关键词: Laser processing , · Abrasive belt grinding , · Bionic sharkskin structure , · Wettability

Abstract: A new process for the fabrication of sharkskin bionic structures on metal surfaces is proposed. The sharkskin bionic surface was successfully machined on the surface of IN718 by laser sequencing of the abrasive belt surface, laser processing of the layered scale-like structure, and ribbed texture grinding. The flexible contact properties of belt grinding allow ribbed structures to be machined uniformly on a hierarchical, scale-like microstructure. Sharkskin bionic microstructures with radii greater than 75 μm were prepared after parameter optimisation. The influence of processing parameters on the geometrical accuracy of the microstructure was investigated, the microstructure microform and elemental distribution were analyzed, and the relationship between the ribbed microstructure and chemical properties of the surface of the bionic sharkskin on wettability was revealed. The results indicate that reducing the laser power and increasing the laser scan rate can reduce the laser thermal effect and improve the microstructure processing accuracy. The laser ablation process is accompanied by a violent chemical reaction that introduces a large amount of oxygen and carbon elements and infiltrates them at a certain depth. The wettability of the surface undergoes a transition from hydrophilic (contact angle 69.72°) to hydrophobic (contact angle 131.56°) due to the adsorption of C–C/C–H and the reduction of C=O/O=C–O during the placement process. The ribbed microstructure changes the solid–liquid contact on the surface into a solid–liquid–gas contact, which has an enhanced effect on hydrophobicity. This study is a valuable guide to the processing of hydrophobic layered bionic microstructures.

Key words: Laser processing , · Abrasive belt grinding , · Bionic sharkskin structure , · Wettability