Production of stable superhydrophilic surfaces on 316L steel by simultaneous laser texturing and SiO₂ deposition

Highlights: • This work focused on the generation of long term superhydrophilic structures on ametallic substrate by one step nanosecond laser surface texturing with in-situ SiO2 deposition. • A range of structureshasbeen produced depending on changing the laser scanning speed and scanning times. • The contact angle of the laser textured surface was increased with increasing the scanning times and decreasing scnning speed. • The durability of superhydrophilicitywas maintained for more than six months. • With increasing the scanning passes and decreasing scanning speed, the roughness and surface oxygen and SiO2 was increased resulting in increasing the surface wettability. • By adjusting laser processing parameters according to the requirement, this method could be explored for a range of applications such as improving the adhesion, coating, reducing friction and controlling cell behaviour. - Abstract: Superhydrophilic surfaces with liquid contact angles of less than 5 ° have attracted much interest in practical applications including self-cleaning, cell manipulation, adhesion enhancement, anti-fogging, fluid flow control and evaporative cooling. Standard laser metal texturing method often result in unstable wetting characteristics, i.e. changing from super hydrophilic to hydrophobic in a few days or weeks. In this paper, a simple one step method is reported for fabricating a stable superhydrophilic metallic surface that lasted for at least 6 months. Here, 316L stainless steel substrates were textured using a nanosecond laser with in-situ SiO₂ deposition. Morphology and chemistry of laser-textured surfaces were characterised using SEM, XRD, XPS and an optical 3D profiler. Static wettability analysis was carried out over a period of 6 months after the laser treatment. The effect of surface roughness on wettability was also studied. Results showed that the wettability of the textured surfaces could be controlled by changing the scanning speed of laser beam and number of passes. The main reason for the realisation of the stable superhydrophilic surface is the combination of the melted glass particles mainly Si and O with that of stainless steel in the micro-textured patterns. This study presents a useful method of fabricating stable superhydrophilic surfaces on metals.