Perspectives for Novel Bioinspired Ship Coatings based on the Salvinia Effect:
Using a Permanent Layer of Air Under Water
Thomas Schimmel1, Stefan Walheim1 and Johannes Oeffner2
1Institute of Applied Physics and Institute of Nanotechnology,
Karlsruhe Institute of Technology (KIT),D-76128 Karlsruhe, Germany
2Fraunhofer Center for Maritime Logistics and Services, 21073 Hamburg, Germany
Three key problems which ships are facing are related to the fact that the ship hull is in contact with water:
• Drag – the largest part of the fuel consumption of ships is due to the friction with the surrounding water.
• Corrosion – a phenomenon which is also largely related to the fact that the ship is in direct contact with the surrounding sea water with its high content of salt.
• Fouling – the growth of sea organisms would not happen if the ship would be surrounded by air instead of water.
Latest developments in the area of bionic surfaces show that avoiding the direct contact between a ship and the surrounding water appears feasible and opens intriguing perspectives for practical applications. The floating water fern Salvinia molesta demonstrates how permanent layers of air can be kept under water for weeks. Within a joint research project of the Universities of Bonn, Karlsruhe and Rostock, a thorough understanding of this effect was achieved [1,2]. This lead to the development of a novel type of artificial surfaces which – based on their topographic structure and chemical functionality – keep a permanent layer of air under water.
The design and fabrication of such artificial surfaces and their properties are studied within the Project AIRCOAT supported by the European Union within the Horizon 2020 program. The talk will give an overview of latest developments based on this biomimetic approach and shows perspectives for future applications – ranging from drag reduction to future bioinspired antifouling ship coatings.
(1) D. Gandyra, S. Walheim, S. Gorb, W. Barthlott, Th. Schimmel: The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness, Beilstein Journal of Nanotechnology, 6 11-18 (2015).
(2) W. Barthlott, Th. Schimmel, S. Wiersch, K. Koch, M. Brede, M. Barczewski, S. Walheim, A. Weis, A. Kaltenmaier, A. Leder, H.F. Bohn:
Advanced Materials 22 (21), 2325–2328 (2010).