance spectroscopy showed that the charge transfer resistances were 3.72 Ω and 4.45 Ω, respectively. Thus, Ni/Ti-coated diamonds enhanced the composite electroplating reaction. The Ni/Ti-coated diamond wire saws also showed superior abrasive density per unit length. These improvements were ascribed to the formation of Ni and Ti coatings on the diamond surface. Moreover, the Ni/Ti-coated diamond wire saw exhibited greater resistance to detachment in cutting trials, allowing at least a twofold increase in diamond exposure. Utilizing Ni/Ti-coated diamond micro-powder as an abrasive in the electroplating of diamond wire saws offers a cost-effective and efficiency-enhancing solution for manufacturers, potentially extending the wire saw's lifespan. This development is poised to drive advancements in the processing technology of hard and brittle materials.