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Abstract

The excellent biocompatibility of titanium and its alloys is intimately related with the properties of the surface in contact with the biological environment, and therefore it is closely connected with the stable, passivating oxide layer that forms on its surface. In the present paper, the oxide layer on the alloy Ti6Al7Nb has been characterized using X-ray photoelectron spectroscopy, scanning Auger microscopy and pH-dependent lateral force microscopy. The alloying elements Al and Nb are incorporated in the oxide layer and detected in their most stable oxidized form, as Al2O3 and Nb2O5. Their distribution in the oxide reflects the underlying alpha-beta microstructure, with enrichment of Al in the alpha- and of Nb in the beta-phase (determined by electron microprobe). Friction measurements (lateral force microscopy) indicate slightly different, pH-dependent, lateral forces above the alpha- and beta-phase structures that point to small local variations in surface charges.

Influence of microstructural changes on corrosion behaviour of thermally aged Ti‐6Al‐7Nb alloy

“…3), did not exhibit potential drops associated with surface activation during 1 hour exposure in the Ringer's solution. This kind of behaviour strongly suggests that the air-formed native oxide consisting of TiO 2 , Al 2 O 3 and traces of Nb 2 O 5 and Ta 2 O 5 is kinetically resistant to chemical dissolution in the body environment as reported by Cittig et al [25]. Titanium oxide can be present on the surface at normal or slightly elevated temperatures as rutile, a tetragonal form of titanium dioxide, and the presence of this surface film provides excellent corrosion resistance in a wide range of corrosive media [26].…”

“…Tantalum and niobium show better electrochemical properties compared to other implant materials [29]. Hence, the addition of 0.5 wt% of Ta in the alloy enhances the chemical structure of the passive film by forming an adherent and pore-free thin surface film of tantalum pentoxide (Ta 2 O 5 ) [25]. Okazaki et al [30] also observed good corrosion resistance of pure metals like Ti, Nb and Ta in Eagle's medium at 310 K with low passive current densities whereas, Al and V showed inferior corrosion resistance with high passive current densities.…”

Ultrabright fluorescent mesoporous silica nanoparticles for prescreening of cervical cancer

“…10-13 Cancer-specific nanoparticles can further be used for targeting drug delivery thereby improving the therapeutic efficacy and reducing side effects of chemotherapeutic drugs. 14 Targeting nanoparticles have been demonstrated for the use as suitable imaging agents in noninvasive tumor imaging 15 , and for diagnosis and delineation of tumor margins during surgical resectioning.…”

On the Stability of Passivity of Ti-Al Alloys in Acidic Environment

“…It has been indeed shown in the literature that the concentration of the alloying elements in the passive films shows laterals variations which reflect the composition of the underlying phase [31,37]. Moreover, the activated surfaces clearly show a non-uniform attack leading to a roughening of the surface - Fig.…”