Zinc-phosphating before painting
For surface treatment before painting by the cataphoretic primer, liquid or powder paint and varnish materials it is applied the technology of generation of zinc-phosphate layer on the surface of metal, that consists of the following technological operations:
- Degreasing
- Activation
- Zinc-phosphating
- Passivation (it is optional if there are the technological stage and/or heightened requirements for the corrosion resistance)
Degreasing
The degreasing stage is required to remove rust-preventing and/or technological lubricants and other types of contamination.
Activation
Surface activation is the essential stage, that provides generation of the uniform, fine-crystalline, dense coating.
Zinc-phosphating
There are 2 types of materials for zinc-phosphating - for spray and immersion application.
Materials for zinc-phosphating can be also divided on:
- traditional three-cationic
- with low content of nickel
- nickel-free
Passivation (optional)
In case if there are heightened requirements to the corrosion protection of the finished product, it is possible to apply chrome-free passivators. Application of these materials compacts the zinc-phosphate layer, additionally providing 100-150 hours of corrosion resistance in comparison with resistance of zinc-phosphate - paint and lacquer coating system without passivation.
Corrosion resistance of zinc-phosphate - paint and lacquer coating system
In case of zinc-phosphating application the corrosion resistance amounts not less than 720 hours in salt-fog chamber and, applying special immersion materials for zinc-phosphating and special cataphoretic primers, it is possible to reach the corrosion resistance up to 1500 hours in salt-fog chamber.
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