Summary for sulfuric acid anodize Discussion
Sulfuric acid anodize is discussed in the context of aerospace use and military specifications. Ted Mooney, P.E. points out that MIL-DTL-81706 applies to conversion coating, not anodizing, and says the correct specification is MIL-A-8625. Terry Lycans of an aerospace firm adds that sulfuric acid anodize is used in many of their products, more often than chromic acid anodize, even though the parts are not structural. He notes that these parts still see great stress in flight, suggesting the process is used in demanding service. The thread therefore centers on identifying the right spec and confirming that sulfuric acid anodize is a common aerospace finish for stressed but non-structural components.
NEEDING INFORMATION ON SETTING UP SULFURIC ACID ANODIZING SYSTEM PER MIL SPECS, POSSIBLE. BOOKS THAT MIGHT BE AVAILABLE.DO I USE DE-IONIZED WATER PRIOR TO BATH SOLUTION AND AFTER
THOMAS DIXON
AEROSPACE FABRICATION/PLATING MANAGER – BIRMINGHAM, AL, USA
December 19, 2008
A. Hi, Thomas. An applicable spec is
MIL-C-81706^MIL-A-8625. An easy book is
Robert Probert’s “Aluminum How-To”. The comprehensive book is
“The Surface Treatment of Aluminum and Its Alloys”. A typical process is alkaline clean, etch, desmut, anodize, seal. Deionized water is almost always a good idea.
Hopefully you realize that on many aerospace parts sulfuric acid anodizing cannot be used because of reduced fatigue strength and the danger of acid bleedout after processing. Good luck.
Regards,
Ted Mooney, P.E.
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December 2008
A. MIL-DTL-81706 deals with conversion coating (not anodizing). The MIL spec you seek is MIL-A-8625.
We are an aerospace firm and employ sulfuric acid anodize in many of our products (more often than chromic acid even). Our parts are not structural, but are subjected to great stress while in flight.
Terry Lycans
Aerospace – Dayton, Ohio, USA
December 19, 2008
Thanks for the corrections, Terry.
Regards,
Ted Mooney, P.E.
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