Talk by Prof. Raj Singh, Head of School of Materials Science and
Engineering at Oklahoma State University, Tulsa, OK, USA
A variety of seals such as metal-metal, metal-ceramic, and ceramic-ceramic are required for a functioning SOFC. These seals must function at high temperatures between 600-800°C and in oxidizing and reducing environments of the fuels and air for up to 40,000 hours. Among the different type of seals, the metal-ceramic and ceramic-ceramic seals require significant attention, research, and development because the brittle nature of ceramics and glasses can lead to fracture and loss of seal integrity and functionality. A novel concept of self-repairable glass useful as seals in Solid Oxide Fuel Cells (SOFC) is proposed, developed, and used for making metal- glass-ceramic seals for enhancing reliability and life. In this concept, cracks created during SOFC operation are repaired by the crack healing process driven by the viscous flow of the glass. An approach for studying the kinetics of crack healing in glasses responsible for the self- repair is described and used to study the crack healing behavior. A crack-healing model, based on the relationship among crack length, time, temperature, glass viscosity and its flow behavior is developed in order to describe and predict the time required for self-repair on a glass surface. The predictions from the developed model is then compared with the experimental data and found to be in good agreement. These results also demonstrated the relative importance of the different stages of crack healing on the overall healing or self repair behavior. These along with a review of the current status of sealing technology for SOFC will be discussed.
Time: 12 to 1 PM on 9th Dec.