Measurement of the interface adhesion of solid oxide fuel cells by indentation

The adhesion between two adjacent layers in a solid oxide fuel cell (SOFC) is critically important to ensure the desired performance. However, measuring the interface adhesion is very difficult because most layers in an SOFC are brittle and/or porous. This paper introduces a simple technique for the quantitative measurement of interface adhesion of SOFCs. A hard, spherically tipped indenter is driven through the top layer(s) and into the underlying substrate of a plate SOFC specimen. Extensive plastic deformation of the substrate causes an interface annular crack. The interface adhesion is then calculated from the radius of the annular crack. The indentation method should be suitable for the adhesion measurement of any SOFC with a porous support. A measurement procedure and the related calculation equations for determining the interface adhesion are presented in this paper. The interface adhesion of a cermet-supported SOFC with a doped ceria electrolyte for operation at 400–600 °C was measured to demonstrate the use of the indentation method. The measurement indicated that the cermet-supported SOFC had sufficient interface adhesion.