Avaliação da eletrodeposição do banho de cobre ácido na produção de semijoias e folheados

Abstract

The metallic products that are marketed in the accessories segment are submitted to a surfaces treatment process seeking to promote properties against wear of the part, chemical corrosion or just for decorative purposes. In this context, the electrodeposition is a process of coating a substrate through electrolysis with alterations of characteristics in relation to the surface finish, ensuring resistance to corrosion, to wear and increasing the product life. In electrodeposition, a bath often used is copper, since, through this bath, it is possible to obtain brighter and more uniform finishes on the pieces, in addition to serving as a reinforcement base for later coatings. In this process, the baths are consumed as the pieces are being bathed, therefore, there is a loss in efficiency. Thus, the objective of this work is to evaluate, through chemical titrations, the consumption of Cu acid solution in the metal electrodeposition process. In this sense, the pieces used were submitted to chemical pre-treatment, called degreasing, and followed with the other steps, which are: alkaline copper, acid copper, nickel free and gold gilding. After leaving each bath, the pieces were washed, activated and washed again. At the end of the deposit procedures on the surfaces of the bathed pieces, it is necessary to identify the final concentration of the electrolyte solution contained in the tanks, in order to maintain the concentration of salts at the ideal level so as not to compromise the quality of the deposit layers of the pieces. Therefore, this concentration can be obtained through the titrimetric method, with the use of a visual indicator, in order to obtain the ideal concentration of CuSO4 and H2SO4, which are the components present in the formulation of the acid copper bath and that need specific maintenance for the deposit on the surface of the piece with quality. The results obtained showed that CuSO4 presented a concentration value with an average of 152.88 g/L while H2SO4 presented 34.05 g/L. When performing the comparison with the ideal values which are, respectively, 200 g/L and 60 g/L, it was found that there was a loss of components in the bath. However, it is possible to correct the bath through chemical analysis and then replace the additives in the electrolyte solution.