Preparation of Molybdenum Coatings by Molten Salt Electrodeposition in Na3AlF6-NaF-Al2O3-MoO3 System

In this paper, electrodeposition of a molybdenum coating was conducted in Na3AlF6-NaF-Al2O3-MoO3 molten salts at 930 degrees C to investigate the availability of preparation of thick molybdenum coatings. The effects of current density and electrodeposition time on the morphology of the produced molybdenum coating were studied. With the increase of current density (10 similar to 70 mA.cm(-2)), the coating thickness was increased from 10 mu m to 30 & mu;m, with all the current efficiency above 97%. Under a current density of 30 mA/cm(2), with the rise of electrodeposition time (10 similar to 60 min), three stages of the deposit growth were observed, including the formation of a large number of fine crystals, transformation into fibrous morphology and well-developed faceted grains. The formation of a large number of fine crystals at the initial stage of the electrodeposition could facilitate electroplating molybdenum coatings with good quality at higher current density and longer duration. Thus electrodeposition at a current density of 100 mA.cm(-2) for 3 h has been performed, resulting in the preparation of relatively flat, dense, and coherent molybdenum coatings with a thickness of 140 mu m on a nickel substrate, with a current efficiency above 85%. It is anticipated that the electrodeposition of molybdenum coatings in the present molten system is suitable for electroplating thick molybdenum coatings.

Automated summary

The electrodeposition of molybdenum coatings in Na3AlF6-NaF-Al2O3-MoO3 molten salts at 930 degrees C was studied to investigate the possibility of producing thick molybdenum coatings. The effects of current density and electrodeposition time on the morphology of the coatings were analyzed. It was found that increasing the current density and electrodeposition time led to thicker coatings with high current efficiency. The electrodeposition process resulted in relatively flat, dense, and coherent molybdenum coatings on a nickel substrate.