1 Micro-cantilever Testing to Evaluate the Mechanical Properties of Thermal Barrier Coatings

Abstract. In this paper, the application of a novel micro-scale mechanical testing technique in multi-layered (7 wt % yttria stabilized zirconia/alumina/NiCoCrAlY) thermal barrier coating system is described. A force measurement system has been introduced into a FEI Helios Dualbeam FIB/SEM workstation to allow the fabrication and testing of micro-scale cantilever beams subject to bend loading. These micro-cantilever specimens created by Ga ion milling were tested in-situ. The beams were produced at various locations to provide results for the TC, TC/BC interface and the BC. As-spayed TBC samples were tested. This allows, for example, the non-linear elastic behaviour of the ceramic layer as well as the interface flexural strength to be evaluated. The results are compared and analysed with data obtained by nano-indentation. In addition, in-situ fractography was undertaken on the fracture surfaces to aid interpretation of the fracture data. The results are discussed with respect to the underlying fracture mechanisms