Developing TiAlN coatings for intermediate temperature solid oxide fuel cell interconnect applications

TiN-type coatings have the potential to be used as SOFC interconnect coatings because of their low resistance and high temperature stability. In this research, various (Ti,Al)N coatings were deposited on stainless steels by filtered-arc method. ASR and XRD tests were conducted on these coatings, and SEM/EDAX analyses were conducted after ASR and XRD tests. SEM/EDAX analyses show that (Ti,Al)N remains stable at temperature up to 700∘C in a short period of time. It is also indicated that Al has beneficial effect on the stability of TiN-type coatings. At 900∘C, (Ti–30Al)N is fully oxidized and some of (Ti–50Al)N coating still remains as nitride. The analyses on cross-sectional samples show that these coatings are an effective barrier to the Cr migration. In summary, (Ti,Al)N coatings are good candidates for the SOFC interconnect applications at 700∘C. The future directions of this research are to improve the stability of these coatings by alloy-doping and to develop multi-layer coatings.