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Evaluation of corrosion resistance of the self-organized nanotubular oxide layers on the Ti13Zr13Nb alloy, has been carried out in 0.9% NaCl solution at the temperature of 37ºC. Anodization process of the tested alloy was conducted in a solution of 1M (NH4)2SO4 with the addition of 1 wt.% NH4F. The self-organized nanotubular oxide layers were obtained at the voltage of 20 V for the anodization time of 120 min. Investigations of surface morphology by scanning transmission electron microscopy (STEM ) revealed that as a result of the anodization under proposed conditions, the single-walled nanotubes (SWNTs) can be formed of diameters that range from 10 to 32 nm. Corrosion resistance studies of the obtained nanotubular oxide layers and pure Ti13Zr13Nb alloy were carried out using open circuit potential, anodic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. It was found that surface modification by electrochemical formation of the selforganized nanotubular oxide layers increases the corrosion resistance of the Ti13Zr13Nb alloy in comparison with pure alloy.

This work reports on determination of the influence of passivation type of Ti15wt.%Mo implant alloy surface on its corrosion resistance in simulated body fluids. The alloy under investigation was subjected to natural self-passivation in air, and forced passivation by autoclaving in steam, boiling in 30 % solution of H2O2, and electrochemical passivation in 0.9 % NaCl solution. Resistance of the passivated Ti15Mo alloy to pitting corrosion was studied at 37ºC in 0.9 % NaCl solution using open circuit potential method, anodic polarization curves, and electrochemical impedance spectroscopy (EIS). Comparative estimation of the determined parameters of corrosion resistance revealed that the obtained passive layers improve anticorrosive properties of the tested alloy. Surface of the alloy subjected to passivation in steam autoclave reveals the highest protection against pitting corrosion. Anodic potentiodynamic curves showed that the Ti15Mo alloy after different passivation types of the surface is characterized by a lack of susceptibility to pitting corrosion up to potential of 9 V. Based on the EIS investigations, the thickness of the formed oxide layers (TiO2, anatase) was determined to be in the range from 2.0 to 7.8 nm in dependence on the applied type of passivation. It was ascertained that electrochemical properties of the Ti15Mo alloy and possibility of its surface passivation using simple methods, make it an attractive material for use in biomedicine for long-term implants.

Przedstawiono wyniki badań ceramiki (Pb1-x Bax )((Zr1-yTiy) 1-zSnz )O3 (PBZTS) dla stałych wartości parametrów ,v =0,03 i y =0,02 oraz z =0, 0,02, 0,04, 0,06 i 0,08. Badane składy PBZTS znajdują się w pobliżu granicy fazowej między fazami o romboedrycznej i ortorombowej deformacji komórek elementarnych. Ceramiczne próbki PBZTS zostały otrzymane z prostych tlenków PbO, ZrOo, TiCb. SnOo i węglanu baru BaCO;,. Proszki po kalcynacji zostały rozdrobnione, a następnie uformowano z nich wypraski i zagęszczono metodą swobodnego spiekania (FS). Dla otrzymanych próbek PBZT/PBZTS przeprowadzono badania EDS, XRD, badania mikrostruktury przełamów, badania podstawowych właściwości dielektrycznych, badania pętli histerezy w różnych temperaturach.

This work investigated two titanium-based alloys with a constant tantalum content and variable contents of alloy additives - niobium and zirconium. The Ti-30Ta-10Zr-20Nb (wt.%) and Ti-30Ta-20Zr-10Nb (wt.%) alloys were obtained using a combination of powder metallurgy and arc melting methods. The influence of alloying additives on the structure and properties of the Ti-Ta-Nb-Zr system was studied using, among others: X-ray diffraction and scanning electron microscopy. The X-ray diffraction confirmed the single-ß-phase structure of both alloys. In addition, the microscopic analysis revealed that a higher amount of zirconium favoured the formation of larger grains. However, the microhardness analysis indicated that the alloy with the higher niobium content had the higher microhardness. Importantly, the in vitro corrosion study revealed that the addition of niobium promoted the better corrosion resistance of the investigated alloy. [ABSTRACT FROM AUTHOR]

A 20 gram batch weight of NiTi alloy, with a nominal equiatomic composition, was produced by mechanical alloying with milling times of 100, 120, and 140 hours. The differential scanning calorimetry was used to analyze the progress of the crystallization process. The X-ray diffraction examined the crystal structure of the alloy at individual crystallization stages. The observation of the powders microstructure and the chemical composition measurement were carried out using a scanning electron microscope equipped with an energy-dispersive detector. After the milling process, the alloy revealed an amorphous-nanocrystalline state. The course of the crystallization process was multi-stage and proceeded at a lower temperature than the pure amorphous state. The applied production parameters and the stage heat treatment allowed to obtain the alloy showing the reversible martensitic transformation with an enthalpy of almost 5 J/g. [ABSTRACT FROM AUTHOR]

