Many of natural structural materials possess very interesting mechanical properties for the technical applications. For this reason the structure of these materials has been investigated during the last decades very well. It turned out the natural materials exhibit a hierarchical structure and have a high filling degree of minerals (ceramic). The other components of the natural materials are bio-polymers. Despite a very high filling degree the natural materials possess unexpected high fracture toughness. A typical example of such a damage tolerant natural material is nacre. Nacre consists of about 95 vol.% calcium carbonate and about 5 vol.% of polymeric material.
Due of good mechanical properties of natural materials many attempts are made to reconstruct this complex hierarchical structural design.
Main aim of the project is the fabrication of tailor-made high-filled and hierarchical composite materials for different applications. For this aim novel processing routes based on fluidization of particles are developed and optimized and the mechanical properties of produced highly filled ceramic-polymer and metal-polymer composites are investigated. Furthermore the influence of the shape of reinforcement particles is investigated.
The process route for the fabrication of composites with high volume fraction of the reinforcement phase and hierarchical structure is the spouted bed coating process combined with subsequent warm pressing. With this method it was possible to fabricate both very highly filled and hierarchically structured ceramic-polymer composites. By the addition of rolling step to the process route also the influence of particle shape on mechanical properties was studied. Fig. 1 shows the spouted bed, which is specially designed for the processing of fine particles and which is used for the coating at the Institute of Solids Process Engineering and Particle Technology.
After the granulation in the spouted bed the granules are pressed to tablets. After pressing tablets are sawed in bending bars. And then mechanical properties such as modulus of elasticity, strength, hardness and toughness of the fabricated composites are tested.
For the optimisation of the process, fluid and particle dynamics in the apparatus are simulated with CFD (Computational Fluid dynamics)-DEM (Discrete Element Method)-Coupling.For optimization of mechanical properties DEM-simulation are carried out.
Within the project hierarchical materials could be fabricated. For it prestructured agglomerates of sub-micron-particles are used as bed particles for the coating in the spouted bed. The granules produced in the spouted bed are then compressed to form a bulk material. Fig. 2 shows SEM pictures of produced agglomerates and the fractured surface. Fig. 3 shows by nanoindentation measured modulus of elasticity and hardness for composites with and without polydopamine.
- Eichner E., Salikov V., Bassen P., Heinrich S., Schneider G.A. Using dilute spouting for fabrication of highly filled metal-polymer composite materials. Powder Technol. 316 (2017) 426–433.
- Georgopanos P., Eichner E., Filiz V., Handge U.A., Schneider G.A., Heinrich S., Abetz V. Improvement of mechanical properties by a polydopamine interface in highly filled hierarchical composites of titanium dioxide particles and poly(vinyl butyral). Compos. Sci. Technol. 146 (2017) 73-82.
- Wolff M.F.H., Salikov V., Antonyuk S., Heinrich S., Schneider G.A. (2013). Three-dimensional discrete element modeling of micromechanical bending tests of ceramic–polymer composite materials. Powder Techn. 248.
- Wolff M.F.H., Salikov V., Antonyuk S., Heinrich S., Schneider G.A. (2014). Novel, highly-filled ceramic–polymer composites synthesized by a spouted bed spray granulation process. Composit. Sci.&Techn. 90.
- Schneider G.A., Wolff M.F.H., Salikov V., Antonyuk S., Brandt K., Heinrich S., Patent WO2013079655-A2.
• Institute of Advanced Ceramics, Hamburg University of Technology (Prof. G.A. Schneider)
• Institute of Polymer Research, Helmholtz-Zentrum Geestacht (Prof. V. Abetz)
• Institute of Physical Chemistry, University of Hamburg (Prof. H. Weller)