Formation mechanism of superhydrophobicity of stainless steel by laser-assisted decomposition of stearic acid and its corrosion resistance

Superhydrophobic surfaces have attracted extensive attention over the past decade, primarily due to their self-cleaning, corrosion resistance and anti-bacterial abilities. However, it is still a challenge to prepare superhydrophobic surfaces with good chemical stability, low cost, environmental friendliness, and suitable for large-scale production applications. In this paper, a hybrid laser-chemical method to prepare superhydrophobic micro-patterns on 316L stainless steel were put forward, which combined laser ablation and laser assisted chemical decomposition of stearic acid (C ₁₇H ₃₅COOH). Experiments show that under the laser power of 10 W, the frequency of 150 kHz, the speed of 20 mm/s, and the mesh spacing of 75 μm, the best superhydrophobicity with a static contact angle of 153.9° can be obtained. The fundamental mechanism of laser-chemical method is the increase of the non-polar C–C(H) bond of specimen by laser assisted hydrodeoxygenation reaction of stearic acid. Moreover, unlike laser ablation-stearic acid coated specimen, the specimen prepared by laser-chemical method can maintain superhydrophobicity after 10 min of ultrasonic cleaning. The electrochemical corrosion experiments shows that the hybrid laser-chemical method can manufacture superhydrophobic specimens with better chemical durability and corrosion resistance.