Does Aluminum Allodine 1200 Outgas in High Vacuum?

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SUMMARY

Allodine 1200, a chromate conversion coating for aluminum, does not have established data regarding its outgassing behavior in high vacuum conditions. This treatment involves the chemical deposition of CrO3 on aluminum surfaces, providing significant corrosion resistance, including over 300 hours of salt spray resistance per ASTM-B117 standards. However, due to the presence of hexavalent chromium in Type I coatings, alternative surface treatments are recommended for high vacuum applications. MIL specifications indicate that low-temperature applications are not advisable for this coating.

PREREQUISITES
  • Understanding of chromate conversion coatings
  • Familiarity with aluminum surface treatments
  • Knowledge of ASTM-B117 testing standards
  • Awareness of hexavalent chromium regulations
NEXT STEPS
  • Research alternative aluminum surface treatments suitable for high vacuum environments
  • Investigate the properties and applications of Type II conversion coatings
  • Study the implications of hexavalent chromium in surface treatments
  • Explore MIL specifications related to aluminum coatings and vacuum applications
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Materials engineers, aerospace professionals, and anyone involved in the treatment of aluminum surfaces for high vacuum applications will benefit from this discussion.

vanesch
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I have a question: does anyone know whether the aluminum surface treatment Allodine 1200 can give rise to outgassing when used in high vacuum conditions ? As I understand it, it is a chemical deposition of CrO3 on the Al surface.
 
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Chromate conversion film on aluminum has very high corrosion resistance - e.g., salt spray resistance (provides 300+ hours resistance - ASTM-B117 I think), and in normal applications it is not recommended to be left unfinished. And yes, it is hexavalent Chromium.

I've never seen anything on chromate conversion films and high vacuum applications.
Unless you need corrosion resistant aluminum, consider another surface film treatment.
 
The MIL specs I deal with do not list anything except the application at low temps is not recommended. I'll hit up some of our materials folks to see if they know of anything about vacuum conditions.

By the way, Type II conversion coating does not contain hexavalent chromium, Type I does.
 

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