Processing microgrooves and craters on the surface of wide band gap mold material using femtosecond laser

Abstract

A femtosecond pulsed Ti: sapphire laser micro-manufacturing system was used to investigate the ablation characteristics and material removal mechanisms of wide band gap mold material SiC in theoretical and experimental aspects. Through percussion and parallel processing methods, two kinds of microstructures regarding craters and grooves, which had important specifically applications in micromachining and replication manufacturing, were fabricated in air respectively. Scanning Electron Microscopy (SEM), Talysurf Profilometer (Talysurf), Atomic Force Microscope (AFM) and Optical Microscope (OM) were used to identify and measure the morphological characteristics and chemical composition of the mold material surface before and after processing. The ablation threshold and waist radius were determined according to the numerical relationship between micro craters and laser fluencies, whose results were 0.31J/cm 2 and 32μm, respectively. Meanwhile, the interacting procedures of samples and photons showed two stages, which were called optical and thermal penetration, with corresponded characteristics 0.13J/cm 2 and 0.61J/cm 2 . Besides, the femtosecond laser repetition rate, pulse numbers, pulse energy and the scanning velocity effect on the modification microstructures surface geometry were examined systematically. Furthermore, the wide band gap mold sample SiC, combining with the micro grooves and craters' topography, material removal mechanisms were also analyzed in detail.