THERMAL INTERFACE STRESSES INCLUDING 3D MICROSTRUCTURES IN LAYERED FREE-FORM CERAMICS

摘要

Processing of complex ceramic parts such as a dental restorations involves sintering of ceramic performs. Intended and unintended microstructures such as voids, cracks and, interfaces exist in these parts. These microstructures contribute to the mechanical response and ultimate life. A combined X-ray computed micro-tomography and X-ray micro-diffraction experiment was implemented on an alumina-zirconia layered free-form fabricated composite. The composite serves as a model for examining the mechanics and material characteristics of ceramic dental restorations. The current in-situ X-ray technique is capable of determining the strain values at prescribed spatial locations on the micron scale using high-energy synchrotron radiation and refractive focusing optics. In coordination with the experimental work, a finite element analysis of the volume generated by micro-tomography was developed. This required implementing a non-trivial procedure of converting the tomograph into a 3D finite element model. Simulation of sintering on this real geometry is compared with the experimental strain results for validation of the model. Once validated, the simulation offers more detailed insight to mechanical properties than experimental measurements offer on their own. This comprehensive procedure of modeling and experimentation including microtomography combined with diffraction offers a powerful method to quantify damage evolution and strain in ceramic layered composites - first intended for dental applications, yet broadly applicable as structural materials.