Preparation and evaluation of composite nitride coating on the surface of Ti bipolar plates for PEMWE

• 1、School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing, Beijing 100083

Abstract：A layer of tantalum is pre-sprayed onto a titanium substrate using thermal spraying, followed by nitriding using the PIRAC (Powder Immersion Reaction Assisted Coating) method to prepare a composite nitride coating on the titanium substrate. The effect of nitriding temperature on the surface morphology, microstructure, corrosion resistance, conductivity, and stability of the coating in a simulated PEM water electrolysis environment was studied. The results show that the surface of the coating exhibits a uniform small particle morphology, and the main components of the coating are TiN, TaN, TiNxOy, and Ta2O5. The corrosion resistance of the sample after tantalum spraying and nitriding is significantly improved compared to the untreated titanium substrate. Samples nitrided at 900℃ exhibit good corrosion resistance in electrochemical tests, with the self-corrosion current decreasing to 0.124 μA cm-2. The coating also improves the conductivity of the sample surface, with the interface contact resistance decreasing to 0.6 mΩ cm2, which reduces the ohmic loss of the electrolytic cell to some extent. The constant potential test results at 1.8 V for 10 hours confirm the stability of the composite nitride coating on the titanium surface under high potential at the PEMWE anode.

Keywords： Ti bipolar plates composite nitride coating powder immersion reaction assisted coating proton exchange membrane water electrolysis thermal spraying of tantalum corrosion resistance.