Development of ceramic sealant for solid oxide fuel cell application: Self-healing property, mechanical stability and thermal stability

In this paper, a ceramic sealant (CaB2O4) is developed for the self-healing design of solid oxide fuel cells (SOFCs). The interface between this ceramic sealant and the anode-supported electrolyte, e.g., 8 mole% yttria-stabilized zirconia (8YSZ), remains intact after sixty thermal cycles from 800 °C to room temperature. An in situ observation verifies that the micro-indentation on the surface of this material can be healed when heating from room temperature to 920 °C at a heating rate of 40 °C min−1. In addition, the weight loss of CaB2O4, held at 850 °C in air for 28 days, decreases from 3.26 ± 0.73 for sealed species to 0.81 ± 0.04 mg cm−2 for fully crystallized species; meanwhile, the weight loss of CaB2O4, held at 850 °C in wet forming gas (30 vol% water vapor) for 28 days, decreases from 14.80 ± 1.83 for sealed species to 6.36 ± 0.64 mg cm−2 for fully crystallized species. Combining with the good mechanical stability and thermal-stability, this self-healing ceramic sealant provides promising solution for the sealing challenge of planar SOFCs.