Development of a two-sided coupled material model for the characterization of ideal process parameters of application-optimized foams

• Applicants: Professor Dr.-Ing. Stefan Diebels; Professorin Dr.-Ing. Anne Jung
• Subject Area: Coating and Surface Technology ; Synthesis and Properties of Functional Materials ; Materials in Sintering Processes and Generative Manufacturing Processes ; Mechanics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 423793605

The growing world population and increasing prosperity lead to an increasing demand for energy and materials. Application-optimized cellular materials achieve greater sustainability and cost savings. This motivates the coating of open-pore polyurethane (PU) foams by electrochemical deposition for the production of hybrid foams. Material transport limitations during the electrode positioning process cause significant coating inhomogeneities that have not been adequately investigated so far. In this project, the influencing parameters on the electrodeposition process are to be determined and optimized. The aim is to develop a macroscopic two-side coupled material model to describe the electrodeposition process on porous materials.For the further development of the electrodeposition on PU foams, an electrochemical flow-through coating cell is developed and hybrid foams are produced with the aid of different parameter sets. A new method for the semi-destructive determination of the coating thickness of hybrid foams based on gravimetric measurements, measurements of the magnetic flux density using a Hall probe and computer tomography images is being developed for a time and cost effective method of measuring the coating thickness. The influence of the parameters velocity, diffusion constant, electric field and sink constant on the electrodeposition process and on the resulting coating thickness homogeneity will be formulated using a one-sided coupled macroscopic material model. The material model is implemented by finiter differences and the electrodeposition process is simulated. To describe the influence of the coating thickness on the electrodeposition process, the relationships of the geometric properties are investigated. These correlations are determined experimentally on the one hand and by virtual structures on the other hand. The correlations are required for modelling the influence of the coating thickness on the electrodeposition process. The two-side coupled material model is also implemented using finite differences and the electrodeposition process is simulated. Optimum process parameters of the electrodeposition process are determined by inverse calculation. These process parameters are used for the production of optimized hybrid foams with exactly this optimal parameter set. Finally, mechanical tests will be carried out on the optimized foams to investigate the influence of coating homogeneity on the material properties.Through these steps the project goal and thus a homogeneous coating thickness of Ni/PU hybrid foams shall be achieved. A homogeneous coating thickness gives the hybrid foams homogeneous material properties, which makes them multifunctional as energy absorbers or catalysts.

• DFG Programme: Research Grants