Multiscale ultrafast laser texturing of marble for reduced surface wetting

TL;DR

This study explores how ultrafast laser texturing modifies marble surfaces to become hydrophobic over time, with potential applications in surface protection, by analyzing surface roughness, chemical changes, and wettability evolution over months.

Contribution

It demonstrates that ultrafast laser processing induces multi-scale roughness and chemical modifications that transform marble surfaces from hydrophilic to hydrophobic over time.

Findings

Surfaces become hydrophobic after a few days post-treatment.

Multi-scale roughness and chemical changes influence wettability evolution.

Laser-treated surfaces maintain hydrophobicity after cleaning.

Abstract

The modification of the wetting properties of marble surfaces upon multi-scale texturing induced by ultrafast laser processing (340 fs pulse duration, 1030 nm wavelength) has been investigated with the aim of evaluating its potential for surface protection. The contact angle (CA) of a water drop placed on the surface was used to assess the wettability of the processed areas. Although the surfaces are initially hydrophilic upon laser treatment, after a few days they develop a strong hydrophobic behavior. Marble surfaces have been irradiated with different scan line separations to elucidate the relative roles of multi-scale roughness (nano- and micro-texture) and chemical changes at the surface. The time evolution of the contact angle has been then monitored up to 11 months after treatment. A short and a long-term evolution, associated to the combined effect of multi-scale roughness and the attachment of chemical species at the surface over the time, have been observed. XPS and ATR measurements are consistent with the progressive hydroxylation of the laser treated surfaces although the additional contribution of hydrocarbon adsorbates to the wettability evolution cannot be ruled-out. The robustness of the results has been tested by CA measurements after cleaning in different conditions with very positive results.