A Comparative Study of Laser Etching and Laser Shock Imprinting (LSI) for the Fabrication of a Multiscale Microtexture on TA1 Foil Surfaces
P. Li, B.Y. Liu, K.N. Meng, S. Hu and Z.B. Shen
Multiscale microtextures were fabricated on the surface of TA1 foil using laser etching and laser shock imprinting (LSI) processes. First, laser etching process was employed to directly fabricate multiscale microtextures on the 20 μm thick TA1 foil as the laser etching workpiece. Then, using the same laser etching parameters, multiscale microtextures were processed on a 1 mm thick TA1 plate surface as the mould for LSI. Finally, the LSI was used to replicate similar multiscale microtextures from the mould surface, and the influence of pulse number and power density on the forming depth and replication degree of the TA1 workpiece was analysed. By comparing the aging effect and durability of the hydrophobic TA1 foils treated by laser etching and LSI processes, the differences in chemical composition stability and mechanical stability between laser etching and LSI surfaces were analysed. The laser etching surface exhibited a super-hydrophilic state within 12 hours and tended to be a superhydrophobic state after 30 days of storage in air. In contrast, no obvious aging effect was observed on the surface of the LSI samples, indicating better stability of surface wettability (110°<CA<126°). The specific reason for the difference lies in the different degrees of hydroxylation caused by the two processes, which have different effects on organic adsorption and wettability. The durability of the laser etching and LSI surfaces was compared under the same testing conditions, and the results showed that, due to the grain refinement and surface hardness enhancement effects in LSI, the mechanical stability of the microtextures was improved, resulting in better wear resistance and impact resistance for the LSI surface.
Keywords: Fibre laser, Nd:YAG laser, TA1 foil, laser etching, laser shock imprinting (LSI), superhydrophobic, aging effect, durability