Measuring fracture toughness of coatings using FIB-machined microbeams

D. Di Maio and S. G. Roberts Department of Materials, University of Oxford, UK keywords: toughness, coating, nanoindentation. Abstract Measuring the toughness of brittle coatings has always been a difficult task. Coatings are often too thin to easily prepare a freestanding sample of a defined geometry in order to use standard toughness measuring techniques. Using standard indentation techniques gives results influenced by the effect of the substrate. A new technique for measuring the toughness of coatings is described here. A precracked micro-beam was produced using FIB (Focussed Ion Beam) machining, then imaged and loaded to fracture using a nanoindenter.