Application of Non-Destructive Testing to Analyse SOFC Cells and Stacks

Assuring high level of manufacturing quality and understanding degradation and ageing phenomena is a key requirement for the SOFC technology. In order to analyse structural failures in SOFC cells and stacks, electron and optical microscopy as well as chemical analysis require the destruction of cells and stacks in order to access the relevant structural areas. Non-destructive test methods like themography and radiography can assist in identifying the so-called 'hidden defects' in cells for both, quality assurance during production and identifying relevant areas for further destructive post mortem analysis. The evaluation of these non-destructive test methods showed that useful information can be obtained with standard equipment, and the resolution limits have been identified. Combination of both thermography and radiography was applied to identify pores and other irregularities in the range of 10-100 mu. Pores in the vicinity of the cathode/electrolyte interface were observed by X-ray tomography.