Most modern magnesium high pressure die castings are not generally used with surface protection, but the high performance magnesium sand castings are often used in the aerospace industry, where surface protection is likely to be added, following aerospace specifications.
The modern magnesium high pressure die castings are made using the high purity, corrosion resistant alloys such as Elektron ® AZ91D, Elektron ® AM50 or Elektron ® AM60. The high purity of the alloy means that the surface protection of the magnesium die castings is not usually needed. The high purity, high performance magnesium sand casting alloys, such as Elektron ® RZ5 (ZE41) , Elektron ® 21, Elektron ® WE43 or Elektron ® WE54 are frequently used in aerospace applications, where severe environmental conditions, coupled with historical aerospace specifications often means surface protection of magnesium components is employed.
Outside the aerospace industry, for applications within a fairly severe environment, high performance sand casting alloys such as Elektron ® 21, Elektron ® RZ5 (ZE41), Elektron ® WE43 and Elektron ® WE54 are often used with a light chromate treatment prior to painting. It is also common for no surface protection at all to be used.
For decorative effect, magnesium components can be subjected to similar treatments to steel or aluminium components. However, care should be taken with slight differences in reactivity and adhesion levels. Chrome plating of magnesium is possible, but because the chrome layer will be slightly porous, consideration must be given to galvanic corrosion.
For surface protection of magnesium components used in severe environments, anodising treatments are most popular. Older treatments such as DOW 17 and HAE are still used, whilst more modern treatments such as Tagnite, MagOxid and Keronite are becoming more common. All anodising treatments must be supplemented with a surface seal treatment before painting to stop any potential 'creep' of corrosion between the component and treatment whilst in service.
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