ELECTROLYTIC ZINC AND ZINC ALLOY COATINGS
Zinc and zinc alloy coatings consist on a layer deposited over a metal substrate by means of an electrolytic process. The electrolytic bath does not contain cyanide compounds.| ZINC COATINGS |
SYSTEM |
|
| Alkaline zinc plating + passivations |
Barrel |
Rack |
| Alkaline zinc-nickel + passivations |
Barrel |
Rack |
| Alkaline zinc-iron + passivations |
Barrel |
Rack |
| Alkaline zinc-cobalt + passivations |
Barrel |
Rack |
PASSIVATIONS
Corrosion resistance in salt spray test acc. to ASTM B117, DIN 50021 ISO 9227 with zinc layer thickness of 8 µm.
|
|
Passivation(*) |
Corrosion resistance (hours NSS) |
|
| White rust |
Red rust |
||
| Zinc |
Transparent |
6 |
72 |
| Black |
24 |
96 |
|
| Yellow |
72 |
144 |
|
| Olive green |
120 |
240 |
|
| Zinc-Iron |
Black |
120 |
400 |
| Zinc-Nickel |
Black |
120 |
400 |
| Yellow |
200 |
600 |
|
(*) The corrosion resistance of passivated layers can be improved by post-treatments like inorganic and organic sealers (JS 500, Finigard, etc.), which also provide temperature resistance to 120 ºC. To reduce the coefficient of friction dry lubricants can be applied over passivated surfaces (such as Torque´n Tension Fluid, Merwin, etc.) to obtain µm= 0,08-0,14 for fasteners.
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