Typically, any metal object that can hold the electrostatic charge needed to affix the sprayed powder and can tolerate the high heat levels of the curing process. Mild steel, galvanized and electroplated steel, aluminium, stainless steel and most other steel alloys can be powder coated.
If you want your old motorcycle or car engine parts looking new then powder coating is the answer. Powder coated surfaces are better than painted finishes especially when it comes to harsh conditions .For example, brake fluid would stain a painted finish however, comparatively, since a powder coat finish is a chemical resistant finish, the brake fluid would leave no damage.
A painted finish is more likely to chip or wear over its lifetime on the road. Painted parts look great when first finished, but only powder coated finishes will retain most of its original lustre over time.
Powder coatings are more durable and more resistant to corrosion, chemicals and weather than liquid coatings