Thread 215/72

Can a part be black hard anodised after chemical film finish ?

2003

I have a part of material Aluminium alloy 7075-T651. It has called for chemical film finishing followed by hard black anodise per MIL-A-8625 / MIL-PRF-8625 [⇦ this spec on DLA], Type III, Class 2. Is this doable. Isn't chemical film coated surface enhances adhesion of subsequent coatings

Thanks,

Nelson Toh
- SINGAPORE
publicly reply to Nelson Toh

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You cannot apply a controlled oxide coating over a chromate conversion coating, Period. However, maybe your customer wants chromate on part of the surface and hard coat on the other. Such a combination is a frequent call out. This is done by various different kinds of masking.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003
publicly reply to Robert H Probert

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First of two simultaneous responses -- 2003

You may be able to do both process on a same part. Try the following process : Pretreatment - Masked the surface for Chemfilm - HardCoat - Seal at boil using nickel acetate sealant - Remove Maskant -Chemfilm.

Good Luck,

S. Y. Yuen
- Hong Kong, China
publicly reply to S. Y. Yuen

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Second of two simultaneous responses --

Somewhere you are missing the Masking indication. This is a common call-out in the industry.

Bill Grayson
- Santa Cruz, California
2003
publicly reply to Bill Grayson

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