Interaction of a Barium‐Calcium‐Silicate Glass Composite Sealant with Sanergy HT 441

The interaction between Sandvik's coated Sanergy HT 441 (EN 1.4509) with a cerium‐cobalt layer as chromium evaporation barrier and a glass‐ceramic composite sealant on the basis of BaO‐CaO‐SiO2 was investigated in this study. The oxidation behavior of the steel was analyzed by long‐term weight change measurements of strip samples at 800 °C for 10,000 h followed by scanning electron microscopy on cross‐sectioned samples. A double oxide layer was formed consisting of chromia close to the steel and a layer with 18 wt.% Cr, 11% Co, 10% Mn to the air side. The interface of the joined samples had a reaction layer similar to the oxidized steel surface with an additional phase formation consisting of Co/Mn/Fe and low in oxygen facing the glass‐ceramic interface. After these preliminary tests the coated Sanergy HT 441 was integrated as frames into a four layered F10‐stack with 80 cm2 cell area and was tested for 3,500 h at operation temperature of 700 °C and 0.5 A cm−2 constant current mode followed by 20 thermal cycles between 700 and 200 °C. The stack had shown similar performance and gas‐tightness compared to stacks assembled with Crofer 22 APU. The post‐test characterization had shown adhesive fracture patterns when dismantling the stack parts.