APLICAÇÃO DA TÉCNICA DE MICROBALANÇA NO ESTUDO DA ELETRODEPOSIÇÃO ALCALINA DE COBRE COM DIFERENTES COMPLEXANTES

Abstract

The baths of copper electroplating industry, currently employed on ferrous substrates are typically alkaline nature in the midst of cyanide. It should be emphasized that although this type of bath produce deposits of excellent features, there is the problem of its high toxicity. The objective of this work is to study the electrodepositing of copper ions on ferrous substrate in alkaline cyanide-free, using the electrochemical quartz microbalance (EQM) associated with the techniques of pulsed current and rotating disk electrode (RDE), also were employed as techniques: voltammetry, pH measurements, scanning electron microscopy, optical analysis, Hull cell, galvanostatic, and potentiodynamic current modular. Interfaces galvanostatic pulse, the EQM and RDE built were tested and the results were satisfactory for the proposed studies. Were studied the influence of 5 complexing and 12 additives in electrodeposition of copper. Studies with EQM at pH 11.5 showed that the complexing tartrate showed the lowest potential deposition relative to other complexing studied and η = 0.55 V until the start of the hydrogen evolution, showing that the evolution of hydrogen might have less interference the deposition of copper on iron in this pH. The results of RDE on carbon steel electrode showed that the deposited copper mass in the presence of ethylenediamine is greater than that observed for the tartrate, ca. 200.71 mg. The measurements with pulsed and continuous current (ton/toff 50/450 ms), showed that the highest deposition efficiency was observed for 1-hydroxy-ethylidene-1,1-diphosphonic acid complexing. Tests on Hull cell showed depositions with good brightness, ethylenediamine at pH = 11 and sorbitol at pH = 13, both with 4 different additives. The tartrate at pH 11.5 showed good brightness with only three additives. The results rMEQ (MEQ+RDE) showed that the electrodeposition of copper over iron is controlled by transport and on changing the rotation from 300 to 2000 rpm, tartrate showed higher increase in deposited mass in the order of 47.9 times greater.