| 配方類型： |
METALS AND THEIR TREATMENT |
| 配方說明： |
Platinum-Plating Baths |
| 配方組成： |
Since platinum deposits are used mostly for ornamental purposes and
as flash plates, for reasons of economy, it has become common practice
to use a nickel undercoat. This is necessary whenever lead, tin, or zinc
alloy articles are to be plated. when heavier than flash deposits of
platinum are applied, they must be scratch brushed intermittently.
The oldest and most widely used platinum-plating solution is based on a
chloroplatinic acid solution. A solution of this type recommen |
| 配制方法： |
This solution is operated close to the boiling temperature at a current density of 5 to 10 amp. per sq. ft. Bright flash deposits can be obtained in 30 to 120 seconds; later the deposit turns cloudy and finaly dull gray.
Another type of plating bath, based on the same formula, uses platinum diaminonitrite instead of the chloride. The bath has a longer useful life since no chlorides are introduced on replenishing the platinum content. An improvement** on this bath is said to consist of 100 g. per liter ammonium nitrate, 10 g. per liter sodium nitrite, 16.5 g. per liter of platinum diaminonitrite, and 50 g. per liter of 28% ammonium hydroxide solution. A more recently proposed platinum-plating bath*** represents a combination of the phosphate and aminonitrite. It contains 100 g. per liter disodium phospahte, 20 g. per liter diammonium phosphate, and 6.5 g. per liter diaminoplatinous nitrite.
**trans. Electrochem. Soc., 59, 273 (1931).
***Blum and Hogaboom, Principles of Electroplating and Electro |
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