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    Wyświetlanie 1-7 z 7
    Tytuł:
    Mechanical and Microstructural Properties of Sheep Hydroxyapatite (SHA)-Niobium Oxide Composites
    Autorzy:
    Demirkol, N.
    Oktar, F.
    Kayali, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1491479.pdf
    Data publikacji:
    2012-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Je
    Opis:
    The aim of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from natural sheep bone and niobium oxide (5 and 10 wt%). Sheep hydroxyapatite (SHA) matrix was reinforced with 5 and 10 wt% of niobium (Nb) oxide powder. The calcinated SHA was ball milled separately with 5% and 10% niobium oxide for 4 h. The samples were subjected to sintering at different temperatures between 1000C and 1300°C. The mechanical properties were determined by measuring compression strength and Vickers microhardness (HV). X-ray diffraction and scanning electron microscopy studies were carried out to analyze the microstructure. With increasing sintering temperature, mechanical properties of composites increased. The SHA-composites with 10 wt% niobium oxide addition had better mechanical properties at all sintering temperatures. The highest mechanical properties were obtained in SHA-10 wt% niobium oxide composite sintered at 1300°C. Adding of niobium oxide to SHA could be a valuable method to produce rigid and high load carrying ability HA composite which is suitable for orthopedic applications.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 1; 274-276
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrospun niobium oxide 1D nanostructures and their applications in textile industry wastewater treatment
    Autorzy:
    Zaborowska, Marta
    Smok, Weronika
    Tański, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/2204528.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electrospinning
    niobium oxide
    photocatalysis
    MB removal
    RhB removal
    textile wastewater treatment
    methylene blue removal
    rhodamine B dye removal
    elektroprzędzenie
    tlenek niobu
    fotokataliza
    usuwanie MB
    usuwanie RhB
    oczyszczanie ścieków włókienniczych
    uswuanie rodaminy B
    uswuanie błękitu metylenowego
    Opis:
    Textile industry emits daily huge amounts of sewage rich in non-biodegradable organic compounds, especially in textile dyes. Such contaminants are highly soluble in water, which makes their removal difficult. Other studies suggest their carcinogenicity, toxicity and mutagenicity. A promising chemical treatment of textile wastewater is the photodegradation of dye molecules in the process of photocatalysis in the presence of a photocatalyst. One-dimensional nanostructures exhibit a high surface-to-volume ratio and a quantum confinement effect, making them ideal candidates for nanophotocatalyst material. Nb2O5 is, among other metal oxides with a wide band gap, gaining popularity in optical applications, and electrospun niobium oxide nanostructures, despite their ease and low cost, can increase the chemical removal of textile dyes from wastewater. Facile synthesis of electrospun one-dimensional niobium oxide nanofibers is presented. The nanophotocatalysts morphology, structure, chemical bonds and optical properties were examined. Based on photodegradation of aqueous solutions (ph=6) of methylene blue and rhodamine B, the photocatalytic activity was established. The photocatalytic efficiency after 180 minutes of ultraviolet irradiation in the presence of Nb2O5 nanofibers was as follows: 84.9% and 31.8% for methylene blue and rhodamine B decolorization, respectively.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 2; art. no. e144941
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Leakage Current Degradation Due to Ion Drift and Diffusion in Tantalum and Niobium Oxide Capacitors
    Autorzy:
    Kuparowitz, M.
    Sedlakova, V.
