Characterization of the morphology, structure and wettability of phase dependent lamellar and nanotube oxides on anodized Ti-10Nb alloy

Abstract

Nanotubes grown on Ti and its alloys have been extensively investigated for the biomaterials applications, since these structures improve the surface biocompatibility and the corrosion resistance due to oxide formation. Some researchers showed that the microstructure of the pure Ti affect the morphology of nanotubes grown by anodic process. However, this subject is rarely investigated for nanotubes grown on Ti alloys. In the same way, nanostructured films formed by concomitant regions of tubes and lamellar structures hardly ever were reported. Investigations concerning these topics are required once beta titanium alloys are suitable candidates to replace the pure Ti and Ti-Al-V alloys for biomedical applications. Beta alloys composed of non-toxic elements (Nb, Ta, Mo) are biocompatible and have an excellent mechanical properties and corrosion resistance. The present work investigated questions regarding to the effect of microstructure of Ti-10Nb alloy on morphology of nanostructured film growth by anodization. The morphology, thickness, composition and atomic arrangement (amorphous/crystalline) of formed oxides, and the contact angle of anodic film were investigated. The X-ray diffraction patterns and SEM image show that the Ti-10Nb alloy is composed by alpha (hcp) and beta (bcc) phases. SEM and TEM techniques revel that self-organized nanotubes grew on alpha phase, whereas a lamellar structure with transversal holes grew on b-phase. Crystalline oxides are formed at oxide-metal interface, as indicated by X-ray diffraction patterns. However, the tubes and lamellas grown over the compact oxide are amorphous, as-prepared and annealed at 230°C for 3 h, as showed by SAED patterns. The nanostructured films annealed at 430°C and at 530°C were damaged. A few changes were observed in XRD patterns of film annealed at 230°C while the morphology held similar as the unannealed film. Finally, the presence of phosphorus ions incorporated into the anodic layer makes the surface hydrophilic, since a similar nanostructured film without phosphorous incorporation results hydrophobic.

Self-Organized Anodic Oxides on Titanium Alloys Prepared from Glycol- and Glycerol-Based Electrolytes

“…Depending on the substrate chemical composition, the dissolution rate of the oxide layer is different and causes local variations of chemical composition as well as differences in grain structure and crystallography, in particular for multiphase alloys [ 14 , 43 ]. Moreover, the growth of anodic titanium oxide nanotubes at α and β Ti phases occurs at different speed and kinetics, which causes the formation of anodic layers with various heights [ 5 ]. In addition, the anodization of Ti alloys gives as a result an anodic oxide consisting of a mixture of oxides of alloying elements with different stoichiometry, depending on the used electrolyte [ 44 ].…”

“…In aerospace and biomedical applications, one of the most commonly used material is the Ti6Al4V alloy [ 3 , 4 ], but it contains vanadium, which can be considered harmful if released to organisms during long-term exposure [ 5 ]. On the other hand, there is a new perspective titanium alloy, Ti6Al7Nb, which contains non-toxic Nb and possesses even higher corrosion resistance and bio-tolerance than Ti6Al4V [ 5 , 6 , 7 ]. Generally, the high bio-tolerance of Ti alloys results from the spontaneous formation of a native passive layer on its surface of a few nanometers.…”

“…The anodizing of Ti alloys is currently the subject of extensive research, particularly in terms of the assessment of optimum process conditions such as anodization voltage, time, or electrolyte for the generation of adherent oxide layers on the surface of titanium alloys designed for biomedical application [ 11 ]. The main advantages of anodic titanium oxides are ease of their formation directly on the surface of the material as well as the possibility to control the layer thickness by means of changing the process parameters [ 3 , 5 , 12 ]. Moreover, the ability to obtain a well-adherent nanoporous oxide layer could markedly facilitate the further development of nano-biomaterials based on Ti [ 13 ].…”

Preparation, structural, microstructural, mechanical, and cytotoxic characterization of Ti‐15Nb alloy for biomedical applications

“…Several works in the literature use the arc fusion technique for the production of titanium alloys. 13,14,16,[19][20][21][22][23][24][25][26][27] This type of furnace is capable of melting high melting materials such as tantalum, so it is known that the furnace is capable of exceeding 3017°C, which is sufficient to reach the melting point of titanium and niobium. The obtained ingot was thermomechanically worked by means of hot swaging to suit the geometric needs of the characterization equipment.…”

Preparação e caracterização de uma liga de titânio com a adição de tântalo e zircônio para aplicações biomédicas

“…A fusão foi realizada utilizando um forno arco-voltaico, com cadinho de cobre refrigerado a água, eletrodo não-consumível de tungstênio e atmosfera controlada de argônio [18,[23][24][25][26][27][28].…”