The Effect of Mercury and Tin from Aluminum Galvanic Anodes on the Corrosion Characteristics of 5086-H34and 6061-T6Aluminum Alloys in Seawater.

摘要

Corrosion behavior studies were conducted in seawater for 696days. There were no indications that corrosion products from either the Al-Hg-Zn or the Al-Sn-Zn galvanic anodes caused increased corrosion. Neither Hg nor Sn was found,by electron microprobe analysis,at corroded areas. The electron microprobe did reveal that the most severe localized corrosion occurred where copper,the source of which was unknown,had redeposited on the structural aluminum specimens. Cathodic protection from either the Al-Hg-Zn or the Al-Sn-Zn anodes virtually eliminated corrosion on the 5086-H34and 6061-T6aluminum specimens that were either continuously or alternately immersed in seawater,except for slight corrosion under some of the anodes. As expected,cathodic protection was only partially effective when it was provided for only the first 186days of the 696days of exposure. The slight corrosion and the buildup of bulky corrosion products between the anodes and the specimens confirmed the advisability of using some type of a barrier,such as zinc oxide paste or an organic coating,between aluminum anodes and the structure on which they are mounted. (Modified author abstract)