Investigation on life of coated electrode and traditional electrode for resistant spot welding of Zn-coated steels

A nickel and a metallic ceramic coating were deposited on to the end surface of a traditional Cr-Zr-Cu resistant welding electrode in order to increase the life of electrode for resistant spot welding of Zn-coated sheet steels. The life of the coated electrode was approximately two and half times than that of the uncoated electrode under the same experimental conditions.The coated electrode had higher ability to prevent the electrode from plastic deformation during welding compared with the uncoated electrode.In addition,there were much more pitting,cracking,intermetallic alloy layer and self-healing layer on the end surface of un-coated electrode.As a barrier,the coatings on the surface of electrode could effectively prevent the adhesions,stripping,and then significantly reduce the diffusion of Zn from the surface of the electrode into the Cr-Zr-Cu electrode to form brittle intermetallic compounds