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Magnesium machined part surface treatment

I have selected Magnesium AZ31B for the material of a spacer to interface with aluminum parts in an optic assembly. Does anyone have experience with Magnesium and if so will you recommend a surface treatment?

The aluminum parts are being anodized. I am not requiring hard anodize at this time. Is there a known problem with the aluminum/magnesium interface? A minimum clearance diameter register is proposed to provide means for centration.

Jim Harper
- Tucson, Arizona, USA
2006

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There are many treatments for magnesium and it depends on your design requirements, whether you want hardness, corrosion resistance, anti-wear properties or a key for painting.

Many of the treatments can be found in SAE-AMSM3171 (the superceding document to MIL-M-3171 ) such as chemical conversion coating (also called chromating in the UK) and DOW 17 anodising.

There are also numerous commercial anodising solutions such as HAE anodising, Tagnite, Tiodize and Keronite. Each has benefits and disadvantages and you need to weigh up what properties you want and what you can afford to lose.

As for compatibility with anodised aluminium, there shouldn't be a problem but it is always worth testing to make sure.

Hope this gives you some ideas.

Brian Terry
Aerospace - Yeovil, Somerset, UK
2006