Oxidation of Cr–C electroplating between 400 and 900 °C in air

The high temperature oxidation of Cr–C electroplated on a steel substrate was studied at 400–900 °C in air. Before oxidation, the deposit consisted primarily of C‐supersaturated, amorphous Cr grains. During oxidation, oxygen diffused inward, while Cr and the substrate elements such as Fe diffused outward. Carbon tended to escape, but some of it remained and existed mainly as graphite throughout the oxide layer and the Cr–C electrodeposit. A Cr 2 O 3 oxide layer having dissolved Fe ions formed on the unoxidized, crystalline Cr layer. The Cr–C electrodeposit oxidized approximately parabolically, with a faster oxidation rate than bulk Cr.