Surface Hardening of Spot-Welding Copper Alloy Electrode for Zinc Coated Steel
Zinc coated steel, spot-welding electrode, titanium carbide, titanium diboride, coating. Abstract: TiC and TiB2/Ni were coated on the surface of cupper alloy electrodes used for spot-welding of zinc coated steel sheets by electrospark deposition to improve its lifespan. The coatings structure and phase compositions were characterized by SEM and XRD, and their life spans were examined by spot-welding test. The results indicate the major phases of the coatings are TiC and TiB2 respectively, and copper diffuses from the substrate into the top surface of the coatings during electrosparking, forming an atomic bonding between the coatings and the substrate. The electrodes are hardened by coatings. Though cracks exist, the coatings can segregate the steel sheets and the substrate and prevent zinc in the surface of steel sheets and copper in the substrate from alloying. The coatings also reduce the deformation of the electrode during spot-welding. As a result, the spot-welding lives of TiC and TiB2/Ni coated electrodes are prolonged significantly by one and two times respectively.
Zhengyi Jiang and Chunliang Zhang
C. Luo et al., "Surface Hardening of Spot-Welding Copper Alloy Electrode for Zinc Coated Steel", Advanced Materials Research, Vols. 97-101, pp. 1475-1478, 2010