Here we report on the systematic study of the qualitative correlation between surface roughness generated by the LbL deposition of dual-size fluorosilane modified TiO2 (FAS-TiO2) and as-received TiO2 nanoparticles (30 nm and 300 nm), and resulting (super)hydrophobicity or (super)hydrophilicity of the coatings. We analyze the wetting properties of the fabricated coatings and their morphology.
COBISS.SI-ID: 1231018
In this work, we present functionalization of AISI 316 L surfaces by nanosecond Nd:YAG laser texturing and adsorption of superhydrophobic fluoroalkylsilane functionalized 30-nm silica nanoparticles. Surface modification by varying the distance between laser-produced micro([micro])-channels leads to different surface roughnesses. After nanosilica coating, the superhydrophilic laser-textured surfaces change into superhydrophobic surfaces with the same [micro] -roughness. A higher [micro] -channel density leads to more hydrophobic surfaces after coating. This enables a study of the combined effect of surface wettability and morphology on the friction coefficient and wear resistance. Experiments were performed in dry and water environments. In the case of dry friction, increased [micro]-roughness leads to a higher friction coefficient, and the water-repellency modification by nanosilica particles has no influence on the tribological behaviour. In contrast, in the water environment, the wettability presents an important contribution to the properties of contact surfaces: hydrophobic surfaces exhibit a lower friction coefficient, especially at higher densities of [micro] -channels. Energy-dispersive X-ray spectroscopy analysis of surfaces before and after the tribological experiments is performed, revealing the difference in weight % of Si in the worn surface compared to the unworn surface, which varies according to the nature of the surface morphology due to laser texturing.
COBISS.SI-ID: 16039707
This work investigates the evolution from superhydrophilic to superhydrophobic surface state on corrosion behaviour of SS316L produced by Nd:YAG nanosecond direct laser texturing (DLT). Results confirm perfect correlation among wettability and corrosion, hence superhydrophobic surface with a contact angle of 168 +/- 3.0° reflects in enhanced passivity, lower anodic dissolution and corrosion current reduction. Characterization of the corrosion attack by 3D microscopy reveals high sensitivity of superhydrophilic surfaces on corrosion propagation direction in regard to the laser beam passage (90°/0°). However, this trend completely diminishes with superhydrophobic development. Further, DLT also completely prohibits intergranular corrosion detected with the non-processed sample.
COBISS.SI-ID: 15482907
TiO2/epoxy coatings were successfully applied to the surface of AISI 316L stainless steel to change the wetting properties, with the aim being to improve the biocompatibility of the superhydrophobic/superhydrophilic surfaces. Contact-angle measurements were used to evaluate the wetting properties of the non-coated, epoxy-coated, as-received TiO2/epoxy-coated and fluoroalkylsilane (FAS)-TiO2/epoxy-coated substrates. The as-received TiO2/epoxy coating and FAS-TiO2/epoxy coating showed superhydrophilic and superhydrophobic characteristics, respectively. The average surface roughness (Sa) of the superhydrophobic surface was higher compared to the superhydrophilic surface due to the formation of agglomerates. The biocompatibility evaluated by cell attachment showed that AISI 316L stainless steel with a hydrophilic nature and low Sa is the most favourable surface for bone osteosarcoma cells (MG-63) growth. On the other hand, the two limiting cases of surfaces, superhydrophilic and superhydrophobic coatings with increased roughness compared to AISI 316L, showed lower biocompatibility.
COBISS.SI-ID: 1404842
Superhydrophilic and superhydrophobic TiO2/epoxy coatings were prepared with as-received TiO2 and fluoroalkylsilane (FAS) functionalised TiO2 nanoparticles and successfully applied to the surface of AISI 316L stainless steel. The wetting properties of the coatings were confirmed with static contact-angle measurements. The corrosion performance of the investigated coatings was studied by electrochemical impedance spectroscopy (EIS). The open-circuit impedance spectra of the AISI 316L stainless steel, the epoxy-coated AISI 316L, the as-received TiO2/epoxy coating on AISI 316L and the FAS-TiO2/epoxy coating on AISI 316L were measured in simulated physiological Hank’s solution. Bode plots and Nyquist diagrams were used to evaluate the corrosion properties of the investigated coatings. The results show the enhanced corrosion resistance of surface-modified stainless steel, especially in the case of the superhydrophobic FAS-TiO2/epoxy coating.
COBISS.SI-ID: 1416362