Wyniki wyszukiwania - Biblioteka Nauki

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Kinetics of Corrosion Process in H2SO4 and HNO3 Aqueous Solutions of Lead Free Sn-Ag-Cu Solder Alloys

100%

Guśpiel J. , Wierzbicka-Miernik A. , Reczyński W.

Archives of Metallurgy and Materials

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2016

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tom Vol. 61, iss. 2A

559--568

EN

This paper presents the results of the corrosion resistance of Sn-Ag-Cu alloys in air-saturated aqueous solutions containing NO3-, SO42- ions, whose concentration was equivalent to their contents in acid rains and in concentrations 10 - 100 times higher. The Ag, Cu and Sn concentrations in the corrosive media were determined using the Atomic Absorption Spectrometry. The specific dissolution rate and corrosion current were derived using the a rotating disc technique. The corrosion rate of Sn- Ag-Cu alloys depends on pH of the examined solutions and on the concentration of oxygen near the phase boundary. In the whole range of concentrations of the applied H2SO4 + HNO3 mixtures of acids, the pure Sn was more corrosion resistant than eutectic alloy as well as the near eutectic one, following the sequence: Sn>Sn3.66Ag0.91Cu>3.8Ag0.7Cu.

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Synthesis, characterization and properties of nanocrystalline perovskite cathode materials

100%

Ghosh S. , Dasgupta S.

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tom Vol. 28, No. 2

427--438

EN

A simple low temperature synthesis route has been presented of preparing nanosized, single phased LaFeO3, La(1-x)SrxFeO3 (x = 0.3, 0.5) and La(1-x)SrxCo0.2Fe0.8O3 (x = 0.2, 0.4) for cathode applications in ITSOFC. A soft chemical method has been applied, using tartaric acid as a template material and nitric acid as an oxidizing agent. Phase pure materials were obtained at temperatures ranging from 550 °C to 700 °C. The synthesized powders were characterized by TGA, XRD, SEM and FTIR analysis. The crystallite size was 45-50 nm, with the surface area of 14-20 m2/g. Electronic conductivity of the material was found to increase upon increasing Sr concentration and the sintering temperature. High electronic conductivities of 355 S/cm and 545 S/cm were obtained at 400 °C for La0.5Sr0.5Fe2O3 and La0.6Sr0.4Co0.2Fe2O3, respectively. Activation energy decreases with the increase in Sr concentration. The values of thermal expansion coefficients (TEC) of the materials are compatible with the TEC of the ceria-gadolinium oxide CGO interlayer between cathode layer and electrolyte.

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Green synthesis and characterization of Ag1/2Al1/2TiO3 nanoceramics

88%

Kumar S. , Jha A. K. , Prasad K.

Materials Science Poland

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2015

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tom Vol. 33, No. 1

59--72

EN

Single phase silver aluminum titanate (Ag1/2Al1/2)TiO3, later called AAT, nanoceramic powder (particle size 2 to 7.5 nm) was synthesized by a low-cost, green and reproducible tartaric acid gel process. X-ray, FT-IR, energy dispersive X-ray and high resolution transmission electron microscopy analyses were performed to ascertain the formation of AAT nanoceramics. X-ray diffraction data analysis indicated the formation of monoclinic structure having the space group P2/m(10). UV-Vis study revealed the surface plasmon resonance at 296 nm. Dielectric study revealed that AAT nanoceramics could be a suitable candidate for capacitor applications and meets the specifications for “Z7R” of Class I dielectrics of Electronic Industries Association. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were performed using the impedance data. Electric modulus studies supported the hopping type of conduction in AAT. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in AAT. The ac conductivity data were used to evaluate the density of states at Fermi level and minimum hopping length of the compound.

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Wykorzystanie technologii druku 3D do konstrukcji anten planarnych

75%

Czerwiński M. , Pasternak M.

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2020

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tom Vol. 69, nr 1

57--65

PL

W pracy analizowano przydatność technologii druku 3D do konstrukcji podłoży antenowych o zadanej przenikalności elektrycznej. Parametr ten, jak wiadomo, ma silny wpływ na parametry anten planarnych. Zastosowanie druku 3D pozwala na dość swobodny dobór wartości przenikalności elektrycznej w granicach pomiędzy wartością dla powietrza i materiału litego. Dobór taki można realizować poprzez zmianę tworzywa wykorzystywanego do druku 3D oraz sposób wypełniania objętości podłoża. Wyniki symulacji i wstępnych pomiarów wskazują, że idea druku podłoży antenowych może być interesująca z konstrukcyjnego punktu widzenia. Przedmiotem opisanej w artykule pracy było wykonanie symulacji wybranych własności anten planarnych na podłożach drukowanych, a następnie realizacja pomiarów z wykorzystaniem wykonanych modeli laboratoryjnych. Porównanie otrzymanych wyników numerycznych z wartościami uzyskanymi w trakcie pomiarów jest źródłem informacji o stosowalności standardowych technik symulacyjnych w odniesieniu do podłoży drukowanych o dość skomplikowanej ażurowej strukturze.

EN

The applicability of 3D print technologies for manufacturing of planar antenna substrates having tailored permittivity was considered in the work. The permittivity is known as a parameter that has strong influence on the planar antennae key parameters. The application of 3D print gives the possibility of changing this parameter in the range between its value for air up to the value for homogeneous solid material. The change can be achieved through the change of the filament material and the way of 3D print pattern. The preliminary results of simulations and measurements show that the idea of printing of planar antennae substrate may be interesting alternative from a design engineering point of view.