SPECIAL FEATURES OF NICKEL–CHROMIUM DIBORIDE NANOPOWDER COMPOSITE COATING ELECTRODEPOSITION

Abstract

The conditions for obtaining composite electrochemical coatings (CEC) have been investigated on the basis of nickel with the use of CrB2 nanopowder as a hardening phase in standard nickel-plating electrolyte. It is established that the maximum saturation of the nickel matrix in using chromium nanoboride takes place when its concentration in the electrolyte is 5–10 kg/m3 that is 8–12 times lower than in using micropowders. CEС microhardness of Ni–CrB2(nano) composition with the content of 0,59–0,65 % hardening phase is 1,16–1,19 times higher than that of Ni–CrB2(micro) coatings containing 2,47–2,86 % boride and 1,64–1,86 times higher than that of the nickel matrix. The optimum conditions of CEC deposition are cathodic current density of 1,0 kA/m2, nanoboride concentration of 5–10 kg/m3 in the electrolyte, pH 5,0–5,5, and temperature of 323 K.