System and method of coating an automotive part with iron oxide for an electric drive unit of a vehicle

A system for coating an automotive part with iron oxide for an electric drive unit of a vehicle, the system comprising:

• an automotive part comprising a body having an outer surface, the part comprising steel;
• an introducer mechanism arranged to suspend the part in an aqueous coating solution comprising sodium metabisulfite, an ionic surfactant, and citric acid to chemically activate the outer surface of the part defining a sample-water interface;
• and
• an ultrasonic mechanism arranged to emit ultrasonic waves in the coating solution to generate acoustic cavitation activity at the sample-water interface and continuously form oxygen and hydrogen species from residual oxides, the citric acid arranged to chemically activate the outer surface and to allow a reaction with the oxygen and hydrogen species to form iron hydroxide, the sodium metabisulfite arranged to react with the iron hydroxide and generate iron oxysulfide on the outer surface such that the iron oxysulfide reacts with the oxygen and hydrogen species producing iron oxide and iron sulfide on the outer surface to define a black oxide coating having iron sulfide platelets disposed thereon.