hat Niobium is not as hard as titanium.
The black finish on Titanium is called PVD coating (vaporised tungsten), they use it to coat pace makers, so that is extremely hard wearing.
Titanium used in the medical industry isn't pure Titanium that was what I was referring to as being an alloy.
The bridge on your Explorer will probably be made from Nickel. I would contact a plater (look 'em up in the yellow pages) to discuss how to remove/add new plating.
Chemical anodizing would be the way to go with that, it’s what motorbike parts, and the like are coated with.