Structural Features of Ni–SiC Composite Electrochemical Coatings with Submicrometer Grain Size, Prepared Using Vibrational Mixing

Abstract

Electrochemical deposition of Ni–SiC composite coatings with submicrometer silicon carbide powder from a suspension electrolyte stabilized by vibrational mixing was studied. The structural features of the coating are described. Irrespective of the vibrational mixing conditions, thin coatings are layers with pronounced relief. Examination of the cross sections shows that the basic fragments forming the relief are metal–ceramic fragments consisting of SiC particles and nickel. A detailed study of thin sections shows that a nickel film is present on the surface of each particle, which indicates that the metal is reduced, in particular, on the particle surface. In the structure of thick composite coatings, agglomerations of SiC particles are also revealed. A coating formation mechanism consisting in the adsorption of SiC particle agglomerates and instantaneous nickel deposition on their surface was suggested. The results of analysis of the coating metal matrix by backscattered electron diffraction agree with the suggested mechanism.