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[Gray Mason]

Hi there, my project is a CNC machined enclosure in 6061-T6 aluminum for an avionics module that’ll be mounted in a wing compartment exposed to temperature swings, some humidity, but not direct salt spray. I’m leaning toward Alodine (Chemfilm) for corrosion protection, mainly to keep electrical conductivity and avoid adding much thickness. I’ve used anodizing before but it’s not ideal here due to grounding and fitment issues. Curious if Alodine holds up well enough long-term or if I’m overlooking better alternatives.

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[Robert400]

Well, it sounds like you’re on the right track here, I can’t fault your approach. Alodine is a very good option, specifically because it maintains electrical conductivity, which anodizing doesn’t. You should be in the clear on the reduced wear resistance (of Alodine compared to anodizing) as the enclosure shouldn’t see much wear at all. So I don’t see any concerns.

Just a note on alodine though, use the type 2 rather than the original type 1, as the type 2 is free of toxic hexavalent chromium and uses trivalent chromium instead. Depending on the brand you buy, this type 2 product will have different names but just check to be sure that it doesn’t contain hex chrome.

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[jeromeb]

I agree with the above comment, alodine is great to use here. Although there are some chrome-free chemical coating alternatives, I don’t think that they’d be better suited to your application.

The great thing about alodine is that you can still paint over it with something else if you want to add a further protective coating against mechanical wear.

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