Characteristics of TiB2 Coating on the Surface of Copper Alloy Prepared by Vibrating Electrospark Deposition

Abstract

Functional TiB2 coating was prepared onto the surface of Cr-Zr-Cu electrodes by vibrating electrospark deposition in order to extend their service life during resistance spot welding of Zinc coated sheet steels. The microstructure and mechanical properties of the coatings have been characterized by scanning electron microscopy, energy dispersive analysis, X-ray diffraction and micro-hardness tests respectively. The results indicate that cracks appear in the coating due to the tensile stress accumulation and delamination of the coating is related to mismatch in the equivalent valence electron. Cu diffuses obviously from the substrate to the surface of the coating, forming a gradient distribution and making the bonding of the interface between the coating and the substrate an atomic one. TiB2 coating is oxidized during deposition under high temperature of electrosparking. The micro-hardness of the coating is approximately 500HV, which is much bigger than the hardness of the uncoated ones.