Large-area fabrication of low- and high-spatial-frequency laser-induced periodic surface structures on carbon fibers

Abstract

The formation and properties of laser-induced periodic surface structures (LIPSS) were investigated on carbon fibers under irradiation of fs-laser pulses characterized by a pulse duration  = 300 fs and a laser wavelength  = 1025 nm. The LIPSS were fabricated in an air environment at normal incidence with different values of the laser peak fluence and number of pulses per spot. The morphology of the generated structures was characterized by using scanning electron microscopy, atomic force microscopy and Fast-Fourier transform analyses.Moreover, the material structure and the surface chemistry of the carbon fibers before and after laser irradiation was analyzed by micro Raman spectroscopy and X-ray photoelectron spectroscopy. Large areas in the cm 2 range of carbon fiber arrangements were successfully processed with homogenously distributed high-and low-spatial frequency LIPSS. Beyond 2 those distinct nanostructures, hybrid structures were realized for the very first time by a superposition of both types of LIPSS in a two-step process. The findings facilitate the fabrication of tailored LIPSS-based surface structures on carbon fibers that could be of particular interest for e.g. fiber reinforced polymers and concretes.

Multifunctional Hierarchical Surface Structures by Femtosecond Laser Processing

“…At the lowest value F = 4.5 J/cm 2 , the micrograph reveals the formation of periodic structures with different spatial periods. They can be attributed to high-spatial frequency LIPSS (HSFL) and low-spatial frequency LIPSS (LSFL), respectively [ 21 , 27 ].…”

“…Since their first observation by Birnbaum in 1965 [ 18 ], LIPSS were intensively investigated in order to unveil their formation process as well as the dependence of influencing parameters [ 1 , 15 , 16 , 17 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. There are two types of LIPSS, the high-spatial frequency LIPSS (HSFL) and the low-spatial frequency LIPSS (LSFL) [ 21 , 27 ]. The first ones that arise below the ablation threshold, have a period much smaller than the incident laser wavelength and generally are aligned perpendicular to the electrical field vector in the case of dielectrics [ 16 , 21 , 28 ].…”

Maxwell Meets Marangoni—A Review of Theories on Laser‐Induced Periodic Surface Structures

“…[33,63] This extension of Sipe's theory is called Sipe-Drude model and was later adopted for other materials. [61,[64][65][66][67][68][69][70] At normal laser beam incidence ( = 0°), the Sipe-Drude model reveals that for increasing electron densities in the CB of semiconductors [33,68] or dielectrics, [61,62] the LSFL-II (RR) feature changes its shape/position and finally diminishes, while the LSFL-I (SEW/SPP) feature becomes very pronounced with large amplitudes, once the irradiated material turns plasmonically active through an increased extinction. At very high values of N e , all peaks disappear and becomes widely constant and approaches zero.…”

Laser-Induced Periodic Surface Structures (LIPSS)

“…Apart from single-step processing strategies for generating LIPSS in spots, lines, or areas on flat surfaces, a two-step processing of hybrid LIPSS structures was demonstrated even on curved sample surfaces such as 10-μm-diameter carbon fibers without affecting their mechanical strength (Kunz et al 2018b). In that approach, LSFL were "written" in a first step at the cylindrical fiber surface, followed by a second irradiation step at a lower peak fluence and at an optimized number of pulses.…”