Fraunhofer Center HTL develops coatings for use at high temperatures. The individual development phases - from material selection to testing of in-service behavior - are accompanied by systematic instruments. Feedback loops allow insights to be incorporated into the development phases and further refined.

The coatings developed at the HTL are suitable as corrosion protection, wear protection, surface sealing, heating layer or anti-adhesion coating.

Coating Processes
Coating of the inner surface of a turbine blade
© Fraunhofer Center HTL
Coating of the inner surface of a turbine blade

The focus at the HTL is on the formulation of liquid coating lacquers and resin systems filled with powder, which can be applied using simple and large-scale application methods such as dipping, spraying or brushing. These application methods offer many degrees of freedom in the layer application. This allows even complex-shaped components or inner surfaces of components to be coated. Compared to gas phase and thermal spraying processes, wet chemical processes often offer the advantage of better-adjustable microstructures in the layer systems.

Depending on the application technique and formulation of the coating paint, layer thicknesses ranging from a few nanometers to over 100 µm are possible. The coating is mainly applied to metallic and ceramic components. After application, the layers must typically be baked. For this purpose, ovens with different atmospheres (air, inert, vacuum, reducing) and in different sizes are available. Alternative baking processes such as laser sintering are also possible. When developing the baking process, it is important not to damage the base material. Close coordination with the customer is required in this regard. If the customer does not want or is unable to use a baking process for certain reasons, alternative approaches can be used to consolidate the coatings.

Customized Solutions
Al2O3 pipe with surface sealing
© Fraunhofer Center HTL
Al2O3 pipe with surface sealing

The HTL offers a variety of coating material systems as standard, including Al2O3, Al2O3-SiO2, SiO2, rare earth silicates, yttrium aluminum garnet, ZrO2, zirconium titanates, TiO2, SiC, BN or SiBNC. The respective coating paints are adjusted in terms of their processing properties depending on the customer's preferred application technique. The properties of the paints are selectively adjusted, among other things, by additives to ensure optimal processability. Suitable material systems can be identified or developed for customer-specific applications. The selection and testing of coating systems are carried out using computer-assisted simulations. Extensive testing options are available for the characterization of the coatings, including testing according to DIN EN certified standards. In addition to standardized tests, further tests are often necessary for the application case. Therefore, in coordination with the customer, test procedures that are relevant to the development or use of the coatings are also realized. Parts or test specimens are coated at the HTL on behalf of customers and, if necessary, tested under application-related conditions.

Service Offering:

  • Development and optimization of customer-specific coatings for high-temperature applications
  • Selection and testing of coating systems using computer-assisted simulation
  • Coating of test specimens and components
  • Coating of textile structures (e.g. fabrics, fibers)
  • Development and sampling of paints at laboratory and pilot plant scale
  • Paint production and application under inert conditions (Ar, N2)
  • Standardized characterization of paints and coatings
  • Application-related testing of coatings

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Lacquers and Coatings