Chromium coatings from trivalent chromium plating baths: Characterization and cathodic delamination behaviour

Highlights: • Electrodeposition from Cr³⁺ electrolytes results in a complex structure and composition. • The electrodeposited oxide is amorphous and deficient in oxygen. • The amorphous oxide shows significant inhibition of electron transfer compared to native oxide on chromium. • The cathodic delamination performance is comparable to the electrodeposits from Cr⁺⁶ electrolytes. Novel two-layer chromium-based coatings comprised of a first layer containing chromium, oxygen and carbon (Cr-O-C) and an oxygen rich (Cr-O) topcoat were electrodeposited from trivalent chromium electrolyte. The complex structure and composition of the coatings were studied using complementary characterization techniques. The electrodeposited oxide was found to be amorphous and oxygen-deficient. In operando ambient pressure X-ray photoelectron spectroscopy when heating the sample from room temperature to 450 °C and Raman spectroscopy after the heating ascertained the metastable nature of the oxide. The cathodic delamination of a weak model polymer on these samples was studied using in situ scanning Kelvin probe.