Corrosion Protection of Magnesium and Magnesium Alloys

摘要

The memorandum deals with the corrosion protection of magnesium and magnesium alloys. The corrosion resistance of these alloys in many natural environments, while not as good as that of copper, nickel, stainless steel, and aluminum, is in the same range as that of the iron and plain carbon steels. Some type of additional corrosion protection is often necessary and, as with steel, the protective measures usually involve some type of coating system and/or surface treatments. Also, magnesium can suffer accelerated attack when coupled, in the presence of a conductive electrolyte, to most metals below it in the galvanic series. This galvanic effect complicates the problem of corrosion protection. A number of coating systems have been proposed and used satisfactorily. Depending upon the application, these coating systems include the use of conversion coatings, organic coatings, metallic coatings, and others. In addition, special designs can be employed to improve the overall corrosion resistance of the system. This memorandum describes many of the coating systems and design methods which are used to reduce corrosive attack on both galvanically coupled and uncoupled magnesium assemblies.