The Effect of Organic Acids in the Presence of Cyclic Lactams on Kinetics of Electrodeposition and Morphology of Nickel Coatings Modified with Polymer

Abstract

Using stationary electrolysis, the effect of the structure and concentration of some organic acids on kinetic parameters of electrodeposition of nickel from sulfate electrolytes containing cyclic lactams, such as ε-caprolactam (CL) and N-methylpyrrolidone (MP), microstructure, mean grain size, and crystallite orientation has been studied. Integrated analysis of the data of polarization, adsorption, and spectral investigations has shown that enhancement of adsorption of amino acids in the presence of lactams leads not only to an increase in the polarization of the process, but also to significant changes of surface morphology. According to X-ray phase analysis and SEM data, the surface becomes smoother in the presence of amino acids, the grain size decreases, and a predominant orientation of crystallites appears in some cases. The formation of metal–polymer sharp-edged grains in the coatings prepared in the presence of CL and glycine has resulted in the formation of continuous smoothed layer and appearance of mirror shine of the deposits.