Thin ceramic plates made for oxygen membranes, fuel cells and for purification of flue gases are usually tape cast, but the process of making the plates is complicated and has its faults. When tape casting ceramic plates, a mixture of substances is smeared on a surface of a plate and then heated in an oven under very controlled conditions, after which the cell is ready for use.
Well sort of ready, as the finished products despite great care and very advanced furnaces always suffers from a greater or lesser degree of distortion from the heating.
The distorted and skewed conditions of the plates can be seen with the naked eye, and each and every bulging dent in the ceramic plates has great impact on the usefulness of the ceramic plates, as the electron migration depends on the porosity and thickness of the material. The skewed plates are also very difficult to stack in the cells and break easily, which affects both the utilization and lifespan of the ceramic plates.
Now, researchers at DTU Energy Conversion in collaboration with researchers from both San Diego State University’s Mechanical Engineering Department and the Moscow Engineering Physics Institute have found a way to anticipate and correct the distortion of the plates.
The research team of De Wei Ni, Vincenzo Esposito, Tesfaye T. Molla, Rasmus Bjørk, Søren P.V. Foghmoes, Henrik L. Frandsen and Nini Pryds from Danish Technical University’s department of Energy Conversion, Eugene Olevsky from San Diego State University, Elena Aleksandrova and Aleksandra Ilyina from Moscow Engineering Physics Institute, describe their solution to the problems with skewed and distorted cells in “The Journal of the American Ceramic Society” (May 21, 2013).
The first of two articles "Sintering of multilayered Porous Structures: Part I - Constitutive Models" explains how the scientists are able to draw up models of what influences the cells under the heating, while the second article "Sintering of multilayered Porous Structures: Part II - Experiments and Model Applications" describe how to counteract the distortions in the materials by using the models.
"The best thing is that we by using optical dilatometry can do all necessary measurements at one go. A single measurement enables us to make a detailed model of all negative impacts to the material," says postdoc at DTU Energy Conversion, De Wei Ni. This enables the researchers to deal with the problems.
"First, we measure the impact, then we make a workable model from the measurement which allow us to tweak and change the parameters and thus counteract the effect. The result is significantly flatter panels. "
Eugene Olevsky from San Diego University developed the theory a few years ago and started cooperation with the research team from DTU Energy Conversion in 2011, as they had the expertise and the equipment. Now the entire team has made it possible to make the particles fall in line and flatten the ceramic plates.