In some passivation solution formulations, acids such as nitric acid, sulfuric acid, phosphoric acid, and acetic acid are added. The advantages include: facilitating the dissolution of chromates, accelerating the formation rate of the passivation film and the dissolution rate of zinc, activating hydrogen generation, accelerating the formation of the passivation film, and imparting a good gloss to the passivation film.
The disadvantages are: reducing the effective thickness of the pure zinc layer, roughening the surface galvanized zinc layer, and causing the appearance of yellow and red spots. The addition of acids is also unfavorable for the treatment of waste gas, waste water, and solid waste.
