Electrodeposition of chromium-cobalt alloy from Cr(III) formate-urea electrolyte

To study the electrodeposition of Cr-Co alloy, as a possible alternative to the deposition of pure Cr, in particular from hexavalent Cr baths, Cr(III) formate-urea electrolyte containing various concentrations of CoCl(2) was used. The deposition rate, composition, phase state and structure of Cr-Co deposits were investigated. The data obtained suggest that the electrodeposition of Cr-Co alloy occurs under acceleration of Cr(III) and inhibition of Co(II) ions electroreductions. It was found that the presence of 1-2 g L(-1) CoCl(2) in Cr(III) bath has an optimum effect on the electrodeposition of the good quality thick (30 mm) Cr-Co alloy obtained. The X-ray diffraction data reveal that the Cr-Co alloy deposit has an X-ray amorphous structure with a grain size of similar to 1.3 nm. The morphology of the deposit shows a significant dependence of the nodular structure on the percentage of Co. X-ray photoemission spectroscopic spectra indicate the presence of oxide and metal phases for both metals in the top layers of as deposited Cr-Co alloy.