Mechanical Plating Of Flake Zinc-Aluminum Coating

Mechanical plating had advantages of that the technics and equipment were simple and it could conserve energy and nonferrous metal powder largely. The new technics also avoided the disadvantage of thin thickness and hydrogen embrittlement in electroplating. Compared with the chemical plating, it avoided the disadvantage of plating solution instability and high cost. Compared with the hot-dip coating, it avoided the disadvantage of anneal of high strength hardware and the large emission of smog and zinc stream. It nearly had no harm to environment, biology and the humanity.Conventional mechanical plating adopted global metal powder. The global metal powder among the coating had the interspaces. The flake coating using flake metal powder's well adhesion and covering power had the better shield effect against aggressive medium, and could reduce the aggressive medium infiltrating into the coating. High-grade-energy contrarotation ball grinding mill was used. Dry contrarotation ball grinding made the zinc-aluminum powder to flake metal powder in order to use in mechanical plating. Activating agent of mechanical plating was reselected. The coatings of mechanical plating zinc and flake zinc-aluminum were made in self-designed machine. To stave the white rust of appearance and to improve the corrosion resistance the coatings were accepted chromate passivation, trivalent chromate passivation, molybdate passivation and superficial organic silicon pore sealing treatment.The coating's performance was compared through mechanical coverage appearance comparison, combining power test, the NSS test and the electrochemical test. It was proved that compared with mechanical plating zinc coating, mechanical plating flake zinc-aluminum coating had the advantage in color and luster, lightness, inner density and corrosion resistance. The corrosion resistance of coating had been improved obviously after the treatment. Superficial organic silicon pore sealing treatment and molybdate passivation could replace the chromate passivation, the best of which was superficial organic silicon pore sealing treatment.