Structural analysis and corrosion studies on an ISO 5832-9 biomedical alloy with TiO2 sol–gel layers

The aim of this study was to demonstrate the relationship between the structural and corrosion properties of an ISO 5832-9 biomedical alloy modified with titanium dioxide (TiO2) layers. These layers were obtained via the sol–gel method by acid-catalyzed hydrolysis of titanium isopropoxide in isopropanol solution. To obtain TiO2 layers with different structural properties, the coated samples were annealed at temperatures of 200, 300, 400, 450, 500, 600 and 800 C for 2 h. For all the prepared samples, accelerated corrosion measurements were performed in Tyrode’s physiological solution using electrochemical methods. The most important corrosion parameters were determined: corrosion potential, polarization resistance, corrosion rate, breakdown and repassivation potentials. Corrosion damage was analyzed using scanning electron microscopy. Structural analysis was carried out for selected TiO2 coatings annealed at 200, 400, 600 and 800 C. In addition, the morphology, chemical composition, crystallinity, thickness and density of the deposited TiO2 layers were determined using suitable electron and X-ray measurement methods. It was shown that the structure and character of interactions between substrate and deposited TiO2 layers depended on annealing temperature. All the obtained TiO2 coatings exhibit anticorrosion properties, but these properties are related to the crystalline structure and character of substrate–layer interaction. From the point of view of corrosion, the best TiO2 sol–gel coatings for stainless steel intended for biomedical applications seem to be those obtained at 400 C.This study was supported by Grant No. N N507 501339 of the National Science Centre. The authors wish to express their thanks to J. Borowski (MEDGAL, Poland) for the Rex 734 alloy

Propriedades de ZrO2 (Y2 O3) reciclado proveniente da confecção de próteses dentárias

RESUMO O objetivo deste trabalho foi a recuperação de descartes de ZrO2(Y2O3) oriundos de laboratórios de próteses dentárias, a partir do seu reprocessamento. Os descartes de ZrO2(Y2O3) foram fragmentados, peneirados e calcinados a 900ºC. Pós com tamanho menor que 32μm foram prensados uniaxialmente a 100MPa e sinterizados em temperaturas entre 1400 e 1600ºC-120min. Análise de difração de raios X realizadas nos materiais calcinados indicaram a presença majoritária da fase ZrO2 tetragonal. Os compactos apresentaram densidade a verde próximo a 47% e as amostras sinterizadas tiveram sua densidade relativa variando entre 83,5% e 95%, para temperaturas de sinterização de 1400 e 1600ºC, respectivamente. Os resultados da análise de difração de raios X indicaram a presença da fase ZrO2 tetragonal, com dureza Vickers e tenacidade máxima obtidos para as amostras sinterizadas a 1600ºC, da ordem de 1100 HV e 5,7 MPa.m1/2 respectivamente

Study on crystallization phenomenon and thermal stability of binary Ni–Nb amorphous alloy

In this paper, a ribbon of binary Ni–Nb amorphous alloy was prepared by the melt spinning technique. Glass transition and crystallization phenomenon of the alloy were investigated by differential scanning calorimetry. Thermal properties of the ribbon of binary Ni–Nb upon heating and cooling were analysed by DTA at a heating/ cooling rate of 0.5 K s-1 under the purified argon atmosphere. The thermal stability of Ni–Nb amorphous alloy was studied by using an X-ray diffractometer equipped with an in situ heating system. The structure and fracture morphology of the ribbons were examined by X-ray diffraction and scanning electron microscopy methods

Wykorzystanie mechanicznej aktywacji do syntetyzowania multiferroikowych proszków Pb(Fe1/2Nb1/2)O3

