Electrochemical methods for obtaining thin films of the refractory metal carbides in molten salts

Abstract

Synthesis of Cr7C3, NbC and TaC coatings on the surface of carbon steels and carbon fibers was carried out using currentless transfer. The corrosion resistance of the Cr7C3, NbC and TaC carbides coatings was studied in concentrated HCl, H2SO4 and H3PO4 acids. The wear resistance was evaluated by the sample mass loss. Due to the high wear and corrosion resistance Cr7C3, NbC and TaC coatings on carbon steels can be applied in aggressive medium with the abrasive wear. Coatings of NbC or TaC on carbon fibers make better the fiber's mechanical resistance. Mo2C coatings were obtained on Mo substrate at the temperature 1123 K by electrochemical synthesis in NaCl-KCl-Li2CO3-Na2MoO4. The Mo2C/Mo composition was tested as a catalyst for the water-gas shift reaction. The steady-state reaction rates for the Mo2C/Mo composition were higher than those for the bulk Mo2C and commercial Cu/ZnO/Al2O3 catalysts over in the temperature range explored.