Both have good abrasion resistance and corrosion protection, I reckon that they should be able to be purchased in Black. Hope this helps. Depending on the end use and the preparation prior to coating an epoxy powder coating should be ok. They are tough,offer corrosion protection and come in all colours. Most industrial coaters will be able to paint the object.
More info is definitely necessary to formulate a proper coating system.
Actual service condition and intended service life is what I'd really need to proceed with a recommendation. Kevin A. Schweikhart, CSI CDT Senior Professional SSPC Protective Coatings Specialist NACE Certified Coating Inspector LAW Engineering and Environmental Services, Inc. I had about the same situation at one time, and what we did was galvanize the material, and the painted over the galvanize with an epoxy paint. If the metal is blast cleaned to SSPC-SP10, you should be able to keep it coated and protected for many years. The only problem with the zinc is it's affinity to lead, so you really need to be careful with the application process of the primer.