For those thinking of powder coating things like calipers and wheels, I found this on the net:
from
http://my.execpc.com/~davewrit/Powder.html
"A metallurgist friend told me a few years ago that things like aluminum wheel spindles should not be powder coated. He explained that aluminum billet material (6061-T6 ?) changed crystal structure at a critical temperature around 410 degrees F (as I recall). The thrust was that the heating step would adversely affect the strength of the material. Non-structural components would be OK, but not something that "holds the spokes on". The metallurgist is correct. Products like wheel billets, scuba tanks, etc. can be powder coated, but only with powders which cure below peak metal temperature of 300 degrees F. The magic temperature is about 275F. The crystalline realignment at 400 degrees F causes the previous ductile aluminum to become brittle. Imagine the catastrophe when an 80 cu. ft. scuba tank explodes under 3000 psi pressure after an unauthorized powder coat (this actually happened). To my knowledge, all Aluminum wheels and other strength-critical aluminum components are powder coated with these cooler curing powders. "
Sherwood