| 配方类型： |
METALS AND THEIR TREATMENT |
| 配方说明： |
Plating On Magnesium |
| 配方组成： |
Tetrasodium Pyrophosphate/16.00 oz. per gal.
Zinc Sulfate Monohydrate/4.00 oz. per gal.
Potassium Fluoride/0.94 oz. pr gal.
Potassium Carbonate/0.67 oz. per gal.
After application of the zinc immersion coating, the parts are
coated with a thin copper deposit in a Rochelle salt copper strike of
the following composition
60% Hydrofluoric Acid/1 fl. oz. per gal.
Temperature/75-180'F.
Mild agitation pH/10.0-10.6
Chromic Acid/37.5 oz. per gal.
Copper Cyanide/5.50 oz. per gal.
Sodium Cyanide/6.80 oz. per gal.
Sodium Carbonate/4.00 oz. per gal.
Phosphoric Acid/1.6 pt.
Rochelle Salt/6.00 oz. per gal.
Sodium Hydroxide/1.00 oz. per gal.
Free Cyanide/0.75 oz. per gal.
Temperature/120'F.
pH/10
Sodium, Potassium, or Ammonium Acid Fluoride/40/3 oz.
Temperature/70-90'F.
Concentrated Nitric Acid/3.25 oz. per gal. |
| 配制方法： |
Electrical contact is made as quickly as possible at a high current density of 30 amp. per sq. ft. for the first 30 seconds. The current density is then decreased to 20 amp. per sq. ft. for 5.5 minutes. This is necessary to cover the zinc immersion coating as quickly as possible to prevent its destruction by the copper cyanide solution.
A pyrophosphate-type copper solution is used for copper plating. The pyrophosphate bath is modified by the addition of 30 to 60 g. per liter of potassium fluoride, to minimize attack in the event of porosity in the strike or failure to cover. A minimum of 0.0008 inn. of copper is deposited in this solution operated at 130'F. for approximately 35 minutes at 25 amp. per sq. ft.
A Watts-type bright nickel solution, operating at a pH of 4.5, is used for nickel plating. The parts are plated with a minimum of 0.0002 in.
nickel, or for approximately 15 minutes at 25 amp. per sq. ft. The operating temperature is 130'F.
For chromium plating, a standard chromic acid |
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