ELECTROPLATING OF INDIUM AND INDIUM-TIN ALLOYS FROM ALKALINE BATHS

In this study indium and indium-tin alloys were electroplated onto low carbon steel substrates, the metal from baths containing InCl3 and Na2C4H4O6&middot2 H2O while the alloys from baths containing InCl3&middotNa2Sn(OH)6 and Na2C4H4O6&middot2 H2O. The pH of every bath was adjusted to 11.5. The effects of the concentration, temperature and current density on cathodic polarization, cathodic current efficiency, composition of the alloys and quality of the deposits were investigated. For indium deposition, the efficiency was low and increased with increasing temperature and indium content of the bath. For the alloy deposition, the results were consistent with the behaviour of an irregular alloy plating system with indium being the preferentially depositable metal.