Novel galvanizing and chrome-free passivating technology

Abstract

A novel galvanizing and chrome-free passivating technology is characterized in that passivating solution with the pH of 2.5 to 3.0 is used for passivating a zinc coating for 45 to 90 s at the temperature of 20 to 40 DEG C, so that a blue passive film can be obtained; and the corrosion resistance of the passive film is improved as the temperature (40 DEG C to 50 DEG C) of the passivating solution is increased and the processing time (100 s to 300 s) is prolonged. The novel galvanizing and chrome-free passivating technology can not only ensure the corrosion resistance of the surface coating of a product, but also solve the problem that the environment and operators are polluted by chrome during the galvanizing and passivating process.

Description

technical field [0001] The invention relates to a new chromium-free purification technology for galvanizing. Background technique [0002] As we all know, the galvanized layer on the surface of steel parts is an excellent sacrificial anodic coating, and the service life of steel parts can be effectively improved by the galvanized layer and the surface passivation treatment of the galvanized layer in the atmospheric environment. Therefore, galvanizing is one of the most commonly used electroplating processes for surface corrosion protection of parts. [0003] For the galvanized layer of parts, surface passivation is also required to effectively improve the corrosion resistance of the coating. The current passivation includes color, blue, black, etc. The passivation film on the surface effectively improves the surface decoration effect of the Zn coating and prolongs the time for the zinc coating to corrode and appear white rust. [0004] In the passivation solution of zinc p...

AI Technical Summary

Problems solved by technology

The passivation film layer formed by these inorganic corrosion inhibitors is relatively thin, and the corrosion resistance effect is not satisfactory, and most of them are in the research and experiment stage; the organic protective film layer is coated on the surface of the Zn layer to improve the corrosion resistance of the Zn layer Performance, is to use an insoluble shielding film formed by organic matter, thereby enhancing the corrosion resistance of the film, but the organic film layer is generally thicker than the chemical passivation film, poor weather resistance, non-conductive, etc.; Chromium galvanizing passivation process, although the toxicity of trivalent chromium galvanizing passivation has been greatly reduced, and the stability of the process can easily cause the hexavalent chromium content on the galvanized surface to exceed the standard