Effects of laser and scanning parameters on surface modification of MONEL® alloy 400 by picosecond laser

Abstract

Due to its excellent properties, MONEL® alloy 400 is widely used in marine and aerospace, among other industries. Laser surface ablation is widely explored for modifying the properties of the surface of various materials for a wide range of applications such as corrosion control, solar cells, micro/nanofluidics, and other areas. In this study, an investigation of laser nano/microstructured surfaces produced on MONEL® alloy 400 through picosecond (ps) laser ablation under different values of laser fluences, scanning velocity, hatching distance, and the number of scanning passes was carried out. The processed surfaces were characterised by surface morphology, surface topography, and wettability. The experimental results reveal that laser fluences, scanning velocity, hatching distance, and the number of scanning passes have a huge influence on the surface morphology of the MONEL® alloy 400. At the lowest fluence, we observed the formation of low spatial frequency-laser-induced periodic surface structures (LSFL), while micro-grooves, micro-holes, and chaotic hierarchical structures were formed as fluence increased. The wettability test of the laser-processed regions showed that most regions were strongly hydrophobicity. The contact angles increase with the increase in laser fluence and with the decrease in hatching distance. This study could be beneficial for modifying the surface of metallic materials using ps laser pulses with high repetition rates and could be useful for high-quality machining for industrial applications.