Fuel cells play a key role in implementing hydrogen as alternative fuel to eliminate CO2-emissions and their performance is largely dependent on the contact resistance of the surface of bipolar plates. For stainless steel bipolar plates titanium carbonitride coatings were suggested for modifying surface properties and thereby reducing contact resistance while maintaining mechanical strength. This study analysed Ti(C,N) coatings with different carbon content in terms of composition, microstructure chemical bonding and contact resistance. The films were deposited either by reactive co-sputtering from a titanium and a graphite target under nitrogen flow or by co-reactive sputtering from a titanium target under flow of nitrogen and methane. It was found that an increase in carbon content results in a nanocomposite of Ti(C,N) and an amorphous carbon (a-C) matrix leading to nanocrystalline films with a smooth surface. Analysing the amount of a-C as a functions of overall carbon content, it is observed that carbon is more effectively incorporated into carbonitride grains when using methane gas as a carbon source. Furthermore, the contact resistance of the titanium carbonitride coatings was found to be lowest (below 10 mΩ) for a small amount of a-C phase and overall lower than that of carbide and nitride reference samples. Therefore, titanium carbonitrides are a promising coating material for electrical contact applications such as fuel cells.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-505641 |
| Date | January 2023 |
| Creators | Kessler, Juliana |
| Publisher | Uppsala universitet, Oorganisk kemi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC K, 1650-8297 ; 23009, Ulf Jansson |
Page generated in 0.0044 seconds