Influence of surface topography and chemistry on the wetting behavior of laser-patterned, metallic surfaces

• Applicants: Professor Dr. Michael Kopnarski; Professor Dr. Michael Moseler; Professor Dr.-Ing. Frank Mücklich
• Subject Area: Coating and Surface Technology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 435334669

The wetting behavior of surfaces has drastic effects on their antimicrobial, friction and wear properties, or their adhesion. The process of laser patterning allows to change the wetting properties of surfaces systematically. The local application of energy modifies both the surface chemistry and the topography, which both have an influence on the wetting properties.The present proposal systematically investigates the influence of laser patterning of metallic surfaces on their wetting properties. In particular, the relevant key parameters shall be identified with the aid of experimental and simulative methods.The first goal is the generation and characterization of laser-patterned copper samples and the creation of suitable simulation models. For laser patterning, the extremely precise and efficient method of Direct Laser Interference Patterning (DLIP) is used. Three different pulsed laser systems (ns, ps, fs) are used in order to obtain different surface chemistry with similar topography by exploiting the varying laser material interaction, which depends on the pulse duration. First, the effect of an inhomogeneous superficial chemistry is to be egalized by sputtering processes. The resulting topography and surface chemistry of the produced samples will be analyzed using high resolution techniques in order to create suitable simulation models. Three different approaches are used: energy minimization, coarse grained molecular dynam-ics (MD) simulations, and fully atomistic MD simulations. Furthermore, the wetting behavior of the chemically homogeneous surfaces is determined both macroscopically and by a specially developed method (Partial Least Squares Algorithm) with high spatial resolution.The second goal is the simulation of the wetting behavior of the chemically homogeneous samples with the above mentioned methods. The influence of the primary laser pattern, the surface chemistry, and a superimposed nano-roughness will be investigated. Furthermore, continuum approach and MD simulations will be compared, which is an important prerequisite for further multi-scale modelling.The final goal is to identify the key parameters in the wetting of laser-patterned, chemically inhomogeneous surfaces and to compare experiment and simulation. In particular, the pre-dictability and the required calculation effort of the simulation methods will be evaluated.This is a milestone in the field of the wetting behavior of laser-patterned metallic surfaces, as there is no consensus in the relevant literature so far.

• DFG Programme: Research Grants
• Cooperation Partner: Professor Dr. Christian Motz