This black coating agent is suitable for alkaline electroplating, and can be used on large workpieces for passivation without rainbow color or flow marks. The salt spray test can last for 96-240 hours. The coating has a nearly interference-free black appearance, and its corrosion resistance (salt water spray test) is comparable to that of hexavalent chromium phosphate black coatings. It does not contain any hexavalent chromium and is a trivalent chromium black coating agent specifically for galvanized materials. The wastewater treatment is simple and only requires general neutralization treatment.
