Chromate-free coatings for corrosion protection of the surface of the electrodeposited Zn-Ni alloy

In this work, the processes of applying protective conversion coatings based on rare-earth metal compounds for passivation of the surface of a Zn-Ni alloy were investigated. The mechanism of formation, composition and corrosion characteristics of passivating films were investigated. It is shown that the investigated chromate-free coatings are comparable to rainbow chromate layers in corrosion resistance and protective ability. It was found that these coatings withstand thermal shock without deterioration of functional characteristics. It has been revealed that cerium-, lanthanum-containing coatings, like chromate coatings, have the ability to self-heal.