EFFECT OF REPLACING COPPER CYANIDE FOR COPPER SULPHATE IN A BRASS ELECTROLESS BATH

Environmental conditions and health protection worldwide, is a search engine solutions for the surface finishing industry, in the sense use bath solutions, which do not contain toxic substances, and difficult to treat waters waste. Here are the results from the replacement of copper cyanide by copper sulphate in the composition of an electroless brass-plating bath; the electroless brass plating process can be applied directly on Zamak alloys, also on low carbon steels and aluminium. The morphological and brass film colour characteristics were evaluated by scanning electron microscopy, optical microscopy, colour parameters L*, a*, b*, with a spectrophotometer and electrochemical techniques, depending on the molar concentration of copper sulphate. This bath was prepared based on a bath of electroless brass patented in Mexico, the composition of this bath using zinc oxide as a source of Zn ions, a suitable complexing agent and a stabilizer, with an alkaline pH and a temperature of 75 ° C. The results indicate that we can control the colour of brass plating with Cu/Zn ratio.