Powder coating is applied via electrostatic gun & will generally be around the 60 - 100 microns in thickness. Think of it as a plastic coating which is applied as a dry powder & fused/melted in an oven generally 30 mins at around 200 - 230 C.
There are various hybrid powder coats around but the main one used will be polyester. Once cured it will be as hard as it will ever get & is always vulnerable to chipping dut to the film thickness & it is a coating always under stress (glass like).
For best performance, the substrate metal should be shot blasted to clean & roughen the surface as a good key base, followed by a suitable chemical cleaning/pre-treatment to help the powder bond better.