LASUR - Investigation of surface treatment of baking plates by means of pulsed laser radiation, in particular ultra-short pulse laser

funded by: FFG, opens an external URL in a new window 

project number: 24159707

Project end: March 2023

The development of laser-induced periodic surface structures was documented as early as a few years after the presentation of the first laser. In the work of Birnbaum the occurrence of periodic structures with a period length just below the wavelength of the radiation used was mentioned. These structures occur in a variety of materials and are called LIPSS (laser induced periodic surface structures) or ripples for short. For example, structures with a periodicity of λ/6 and smaller can occur during processing with fs pulses when irradiated with an intensity just below the ablation threshold for a single-pulse ablation. So far, structures with a minimum periodicity of about 120 nm have been observed on metal surfaces by the Process Engineering Group at the Institute of Production Engineering and Photonic Technologies. There are different approaches to explain the origin of this High Spatial Frequency LIPSS (or HSFL for short), but the investigation of the mechanism of its formation is not the focus of this project. However, the generation of such nanostructures is of fundamental interest, since the wetting behaviour of surfaces can be influenced and thus hydrophobic or even hydrophilic properties of the processed materials can be achieved.



links: Oberfläche mit runden Kratern unterschiedlichster Größen; rechts: Kontaktwinkel von Flüssigkeitstropfen und Oberfläche abhängig von Rauheit.

© TU Wien

Surface structures on steel samples after processing with an ultrashort pulse laser and different processing parameters. The samples show hydrophobic or superhydrophobic behavior, which remains mostly stable even after several heating and cooling cycles.

We assume that the adhesion of baked products can also be influenced by an appropriately designed surface. This assumption is supported by the results of laser-purified samples available so far. Regarding the corrosion problem mentioned above, it should also be noted that nanostructuring also influences the corrosion properties. Within the framework of the present project, different sample materials used for the production of baking plates are therefore to be systematically processed with different laser systems. On the one hand, we want to gain a better understanding of the mechanism that leads to the observed extension of cleaning intervals by laser cleaning, and on the other hand, we want to produce and investigate (super)hydrophobic surfaces by laser processing. In order to be able to classify the results of nanostructured, superhydrophobic samples, they will be judged against the performance of laser-cleaned samples. Within the scope of this project, therefore, processing parameters are to be determined with which structures can be created on the samples provided by the company partner, which can impede the aforementioned adhesion of baking products. On the one hand, the investigations will help to understand the mechanism of the so far only empirically determined improvement of the surface properties of baking plates and, on the other hand, to produce specific structures that make adhesion more difficult. After completing the project we expect to understand the mechanism of adhesion on the surface of baking plates and to be able to give hints on the optimal surface structure of baking plates. Based on the results of this project, the development of an industrial process for the surface refinement of baking plates will be a foundation stone.