TECHNICAL ARTICLES / RESOURCES
ZINC PLATING
ZINC Plating is widely employed for providing sacrificial protection to steel. Being electronegative to iron, meaning that the zinc will corrode preferentially to the underlying metal, zinc plating gives excellent corrosion resistance to iron and steel components, particularly in industrial and urban environments.
ZINC Plating provides an attractive finish with a relatively uniform thickness, which does not tend to fill up slots and screws holes or obliterate threads and other fine details of work. The coating can subsequently be passivated or dyed to further improve corrosion resistance or for part identification.
ZINC Plating also serves as an effective undercoat for powder coated and wet paints.
Corrosion Protection of Chromate Coatings
|
Type of Chromate
Clear (Bright Blue)
Iridescent Yellow
Olive Drab
Black |
Time to white salts on zinc plate
(salt spray test)
12 - 72 hours
72 - 250 hours
96 - 300 hours
12 - 150 hours |
Australian Standard for Zinc Electroplated Coatings
on Iron and Steel - AS 1789-1984
|
Service Condition
4
3
2
1 |
Classification Code
Fe / Zn 25c
Fe / Zn 12c
Fe / Zn 8c
Fe / Zn 5c |
Minimum Thickness
25 micron
12 micron
8 micron
5 micron |
Service Condition 4 is for exceptionally severe corrosion conditions such as marine parts, some exterior motor car and motor cycle components and those exposed to industrial atmospheres.
Service Condition 3 is for severe corrosive conditions such as washing machine components and moderate outdoor exposures such as bicycle parts and some exterior motor car components.
Service Condition 2 is for moderate corrosive conditions such as indoor conditions where condensation may occur.
Service Condition 1 is for mild, dry indoor conditions
The letter c indicates that a chromate treatment is to be applied.
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