    Grmela, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/221515.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    niobium oxide capacitors
    tantalum capacitors
    leakage current
    ion diffusion
    ion drift
    Opis:
    High temperature and high electric field applications in tantalum and niobium capacitors are limited by the mechanism of ion migration and field crystallization in a tantalum or niobium pentoxide insulating layer. The study of leakage current (DCL) variation in time as a result of increasing temperature and electric field might provide information about the physical mechanism of degradation. The experiments were performed on tantalum and niobium oxide capacitors at temperatures of about 125°C and applied voltages ranging up to rated voltages of 35 V and 16 V for tantalum and niobium oxide capacitors, respectively. Homogeneous distribution of oxygen vacancies acting as positive ions within the pentoxide layer was assumed before the experiments. DCL vs. time characteristics at a fixed temperature have several phases. At the beginning of ageing the DCL increases exponentially with time. In this period ions in the insulating layer are being moved in the electric field by drift only. Due to that the concentration of ions near the cathode increases producing a positively charged region near the cathode. The electric field near the cathode increases and the potential barrier between the cathode and insulating layer decreases which results in increasing DCL. However, redistribution of positive ions in the insulator layer leads to creation of a ion concentration gradient which results in a gradual increase of the ion diffusion current in the direction opposite to the ion drift current component. The equilibrium between the two for a given temperature and electric field results in saturation of the leakage current value. DCL vs. time characteristics are described by the exponential stretched law. We found that during the initial part of ageing an exponent n = 1 applies. That corresponds to the ion drift motion only. After long-time application of the electric field at a high temperature the DCL vs. time characteristics are described by the exponential stretched law with an exponent n = 0.5. Here, the equilibrium between the ion drift and diffusion is achieved. The process of leakage current degradation is therefore partially reversible. When the external electric field is lowered, or the samples are shortened, the leakage current for a given voltage decreases with time and the DCL vs. time characteristics are described by the exponential stretched law with an exponent n = 0.5, thus the ion redistribution by diffusion becomes dominant.
    Źródło:
    Metrology and Measurement Systems; 2017, 24, 2; 255-264
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Bioactivity Properties and Characterization of Commercial Synthetic Hydroxyapatite - 5 wt.% Niobium (V) Oxide - 5 wt.% Magnesium Oxide Composite
    Autorzy:
    Demirkol, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1031119.pdf
    Data publikacji:
    2017-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.85.J-
    Opis:
    Hydroxyapatite is widely used for bone grafts due to its chemical and structural similarities to the mineral phase of hard tissues and due to its bioactivity and biocompatibility. However, hydroxyapatite has poor mechanical properties due to its brittleness. To improve mechanical properties of hydroxyapatite-ceramics, ceramic oxides, whiskers or fibers have been suggested. In this study, commercial synthetic hydroxyapatite composite reinforced with 5 wt.% Nb₂O₅ and 5 wt.% MgO was characterized. Microstructural properties of all samples sintered at different temperatures were characterized using scanning electron microscopy technique. Phase analysis was carried out using X-ray diffraction technique. Mechanical properties were measured by compression and hardness tests. The bioactivity property was determined by in vitro bioactivity test. The best obtained values of density, compression strength and Vickers Microhardness were 3.01 g/cm³, 96 MPa and 393 HV, for composite sintered at 1300°C for 4 hours. Bioactivity results for composite, sintered at 1300°C, show that apatite formation has started after two weeks in a simulated body fluid. At the end of the fourth week, the dense apatite layer and clusters were observed on the surface of the composite.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 3; 786-788
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anodic oxide films on niobium and tantalum in different aqueous electrolytes and their impedance characteristics
    Autorzy:
    Verma, N.
    Singh, K.
    Marí, B.
    Mollar, M.