In the study, the method of high-energy powder milling - mechanical activation (MA) was used for synthesizing Pb(Fe1/2Nb1/2)O3 (PFN) powders. For the purpose of comparing the influence of high-energy milling on PFN synthesis, two groups of powder samples were used. The first mixture consisting of simple oxide powders; the second one consisting of compound oxide powders. The obtained powders were subjected to structural analysis with the use of XRD and Mőssbauer spectroscopy. Tests revealed that during the process of high-energy milling of initial constituents a partial synthesis of PFN material phases occurs. By comparing the two methods of PFN synthesizing it may be stated that mechanical activation in the case of a simple oxide mixture (PFN1) is equally effective as for a compound oxide mixture (PFN2).W pracy, w procesie technologicznym, wykorzystano metodę wysokoenergetycznego mielenia proszków – mechanicznej aktywacji (MA) do syntezowania proszków Pb(Fe1/2Nb1/2)O3 (PFN). Do porównania wpływu wysokoenergetycznego mielenia na synteze PFN wykorzystano dwie grupy próbek proszkowych. Pierwsza mieszanine stanowiły proszki prostych tlenków (jednoetapowa metoda otrzymywania – PFN1), druga stanowiły proszki złozonych tlenków (dwuetapowa metoda otrzymywania – PFN2). Otrzymane proszki poddano analizie strukturalnej przy użyciu XRD i spektroskopii Mossbauera. Badania potwierdziły, ze podczas procesu wysokoenergetycznego mielenia składników wyjsciowych zachodzi czesciowa synteza faz materiału PFN. Porównujac dwie metody syntetyzowania PFN można stwierdzić, że mechaniczna aktywacja jest jednakowo skuteczna w przypadku mieszaniny prostych tlenków (PFN1) jak i dla mieszaniny złożonych tlenków (PFN2)

Processing, Microstructure and Dielectric Properties of the Bi 5

The aim of the present work is the analysis of microstructure, dielectric permittivity and thermal properties analysis of $Bi_5Ti_3FeO_{15}$ ceramics obtained by two methods. The studied $Bi_5Ti_3FeO_{15}$ ceramics were prepared by conventional synthesis and hot uniaxial pressing reaction from the conventional mixture of oxides, viz. $TiO_2$, $Fe_2O_3$, $Bi_2O_3$. The studied material has layered perovskite like structures, first described by Aurivillius in 1949 and Subbaro in 1969. The ceramic $Bi_5Ti_3FeO_{15}$ is known to contain a series of compounds with the general formula: $Bi_{m+1}Fe_{m-3}Ti_3O_{3m+3}$. The X-ray diffraction methods were used for qualitative phase analysis of studied samples. The morphology was analyzed by scanning electron microscopy method. The thermal properties of the studied materials were measured using the differential thermal analysis at a constant heating rate of 15 K/min under an argon protective atmosphere. Thermal dependence of dielectric permittivity was studied between room temperature and 1137 K

Processing, Microstructure and Dielectric Properties of the Bi5Ti3FeO15Bi_5Ti_3FeO_{15} Ceramic

The aim of the present work is the analysis of microstructure, dielectric permittivity and thermal properties analysis of $Bi_5Ti_3FeO_{15}$ ceramics obtained by two methods. The studied $Bi_5Ti_3FeO_{15}$ ceramics were prepared by conventional synthesis and hot uniaxial pressing reaction from the conventional mixture of oxides, viz. $TiO_2$, $Fe_2O_3$, $Bi_2O_3$. The studied material has layered perovskite like structures, first described by Aurivillius in 1949 and Subbaro in 1969. The ceramic $Bi_5Ti_3FeO_{15}$ is known to contain a series of compounds with the general formula: $Bi_{m+1}Fe_{m-3}Ti_3O_{3m+3}$. The X-ray diffraction methods were used for qualitative phase analysis of studied samples. The morphology was analyzed by scanning electron microscopy method. The thermal properties of the studied materials were measured using the differential thermal analysis at a constant heating rate of 15 K/min under an argon protective atmosphere. Thermal dependence of dielectric permittivity was studied between room temperature and 1137 K

Mössbauer Spectroscopy, X-Ray Diffraction and SEM Studies on Multiferroic Bi5Ti3FeO15Bi_5Ti_3FeO_{15} Ceramics

Magnetoelectric multiferroics are materials which exhibit both magnetic order and ferroelectricity in the same phase. Multiferroic materials, where ferroelectricity and magnetism coexist, were extensively studied. This class of materials offers a large application potential for new devices due to the two coupled degrees of freedom based on the local off-centered distortion and the electron spin. The studied $Bi_5Ti_3FeO_{15}$ ceramics was prepared by conventional synthesis and hot uniaxial pressing reaction applying the conventional mixture of $TiO_2$, $Fe_2O_3$ and $Bi_2O_3$ oxides as precursor materials. The present work focuses on the structure analysis of multiferroic $Bi_5Ti_3FeO_{15}$ ceramics performed by X-ray diffraction method, scanning electron microscopy and the Mössbauer spectroscopy methods

Evaluation of Corrosion Resistance of Nanotubular Oxide Layers on the Ti13Zr13Nb Alloy in Physiological Saline Solution / Ocena Odporności Korozyjnej Nanotubularnych Struktur Tlenkowych Na Stopie Ti13Zr13Nb W Środowisku Płynów Ustrojowych”

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