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    Tytuł:
    Production of High-Purity Tantalum Metal Powder for Capacitors Using Self-Propagating High-Temperature Synthesis
    Autorzy:
    Lee, Yong-Kwan
    Sim, Jae-Jin
    Byeon, Jong-Soo
    Lee, Yong-Tak
    Cho, Yeong-Woo
    Kim, Hyun-Chul
    Heo, Sung-Gue
    Lee, Kee-Ahn
    Seo, Seok-Jun
    Park, Kyoung-Tae
    Powiązania:
    https://bibliotekanauki.pl/articles/2049150.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    tantalum
    self-propagating high-temperature synthesis
    tantalum oxide
    magnesium
    capacitor
    Opis:
    In this study, high-purity tantalum metal powder was manufactured via self-propagating high-temperature synthesis. During the process, Ta2O5 and Mg were used as the raw material powder and the reducing agent, respectively, and given that combustion rate and reaction temperature are important factors that influence the success of this process, these factors were controlled by adding an excessive mass of the reducing agent (Mg) i.e., above the chemical equivalent, rather than by using a separate diluent. It was confirmed that Ta metal powder manufactured after the process was ultimately manufactured 99.98% high purity Ta metal powder with 0.5 μm particle size. Thus, it was observed that adding the reducing reagent in excess favored the manufacture of high-purity Ta powder that can be applied in capacitors.
    Źródło:
    Archives of Metallurgy and Materials; 2021, 66, 4; 935-939
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dissolution of manganese (IV) oxide from tantalum capacitor scrap by organic acids
    Autorzy:
    Piotrowicz, Andrzej
    Pietrzyk, Stanisław
    Powiązania:
    https://bibliotekanauki.pl/articles/105800.pdf
    Data publikacji:
    2019
    Wydawca:
    Centrum Badań i Innowacji Pro-Akademia
    Tematy:
    tantalum capacitors
    tantalum recycling
    eco-friendly recycling
    transition metals recovery
    kondensatory tantalowe
    recykling tantalu
    recykling przyjazny środowisku
    odzysk metali przejściowych
    Opis:
    The dissolution of MnO2 from tantalum capacitor scrap using organic acids in various process conditions was studied. The initial materials were of two types: LTC (leaded tantalum capacitors) and SMDTC (surface-mounted device tantalum capacitors). The research materials were prepared by pyrolysis, grinding and sieving and the preparation processes were characterized. Dissolution of MnO2 was carried out with the use of sulfuric acid solutions with the addition of acetic, ascorbic, citric and oxalic organic acids. Results show that the addition of organic acids significantly improves dissolution yields (72-94 vs 90-99 % for H2SO4 and acid mixtures, respectively). In practice, a concentration of organic acid above 1 M results in the complete removal of MnO2.
    Źródło:
    Acta Innovations; 2019, 32; 63-77
    2300-5599
    Pojawia się w:
    Acta Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fabrication of 4N5 Grade Tantalum Wire from Tantalum Scrap by EBM and Drawing
    Autorzy:
    Yu, Ji-Won
    Choi, Sang-Hoon
    Sim, Jae-Jin
    Lim, Jae-Hong
    Seo, Kyoung-Deok
    Hyun, Soong-Keon
    Kim, Tae-Youb
    Gu, Bon-Woo
    Park, Kyoung-Tae
    Powiązania:
    https://bibliotekanauki.pl/articles/353005.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electron beam melting
    drawing
    tantalum scrap
    recycling
    high purity
    Opis:
    Electron beam melting(EBM) is a useful technique to obtain high-purity metal ingots. It is also used for melting refractory metals such as tantalum, which require melting techniques employing a high-energy heat source. Drawing is a method which is used to convert the ingot into a wire shape. The required thickness of the wire is achieved by drawing the ingot from a drawing die with a hole of similar size. This process is used to achieve high purity tantalum springs, which are an essential component of lithography lamp in semiconductor manufacturing process. Moreover, high-purity tantalum is used in other applications such as sputtering targets for semiconductors. Studies related to recycling of tantalum from these components have not been carried outuntil now. The recycling of tantalum is vital for environmental and economic reasons. In order to obtain high-purity tantalum ingot, in this study impurities contained in the scrap were removed by electron beam melting after pre-treatment using aqua regia. The purity of the ingot was then analyzed to be more than 4N5 (99.995%). Subsequently, drawing was performed using the rod melted by electron beam melting. Owing to continuous drawing, the diameter of the tantalum wire decreased to 0.5 mm from 9 mm. The hardness and oxygen concentration of the tantalum ingot were 149 Hv and less than 300 ppm, respectively, whereas the hardness of the tantalum wire was 232.12 Hv. In conclusion, 4N5 grade tantalum wire was successfully fabricated from tantalum scrap by EBM and drawing techniques. Furthermore, procedure to successfully recycle Tantalum from scraps was established.
