Electrochemical synthesis of NbC-Sn composite powder in molten chloride

NbC-Sn composite powder was successfully prepared from SnO2, Nb2O5 and carbon by electrochemical reduction and carbonization in CaCl2-NaCl molten salt at 900 °C. The reaction pathway was investigated by terminating electrochemical experiments for various durations. The influence of carbon on the final products was considered. NbC particles were obtained by leaching the composite with acid. The results showed that the aggregated NbC-Sn composite powdev contained NbC particles about 50-100 nm and Sn particles about 200 nm. SnO2 was reduced to Sn in the sintering process. Nb2O5 was electrochemically reduced to Nb in molten salt, experiencing some intermediate products of calcium niobates and niobium suboxides. Nb metal obtained was converted to NbC with assistance of carbon. The reduction of Nb oxides may be incomplete and Nb3Sn would be formed if carbon is insufficient in the cathodic pellet. NbC with good dispersity is produced by leaching NbC-Sn with HCl.