Scientists and medics are still searching for new metallic materials that can be used in medicine, e.g., as material for implants. The following article proposes materials based on titanium with vital elements prepared by combined powder metallurgy and arc melting methods. Four compositions of Ti-28Ta-9Nb, Ti-28Ta-19Nb, Ti-28Ta-9Zr and Ti-28Ta-19Zr (wt.%) have been prepared. The tested material was thoroughly analyzed by X-ray diffraction and scanning electron microscopy. Qualitative phase analysis using X-ray diffraction showed the presence of two phases, a' and ß titanium. In addition, a microhardness test was conducted, and the material was characterized in terms of corrosion properties. It was found that the corrosion resistance decreases with an increase of the ß phase presence. [ABSTRACT FROM AUTHOR]

Dental/osseous implants manufactured of titanium (Ti) have become a routine and affordable method in medical practice. To increase the overall safety and longtime stability of the implants further, the sophisticated approaches have been investigated in order to supply the implants with the bioactive surface layers. They have to serve two purposes: to increase the osseointegration capacity of the implants and to reduce the chances of bacterial growth and formation of bacterial biofilms leading to periimplantitis. Plasma electrolytic oxidation (PEO) is becoming a promising method to introduce functionalized surface layers on a metal substrate. Various PEO protocols have been suggested in order to achieve better biocompatibility of the dental implants and to increase their resistance to bacterial infections. It was also suggested that the PEO layers could increase resistance to corrosion on the surfaces of metallic implants. The dynamic processes running on the surface of Ti during the PEO processing still require efforts to fully understand the molecular mechanisms of the formation of hard and porous oxide surface layers. We and others have already shown that addition of a chelating agent to the bath electrolyte leads to better outcomes in the morphology and functional characteristics of the implants. Here we report in depth characterization of the PEO parameters and the produced PEO surface layers using the bath electrolyte containing another widely used chelating agent, nitrilotriacetic acid (NTA) along with potassium phosphate and calcium formate. The results will contribute to further understanding the mechanisms of the PEO process and to establishing routine protocols for commercial exploitation of the PEO method. [ABSTRACT FROM AUTHOR]

The paper presents the technology and basic properties of three compositions of lead-free ceramics: (i) (K0.44Na0.52Li0.04) NbO3, (ii) (K0.44Na0.52Li0.04)NbO3+0.5%mol Nd2O3 and (iii) (K0.44Na0.52Li0.04)NbO3+0.5%mol Pr2O3. Powders of the designed compositions based on KNLN were obtained with the classic ceramic technology, as a result of solid phase synthesis, from a mixture of simple oxides and carbonates. The synthesis of ceramic powders was carried out at Ts = 900°C for ts = 4 h, while compaction by free sintering at Tsint = 1100°C for tsint = 2 h. XRD studies have shown that doping with praseodymium and neodymium promotes the formation of the tetragonal phase in the base composition (K0.44Na0.52Li0.04)NbO3 at lower temperatures. On the other hand, microstructural tests have shown that the admixture of neodymium and praseodymium improves the sinterability of ceramic samples during the technological process; however, the ceramic samples still exhibit high porosity. [ABSTRACT FROM AUTHOR]

Byline: G. Dercz, K. Prusik, B. Formanek, L. Pajak The studied composite powder of high corrosion resistance was prepared using the Self-propagating High-temperature Synthesis (SHS) process. The as-prepared material was crushed and was subjected to a milling process by high-energy attritory mill for two and ten hours. The powder morphology was analysed through the Scanning Electron Microscopy (SEM) method. The structure investigations were performed using the SEM and XRD methods. The presence of Cr7C3, FeCr and FeO phases, besides the most desired FeAl(Cr), Cr3C2 and TiC ones, was noted. It was found that the FeAl(Cr) phase is of the ordered B2-type structure and the ordering degree diminishes with the increase of milling time. The crystallite size of this phase, both in the as-prepared state and after the milling process, is in the nanoscale. The crystallite size of the FeO phase diminishes to 75 nm in the sample ground for 10 h, whereas those of the other phases are above 100 nm for the as-prepared and ground samples.

