In-situ corrosion of TiCxN1-x protective coatings

Fuel cells are promising devices capable to converting chemical energy into electrical energy, via reactions of hydrogen and oxygen. The continuous supply of hydrogen fuel makes fuel cells especially interesting for heavy transportation. Fuels cells are composed by many Membranes Electron Assembly, where the reactions take place, and each of them are separated by bipolar plates. The latter control the heat, provide a conductive bridge, and transport reactants between the membranes. However, their crucial roles are limited by the harsh environment they are surrounded by. For this reason, a protective coating against corrosion is needed. Metal carbide and metal nitride have been tested as promising materials for coatings applications. Numerous studies has been made on Titanium Carbide (TiC) and Titanium Nitride (TiN), which are both completely miscible. Therefore, Titanium Carbonitride (TiCN) seems to be a promising material to form a passive film and to fulfil the role of a protective coating. However, further information of the titanium carbon nitride mixture are needed. Our goal is to understand the chemical composition of the oxide formed at the surface of the material, and how this changes in acidic and alkaline environments and with applied potential, to simulate the harsh environment in a fuel cell. To investigate the solid-liquid interface, we plan to use NEXAFS in combination with a liquid cell. The goal is to understand how the surface composition changes under the influence of a liquid electrolyte, acidic and alkaline, and when applying a potential. This information would help to enhance the corrosion resistance of TiCN films making it suitable as a protective layer for fuel cell bipolar plates.