Formation of chromium composite electrochemical coatings from sulfate oxalate solutions based on Cr(III)

The mechanism responsible for the inclusion of Al₂O₃ and SiC nanoparticles, the mixture of Nb₂N and Ta₂N (1: 1), MoS₂, Cr₂O₃, and SiO₂ with diverse electric conductivity, hydrophilicity, and resistance to solution components in chromium deposits from the sulfate–oxalate suspension solutions based on Cr(III) was studied. The main factors that determine the formation of chromium composite electrochemical coatings, their composition, and surface morphology were determined. The film on the surface of the growing deposit of the intermediates of the reduction of chromium ions plays the key role in the formation of composite coatings from Cr(III) and Cr(VI) sulfate–oxalate suspension solutions. The film can play the role of a structural mechanical barrier that hinders the incorporation of particles in the deposit, or it can fix the particles on the electrode surface by creating hydroxo bridges with chemisorbed hydroxide compounds on the particle surface.