Weibull parameter estimation of interfacial fracture toughness at the electrode/electrolyte interfaces in SOFCs

Abstract

The interfacial fracture characteristic of SOFC electrode/electrolyte interfaces is one of the key factors for improving the reliability and durability of the cell. The fracture toughness at a porous/dense interface was evaluated using all-ceramic four-point bending specimens consisting of a thin porous NiO–8YSZ electrode layer sandwiched between two dense 3YSZ electrolyte beams. The Weibull plot of the interfacial fracture toughness data shows that the Weibull modulus was smaller than that of bending strength in a single material of 3YSZ or NiO–8YSZ, and the variation of the interfacial fracture toughness was large. In addition, when the specimens were reduced and the electrode was changed to Ni–8YSZ, the interfacial fracture toughness tended to decrease.