Flexural strength and flaw distributions of SrFe0.2Co0.4Mo0.4O3−δ ceramic‐supports for SOFCs at operating conditions. Issue 12 (18th July 2019)

• Record Type: Journal Article
• Authors: Stanley, Patrick; Hussain, Abdul Mohammed; Hays, Thomas; Robinson, Ian; Wachsman, Eric D.
• Is Part Of: Journal of the American Ceramic Society. Volume 102:Issue 12(2019)
• Page Start: 7606
• Page End: 7616
• Publication Date: 2019-07-18
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.16678
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Solid‐oxide fuel cells (SOFCs) have the potential to increase electricity generation efficiency, but traditional SOFCs supported by nickel cermets suffer from reliability challenges due to weaker mechanical strength caused by cracking after redox cycling. To solve this problem, a new ceramic anode material, SrFe0.2 Co0.4 Mo0.4 O3−δ (SFCM) combined with Ce0.9 Gd0.1 O2 (GDC), was evaluated for conductivity and mechanical strength at SOFC operating conditions and after redox cycling. Fracture toughness of SFCM was determined to be (0.124 ± 0.023) MPa√m at room temperature in air, increasing to (0.286 ± 0.038) MPa√m at 600°C. A mixture of SFCM:GDC showed fracture toughness between the two materials, following SFCM's trend with temperature. The SFCM‐GDC anode supported half‐cell strength increases by 31% from room temperature to 600°C as intrinsic stresses remaining from sintering are relaxed and thermal expansion pushes existing cracks closed. Exposure to reducing gasses decreases strength by 29% compared to ambient, due to oxygen vacancy formation and microstructural flaw changes. It is found that SFCM‐GDC based cells tolerate cycling well because of phase stability but weaken from 34.3 to 22.4 MPa due to uniform growth of critical microstructural flaws.