The m ain purpose of this study was to identify the mineral composition of soil sample taken from the upper layer of topsoil. High absorption of chemical substance is a characteristic for humus-organic layer of topsoil. The source of those substance could be a pollutant emitted to the atmosphere by human activity. The research area includes Upper Silesia region, which is the most industrial region of Poland. In the present study, the phase composition of the top soil separates were analyzed by using X-ray diffraction and Mössbauer spectroscopy. X-ray diffraction analysis revealed the presence of seven mineral phases in the material magnetic separated by lower current (quartz, illite, kaolinite, Fe3+ oxides, hematite, magnetite and pyrite). In case of higher current were identified four phases (quartz, muscovite, kaolinite and K0.94 Na0.06(AlSi3O8)). Mössbauer spectroscopy was used for an extensive analysis of iron-containing phases (pyrrhotite, magnetite, aluminosilicate oxides with Fe3+ and kaolinite/Fe2+ silicate). [ABSTRACT FROM AUTHOR]

This paper presents the study of microstructure and properties of 8 mol% yttrium stabilized zirconia coating fabricated by Plasma Spray Physical Vapor Deposition technique on commercial pure titanium. The coating was characterized by X-ray diffraction, high resolution scanning electron microscope, profilometer, nanoindentation and nanomachining tests. The X-ray phase analysis exhibit the tetragonal Zr0.935Y0.065O1.968, TiO and a-Ti phases. The Rietveld refinement technique were indicated the changes of crystal structure of the produced coatings. The characteristic structure of columns were observed in High Resolutions Scanning Electron Microscopy. Moreover, the obtained coating had various development of surfaces, thickness was equal to 3.1(1) µm and roughness 0.40(7) µm. Furthermore, the production coatings did not show microcracks, delamination and crumbing. The performed experiment encourages carried out us to tests for osseointegration. [ABSTRACT FROM AUTHOR]

The current study were performed in order to assess the fabrication possibility of the metal-ceramic composites based on nanocrystalline substrates. The influence of the variable time of the high energy ball-milling (10, 30 and 50 h) on the structure, pores morphology and microhardness of Ti/ZrO2 and Ti/Al2O3 compositions was studied. The X-ray diffraction analysis confirmed the composite formation for all milling times and sintering in the case of Ti/ZrO2 system. Decomposition of substrates during milling process of Ti/Al2O3 system was also observed. Additionally, the changes of lattice parameter as a function of milling time were studied. The morphology of powders and the microstructure of the sintered samples were observed by scanning electron microscopy (SEM). Also, analysis of microhardness and pores structure were performed. [ABSTRACT FROM AUTHOR]

An equiatomic multi-component alloy Ni20Ti20Ta20Co20Cu20 (at. %) was obtained using vacuum arc melting. In order to characterize such an alloy, microstructure analysis has been performed using Scanning and Transmission Electron Microscopy, Electron Backscattered Diffraction, X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Microstructure analysis revealed the presence of one rhombohedral and two cubic phases. Energy Dispersive X-ray Spectroscopy measurements revealed that both observed phases include five chemical elements in the structure. Using Rietveld refinement approach the lattice parameters were refined for the observed phases. [ABSTRACT FROM AUTHOR]

The Ti15Mo alloy has been studied towards long-term corrosion performance in saline solution at 37° C using electrochemical impedance spectroscopy. The physical and chemical characterization of the material were also investigated. The as-received Ti15Mo alloy exhibits a single ß-phase structure. The thickness of single-layer structured oxide presented on its surface is ~4 nm. Impedance measurements revealed that the Ti15Mo alloy is characterized by spontaneous passivation in the solution containing chloride ions and formation of a double-layer structured oxide composed of a dense interlayer being the barrier layer against corrosion and porous outer layer. The thi ckness of this oxide layer, estimated based on the impedance data increases up to ~6 nm during 78 days of exposure. The obs erved fall in value of the log|Z|f = 0.01 Hz indicates a decrease in pitting corrosion resistance of Ti15Mo alloy in saline solution along with the immersion time. The detailed EIS study on the kinetics and mechanism of corrosion process and the capacitive behavior of the Ti15Mo electrode | passive layer | saline solution system was based on the concept of equivalent electrical circuit with respect to the physical meaning of the applied circuit elements. Potentiodynamic studies up to 9 V vs. SCE and SEM analysis show no presence of pitting corrosion what indicates that the Ti15Mo alloy is promising biomaterial to long-term medical applications. [ABSTRACT FROM AUTHOR]

The preparation of high-density lead-free potassium-bismuth titanate K0.5Bi0.5TiO3 about 96-98% of the calculated density (X-ray), confirmed by the Archimedes method, is presented. All stages of the technological process are explained in detail. The control of microstructure was performed by scanning electron microscopy. The crystal structure and phase content of samples were determined by X-ray diffraction at each stage of sintering. Four types of samples were obtained under various technological conditions. The ultrasonic measurements of the obtained samples were carried out and basic parameters were determined, such as Young and Kirchoff modulus and Poisson’s ratio were determined at room temperature. The dielectric measurements show that the maximum value of dielectric permittivity is shifted towards higher temperatures as the frequency increases. This feature is characteristic of ferroelectric relaxor materials. The presented materials can be a good starting point for the development of lead-free ceramics. [ABSTRACT FROM AUTHOR]