Zinc Coating

Green Coat- Advanced Coating Technologies / Zinc Coating
The Zinc coating provides a smooth look as well as good anti-corrosive protection.

Iron metals rust relative quickly, even in a non-corrosive environment.

The rust not only harms the aesthetically smooth look, but also its mechanic needs.
The Zinc coating provides a smooth look as well as good anti-corrosive protection.

Our Zinc coating is carried out according to:
ASTM B-633 ELECTRODEPOSITED COATINGS OF ZINC ON IRON AND STEEL.


The coating is made according to demand, where the distribution is as follows:
 

Class  Demand  Service Condition  Minimal thickness in microns
I  Fe/Zn25  SC4{very severe}  25 micron
II  Fe/Zn12 SC3{ severe}  12 micron
III Fe/Zn8 SC2{moderate} 8 micron 
IV Fe/Zn5 SC4{mild} 5 micron


The Zinc coating on the steel does not last shiny for long, and so a further thick layer coating is added, called passivation. There are different passivation colors: shiny blue- white, colorful-yellow, black and olive green.


The type of passivation is determined according to the required characteristics, and is divided into groups:

Type Description Corrosion Resistance
according to ASTM B117 		 Remarks
Type I Zinc coating with no additional treatment NA Usually non applicable
Type II     Zinc coating with colorful chromate passivation 96 hours
48 hours
160 hours		 Yellow-iridescent
Black
Olive Green
 
Type III Zinc coating with colorless chromate passivation 12 hours Colorless to blue
Type IV  Zinc coating with phosphate passivation NA NA in GREEN COAT
Type V  Zinc coating with colorless RoHS compliance passivation  72 hours
 		  Colorless to blue
Type VI Zinc coating with colorful RoHS compliance passivation 120 hours Yellow-iridescent
Black

 

Coating characteristics and usage

 

1. Corrosion resistance

Colorful chromate passivation gives corrosion resistance ability of 96 hours according to ASTM B117 until white spots-intended to parts used in a high corrosive environment –outdoor.
Colorful RoHS compliance passivation gives corrosion resistance ability of 120 hours according to ASTM B117 until white spots-also intended to parts used in a high corrosive environment –outdoor. Available colors are iridescent and black
Colorless chromate passivation gives corrosion resistance ability of 12 hours according to ASTM B117 until white spots-intended to parts used in a light corrosive environment –indoor.
Colorless RoHS compliance passivation gives corrosion resistance ability of 72 hours according to ASTM B117 until white spots-also intended to parts used in a high corrosive environment –outdoor.
Olive green passivation is a chromate passivation in a green hue that gives excellent corrosion resistance ability -160 hours in a salt spray test and is a good base for paint. The electrical resistance of this green layer passivation is very high because it is thick in relative to other passivations
 

2. Decorative charastreistics

The exterior visual determined according to last layer.
The black layer has also additional target –prevention of light reflection from the part and is used for optical parts.

 

3. Electrical charasteristics

As much as the last layer of the passivation is thin the electrical resistivity is low.
Olive green and Black passivation is thick and has high electrical resistance.
Iridescent and Colorless passivation is thin and has low electrical resistance.