    Jindal, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1075354.pdf
    Data publikacji:
    2016-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    68.37.Hk
    68.55.J-
    68.60.Bs
    Opis:
    The anodic oxide films were prepared on the niobium and tantalum in aqueous electrolyte mixtures containing 1 M CH₃COOH + 1 M H₃PO₄ or 1 M CH₃COOH + 1 vol.% HF or 1 M CH₃COOH + 1 M H₃PO₄ + 1 vol.% HF at 30 V for 30 min. The barrier films were obtained on both niobium and tantalum surfaces in all electrolyte mixtures except niobium oxide film formed in 1 M CH₃COOH + 1 vol.% HF which is porous in nature. The anodic oxide films were characterized by FESEM. Also, electrochemical impedance spectroscopy at open-circuit potential on Nb and Ta was applied and obtained data were analyzed by fitting with four different equivalent circuits.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 3; 297-303
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of Adding Niobium and Vanadium to Fe-Based Oxide Dispersion Strengthened Alloy
    Autorzy:
    Park, Chun Woong
    Choi, Won June
    Byun, Jong Min
    Kim, Young Do
    Powiązania:
    https://bibliotekanauki.pl/articles/353024.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Fe-based ODS
    vanadium
    niobium
    superalloy
    hardness
    Opis:
    In this study, the effects of adding niobium and vanadium to Fe-based oxide dispersion strengthened alloys are confirmed. The composition of alloys are Fe-20Cr-1Al-0.5Ti-0.5Y2 O3 and Fe-20Cr-1Al-0.5Ti-0.3V-0.2Nb-0.5Y2 O3. The alloy powders are manufactured by using a planetary mill, and these powders are molded by using a magnetic pulsed compaction. Thereafter, the powders are sintered in a tube furnace to obtain sintered specimens. The added elements exist in the form of a solid solution in the Fe matrix and suppress the grain growth. These results are confirmed via X-ray diffraction and scanning electron microscopy analyses of the phase and microstructure of alloys. In addition, it was confirmed that the addition of elements, improved the hardness property of Fe-based oxide dispersion strengthened alloys.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 4; 1265-1268
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanostrukturalna warstwa tlenkowa otrzymywana metodą anodowania na tytanie i jego stopie z niobem
    Nanostructural oxide layer formed by anodizing on titanium and its implant alloy with niobium
    Autorzy:
    Krasicka-Cydzik, E.
    Głazowska, I.
    Kaczmarek, A.
    Klekiel, T.
    Kowalski, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/286167.pdf
    Data publikacji:
    2009
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
    Tematy:
    stopy tytanu
    utlenianie elektrochemiczne
    nanorurki
    titanium alloys
    electrochemical oxidation
    nanotubes
    Opis:
    W pracy przedstawiono rezultaty zastosowania metody utleniania elektrochemicznego do formowania warstwy nanorurek na tytanie i jego implantowym stopie z niobem Ti6Al7Nb. Celem prowadzonych badań było porównanie efektów anodowania 2 materiałów implantowych, o zróżnicowanym składzie chemicznym i fazowym, a zwłaszcza stwierdzenie, czy metoda ta pozwala na wprowadzenie fosforanów do nanorurkowej warstwy wierzchniej dla stymulacji osteointegracji. Anodowanie prowadzono w 1M roztworze kwasu fosforowego z dodatkiem 0,4%wt. kwasu fluorowodorowego. Porównanie właściwości warstw nanostrukturalnych na tytanie i jego stopie z niobem oparto na analizie obrazów otrzymanych metodą mikroskopii skaningowej SEM oraz mikroanalizie EDS, a także rezultatach rentgenowskiej analizy spektroskopowej XPS. Podobieństwo i różnice właściwości chemicznych pomiędzy tytanem a niobem znalazło potwierdzenie w morfologii i składzie chemicznym nanorurek powstałych na ich powierzchni, składających się z tlenku tytanu i tlenków metali stopowych tworzących Ti6Al7Nb.
    In this work the results of studies on the use of electrochemical oxidation method to form layer of nanotubes on titanium and its Ti6Al7Nb alloy are presented. The aim of the studies was to compare the effect of anodising of 2 implant materials of different chemical and phase composition, and to confirm whether the anodising method allows to introduce phosphates into the nanotubes in order to enhance the osteointegration. Anodising wasperformed in 1M H3PO4solution with the addition of 0.4%wt of HF. The comparison of nanotube layers properties was based on the analysis of SEM images and EDS results, as well as on the results of the XPS examination. The similarities and differences between chemical properties of titanium and niobium were confirmed in morphology and chemical composition of nanotubes made of titania and oxides of alloying elements of Ti6Al7Nb.
    Źródło:
    Engineering of Biomaterials; 2009, 12, no. 89-91; 105-109
    1429-7248
    Pojawia się w:
    Engineering of Biomaterials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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