As a64pilot notes, you can powder coat over anodized aluminum.
However, some anodized surfaces do not work
well with powder, because they have inorganic dyes or other issues that make the surface incompatible with powder*.
In most cases for new anodized aluminum, a light sanding
of the surface and acetone wipe will suffice.
However, older anodized aluminum will most likely need abrasive blasting. You can then powder coat to color, put in the oven
for curing, then put in service
* I’ve read the suggestion to perform routine wet adhesion testing, as described in AAMA 2604 (126.96.36.199) and 2605 for anodized surfaces.
The surface is cross-hatched and subjected to boiling demineralized water
for 20 minutes. After removal
, a tape pull test can be used to confirm adhesion.
If this test is successful, the part should be good.
If it consistently fails, the anodizing process is not compatible with powder. If it fails periodically, the anodizing process needs more precise control, or the coater needs a better pretreatment process.
“How to Decide Between Anodizing, Painting, and Powder Coating”
Choosing the right coating for your Aluminum ➥ https://www.saf.com/how-to-specify/h...owder-coating/