[RV7Guy]

Aviation related but not directly RV's.

Does standard color anodizing (not hard anodizing) change the structural characteristics of the aluminum?

Thanks in advance.

 

[Guy Prevost]

Yes.

Anodizing converts the outer layer of aluminum to aluminum oxide, or alumina, which is a ceramic. This provides a nice non-conductive wear resistant layer that protects the aluminum from further corrosion. Another benefit is that you can dye this layer of oxide. The downside is that you reduce the fatigue life of the part. It's all a trade off.

 

[RV6AussieNick]

Hard Anodising or Chromic anodising is mostly used for a more robust corrosion prevention unfortunately it cant be coloured (dyed) it's a light grey colour following the anodising process.

Sulphuric anodising is mainly used for decorative coatings it can be coloured by dipping the anodised part in a dye, from memory you can choose from Red, Blue and yellow and Grey.

To answer your question, Anodising has a minimal effect of strength, the layer of anodised coating isn't very thick, less than .001" for Sulphuric Anodising and between .001-.002" for Chromic (Hard) Anodising.

Hope that helps,

 

[az_gila]

The Mil-Spec...

...and I'm sure the equivalent commercial specifications, allow the hard anodising (called anodic, not chromic) to be dyed.

Hard black anodising is common, and called out as

Type III, Class 2

http://www.anodizing.org/Publications/bulletin_3.html

http://www.everyspec.com/MIL-SPECS/MIL+SPECS+(MIL-A)/download.php?spec=MIL-A-8625F.002377.pdf

If you want non-decorative, but hard wearing, this is probably what you need.
The 0.002 build-up of thickness may affect small tapped holes or other close fits.

Hard Anodising or Chromic anodising is mostly used for a more robust corrosion prevention unfortunately it cant be coloured (dyed) it's a light grey colour following the anodising process.

Sulphuric anodising is mainly used for decorative coatings it can be coloured by dipping the anodised part in a dye, from memory you can choose from Red, Blue and yellow and Grey.

To answer your question, Anodising has a minimal effect of strength, the layer of anodised coating isn't very thick, less than .001" for Sulphuric Anodising and between .001-.002" for Chromic (Hard) Anodising.

Hope that helps,