Anodize Specification 1

[jdsewell]

I have a Dassault Aviation general specification that references BF4/BF5 anodizing treatment. I've never heard of this. Its not mentioned in MIL-A-8625 and web searches are not giving me any information.
Has anyone encountered this?
Does this have a MIL-A-8625 equivalent?

 

[kenvlach]

As Dassault is a French company, it may be a type of anodizing defined within the French spec. NF A-91-450 (Décembre 1981) Traitement de surface des Métaux – Anodisation de l’alu et de ses alliages. Spécifications générales.
[“Anodizing of aluminum and its alloys – general specifications for anodic oxide coatings on aluminum.”]

Maybe contact Dassault

http://www.dassault-aviation.fr/index_gb.htm

directly
or the European Anodizing Association (EURAS) [I cannot locate, it may have morphed into the Association for European Surface Treatment on Aluminium , but the link I found

http://www.estal.ch/

seems dead].

If I had to guess, judging from the age of the spec. and its aircraft use, it might be chromic acid anodizing (MIL-A-8625F Type I, IB or IC)

http://www.anodizing.org/reference_guide.html

However, a wrong guess could be very expensive so here are some other places to try:
The European Aluminium Association

http://www.aluminium.org/extra/about/abouteaa.asp

Pechiney Aluminium

http://www.aluminium.org/extra/about/abouteaa.asp

Their anodized aluminum sales manager (for export) is
Marc Jobert
Sales manager - Export
33 04 76 97 21 00
33 04 76 97 21 05
bandoxal_bandoxal@pechiney.com

 

[kenvlach]

The Association for European Surface Treatment on Aluminium is at

http://www.estal.org/

However, their website only mentions sulfuric acid anodizing and painting as finishes for aluminum, not chromic acid anodizing.

 

[kenvlach]

The French anodizing specification AFNOR NF A91-450 is available for $46US (hard copy, 11 pages) from Global Engineering:

http://global.ihs.com/

 

[IRstuff]

The following documents mentions the BF4 and BF5 treatments as chromic anodize:

http://www.mecaprotec.fr/french/pdf/Homologations.pdf

http://www.arcs.ac.at/AMTT/reports/reportII-27.pdf

TTFN

 

[yates]

jdsewell

BF4 and BF5 are both oxalo-chromic anodisation operations (with slighly varying compositions and bath temperatures) They are described in Dassault spec. CR 0.4.2.27. Four further companies in France are approved by Dassault for this process, aside from the first link IRstuff provided you.