1) Cyanide galvanized: divided into high cyanide galvanized, medium cyanide galvanized, low cyanide galvanized;
2) Acid zinc plating: sulfate zinc plating, weak acid potassium chloride zinc plating, ammonia triacetic acid-ammonium chloride zinc plating;
3) Alkaline cyanide-free zincate zinc plating.
Types of zinc passivation
1) Galvanized white passivation;
2) Galvanized blue-white passivation;
3) Galvanized color passivation; (generally refers to color passivation when not noted)
4) Galvanized military green passivation;
5) Galvanized black passivated.
According to the components in the passivation solution, it is divided into: trivalent chromium passivation and hexavalent chromium passivation. The passivation treatment of the galvanized layer is basically chromate, which generates colorful zinc-chromium compound salt, which makes the surface passivated. The chromic acid concentration used in the early passivation solution is very high, and the obtained passivation film has good corrosion resistance and beautiful color. This passivation solution containing high concentration of chromic acid is called high chromium passivation, but Since chromic acid is a serious source of environmental pollution, it has been a restricted chemical for a long time, so a low-concentration passivation solution has been developed, and the chromic acid per liter is only about 5 grams. After the use of chromates was more strictly controlled, trivalent chromium passivation with relatively low toxicity became popular, but now chromium-containing passivation films have been included in the banned list, so passivation without chromium salts has been developed. This is a passivation process that replaces chromate with titanium salts, silicates, molybdenum salts, etc., which is called chromium-free passivation.