Direct and indirect nanostructuring for the functionalization of metallic surfaces

分级表面结构可用于影响表面性质，例如润湿性以及金属材料的摩擦和磨损行为。具有超疏水行为的功能表面结构，如在食品工业中可能是重要的，通常具有从纳米范围到微米范围内的较大长度尺度的结构尺寸。特别是对于用于技术应用的耐腐蚀钢（镁合金）的功能化，在较大区域上精确引入分层表面结构是一个重大挑战，将在本项目中解决。为此，本项目将开发一种激光干涉法和纳米压印相结合的方法，用于金属材料的分层结构化。激光干涉法将用于直接结构的研究材料以及工具的纳米压印。以这种方式创建的工具的表面结构将通过塑料压花工艺转移到不同的模型材料上。压印过程中的流动过程和可实现的表面结构尺寸取决于工具几何形状、过程控制以及材料的微观结构（晶粒尺寸、亚晶粒尺寸）和凝固行为。这里的特殊挑战是进一步开发超短脉冲DLIP（USP-DLIP），以在所研究的材料和用于纳米压印的WC-Co碳化物工具上生成分层微观结构，特别是纳米结构。材料进入模具结构的流动行为和压印过程中产生的表面结构的设计可能性是研究的进一步焦点。特别是，硬化行为的影响，以及纳米压印过程中的流动过程中的晶粒和亚晶粒尺寸将被考虑。直接和间接结构将研究奥氏体钢和铜基模型材料。此外，所产生的表面结构的润湿性将被认为是一个重要的功能特性。特别感兴趣的是化学和微观结构的影响，这两个过程的润湿行为。因此，该项目的目的是阐明金属表面的直接（USP-DLIP）和间接（纳米压印）结构化所涉及的过程，并以润湿性为例展示不同应用领域的表面结构设计可能性。

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.