Functional coatings for exterior applications

Functional coatings for exterior applications face a variety of requirements to ensure the functionality and safety of equipment. External influences such as ice formation and erosion pose a major challenge, as they can compromise safety and lead to high repair and maintenance costs.

To reduce these effects, Fraunhofer IFAM develops innovative coating technologies. The focus is particularly on:

• Ice-repellent coatings
• Heating layers for de-icing
• Erosion protection layers

 

Customized anti-icing coatings and systems

The portfolio of coating technologies is defined by customer-specific requirements and relevant icing conditions for the various industries. This includes the following coatings:

• hydrophobic and superhydrophobic
• nano- and microstructured
• ultra-smooth and slip-promoting
• freezing point lowering

The goals are to prevent ice formation, remove ice that has formed, or increase the efficiency of heating and mechanically based ice protection systems.

To realize the specific coatings, Fraunhofer IFAM offers material developments according to customer-specific requirements. The toolbox includes, among other things:

• Sol-gels
• Polyurethanes
• SLIPS (Slippery Liquid-Infused Porous Surfaces)
• PFAS-free silane- and siloxane-based materials
• Elastomers and
• Temporary freezing point-lowering coatings

 

Heating layers

The coatings developed at the institute can be used for near-surface heating. The following technologies are used:

• Induction
• Resistance heating

The advantages lie in low layer thicknesses, flexible geometry design through spray application, and high energy efficiency.

 

Erosion protection coatings

Raindrops and sand particles can cause damage through erosion. The mechanical effects lead to increased component wear and a shorter service life. As a result, the necessary maintenance and repair work increases.

The Coating Technology department at Fraunhofer IFAM is actively developing coatings that offer high erosion resistance. Current development projects are focusing on the following materials:

• Elastomeric coating materials
• Reinforcing fillers
• Self-healing properties
• Improved sliding behavior
• Repair kits

Our R&D services range from material screening to the development of a guideline formulation with application testing and are aimed at raw material and coating manufacturers as well as potential end users of anti-icing and erosion protection coatings. Fraunhofer IFAM also has numerous testing and trial facilities at its disposal. For example, an ice wind tunnel can simulate realistic environmental conditions for anti-icing coatings.

The development of anti-icing coatings and icing tests is part of the work carried out at Fraunhofer IFAM on functional coatings. Nadine Rehfeld uses the experience gained from publicly funded projects in the fields of aviation, wind energy, automotive and rail vehicle construction, as well as refrigeration and air conditioning technology, to make significant contributions to international committee work on test standards and the definition of design and material specifications.

 

Current projects

As part of the EU-funded Carbo4Power (H2020) project, Fraunhofer IFAM is developing multifunctional coatings whose long-term durability is designed for use on rotor blades of wind turbines and tidal power plants.

In addition, work is being carried out on repair concepts for erosion protection of rotor blades on wind turbines, which are being developed in the BMWE-funded MARiLEP project.

New erosion protection concepts are also currently being developed in the aviation sector and tested in the EU-funded Ultra Performing Wing project of the Clean Aviation aviation program.

For ice protection systems, layer-based heating technologies are currently the focus of development. As part of the aviation research program (funded by the BMWE), the HYBATS project was able to prove its functionality in an ice wind tunnel.

 

Publications

The standard work on functional coatings:

• Stenzel, V. und Rehfeld, N. (2013): Funktionelle Beschichtungen, Farbe und Lack Edition, Vincentz Network, Hannover, Deutschland

Our experts are constantly developing and testing new functional coatings. Read more in our latest publications.:

• Rehfeld, N.; Speckmann, B.; Schreiner, C.; Stenzel, V. Assessment of Icephobic Coatings—How Can We Monitor Performance Durability? Coatings 2021, 11, 614.
• Rehfeld, N.; Speckmann, B.; Stenzel, V. Parameter Study for the Ice Adhesion Centrifuge Test. Appl. Sci. 2022, 12, 1583.
• Jones, S.M.; Rehfeld, N.; Schreiner, C.; Dyer, K. The Development of a Novel Thin Film Test Method to Evaluate the Rain Erosion Resistance of Polyaspartate-Based Leading Edge Protection Coatings. Coatings 2023, 13, 1849. 
• Rehfeld, N.; Brassard, J.-D.; Yamazaki, M.; Sakaue, H.; Balordi, M.; Koivuluoto, H.; Mora, J.; He, J.; Pervier, M.-L.; Dolatabadi, A.; et al. Round-Robin Study for Ice Adhesion Tests. Aerospace 2024, 11, 106. 
• Nadine Rehfeld, Niklas Pengemann, Sascha Kull, Volkmar Stenzel, Ice shedding tests for the assessment of hybrid ice protection systems, Cold Regions Science and Technology, Volume 223, 2024, 104223, ISSN 0165-232X.