It's actually black polycoat, a powder coating. Mine is over 10 years old and wearing extremely well.
generic definition of powder coating - "typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin." The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint."
And if you do chip it or wear off a section, the metal is parkerized (zinc phosphate) underneath for major protection.
John