Mechanical Characterization of Coatings Using Microbeam Bending and Digital Image Correlation Techniques

A new technique for characterizing end-supported microbeams of coating materials is presented. Microbeams are fabricated using micro-EDM machining to isolate the material under investigation from the underlying substrate. Three- and four-point bending is realized by a custom-built microspecimen testing system, and digital image correlation is employed to capture full-field strains and displacements in theses microbeams. These experiments provide the foundation for the use of finite element modeling and inverse methods to determine the mechanical properties (elastic moduli, strength, interfacial toughness) of the coatings. Here, the experimental details of the microbeam bending experiments are explained, discussed and illustrated through application to a multilayered metal/oxide/ceramic thermal barrier coating system commonly used in aero-turbines.