Cze stochowa University of Technology

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Poland
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Kubiak M.,Cze stochowa University of Technology | Piekarska W.,Cze stochowa University of Technology
Archives of Mechanics | Year: 2015

THIS PAPER CONCERNS THE MATHEMATICAL and numerical modelling of thermal phenomena and phase transformations in the solid state accompanying laser heating processes. Thermal phenomena with the motion of a liquid metal in the fusion zone are analyzed on the basis of numerical solution of equations for mass, momentum and energy conservation. Phase transformations in solid state are estimated using classic models of the kinetics of phase transformations as well as continuous heating transformations (CHT) and continuous cooling transformations (CCT) diagrams for S355 steel. Computer simulations are executed for the laser welding process in order to predict the influence of welding speed on the structural composition as well as thermal and structural strains in the joint. Copyright © 2015 by IPPT PAN.


Durajski A.P.,Cze stochowa University of Technology
Solid State Communications | Year: 2014

The electron-doped silicene under the influence of the biaxial tensile strain is predicted to be the phonon-mediated superconductor. By using the Eliashberg formalism, we investigate the thermodynamic properties of the superconducting silicene in the case when the tension is 5% and the electron doping equals 3.5×1014cm-2. Under such conditions, silicene monolayer is expected to exhibit the highest superconducting transition temperature (TC). In particular, based on the electron-phonon spectral function and assuming a wide range of the Coulomb pseudopotential values (μ∗ ∈ 〈0.1,0.3〉) it is stated that the superconducting transition temperature decreases from 18.7 K to 11.6 K. Similar behavior is observed in the case of the zeroth temperature superconducting energy gap at the Fermi level: 2Δ(0)∈ 〈6.68,3.88〉 meV. Other thermodynamic parameters differ from the predictions of the Bardeen-Cooper-Schrieffer theory. In particular, the ratio of the energy gap to the critical temperature changes in the range from 4.14 to 3.87. The ratio of the specific heat jump to the specific heat in the normal state takes the values from 2.19 to 2.05, and the ratio of the critical temperature and specific heat in the normal state to the thermodynamic critical field increases from 0.143 to 0.155. It is also determined that the maximum value of the electron effective mass equals 2.11 of the electron band mass. © 2014 Elsevier Ltd. All rights reserved.


Durajski A.P.,Cze stochowa University of Technology
Superconductor Science and Technology | Year: 2014

The present paper discusses the thermodynamic properties of the superconducting state which gets induced in the following compounds due to the influence of the high pressure: ScH3( p = 18 GPa) and LaH3(p = 11 GPa). Using the Eliashberg formalism, for the Coulomb pseudopotential equal to 0.1, the following quantities have been determined: the maximum critical temperature ([TC]ScH3= 19.3 K and [TC]LaH3= 22.5 K), the energy gap at the Fermi surface (G), the free energy (F), the thermodynamic critical field (HC), and the specific heat (both for the superconducting (CS) and the normal (CN) state). Then, the dimensionless parameters, namely, RG≡ G(0)/kBTC, RH≡ TCCN(TC)/HC 2(0), and RC≡ (CS/(TC- CN(TC))/CN(TC), have been obtained. Those ratios deviate from the predictions of the BCS theory in the case of the studied compounds: [RG]ScH3= 3.85, [RG]LaH3= 3.92, [RH]ScH3= 0.160, [RH]LaH3= 0.154, [RC]ScH3= 1.84, and [RC]LaH3= 2.09. In the last step, it has been proven that the ratio of the electron effective mass (me∗) to the electron band mass (me) takes relatively high values, which are weakly dependent on the temperature. For example, it has been shown that [me∗/me]ScH3= 1.833 and [me∗/me]LaH3= 1.845 for T = TC. © 2014 IOP Publishing Ltd.


Mirek P.,Cze stochowa University of Technology | Ziaja J.,Cze stochowa University of Technology
Chemical and Process Engineering - Inzynieria Chemiczna i Procesowa | Year: 2011

The article presents the results of laboratory tests carried out on a scaling model of the 966MWth fluidised-bed boiler operating in the Lagisza Power Plant, made on a scale of 1:20 while preserving the geometrical similarity. The tests were carried out for scaled-down material taken from different locations on the circulation contour in the state of full boiler loading. To reflect the hydrodynamic conditions prevailing in the combustion chamber, solids with properly selected density and particle size distribution were used. The obtained results have made it possible to determine the location for taking the most representative granular material sample.


