SEALING COMPOSITE FOR FLAT SOLID OXIDE FUEL CELL STACK HAVING HIGH FRACTURE RESISTANCE AND THE FABRICATION METHOD THEREOF

摘要

A composite sealant of the present invention increases a fracture toughness of glass which has an excellent gas tightness but has a low fracture resistance, to enhance the thermal cycle stability while maintaining the gas tightness of a stack. For this, alpha-alumina fiber particles, alpha-alumina granular particles, and metallic particles are mixed and added to a glass matrix for remarkably increasing the fracture toughness from 0.5 MPa • m05 to 6 MPa • m°'5 through the multiple effects of crack deflection and crack bridging by the fiber and granular particles, and effects of crack arresting and plastic deformation by the metallic particles. When using the high fracture toughness composite sealant of the present invention, since the gas tightness and the stability of the stack can be maintained even when there is a thermal stress produced by a non-uniform temperature distribution or a thermal cycle condition in the stack, increasing the fracture toughness of the composite sealant works as the most important factor for enhancing the reliability of a large-area stack.