Laser-chemical treated superhydrophobic surface as a barrier to marine atmospheric corrosion

Abstract

A time efficient and cost-effective laser-based surface texturing technique combining nanosecond laser ablation and chemical immersion treatment was developed for steel alloy to achieve enhanced corrosion resistance in marine atmospheric environment. Three different surface patterns were created by nanosecond laser ablation and the laser patterned samples were subsequently immersed in 1H,1H,2H,2H-perfluorooctyl silane (FOTS) solution to tune surface chemistry. Dual-scale surface structure was formulated on the laser-chemical treated surface, as confirmed by the scanning electron microscopy (SEM) and confocal laser scanning microscope analyses. X-ray photoelectron spectroscopy (XPS) analysis was conducted to validate that desired surface chemistry was achieved on the laser-chemical treated surface. The effect of surface pattern on several key surface functionalities, including surface wettability, corrosion resistance and chemical stability was systematically presented in this work. Firstly, it was demonstrated via wettability measurements that the laser-chemical treated surface achieved superhydrophobicity with a water contact angle of 158.9°. Secondly, electrochemical and NaCl deliquescence tests were conducted to determine the corrosion resistance of the laser-chemical treated surfaces in marine atmospheric environments. It was confirmed that the laser-chemical treated surface can prevent marine atmospheric corrosion induced by salt deliquescence. Furthermore, it was revealed by electrochemical test that the laser-chemical treated superhydrophobic surface exhibited distinctly better anti-corrosion performance. The experimental results showed that the corrosion rate for the laser-chemical treated surface with microgroove pattern is approximately 5.4% of the corrosion rate for the untreated surface, indicating significant improvement of corrosion resistance for the laser-chemical treated surface. Thirdly, the high water contact angle of 151.0° sustained on the laser-chemical treated surface after electrochemical tests helped confirm the improvement of its chemical stability in corrosion medium. These experimental findings clearly demonstrate the developed nanosecond laser-chemical treatment method can be very effective for fabrication of stable superhydrophobic metal surface as a barrier to marine atmospheric corrosion with enhanced corrosion resistance.