Epoxy/TiO₂/epoxy and epoxy/FAS-TiO₂/epoxy coatings were applied to the surface of AISI 316L stainless steel with the aim to improve the biocompatibility and antibacterial properties. Contact-angle measurements were used to evaluate the wetting properties of the epoxy, epoxy/TiO₂/epoxy and epoxy/FAS-TiO₂/epoxy coatings. The epoxy and epoxy/TiO₂/epoxy coatings were hydrophilic compared with the strongly hydrophobic epoxy/FAS-TiO₂/epoxy coating. The average surface roughness (S_a) of the epoxy/FAS-TiO₂/epoxy coating was higher than that of the epoxy/TiO₂/epoxy coating due to the formation of agglomerates. The biocompatibility evaluation revealed that the cell attachment was significantly higher on the epoxy/FAS-TiO₂/epoxy and epoxy/TiO₂/epoxy coatings compared with the pure epoxy coating. We also observed improved antibacterial properties for the epoxy coatings with the addition of both TiO₂ and FAS-TiO₂ nanoparticles.

We present the modification of Ti-6Al-4V surfaces with a diode end-pumped Nd:YVO4 laser by varying the distance between laser-produced micro(μ)-channels. We analyzed the influence of laser texturing on the morphology, microstructure, surface and corrosion properties of Ti-6Al-4V. SEM imaging reveals a characteristic μ-channel pattern with different scan line separations, while electron backscatter diffraction (EBSD) indicates that laser texturing with the current parameters influences the microstructure up to 2 µm deep with the most significant influence at the tips, where melting and rapid solidification occur. The Vickers hardness test indicates a surface hardening effect of the laser-textured compared to the as-received Ti-6Al-4V surfaces. The XPS analysis showed that the oxide layer on the laser-textured samples was considerably thicker compared to the as-received sample, at 20 and 7 nm, respectively. We observed that the wettability was strongly correlated with the scan line separation. The results show increased hydrophobicity with increased scan line separation. The corrosion resistance was improved for laser-textured surfaces compared to the as-received surface and increased with the scan line separation.

We present the results of one year observation of wetting and corrosion properties of nanosecond fiber laser-textured stainless steel, uncoated and coated with epoxy or FAS (fluoroalkylsilane)-TiO₂/epoxy. A comparative study was performed on samples kept under ambient conditions and in reduced air pressure and humidity. The results show the ability to induce wettability conversion from initially superhydrophilic to final superhydrophobic state either indirectly by ageing the uncoated laser-textured surface or directly by application of FAS-TiO₂/epoxy coating. The storage conditions significantly influenced the wettability development of uncoated laser-textured steel, i.e., the process of ageing was slowed down in reduced air pressure and humidity. Detailed surface chemical analysis revealed that adsorption of the organic matters from the surrounding media influences the wettability conversion and ageing. However, the ageing of the coated surfaces was not affected by the storage conditions. Corrosion stability of uncoated laser-textured surfaces was enhanced over time due to the wettability transition, depending on their morphology. Coatings represent a superior barrier over the texture and wettability with the stable long-term surface protection against aggressive media.

Laser-powder bed fusion (LPBF) is one of the preferred techniques for producing Co-Cr metal structures for dental prosthodontic appliances. However, there is generally insufficient information about material properties related to the production process and parameters. This study was conducted on samples produced from three different commercially available Co-Cr dental alloys produced on three different LPBF machines. Identically prepared samples were used for tensile, three-point bending, and toughness tests. Light microscopy (LM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) analyses of microstructure were performed after testing. Differences were observed in microstructures, which reflected statistically significant differences in mechanical properties (one-way analysis of variance (ANOVA) and Scheffé post hoc test (α = 0.05)). The material produced on the 3D Systems DMP Dental 100 had 24 times greater elongation ε than the material produced on the Sysma MySint 100 device and the EOS M100 machine. On the other hand, the material produced on the EOS M100 had significantly higher hardness (HV0.2) than the other two produced materials. However, the microstructure of the Sysma specimens with its morphology deviates considerably from the studied group. LPBF-prepared Co-Cr dental alloys demonstrated significant differences in their microstructures and, consequently, mechanical properties.

Nitinol is a group of nearly equiatomic alloys composed of nickel and titanium, which was developed in the 1970s. Its properties, such as superelasticity and Shape Memory Effect, have enabled its use, especially for biomedical purposes. Due to the fact that Nitinol exhibits good corrosion resistance in a chloride environment, an unusual combination of strength and ductility, a high tendency for self-passivation, high fatigue strength, low Young’s modulus and excellent biocompatibility, its use is still increasing. In this research, Atomic Layer Deposition (ALD) experiments were performed on a continuous vertical cast (CVC) NiTi rod (made in-house) and on commercial Nitinol as the control material, which was already in the rolled state. The ALD deposition of the TiO₂ layer was accomplished in a Beneq TFS 200 system at 250 °C. The pulsing times for TiCl₄ and H₂O were 250 ms and 180 ms, followed by appropriate purge cycles with nitrogen (3 s after the TiCl₄ and 2 s after the H₂O pulses). After 1100 repeated cycles of ALD depositing, the average thickness of the TiO₂ layer for the CVC NiTi rod was 52.2 nm and for the commercial Nitinol, it was 51.7 nm, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM) using Energy-dispersive X-ray (EDX) spectroscopy. The behaviour of the CVC NiTi and commercial Nitinol with and without the TiO₂ layer was investigated in a simulated body fluid at body temperature (37 °C) to explain their corrosion resistance. Potentiodynamic polarisation measurements showed that the lowest corrosion current density (0.16 μA/cm²) and the wider passive region were achieved by the commercial NiTi with TiO₂. Electrochemical Impedance Spectroscopy measurements revealed that the CVC NiTi rod and the commercial Nitinol have, for the first 48 h of immersion, only resistance through the oxide layer, as a consequence of the thin and compact layer. On the other hand, the TiO₂/CVC NiTi rod and TiO₂/commercial Nitinol had resistances through the oxide and porous layers the entire immersion time since the TiO₂ layer was formatted on the surfaces.