Incorporation of TiO2 Nanoparticles in Thin Films Deposited on AISI 304 Stainless Steel using the Cathodic Cage Technique: A Preliminary Study

TiO2 (titanium dioxide) nanoparticles have been widely used in various industrial sectors, such as photodegradation and photocatalysis systems, photovoltaic cells and biomedical applications, exhibiting osseointegration, bactericidal, antitumor and cell differentiation properties. These nanoparticles can be used in the form of powders, crystals, nanorods, nanotubes and thin films. In this sense, as an alternative to improve the surface properties of AISI 304 stainless steel, TiO2 nanoparticles (powders) were incorporated into thin films obtained through duplex plasma treatment (conventional plasma nitriding followed by cathodic cage plasma deposition) in order to evaluate the mechanical properties, wettability and bacterial response. The thin films were characterized using Grazing Incidence X-Ray Diffraction (GIXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Rockwell C adhesion, Vickers microhardness, surface roughness (Ra and Rg), wettability and bacterial adhesion tests. The treatment was efficient in depositing coatings incorporating TiO2 nanoparticles on the surface of AISI 304 steel, obtaining thin films with good layer uniformity and excellent adhesion to the substrate. All the treated samples had a higher surface microhardness than the untreated sample. After the treatments, the films showed an increase in surface roughness which corroborated in obtaining more hydrophilic surfaces, with contact angle reductions of up to 88.94%, and lower bacterial adhesion activity, showing reductions of up to 78.42%. The set of attractive and promising properties obtained with the deposition of these films may arouse interest in their use in biomedical applications, such as their possible use in metal prostheses.