3D evaluation of thermal stresses on ceramic-metal composites used at high temperature operation.

Ceramic-metal composites (CMC) have been used for various high temperature applications including combustion engines, steam and gas turbines, industrial heaters and ceramic fuel cells. Reliable incorporation of the CMC at elevated temperatures, however, is very difficult in practice for the following reasons. First, meting and sublimation points of those solids are different causing undesired diffusion and mixing of elements across the material boundaries degrading functions of the materials. Secondly, maintaining temperature and pressure regimes for desired phases of the component materials is challenging during operation in many of practical cases. Lastly, thermal expansion rates of those two materials are significantly different frequently causing mechanical stresses and fractures. There have been numerous efforts to evaluate and design the CMC materials to minimize the thermo-mechanical stresses. Among various techniques, the focused ion beam-scanning electron microscope (FIB-SEM) tomography has been proved as a state-of-art technique to obtain 3D compositional and structural information of the CMC materials. In this study, we have evaluated thermal stresses applied on nickel-zirconia CMCs by using the FIB-SEM 3D tomography and finite element analysis.