Xylan coating on 7075 Aluminum 3

[tdw]

I need a coating for 7075-t6 aluminum that can be applied at a temperature that won't degrade the properties of the aluminum.
The coating must;
1. Have a low (<.2 static coefficient of friction against UHMW.
2. be abrasion resistant.
3. be corrosion resistant.

What time/temp. does 7075-t6 aluminum start to anneal?

I've been thinking about Xylan 1010 (cures at 450F for 20 minutes), but I'm open to any suggestions.

 

[TVP]

Whitford's Engineering Design Guide recommends pretreating the aluminum surface by degreasing or alkaline wash, then grit blasting to 203 micrometer surface roughness, then apply coating. Cure would be 205-260 C. The coating could then be polished as a postreatment, in order to further reduce friction.

ASM HANDBOOK Volume 4 Heat Treating recommends that the maximum exposure time for 7075-T6 at 205 C to be 5-10 minutes. Longer durations at 205 C, or any temperature exposure greater than 205 C, will result in more strength degradation, due to overaging of the precipitates, not due to annealing (which is a separate phenomenon).

The loss in strength is probably not that significant, but you will need to make that determination. You may want to investigate a different coating system, one that may be cured at lower temperatures. I am not that familiar with MoS₂ coatings, but they may be able to be applied at lower temps. E/M may be a good place to look for more info, as they do a lot of different types of coatings, not just PTFE-based. Their website is

http://www.emcoatings.com/

.

 

[CoryPad]

How about anodizing plus an organic topcoat? That should meet all your requirements.

 

[tdw]

Because of the high temperataures involved in Xylan and Teflon coatings, I am now considering a Hardtuf-X20 anodize coating.