Electrodeposition of Composite Chromium Coatings from Cr(III) Sulfate
Oxalate Solution Suspensions Containing Al2O3, SiC, Nb2N, and Ta2N Particles
N. A. Polyakov, Yu. M. Polukarov, and V. N. Kudryavtsev*
Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia
* Mendeleev University of Chemical Technology of Russia, Miusskaya pl. 9, A-47, Moscow, 125047 Russia
e-maol: grottopna@ mail.ru
Received November 1, 2008
Abstract — The effect of concentration and nature of particles (dielectric Al2O3, broadband semiconducive SiC, and conductive Nb2N and Ta2N) on the adhesion of particles to the surface of coatings and the composition of electrochemical composite coatings deposited from Cr(III) sulfate–oxalate solution suspensions of various concentrations is studied. Adding particles of any nature to the solution does not affect the character of the formation of an X
ray amorphous chromium matrix and the content of hydrogen in the coating. The mechanisms of inclusion of Al2O3, SiC, Nb2N + Ta2N particles in chromium layers are different. In the former case (Al2O3 and SiC), the inclusion of particles is determined by kinetic factors (in the absence of current, there is no adhesion of particles), while, in the latter case, the particles demonstrate a strong adhesion in the absence of current. Accordingly, the distribution of SiC and Al2O3 particles depends on the depth by contrast to Nb2N and Ta2N particles, whose concentrations close to the substrate do not noticeably differ from those in the bulk and surface layers of the coating. An increase in the temperature of solution promotes the codeposition of chromium and these particles.
ray amorphous chromium matrix and the content of hydrogen in the coating. The mechanisms of inclusion of Al2O3, SiC, Nb2N + Ta2N particles in chromium layers are different. In the former case (Al2O3 and SiC), the inclusion of particles is determined by kinetic factors (in the absence of current, there is no adhesion of particles), while, in the latter case, the particles demonstrate a strong adhesion in the absence of current. Accordingly, the distribution of SiC and Al2O3 particles depends on the depth by contrast to Nb2N and Ta2N particles, whose concentrations close to the substrate do not noticeably differ from those in the bulk and surface layers of the coating. An increase in the temperature of solution promotes the codeposition of chromium and these particles. DOI: 10.1134/S2070205110010119