Superfícies de titânio modificadas por oxidação a plasma em cátodo oco

Abstract

A new methodology for oxidation of titanium implant surfaces was developed to remove primary oxides formed spontaneously during titanium parts machining. With the aim of resolving the problem, this study used plasma as an energy source both in removing these oxides and oxidizing the titanium surface. In this respect, Ti disks had their oxides removed by plasma in an atmosphere of 50% Air + 50% H2, followed by oxidation using the hollow cathode discharge technique. Oxidation was performed for 60 min at 500°C, in a mixture of argon (60%) and oxygen (40%) until reaching a pressure of 220 Pa. Next, the oxidized surfaces were characterized by XRD (X-Ray diffraction), AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy). Results obtained by grazing incidence X-Ray indicated that the oxide removal process was effective, reducing TiO2 to Ti. With respect to the oxidation process, there was an increase from 61% to 76% in O2 concentration and the oxidized sample was rich in oxides such as TiO2. Characterization of AFM revealed that the oxidized samples exhibited surface defects with varied geometry for peaks and valleys. The topographic differences between the oxidized surface and the control are discussed in terms of mean pore dimensions and roughness parameters (Ra, Rp and Rz). Biological assays were also conducted to observe adhesion and cell proliferation. SEM showed cell spreading, a larger number of filopodial projections and morphological differences in the cells of oxidized samples when compared to the control sample. In cell proliferation, cells showed a preference for oxidized surfaces where the number of adherent cells was comparatively higher than in the control sample. We concluded that the process was efficient in removing primary oxides as well as in oxidizing titanium surfaces