The influence of different parameters of magnetron sputtering on the structure and chemical composition of titanium alloy implant surfaces

Abstract

The aim of the investigation is to study the influence of different parameters of magnetron sputtering on the structure and chemical composition of titanium and titanium alloy surfaces used for endosseous implantation. Materials and Methods. The study involved the use of the NSC-3500 magnetron sputtering system (NANO-MASTER Inc., USA) providing the possibility to obtain coatings of almost any metals, alloys and semiconductors materials without a shift in the stoichiometric composition. High-purity argon (99.99%) was used as the sputtering gas. A high-purity titanium (99.99%) target was used as the source of the coating material. Polished titanium washers of Grade IV and Grade V (according to ASTM) were used as substrates for growing titanium coatings. Titanium coatings were grown on the titanium washers at the temperature of 150°C and magnetron sputtering power of 200–300 W. After obtaining the titanium coatings, the samples were heat-treated in vacuum at 450°C for 2 h. Titanium coating surface morphology was studied using atomic force microscopy on the SOLVER NEXT unit (NT-MDT, Russia). Results and Discussion. The influence of different technological modes of deposition on the surface morphology and roughness of the obtained titanium coatings was studied. It was found that an increase in the sputtering power (from 200 to 300 W) led to significant structural changes accompanied by the change in the grain size and the resulting surface roughness. Magnetron treatment of a pure titanium sample with chemically pure titanium allows creating a nanostructured surface bonded to the substrate at the atomic level. The surface morphology varies at the nano-scale depending on the radiation power. Subsequent heat treatment (at 450°C) does not lead to significant changes in morphology, heterogeneity or granularity profile of the sample surface. When the surface of titanium aluminum-vanadium alloy Grade V was coated with chemically pure titanium, the elemental composition of the modified surface corresponded to the composition of titanium Grade IV (there was the complete absence of vanadium and minor aluminum impurities). Conclusion. Magnetron sputtering of pure titanium onto implants made of titanium and titanium alloys allows obtaining high-quality nanostructured surfaces with unusual physical properties (thickness, porosity, adhesion, etc.)