THE INFLUENCE OF ELECTROLYTE COMPOSITION ON THE CORROSION RESISTANCE OF NICKEL-BASED METAL-RESISTIVE COATINGS

Abstract

This paper presents a study of the corrosion resistance of metal resistive nickel coatings and the influence of glossforming additives on it, which can be introduced into the electrolyte to improve the quality and uniformity of electroplated coatings. Based on the conducted potentiodynamic polarization measurements and construction of corrosion diagrams, it has been shown that in a 3 % acetic acid solution, a 3 % sodium chloride solution, and a 3 % sodium chloride solution with the addition of 6 ml/l of acetic acid, the corrosion destruction of galvanic nickel deposits mainly occurs with cathodic control, and the limiting stage is, respectively, the stage of oxygen transport to the metal surface. It has been established that the corrosion destruction of nickel galvanic metal-resistive coatings in an alkaline copper-chloride solution for etching the conductive pattern of printed circuit boards occurs with mixed and predominant anodic control. It has been shown that due to the depassivating effect of inclusions of decomposition products of gloss-forming additives in the structure of nickel deposits, intensive destruction of the metal-resistive coating occurs in the environment of an alkaline copperchloride solution for etching the conductive pattern of printed circuit boards. In the case of sulfur-free matte nickel deposits, contact with copper leads to a significant reduction in the corrosion rate, due to the possible stimulation of passive film growth. This is also, to a much lesser extent, inherent in bright sulfur-containing coatings. It has been found that in order to apply corrosion-resistant nickel metal-resistive coatings, the use of sulforogenic surfactants, such as saccharin, should be limited.