Posted on 2018-08-13 The principle of Dacromet surface treatment is to isolate the interaction between water, oxygen and iron to obtain a strong antiseptic effect. The principle is mainly the cooperation of three protection approaches.
Barrier effect: The flaky zinc and aluminum layers in the coating overlap on the surface of the steel to form the first protective layer, which hinders the corrosive medium such as water and oxygen from contacting the substrate, which plays the most direct isolation effect.
Passivation: In the process of coating treatment of chromic acid with zinc, aluminum powder and base metal Dacromet, the passivation film formed on the surface by chemical reaction, the passivation film is not prone to corrosion reaction, and also acts as a barrier. The action of corrosive media, together with the barrier effect, provides a two-layer defense that reinforces the effects of physical isolation.
Cathodic protection: This is the most important protective effect. As with the principle of the galvanized layer, cathodic protection is applied to the substrate at the chemical layer by sacrificing the anode.
On the one hand, these three kinds of protections insulate the corrosive effect of the corrosive medium on the steel. On the one hand, the substrate is electrically corroded, and it is no wonder that there are several times the protection effect of the traditional electroplating zinc.
Post time: Jan-13-2022