Investigation on TaC (1 1 1)/TiC (1 1 1) interface for coating with high-performancse corrosion resistance: First-Principle calculations and experiments

In this study, first-principle calculation is used to investigate the TiC (1 1 1)/TaC (1 1 1) interface in terms of surface energy, work function, adhesion energy, and electronic structure. Compared with TaC (1 1 1), the TiC (1 1 1) surface shows a higher surface energy and a lower electronic work function. The surface passivation of TiC can be achieved by covering the TaC layer. Besides, the interface bonding configuration of TiC (1 1 1)/TaC (1 1 1) that relates to corrosion resistance is studied in detail. In experimental verification, a set of TiC-based coatings are investigated by potentiodynamic polarization, potentiostatic polarization, and impedance. Compared with pure TiC and TiC/C coatings, the TaC/TiC/TaC/C structure exhibits the lowest corrosion current density of 0.28 μA cm−2 and the lowest corrosion tendency. SEM observation also reveals its minimal morphological damage after potentiostatic polarization. The modified multilayer coating presented in this work is successfully used as the protecting structure of stainless-steel bipolar plate, which may be of great significance to the light weight metallic bipolar plate in proton exchange membrane fuel cells.