Femtosecond Laser Fabrication of Stable Hydrophilic and Anti-Corrosive Steel Surfaces.

Christina Lanara,Emmanuel Stratakis,Alexandros Mimidis

doi:10.3390/ma12203428

Abstract

We report on a novel single-step method to develop steel surfaces with permanent highly hydrophilic and anti-corrosive properties, without employing any chemical coating. It is based on the femtosecond (fs) laser processing in a saturated background gas atmosphere. It is particularly shown that the fs laser microstructuring of steel in the presence of ammonia gas gives rise to pseudoperiodic arrays of microcones exhibiting highly hydrophilic properties, which are stable over time. This is in contrast to the conventional fs laser processing of steel in air, which always provides surfaces with progressively increasing hydrophobicity following irradiation. More importantly, the surfaces subjected to fs laser treatment in ammonia exhibit remarkable anti-corrosion properties, contrary to those processed in air, as well as untreated ones. The combination of two functionalities, namely hydrophilicity and corrosion resistance, together with the facile processing performed directly onto the steel surface, without the need to deposit any coating, opens the way for the laser-based production of high-performance steel components for a variety of applications, including mechanical parts, fluidic components and consumer products.

Highlights

The ultrafast laser processing of solid surfaces has been established as a reliable method to modify a material to selectively control the wetting [1,2,3,4], optical [5,6] and tribological properties [7]
It is shown that the fs laser microstructuring of steel in the presence of ammonia gas gives rise to pseudoperiodic arrays of microcones (MCs) exhibiting highly hydrophilic properties, which are stable over time, at least for a five-month period
The fs laser microstructuring of steel in the presence of ammonia gas provides a dual functionality on steel, namely hydrophilicity and corrosion resistance

Summary

Introduction

The ultrafast laser processing of solid surfaces has been established as a reliable method to modify a material to selectively control the wetting [1,2,3,4], optical [5,6] and tribological properties [7]. Many works have been reported on the modification of steel wettability via conventional laser texturing, the wetting properties attained are unstable and always switch from a superhydrophilic to a highly hydrophobic state within a few days after irradiation [15,16,17]. It is evident that such evolution of the surface chemistry, energy and wettability substantially limits the potential applications of laser-processed steel [1,8] In this context, it is a challenge to maintain stable hydrophilic characteristics, in the long term, on a metallic surface. Rajab et al showed that the surface chemistry of laser-textured steel can be rendered superhydrophilic for a long time upon the post-processing deposition of a hydrophilic coating.

Methods

Results

Conclusion