    Źródło:
    Archives of Metallurgy and Materials; 2019, 64, 3; 935-941
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    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:
    Activation mechanism of tantalum niobium flotation by lead ions in a combined collector flotation system
    Autorzy:
    He, Mingfei
    Li, Shuangke
    Cao, Miao
    Gao, Yude
    Bu, Hao
    Meng, Qingbo
    Powiązania:
    https://bibliotekanauki.pl/articles/1448361.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    tantalum niobium ore
    Pb2+ ions activation
    ammonium dibutyl dithiophosphate
    coadsorption
    Opis:
    The effect of lead ions on the flotation activation of tantalum niobium ore (TNO) was studied by micro-flotation, adsorption capacity experiments, solution chemical composition calculations, and infrared spectral analysis. The experimental demonstrated that the combined collector of salicylhydroxamic acid (SHA) and ammonium dibutyl dithiophosphate (ADDP) resulted in a strong collection capacity for TNO in the presence of lead ions. The solution chemistry calculations determined that the dominant source of lead ions in the aqueous solution was $Pb(OH)^+$ at a pH of 8, which was conducive to the adsorption and interaction of SHA and ADDP anions. In the lead ion activation system, the combined reagent co-adsorbed onto the TNO surface, causing a large negative shift in the zeta potential. The co-adsorption mechanism of the combined collector consisted of complex chemisorption between SHA and the TNO surface active particles, while the main adsorption of ADDP is physisorption.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2021, 57, 1; 29-38
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wetting and joining of HfB2 and Ta with Ni
    Zwilżanie i łączenie HfB2 i Ta z Ni
    Autorzy:
    Sobczak, N.
    Nowak, R.
    Passerone, A.
    Valenza, F.
    Muolo, M. L.
    Jaworska, L.
    Barberis, F.
    Capurro, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/391411.pdf
    Data publikacji:
    2010
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Odlewnictwa
    Tematy:
    zwilżanie
    połączenie
    borek hafnu
    tantal
    nikiel
    wetting
    joining
    hafnium boride
    tantalum
    nickel
    Opis:
    The wetting behavior of Ni on a HfB2/Ta assembly was examined in vacuum using dense HfB2 (99.5% purity) produced, without sintering aids, by HP-HT at 7 GPa. The real-time imaging by a high resolution digital camera and precise temperature control demonstrated solid-state Ni/HfB2 interaction resulting in metal contact melting at ˜ 1300°C. Ongoing heating, the in situ formed Ni-B alloy wets, spreads over HfB2 and penetrates the HfB2/Ta capillary interface to form a joint of complex graded structure and good bonding.
    Przeprowadzono badania procesu zwilżania w próżni układu HfB2/Ta przez Ni. Zwarte próbki HfB2 (czystość 99.5%) otrzymano sposobem spiekania w wysokiej temperaturze bez dodatków aktywujących spiekanie, stosując wysokie ciśnienie 7 GPa. Rejestracja procesu zwilżania w czasie rzeczywistym za pomocą kamery cyfrowej o wysokiej rozdzielczości w połączeniu z zastosowanym precyzyjnym pomiarem temperatury wykazały, że intensywne oddziaływanie w parze Ni/HfB2 zachodzi podczas wspólnego nagrzewania w temperaturze kiedy Ni jest jeszcze w stanie stałym a nadtapianie metalu w obszarze kontaktu dwóch materiałów występuje już w temperaturze ˜ 1300°C. Następnie stop Ni-B, powstający in situ podczas nagrzewania, zwilża i rozpływa się po całej powierzchni HfB2, wypełniając szczelinę pomiędzy dwoma materiałami w parze HfB2/Ta, tworząc połączenie o złożonej strukturze gradientowej i dobrej wytrzymałości.
    Źródło:
    Prace Instytutu Odlewnictwa; 2010, 50, 2; 5-14
    1899-2439
    Pojawia się w:
    Prace Instytutu Odlewnictwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microstructure and Properties of Composite Produced by Vacuum Sintering of Vanadis 4 Extra Steel Powder with Tantalum Carbides and Following Heat Treatment
    Autorzy:
    Huang, Kuo-Tsung
    Chang, Shih-Hsien
    Chuang, Chan-Yu
    Powiązania:
    https://bibliotekanauki.pl/articles/353735.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    tantalum carbide
    Vanadis 4 Extra steel
    transverse rupture strength
    polarization resistance
    sub-zero heat treatment
    Opis:
    In this study, different amounts of tantalum carbide (TaC) powders (5, 10 and 15 wt.%) are added to Vanadis 4 Extra steel powders. The composite powders are sintered at 1260, 1280, 1300, 1320, 1340 and 1360°C for 1 h, respectively. The experimental results showed that good mechanical properties (hardness 79.7 HRA, TRS 2246 MPa) were obtained by the addition of 10% TaC sintered at 1320°C for 1 h. Furthermore, the optimal sintered V4ES/TaC (Vanadis 4 Extra steel / TaC) composites after sub-zero treatment possess the highest hardness (80.9 HRA) and transverse rupture strength (TRS) values (2445 MPa), as well as a better polarization resistance (658.99 Ω·cm2). After sub-zero treatment, the VC carbides decompose and re-precipitate refined VC carbides within the grains (VC carbides are formed in steel powder); moreover, the TaC particles are still uniformly distributed around the grain boundaries, which results in dispersion strengthening and precipitation hardening. The results clearly reveal that sub-zero heat treatment effectively improves the microstructure and strengthens the V4ES/TaC composite.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 2; 555-563
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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