ELECTRODEPOSITION OF INDIUM FROM A SULFATE ELECTROLYTE WITH HALIDE ANIONS

The effect of halide anions (fluorides, chlorides, bromides, and iodides) on the electrochemical crystallization of indium from an acidic sulfate-halide electrolyte using stationary and galvanostatic unipolar pulsed electrolysis was studied. It was experimentally established that at a content of indium (III) sulfate of 0.087 moll, sulfuric acid of 0.185 moll, and the gloss-forming additive Limeda BK-10A of 2 ml/l, the introduction of fluorides up to 1.00 moll does not lead to the formation of indium coatings on the cathode surface. The addition of chlorides, bromides, and iodides dramatically increases the rate of indium coating formation and increases the cathodic current yield of indium. The range of concentrations of chloride anions (0.34...0.42 mol/l), at which the electrodeposition of coatings of the best quality with a high current yield is observed. With an increase in the order number of the halogen in the Periodic table of D.L Mendeleev, the degree of its influence on the cathode process of indium coating formation increases. Halide anions in the electrolyte form complex indium compounds, which are proved by the shift of the cathodic potentials and curves to the region of more negative potential values. However, in the presence of bromides and iodides in the electrolyte, the formation of poorly soluble indium monohalides, which violate the stability of the electrolyte and prevent its industrial use, was found during the transmission of an electric current. The effect of the addition of Limed BK-10A on the current output of indium was determined. The process of indium electrodeposition from a sulfate-chloride electrolyte using square-shaped galvanostatic pulses is investigated, and the dependences of the indium current yield on the pulse duration, duty cycle, and amplitude are investigated. The possibility of using combined indium and inert anodes in practice is proved. The properties of indium coatings made of sulfate-chloride electrolyte are studied.