The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Protecting Aluminum From Steam

February 11, 2010

I have designed a steam turbine to be made out of aluminum, but unfortunatly aluminum corrodes in this environment.

I have some 6061, 7075, and 2024 I need to protect from steam at 150C (302F). What is the best way to do this? If I strip the oxide, and paint it with BBQ paint, how long will the paint last?

Are there any additives which can be added to the boiler water, to make the steam less corrosive?


sincerely,

Brendan Murphy
product designer - London, Ontario, Canada

---

Dear Sir:

I don't know as you don't provide dimensions for this turbines, but if this turbines may fit in a submersion tank, you can try Aluminum Anodizing Type 1 (Chromic Acid Anodizing). Parts treated with this process can withstand 1,000+ hours Salt Spray Test with no sign of corrosion or Decay. Also can Try Type 3 (Hard Coat Anodizing) which is very durable for extreme wear and corrosion environments. But I strongly recommend Anodizing Type 1, we have tried before for boat parts, high humidity and salt corrosive environments and the results are excellent resistance to this environments effects on the aluminum parts. There are lots of companies that can help you on this. Good Luck

Julio Nazario
- San German, Puerto Rico
February 17, 2010

I doubt anything cheap will work. Steam not only attacks blades by corrosion, it may also act as a blasting media at high speeds. You will probably have to look into HVOF coatings or suitable platings such as high ductility nickel, either straight or alloyed. Perhaps you could have a chance with sprayed teflon like the one used for frying pans.

Guillermo Marrufo
Monterrey, NL, Mexico
February 23, 2010