中國有色金屬學(xué)報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 21 No. 2 February 2011 |
electrode prepared by electrospark deposition
（1. Department of Materials Engineering, Hubei University of Automotive Technology, Shiyan 442002, China;
2. State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China;
3. School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China）
Abstract:In order to improve the lifespan of spot-welding electrodes used for welding zinc coated steel sheets, titanium diboride was deposited onto their surface after precoating nickel as an intermediate layer. The microstructures and phase compositions of TiB2 and Ni coatings were characterized by SEM and XRD. The coating hardness was measured using a microhardness tester. The results indicate that a satisfactory TiB2 coating is obtained as a result of the intermediate nickel layer acting as a good binder between the TiB2 coating and the copper alloy substrate. Owing to its capacity of deforming, the precoated nickel layer is dense and crack free, while cracks and pores are observed in the TiB2 coating. The hardness of the TiB2/Ni coating decreases with the increase of voltage and capacitance because of the diffusion of copper and nickel and the oxidation of the coating materials. Because of the good thermal and electrical conductivities and high hardness properties of TiB2, the deformation of the electrode with TiB2/Ni coating is reduced and its spot-welding life is by far prolonged than that of the uncoated one.
Key words: titanium diboride; electrospark deposition; copper; electrode; nickel; coating
