Chemical conversion coatings of magnesium alloy by solution can be divided into: chromium salts, organic acids, phosphates, KMnO4, rare earth element systems and Tin salts, and so on.
Traditional chromate film to Cr for skeleton structures are compact, structure of water-containing Cr has very good self-healing capabilities, strong corrosion resistance. But Cr have greater toxicity, wastewater treatment cost is high, it is imperative to develop chromium-free conversion coating. Magnesium alloys in KMnO4 solution available to deal with the chemical conversion coating of amorphous organization, the corrosion resistance of chromate film. Alkaline chemical conversion treatment of Tin salts can be used as a pretreatment of electroless nickel plating on magnesium alloy, instead of the traditional technology of Cr, f or harmful ions such as CN. Chemical conversion coatings on porous structure of activated before plating showed good adsorption, and modified nickel coating adhesion and corrosion resistance.
Organic acids conversion coatings obtained by both corrosion protection and comprehensive performance such as optics, electronics, chemical conversion treatment plays an important role in the new development.
Chemical conversion coating is thin, soft, protective ability, usually only used as a decorative or protective coating the middle tier.