Magnetron-sputtered cobalt-based protective coatings on ferritic steels for solid oxide fuel cell interconnect applications

Co, Co–Mn (67:33 at.%) and Co–Cu (67:33 at.%) coatings were fabricated using magnetron sputtering on two kinds of ferritic stainless steels (Crofer22APU and F17TNb) in order to form spinel protective coatings on metallic interconnects for solid oxide fuel cells. Despite the thickness unevenness at different regions, dense metallic coatings were successfully applied onto all necessary surfaces of the channelled interconnect substrates. Upon oxidation, spinel oxide coatings with very low Cr content were formed, reducing effectively the Cr release. Among the three protective coatings, Co–Cu coating showed the lowest area specific resistance (<15 mΩ cm2 at 800 °C).

► Co/Mn/Cu coatings prepared by magnetron sputtering on ferritic steel substrates.
► Steel substrates are channelled as interconnect for solid oxide fuel cells.
► Geometric effect: thinner coating inside the channel than on the top surface.
► Metallic coatings oxidised into spinel protective layers against Cr-evaporation.
► Co–Cu coating offers the lowest area specific resistance.