plating, anodizing, & finishing Q&As since 1989
Can a part be black hard anodised after chemical film finish ?
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 [affil. link or DLA] , Type III, Class 2. Is this doable. Isn't chemical film coated surface enhances adhesion of subsequent coatings
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
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
Second of two simultaneous responses -- 2003
Somewhere you are missing the Masking indication. This is a common call-out in the industry.Bill Grayson
- Santa Cruz, California