Electrochemical formation and control of chromium nitride films in molten LiCl-KCl-Li3N systems

Electrochemical formation and control of chromium nitride films have been investigated in molten LiCl-KCl-Li₃N systems at 723 K. Chromium nitride films were obtained by means of potentiostatic electrolysis of chromium electrodes in the melts. From XPS and XRD analyses, it was confirmed that all obtained films consisted of Cr₂N and CrN, and the composition of each nitride layer was effected by the applied potential value. For instance, a nitride layer consists mostly of Cr₂N on a chromium specimen after potentiostatic electrolysis at 1.0 V (vs. Li⁺/Li), and it consists mostly of CrN at 1.5 V. At the potential range from 1.0-1.5 V, the ratio of CrN-Cr₂N in the nitride layer increases, as the applied potential is more positive. Furthermore, the thickness of the nitride layer increases with increasing the electrolysis time. The obtained results suggest that compositions and thickness of nitride films can be controled by electrolytic conditions, e.g. applied potential and electrolysis time.