The anodic treatment of aluminum Plating-Polishing-Finishing, Feb. 1932.
✍ Scribed by T.K.C.
- Publisher
- Elsevier Science
- Year
- 1932
- Tongue
- English
- Weight
- 49 KB
- Volume
- 213
- Category
- Article
- ISSN
- 0016-0032
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✦ Synopsis
The Anodic Treatment of Feb. I932.) Aluminum and its alloys are especially desirable in the fabrication of machinery and apparatus where comparative lightness is desired. Against these attractive features is set the fact that the metal is relatively susceptible to corrosion especially by salt spray and dilute solutions of acids and alkalies. This so-called anode treatment of aluminum results in the formation of a dense deposit of aluminum oxide over the surface of the metal and the coating varies from three to five hundred-thousandths of an inch in thickness.
The details of the process are given by Edwin Joyce who states that the aluminum or aluminum alloy is immersed in a tank of chromic acid solution. While thus immersed an electric current is passed through the solution, the aluminum serving as the anode. As is well known, oxidation tends to occur at this point while at the other electrode, the cathode, hydrogen instead of oxygen is liberated and a reducing action occurs. The concentration of chromic acid may vary from 3 to Io per cent. and the current density from 2 to Ioo amperes per square foot depending upon the type of alloy and its complexity of form. The treatment consumes about 60 minutes.
T. K. C.