Direct and indirect nanostructuring for the functionalization of metallic surfaces

• Applicants: Professor Dr.-Ing. Karsten Durst; Professor Dr.-Ing. Frank Mücklich
• Subject Area: Coating and Surface Technology ; Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517909685

Hierarchical surface structures can be used to influence surface properties such as wettability and also the friction and wear behavior of metallic materials. Functional surface structures with superhydrophobic behavior, as can be of importance in the food industry, often have structure sizes ranging from the nanometer range to larger length scales in the micrometer range. Especially for the functionalization of corrosion-resistant steels (austenites) for technical applications, a precise introduction of hierarchical surface structures on larger areas is a major challenge and will be addressed in this project. For this purpose, a combined approach of a laser interference method and nanoimprinting for hierarchical structuring of metallic materials will be developed in this project. The laser interference method will be used for direct structuring of the investigated materials as well as of tools for nanoimprinting. The surface structure of the tool created in this way will be transferred to different model materials by a plastic embossing process. The flow processes during the embossing process and the achievable surface structure sizes depend on the tool geometry, the process control as well as on the microstructure (grain size, subgrain size) and the solidification behavior of the materials. The particular challenge here is the further development of ultrashort pulsed DLIP (USP-DLIP) to generate hierarchical microstructures and, in particular, nanostructures both on the materials under investigation and on the WC-Co carbide tools used for nanoimprinting. The flow behavior of the materials into the tool structure and the design possibilities of the surface structures resulting from the imprinting process are a further focus of the investigations. In particular, the influence of the hardening behavior, as well as the grain and subgrain size on the flow processes during nanoimprinting will be considered. Direct and indirect structuring will be investigated on austenitic steels and Cu-based model materials. Furthermore, the wettability of the generated surface structures will be considered as an essential functional property. Of particular interest are the chemical and microstructural influences of the two processes on the wetting behavior. The aim of the project is thus to clarify the processes involved in the direct (USP-DLIP) and indirect (nanoimprinting) structuring of metallic surfaces and to demonstrate the design possibilities of the surface structures for different fields of application using the example of wettability.

• DFG Programme: Research Grants