The mechanism of electrodeposition of chromium coatings with different phase structure

Study of chromium phase structure and the surface composition of chromium deposited by pulsed current has shown that when the hcp structure forms, the thickness of oxy-hydroxide Cr(III) compounds film increases on the deposit surface. Increase of this film thickness over some value (about 100 Angstrom) results in maintenance of the hydride CrH as the first stage of chromium crystallization. Study of the phase structure of chromium from solutions with formic acid has shown that formation of the hcp structure is promoted by oxidation of the organic additive by chromic acid (i.e., by increasing the Cr(In) concentration in the solution and by decreasing its acidity). This intensifies the formation of oxy-hydroxide Cr(III) compounds on the chromium surface during electrolysis.