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To study electrocatalytic properties of chromium, its deposits are obtained from Cr(III) electrolytes containing formic acid and its four derivatives (formaldehyde, methyl alcohol, formamide, dimethylformamide) and comprehensively examined. Amorphous structure of the deposits is established with an x-ray diffraction analysis. The valence state of chromium and major extrinsic elements is studied by x-ray photoelectron spectroscopy. The carbon reduction degree and the organization of carbon particles in deep layers of the deposits (chainlike or graphite-like structures) is shown to depend on the nature of organic compounds added into the chromium-plating electrolyte. The corrosion–electrochemical behavior of the obtained deposits in 0.5 M H2SO4 is compared to that of polycrystalline chromium and deposits plated from sulfate–oxalate Cr(III) electrolytes. [ABSTRACT FROM AUTHOR]

The hydrogen content in electroplated chromium layers and multilayer nickel–chromium coatings applied by periodic current from sulfate–oxalate baths is discussed. Chromium electroplating at periodic and pulsed currents is found to increase the hydrogen content to 54 cm3 /g as compared with 24 cm3 /g for chromium deposits obtained in a direct-current mode. The hydrogen content in multilayer Ni–Cr coatings is found to be substantially lower. As shown by mass-spectrometric studies, hydrogen preferentially absorbs in chromium layers. The peculiarities of concurrent hydrogen evolution and chromium deposition giving supersaturated solid solutions are discussed. [ABSTRACT FROM AUTHOR]