It is well known that Dacromet is a dispersible aqueous solution consisting of zinc flake, aluminum flake and additives. Workpieces after dipping and spraying, curing 20min at 80 ℃ in pre-heating furnace,30min at 300 ℃ at curing furnace. Make hexavalent chromium was adipic alcohol and organic reduction into fluid of dacromet coating does not dissolve in water.
It should be noted that the reduction of hexavalent chromium into trivalent chromium and trivalent chromium oxidation into hexavalent chromium is a reversible process. Therefore, in the sintered workpiece, trivalent chromium will continue to be oxidized to hexavalent chromium, and hexavalent chromium is a carcinogen, so contact will bring harm to health. Therefore, the traditional chromium-containing coating solution is not completely zero emissions, as long as the existence of hexavalent chromium, it will have a certain impact on the environment and people, therefore, the popularity of chrome free Dacromet is imperative.
With the national environmental protection efforts continue to strengthen, more and more auto parts manufacturers require chrome free dacromet coated parts. And even developed chrome free dacromet coating technical standards. Such as Volkswagen GMW3359, GM7111M etc.
Chrome free Dacromet is mainly looking for other substances instead of chromic acid passivation and bonding. Chrome free Dacromet coating mainly uses organic silicon, inorganic silicon, molybdate, tungstate, phosphate as binder, the same use of scaly zinc / aluminum flake as the main filler component, and through a series of seal Post-treatment, to achieve the same excellent corrosion resistance with chromium-containing Dacromet coating.
Chrome free Dacromet technology is not only have advantage of chromium-dacromet technology, but also from paint preparation, coating, film, coating itself is completely free of hexavalent chromium, the true sense of the realization of the green non-toxic harmless. From the environmental point of view, in the global scope of chrome free Dacromet instead of chrome dacromet general direction will not change, will bring a new round of anti-corrosion technology field of environmental revolution.