THE SURFACE CHARACTERIZATION OF THE ANODIZED ULTRAFINE-GRAINED Ti-13Nb-13Zr ALLOY

Titanium alloys are metal materials widely used in medicine owing to their suitable characteristics such as low density, good corrosion resistance and biocompatibillity. High biocompatibility of the titanium alloy results from the creation of a spontaneous oxide layer with good adhesion and homogeneous morphology. In order to improve characteristics of the metallic materials for application in medicine, electrochemical methods that enable surface nanostructured modification are extensively used, and one of these methods is electrochemical anodization which makes it possible to obtain a nanostructured oxide layer composed of nanotubes on the surface of the metal material. The tested material was ultrafine-grained Ti-13Nb-13Zr (UFG TNZ) alloy obtained by the severe plastic deformation (SPD) processing using the high pressure torsion (HPT) process. Nanostructured oxide layer on the titanium alloy was formed by electrochemical anodization during the time period from 30 to 120 minutes. Characterization of the surface morphology obtained during different times of electrochemical anodization was done using scanning electron microscopy (SEM), while the topography and surface roughness of the titanium alloy before and after electrochemical anodization was determined using atomic force microscopy (AFM). Scratch test was used to determine the cross profile of the surface topography and critical load during scratching. Electrochemical anodization led to the formation of a nanostructured oxide layer on the surface of the titanium alloy. The obtained results indicated strong influence of the electrochemical anodization time on the oxide layer morphology - with its increase the diameter of the nanotubes increases too, while the wall thickness of nanotubes decreases. Also, electrochemical anodization led to an increase in the surface roughness

Mechanical characterization of surface modified Ti-based alloy before and after severe plastic deformation

The intent of the study was to modify virgin biomedical Ti-13Nb-13Zr alloy in aim to realize whether applied modifications could improve mechanical properties. Two groups of modifications were applied to the prepared samples: structural modification achieved by severe plastic deformation (SPD) and modification of alloy surface obtained by electrochemical method. Structural modification was performed by using high pressure torsion (HPT) as one of the SPD methods. Pressure of 4.1 GPa was applied and up to 5 rotations were made at room temperature. After HPT treatment an ultrafine-grained (UFG) structure was obtained. The homogeneity of the UFG alloy was checked by using Vickers microhardness tester. Electrochemical anodization was done in the 1M H3PO4 + NaF electrolyte during 90 minutes, resulting in formation of an oxide layer on the alloy surface. Surface roughness was determined using an atomic force microscope. Tensile properties of the alloy before and after electrochemical anodization and HPT processing were determined. The scanning electron microscopy was used to characterize both morphology of anodized surfaces and the fracture surfaces after the tensile tests. The HPT treated alloy has higher values of tensile strength and modulus of elasticity and lower value of plasticity than the virgin alloy. Surface modification of virgin alloy leads to a decrease of these values compared to non-treated samples and practically has no influence on tensile properties on the UFG alloy. Mechanical properties of the surface – modulus of elasticity and nanohardness were determined using a nanoindentation test. The surfaces of anodized alloys (both virgin and HPT treated) have lower modulus of elasticity than surfaces of non-anodized ones

Enhanced absorption of TiO 2 nanotubes by N-doping and CdS quantum dots sensitization: insight into the structure

International audienc

TiO 2 /ZrO 2 THIN FILMS SYNTHESIZED BY PLD IN LOW PRESSURE N-, C-AND/OR O-CONTAINING GASES: STRUCTURAL, OPTICAL AND PHOTOCATALYTIC PROPERTIES

Doped TiO 2 /ZrO 2 films were obtained by Pulsed Laser Deposition method under different synthesis conditions. The onset of absorption spectra was red shifted for the films obtained in N 2 containing gas mixtures, while a broad absorption in visible was observed in the case of films deposited in CH 4 atmosphere. The presence of O-Ti-N bonds revealed by XPS corresponded to the highest photocatalytic performance. XPS spectra of the samples obtained in N 2 /CH 4 gas mixtures evidenced a more effective incorporation of nitrogen in the structure due to oxygen deficiency. Nevertheless, no atomic carbon presence in the TiO 2 /ZrO 2 structures has been detected