Oxide layers on titanium obtainedby anodizing in orthophosphoric acid

Purpose: Titanium is an essential material used in modern dentistry, mostly due to its tissue compatibility. However, there are another physicochemical assets, which can be harnessed. One of these is enhancing the bonding strength of titanium with another materials. In view of the advantageous effect of oxide layers on the bond with the ceramics, an attempt was made at creating oxide layers on samples of commercially pure titanium applied as the material for metal frameworks of prosthetic restorations. Design/methodology/approach: As the research material cylindrical wet grinded commercially pure titanium, Grade II samples were used. The samples were divided into three groups and underwent anodic oxidation in 1 M orthophosphoric acid, with the voltages: 120 V, 160 V, 200 V. After the anodizing process, the samples were subjected to the X-ray diffraction, analysis of the element distribution from the surface towards the inside of the materials using an optical spectrometer, finishing with the tests performed with a scanning microscope to determine the morphology of the obtained layers. Findings: Layers of 0.26 μm to 0.65 μm thick were achieved. The performed studies demonstrated that increasing reaction voltage contributes not only to thickening of the oxide layers but also influences to porosity. The layers obtained in the electrolyte which contained monomolar orthophosphoric acid consist of only one allotropic type of titanium oxide – anatase. The spectrometric tests showed that the content of titanium and oxygen in the layer is not constant, which proves that the formed layer does not have a strictly stoichiometric composition TiO2, but rather TiO2-x. Research limitations/implications: It is necessary to provide the optimal voltage directly related to the employed acid solution to preserve the usable thickness of oxide layers. Too thick (over 1 μm) coating may lead to exfoliating. Contrary, distinctly thin layers present fractures and decrements, accordingly do not veneer entire surface of titanium sample. Originality/value: Usually oxide layers obtained by anodic oxidation are examined paying special attention to tissue integration and usability in implantology. Following paper is focused on bonding titanium with dental ceramics to facilitate process of designing porcelain-fused-to-metal fixed dentures.