M. Lubas

Raman spectroscopy of TiO2 thin films formed by hybrid treatment for biomedical applications.

The paper presents the results of the investigations of the surface layer obtained after application of the combined hybrid method of oxidation in a fluidized bed (FB) and deposition of the oxide coating by PVD technique. The material used in the study was Ti Grade 2. The process of diffusive saturation was carried out in a fluidized-bed reactor at the temperature of 640°C for 8h in air while the top oxide layer was obtained through PVD method - magnetron sputtering using TiO2 target and argon atmosphere with the pressure of 3×10(-2)mbar and the distance between the substrate to the target of 60mm. In order to determine changes in the properties that occur as a result of modification of the Ti surface, the following examinations were carried out by SEM-EDX, X-ray diffraction methods, Raman spectroscopy, Glow Discharge Optical Spectroscopy (GDOS) and Secondary Ion Mass Spectrometry (SIMS). The coatings obtained were characterized by zonal structure comprising the solution zone of Tiα(O) and oxide zone of TiO2 with modifications of rutile and anatase, depending on the oxidation method. It was found that formation of oxide layers using the hybrid method (FB+PVD) leads to limitation of defects in the oxide layer after fluidized-bed thermal treatment and obtaining a uniform, tight coating with improved corrosion properties which are important from the biomedical standpoint.

Fabrication and characterization of oxygen - diffused titanium using spectroscopy method.

A thin native oxide film that forms on the titanium surface makes contact with the bone tissue has been considered to be of great importance to successful osseointegration. The study investigated oxygen-diffused grade 2 titanium obtained by introducing oxygen into the titanium crystal lattice using thermal treatment in fluidized bed performed at 610°C and 640°C in 6, 8, 12h. The thermal treatment at different temperatures and different times led to the formation of a TiO2 rutile film on the titanium surface and a concentration gradient of oxygen into titanium (XRD/GID analyses and GDOS results). Moreover Raman spectroscopy results showed that the TiO2 film on the surface titanium was composed of two oxides (TiO2), i.e. anatase and rutile, for the analyzed variants of heat treatment. The aim of the present study was to establish the optimum conditions for obtaining oxygen-diffused TiO2 film. The results obtained in the study demonstrated that the use of a fluidized bed for titanium oxidation processes allows for obtaining uniform oxide layers with good adhesion to the substrate, thus improving the titanium surface to suit biomedical applications.

Structural and microstructural aspects of asbestos-cement waste vitrification

The main goal of the work was to evaluate the vitrification process of asbestos-cement waste (ACW). A mixture of 50 wt% ACW and 50 wt% glass cullet was melted in an electric furnace at 1400 °C for 90 min and then cast into a steel mold. The vitrified product was subjected to annealing. Optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to evaluate the effects of the vitrification. The chemical constitution of the material before and after the vitrification process was also analyzed. It was found that the vitrified product has an amorphous structure in which the components of asbestos-cement waste are incorporated. MIR spectroscopy showed that the absorption bands of chrysotile completely disappeared after the vitrification process. The results of the spectroscopic studies were confirmed by X-ray studies - no diffraction reflections from the chrysotile crystallographic planes were observed. As a result of the treatment, the fibrous asbestos construction, the main cause of its pathogenic properties, completely disappeared. The vitrified material was characterized by higher resistance to ion leaching in an aquatic environment than ACW and a smaller volume of nearly 72% in relation to the apparent volume of the substrates. The research has confirmed the high effectiveness of vitrification in neutralizing hazardous waste containing asbestos and the FT-IR spectroscopy was found to be useful to identify asbestos varieties and visualizing changes caused by the vitrification process. The work also presents the current situation regarding the utilization of asbestos-containing products.

Duplex Titanium Oxide Layers for Biomedical Applications

This article presented the results of Ti Grade 2 oxidation with the duplex/hybrid method, which combined fluidized bed atmospheric diffusive treatment (FADT) and treatment with plasma methods (PVD). The process was realized to form a titanium diffusive layer saturated with oxygen in the diffusion process and to produce a tight homogeneous oxide coating on Ti substrate, deposited with the magnetron spraying technique. The techniques applied made it possible to combine the synergetic effects of the layers generated and to reduce the stresses in the area of the PVD coating/oxidized Ti substrate interface. In addition, the processes influenced the decrease in the surface roughness parameter and the increase in substrate bio-compatibility, which resulted in easier hydroxyapatite clusters deposition. The diffusion process was realized in Al2O3 fluidized bed reactor, at 913 K for 8 h with air atmosphere, while the deposition of the oxide coatings was realized with magnetron sputtering, with the use of TiO2 target at a pressure of 3 × 10−2mbars. In order to assess the effects of Ti hybrid oxidation, microscopic (AFM, SEM, TEM-EFTEM), spectroscopic (GDOS), and X-ray tests (XRD, sin2Ψ) were performed. The coatings formed had structure, with a Tiα(O) diffusion zone and a TiO2 rutile and anatase oxide zone deposited on the substrate. It was concluded that hybrid method of duplex coatings formation (FADT + PVD) leads to reducing oxide layer defects after fluidized bed heat treatment and to generating a tight homogeneous layer with a favorable state of stress, which results in improving the bio-compatibility of the generated substrate, important from the biomedical applications point of view.

Investigation of TiO2 Thin Coatings for Medical Applications by X-Ray Diffraction and Raman Microspectroscopy

The titanium and titanium alloys endoprostheses surface may be improved by forming TiOx single layer or TiOx – hydroxyapatite multi – layer on their surface. Biocompatibility of TiOx layers depends highly on their microstructure, parameters of formation method and properties of substrate. Paper presents microstructure of the TiOx layer formed on titanium surface in fluidized bed reactor. In order to evaluate thickness, microstructure and Ti:O concentration ratio X-ray diffraction, Confocal Raman microspectroscopy methods are realized. Methods enables to define every type of TiOx structure simultaneously including rutile which dominates in investigated layers.