The authoritative public forum
  for Metal Finishing since 1989
-----

Al 6061T6+Hardcoat anodizing+Saltwater fog= still not working

I am currently working on a project for a medication delivery application that requires plates of Al 6061-T6 in a saltwater spray/fog environment. They still corrode despite the fact that we are using hard-coat anodizing for corrosion resistance. Are there any other methods (subsequent or alternative) that can be used that will avert corrosion a little better than the current strategy?

Joe Bigalke
mechanical engineer I - Round Lake, IL, US
2004

---

Was the anodizing sealed? Was the corrosion examined using a magnifying glass or microscope? Is hard anodizing required for abrasion resistance? Try conventional anodizing (MIL-A-8625 / MIL-PRF-8625 [on DLA]F, Type II), sealed. For corrosion resistance, a thin, intact layer is better than a thick, "crazed" one (cracked from differential thermal expansion vs. the Al).

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2004

---

Hardcoat anodize should have very good corrosion resistance in a neutral salt fog environment. What is the pH of your system? Sealing, not normally done on hardcoat, will further improve corrosion resistance.

Chris Jurey, Past-President IHAA
Luke Engineering & Mfg. Co. Inc.

Wadsworth, Ohio

2004