Mn–Te ELECTROLYTIC DEPOSITION: SEARCH OF ELECTROLYTE AND INVESTIGATION OF POLARISATION

Preparation of stable manganese electrolyte with Te(VI) additive was investigated. The best Te(VI) additive was found to be orthotelluric acid H6TeO6 which does not muddle the manganese electrolyte at pH < 3.7. Orthotelluric acid was obtained from sodium tellurate Na2TeO4·2H2O solution during its acidification with concentrated sulphuric acid. The influence of Te(VI) additive on cathode polarization in manganese electrolyte was investigated. At low (0.55–2.20 mmol/l) concentrations of Te(VI) additive, electrodeposition of manganese, electrochemical and chemical Te(VI) reduction to Te(IV) and elemental Te take place on the surface of the steel cathode. The current efficiency of manganese coatings electrodeposited from acid manganese electrolyte with 2.20 mmol/l Te(VI) additive reached 35%, and the concentration of tellurium inserted in coatings was 0.85%. No manganese coating from electrolyte without Te(VI) additive was obtained.