If you truly want a finish that will take REAL WORLD abuse then there is only one process that really measures up.
Vapor Deposition. Take a moment to look up MMI (Molecular Metalurgy Inc.) in Southern California. The guy's name is Nathan.
Vapor Deposition is a process where various elements are introduced into a vacuum and then electrically deposited onto a surface. This results in a very very thin film layer that is permanently bonded to the substrate. Typically the blend is Titanium Aluminum Nitride and that results in a charcoal finish. There are many options though when it comes to colors and surface finishes.
Surfaces hardness is around 96 Rockwell C scale, it is corrosion PROOF.
This is the same process that's done on carbide tooling used in CNC equipment, Kershaw knives, drills, etc.
It's not the most affordable option, but if you want it to last and want it tough then it is the ONLY option.
Good luck.
Chad