Thick chromium electrodeposition from trivalent chromium bath containing carbamide and formic acid

Effect of bath composition and electrolysis conditions on the current efficiency, electroplating rate and surface morphology of Cr-coatings was studied using a trivalent chromium bath containing chromium sulfate, sodium sulfate, aluminium sulfate, boric acid, formic acid, carbamide and surfactant. The optimal concentrations of Cr(III)-ions, carbamide and formic acid were stated to be 1.0, 0.5 and 0.5 M, respectively. At optimal bath composition and electrolysis conditions, the deposition rate does not appreciably diminish during electrolysis time and reaches ≈1-1.5 μm min−1. The value of current efficiency of chromium electrodeposition process is close to ≈30-40%. The thick chromium coatings deposited from the bath under consideration are bright and smooth; they exhibit nodular type of surface structure.