Preparation of highly dewetted porous steel for shallow water AUV based on laser ablation method

Abstract

Over the past two decades, autonomous underwater vehicles (AUVs) have been developed for various marine, commercial, and military applications. Porous metals, known for their lightweight high performance, suit AUV hulls, especially in shallow waters. However, because of their inherent hydrophilicity and porous structure, high humidity causes corrosion. In this study, a novel solution involving laser ablation and subsequent heat treatment of porous steel is proposed to improve the waterproofing performance both above and below water. By analyzing the surface structures, wetting attributes, and droplet behavior, the optimal laser and heat treatment parameters for superior performance are revealed. The porous nested structures created by laser ablation effectively reduce fog accumulation and, enhance the anti-fogging capabilities. Furthermore, the underwater stability ofsuperhydrophobic porous steels at different depths is systematically investigated. A method involving air injection into porous steel is proposed to address the limited air-pocket lifespan and instability of dehumidified surfaces. Experimental results confirm rapid and complete restoration of superhydrophobicity at a 0.9-meter depth. Thus, this study presents a practical corrosion-resistant surface material for AUVs in shallow-water environments and a new approach for achieving corrosion resistance in porous metals exposed to long-term aquatic conditions.