-- The Home Page of the Finishing Industry

on this site
current topics

60,000 Q&A topics -- Education, Aloha, & Fun

topic 8127

Hardcoat Anodizing of Aluminum Diecastings


What is the actual process of Black Oxide or hardcoat anodizing? Where can I get a procedure or standard for hardcoat anodizing of al diecastings?


Wendell Goodson


Black Oxide is different than Hardcoat. Black Oxide (or chemical blacking) is a common treatment on steels and is essentially rust. It affords no real protection and basically colours the base metal. I've never heard of being able to do this in non ferritic metals...

I once specified black oxide for a part made of plain carbon steel and within a month, sitting on my desk in an air-conditioned office, rust had started to form! I then specified black zinc for the same part and found it to afford good protection though it was not as black as the black oxide part.

Hardcoat anodizing leaves a good, thick finish (~.002) on aluminum. I've used this process successfully on sliding parts but I have found that it is prone to chipping around corners. I've also heard of (but have no experience with) a teflon hardcoat for aluminum.

J. Scott Clinton
- Philadelphia, Pennsylvania

adv.   accurate anodizing banner   

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental Compliance

©1995-2020, Inc., Pine Beach, NJ   -   About   -  Privacy Policy
How Google uses data when you visit this site.