Generation of hierarchical wetting microstructures by the ultrasonic vibration-assisted mechanical ruling

Abstract

This paper presents an innovative method that combines ultrasonic vibration and mechanical ruling to fabricate hierarchical wetting microstructures with controllable adhesion properties on widely used 304 stainless steel. These hierarchical microstructures, obtained through the ultrasonic-assisted mechanical ruling process, enable both hydrophobicity and controllable adhesion by adjusting the vibration amplitude and ruling speed. When the amplitude increased from 2μm to 4μm, there was a 5% rise in the contact angle in the parallel direction, ranging from 132.1° to 138.9°, while in the perpendicular direction, it increased by 3.9%, from 121.1° to 125.8°. Similarly, as the ruling speed increased from 6mm/s to 8mm/s, the contact angle in the parallel direction increased by 3.3%, from 134.4° to 138.8°. In the perpendicular direction, the contact angle increased by 3.6%, from 127.8° to 132.5°. Notably, with an amplitude of 4μm and a ruling speed of 10mm/s, the resulting hierarchical microstructured surface exhibited significantly reduced adhesion. This paper effectively demonstrates the one-step production of hydrophobic structures with adjustable adhesion using ultrasonic-assisted mechanical ruling. This approach enhances processing efficiency and showcases the advantages of ultrasonic-assisted mechanical ruling in fabricating hierarchical microstructures.