Nanodyn: Anti-icing coating

Reduced friction and ice adhesion – optimization by means of plasma technology

According to estimates, losses equal to five percent of the gross national product occur in the industrialized countries due to friction and wear on the surfaces of machines, for example in roller bearings. These losses can be substantially reduced; there are large potentials for reduction via directed change in the physical-chemical properties of the material surfaces. By reducing friction and wear, energy which would otherwise be lost as heat can be saved. In this context, a very promising approach is to change the wetting behavior of surfaces with regard to media – such as lubricants or also atmospheric humidity, water and cleaning agents – by means of a plasma modification.

Additionally, the adhesion of ice to wings or external sensors on airplanes and helicopters is influenced by the wetting behavior of the surfaces. By means of plasma functionalization, ice formation can be delayed and the adhesion of ice to the surfaces can be prevented. Expensive de-icing of planes, consumption of large quantities of de-icer, but above all consumption of up to 30 percent aviation gasoline and thus substantial CO2 emissions could thus be avoided. Beyond this, anti-icing surface functionalization would make a considerable contribution to aviation and building safety.

NANODYN joint project

Plasma-functionalized roller bearings for the food industry.

Plasma-functionalized roller bearings for the food industry.

With the objective of developing microscale and nanoscale structured layers in order to control the wetting behaviors of surfaces, two research institutes and four industrial enterprises have teamed up in the NANODYN joint project. The University of Bremen is concerned with the simulation of structured wetting and dewetting surfaces, whereas the Fraunhofer IGB supports the project via the development of new plasma coatings, the creation of surface structuring as well as selective analysis of the structures generated.

Structured surfaces by means of plasma

Precision bearings.

Precision bearings.

Micro- and nanostructured surfaces exhibit ordered structures up to a size range of only a few nanometers. In addition to the chemical properties, structuring of the surfaces influences the wetting properties. Both the chemistry of the surface and the topography can be specifically adapted to the application via a plasma coating. By means of a special mask technology, the structures can also be applied to plastic foils, which are available as rolled goods. The ice adhesion to the modified surfaces is investigated in an ice chamber by studying ice formation (icing) and de-icing. In the chamber the temperature and atmospheric humidity can be selectively adjusted.

Application fields for plasma structuring

Ice formation on an untreated airplane wing in wind tunnel test.

Ice formation on an untreated airplane wing in wind tunnel test.

The diversity of application fields in which the new technology is to be used can be easily read off the list of participating companies. For example, the bearing manufacturer Cerobear hopes to increase resource efficiency in production and the service lives of roller bearings in applications. For ROWO Coating efficiency increases, which could be achieved by coating film materials, are of interest. EADS Surface Technology, which expects a minimization of ice formation on airplane wings, comes from a completely different field. The incorporation of PINK Thermosysteme, a manufacturer of plasma reactors, ensures that the new coating technology can also really be implemented on an industrial production scale.

Results

Iced-up helicopter sensors.

Iced-up helicopter sensors.

Friction could be reduced by up to 30 percent in coated roller bearings by means of a plasma surface coating. On textiles and plastic films we could selectively adjust the wetting properties from hydrophilic to super-hydrophobic. This allows us to incorporate novel sensors, for example, for atmospheric humidity, temperature or electrical voltage into the coated textiles. Without functionalization of the textiles, the sensors would be very slow or would not function long enough. For the aviation industry, we have developed plasma-functionalized nanostructured PU films. Compared to uncoated films, the ice adhesion could be reduced by more than 90 percent on plasma-coated PU films.

Perspective

The developed surface functionalizations will be used in a large number of products, such as in roller bearings for the food industry or wetting and dewetting sensor textiles. Plasma functionalized plastic films with modified wetting properties can be glued to airplane wings to reduce or eliminate hazardous surface icing. Additionally, they are also appropriate for wind turbines, on solar panels and on buildings whose surface is to be kept free of snow and ice.

Funding

We would like the thank the German Federal Ministry of Education and Research (BMBF) for funding and the Projektträger Karlsruhe for supervising the “NANODYN” project, promotional reference 02PO2481.

Project partners

  • University of Bremen, Germany
  • Cerobear GmbH, Herzogenrath, Germany
  • ROWO Coating Gesellschaft für Beschichtung mbH, Herbolzheim, Germany
  • PINK Thermosysteme, Wertheim-Bestenheid, Germany
  • EADS, Munich, Germany