Chemical Behavior and Corrosion Resistance of Medical Grade Titanium after Surface Modification by Means of Ion Implanta
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Chemical Behavior and Corrosion Resistance of Medical Grade Titanium after Surface Modification by Means of Ion Implantation Techniques Frank Schrempel1, Gerhard Hildebrand2, Marion Frant2, Werner Wesch1, Klaus Liefeith2 1 Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, D-07743 Jena, Germany 2 Abteilung Biomaterialien, Institut für Bioprozess- und Analysenmesstechnik, Rosenhof, D-37308, Heilbad Heiligenstadt, Germany ABSTRACT This work presents data on topographical structure, chemical surface composition, physicochemical properties and corrosion resistance of medical grade titanium after ion implantation. Pure commercial titanium has been implanted with 30 keV Na-, Ca- and P-ions at fluences of 2.0 x 1017 cm-2 and 1.5 x 1017 cm-2, respectively. Some of the samples were heat treated at 600 °C for 40 min. Atomic force microscopy (AFM) was used for surface analysis. The chemical composition was investigated using Rutherford backscattering spectrometry (RBS). Physicochemical investigations were carried out using contact angle measurements to determine the polarity of the modified titanium surfaces. Moreover, the electrokinetic zeta potentials on a physiological pH value have been determined. Finally, the corrosion resistance was examined in simulated body fluid (SBF) containing 4 g/l bovine serum albumin (BSA) using cyclic voltametry. Considering the P-implantations, the measured depth distribution of phosphorus agrees well with calculations. For the implantation of Na and Ca, the concentration of implanted atoms in the maximum of the depth distribution is noticeably lower and the distribution extends to larger depths compared to the predictions. This finding is associated with a strong incorporation of oxygen over the whole penetration depth of the implanted ions. According to topographical and chemical changes different contact angles as well as zeta potentials have been detected for the ion implanted surfaces compared to pure titanium. The electrochemical examinations indicate that the implantation has no negative influence on the corrosion resistance in comparison to unmodified medical grade titanium. The results show that ion implantation using certain ions can be used to design tailor-made titanium surfaces from a physicochemical point of view.
INTRODUCTION Artificial materials implanted into bone defects are often encapsulated by fibrous tissue such that they are isolated from the surrounding bone. However, some bioactive ceramics, such as Bioglass®, sintered hydroxyapatite (HA) and glass-ceramics, show the desired bone-bonding capacity due to a spontaneous formed bond to living bone through a bone-like apatite layer without forming a surrounding fibrous tissue [1]. Meanwhile, it is well known that their surface reactivity is mainly attributed to CaO, P2O5, SiO2 and sodium containing phases. Because the fracture toughness values of these materials are not as high as that of human cortical bone, bioactive ceramics can not be used as bulk material to produce l
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