Session: 1.1.1 - Fuels, Combustion & Material Handling

Paper Number: 108848

108848 - Using Simulation and Experiment to Develop a Design Methodology for Self-Shaping Solid Oxide Fuel Cell Multilayer Ceramic Composites 

Traditional ceramic manufacturing techniques offer a limited assortment of achievable 3D geometries. Encapsulated structures like Swiss-rolls, and interlocked structures like chains or hinges are unattainable without the use of mechanically inferior adhesives and thin curved surfaces collapse without support as a green body. For multilayer ceramic composites, such as solid oxide fuel cells, this is further limited to only planar and tubular forms. While there has been interest in a variety of advanced manufacturing techniques such as 3D printing, a less conventional option has also gained interest. Self-shaping of multilayer ceramic composites utilizing mismatched thermal expansion coefficient driven bilayer shrinkage is an alternative manufacturing strategy which circumvents many issues associated with other techniques. In this process, a tape-casted substrate is sprayed with a patterned or uniform film which contracts relative to the substrate while cooling from the peak sintering temperature to room temperature resulting in controlled deformation. This process can be modified in various ways to achieve an assortment of geometries. For example, origami shapes may be produced using patterned spraying where a mask blocks much of the sheet. The remaining areas are coated with the film, becoming valley folds. By repeating on the other side of the sheet, a network of mountain and valley folds can be formed, causing the sheet to shape itself into origami shapes such as the Miura-ori pattern. Similarly, by spraying homogenous films, the composite can be designed to deform, but the direction and degree of deformation becomes harder to predict. This complication, as well as other factors related to the complex material behaviors often seen with ceramics, pose significant barriers which are necessary to overcome in pursuing self-shaping ceramics as a commercially viable alternative to currently available traditional and advanced manufacturing techniques. One underlying question, which is found regardless of material, is how to successfully predict the final shape a sheet under shrinkage stress will obtain. While these sheets can be described successfully using non-Euclidian metrics, this is difficult to generalize to any design and becomes exponentially harder as the desired shape becomes more complex. Instead, empirically derived scaling laws which describe energy may be developed. This work looks at several geometries for which these scaling laws have already been developed and applies them to the ceramic system both through experimentation and simulation. It also introduces an unexpected complexity unique to the ceramic system. The natural curvature, or the curvature a 2D bilayer composite would obtain, can be well-predicted by finite element analysis as well as with an analytical relationship derived by Stephen Timoshenko. However, there is significant disagreement between these predictions and experimental samples. By comparing experiment and simulation, we can modify our model to accurately represent the real material behavior. We seek to accommodate this disagreement so that we may accurately apply the above-mentioned scaling laws to efficiently design starting substrate and film.

Presenting Author: Alexander R. Hartwell Syracuse University

Presenting Author Biography: Alexander R. Hartwell is a Ph.D. candidate in the Department of Mechanical and Aerospace Engineering at Syracuse University. He is the lab manager of the Combustion and Energy Research Laboratory (COMER) led by Dr. Jeongmin Ahn and has been involved with a wide variety of projects focusing on material science, energy conversion, and heating, ventilation & air conditioning. His dissertation work focuses on an idea he developed to produce self-shaping ceramic structures using the phenomenon known as bilayer shrinkage where two bonded plates shrink to different extents causing deformation. He has assembled a team of researchers to address both fundamental behaviors associated with this process and it application in potentially high-impact technologies such as solid oxide fuel cells, electrolyzers, batteries, fluid control, and micro-electro-mechanical systems.