Preparation and Analysis of Ti and Alloyed Ti Surfaces Used in the Evaluation of Biological Response

Abstract

AbstractThe biocompatibility of Ti and Ti alloys is closely associated with the passivating surface oxide which covers these materials. In this paper results are presented from a broad surface characterization of pure Ti and Ti6A14V alloy surface oxides prepared by thermal oxidation by machining, or by electrochemical procedures (electropolishing and anodic oxidation). The chemical composition of the surface oxide on both materials is mainly TiO2, as shown by XPS, AES, and SIMS analyses. Significant differences exist for both the thermal and anodic oxides, in that the alloying elements are present in the surface oxide of the alloy. TEM and STEM studies show that the microstructure of the anodic oxide films is rather heterogeneous with areas of different porosity which can be correlated with the grain structure of the bulk metals. Oxides on the alloy are even more heterogeneous than on Ti, due to the more complex (two-phase) microstructure of the bulk metal, and also differ in crystallinity. The differences in the surface oxide properties can be expected to lead to differences in the biological response to these two materials. With the alloy, one must consider the risk of Al and/or V dissolution into the biological system.