Garus S.,Cze stochowa University of Technology | Nabialek M.,Cze stochowa University of Technology | Garus J.,Cze stochowa University of Technology
Acta Physica Polonica A | Year: 2014

This paper presents the results of studies on the magnetic properties of the Fe60Co10Mo2Y8B20 alloy. The samples were fabricated in the form of plates by the injection-casting method. The structure of the investigated alloy, in the as-quenched state and after annealing, was verified by using X-ray diffractometry. The magnetization curves as a function of temperature were measured by a force magnetometer. From thermomagnetic curves the Curie temperature of the alloy was determined. As a critical parameter β was chosen to be equal to 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of the Heisenberg type. Additionally, using a vibrating sample magnetometer the magnetization and coercivity field were studied (in magnetic field up to 2 T). © 2014, Polish Academy of Sciences. All rights reserved.


Garus S.,Cze stochowa University of Technology | Nabialek M.,Cze stochowa University of Technology | Bloch K.,Cze stochowa University of Technology | Garus J.,Cze stochowa University of Technology
Acta Physica Polonica A | Year: 2014

The study analyzed the influence of structural defects on the process of magnetization in the area called the approach to ferromagnetic saturation for bulk Fe60Co10WxNb2Y8B20-x (x = 0, 1) alloys. For this purpose, the magnetization studies were performed in the fields range of 0 T to 2 T using a LakeShore vibrating magnetometer. On the basis of the Kronmüller theory an analysis of the magnetization curves was conducted and the type of occurring structural defects in the studied alloys was established. Then, using a Monte Carlo method the effective anisotropy of the tested samples was designated. © 2014, Polish Academy of Sciences. All rights reserved.


Garus J.,Cze stochowa University of Technology | Garus S.,Cze stochowa University of Technology | Nabialek M.,Cze stochowa University of Technology | Szota M.,Cze stochowa University of Technology
Acta Physica Polonica A | Year: 2014

The aim of this paper were studies of the structure and magnetic properties of the bulk Fe60Co10WxMo2Y8B20-x (x = 0, 1, 2) alloys. Ingots of the alloys were prepared by arc melting of high purity elements in an argon atmosphere. The samples in the form of plates were obtained by a rapid solidification of liquid metal in a copper mold cooled with water. Topography of produced samples were examined using a ZEISS SUPRA 35 high resolution scanning electron microscope. Furthermore, using a vibrating sample magnetometer the magnetization in high magnetic fields was studied. Moreover, from initial magnetization curves the parameters related with the Holstein-Primakoff paraprocess were determined. © 2014, Polish Academy of Sciences. All rights reserved.


Wolczynski W.,Polish Academy of Sciences | Pogoda Z.,Jagiellonian University | Garzel G.,Polish Academy of Sciences | Kucharska B.,Cze stochowa University of Technology | And 2 more authors.
Archives of Metallurgy and Materials | Year: 2014

A mathematical description for the (Zn) - coating formation with the presence of flux in the zinc bath is presented. This description includes the progressive vanishing of the products of the flux disintegration. A function which expresses the flux vanishing is formulated. The solidification of some phase sub-layers in the (Zn) - coating is considered with the use of a hypothetical pseudo-ternary phase diagram Fe-Zn-flux. Some relationships are formulated to define the varying Zn - solute redistribution as observed across the sub-layers. The relationships are based on the mass balance analyzed for the coating / bath / flux system. An amount of the growing phase in a given sub-layers is also defined mathematically. © 2014, Committee of Metallurgy. All rights reserved.


Szcze sniak R.,Cze stochowa University of Technology | Szcze sniak R.,Jan Dlugosz University in Czestochowa | Durajski A.P.,Cze stochowa University of Technology | Herok L.,Jan Dlugosz University in Czestochowa
Solid State Communications | Year: 2015

The aim of the present work is to explore the physical properties of the transition-metal based antiperovskite MgCNi3 in superconducting state. In particular, the critical value of the Coulomb pseudopotential and temperature dependence of the energy gap, specific heat, thermodynamic critical field and London penetration depth are theoretically analyzed within the framework of the Eliashberg formalism. Moreover, we determined the dimensionless ratios which are related to the above thermodynamic functions: 2Δ(0)/kBTC=4.19, ΔC(TC)/CN(TC)=2.27 and TCCN(TC)/HC2(0)=0.141. Our calculations show that obtained results significantly diverge from the values predicted by the BCS model due to the strong-coupling corrections and retardation effect existing in investigated antiperovskite. © 2014 Elsevier Ltd. All rights reserved.


Szcze sniak R.,Cze stochowa University of Technology | Szcze sniak R.,Jan Dlugosz University in Czestochowa | Durajski A.P.,Cze stochowa University of Technology | Herok L.,Jan Dlugosz University in Czestochowa
Physica Scripta | Year: 2014

The thermodynamic properties of a SrPt3P compound in the superconducting state have been investigated by taking the Eliashberg approach. The anti-perovskite SrPt3P is identified as a strong-coupling (λ = 1.33) s-wave superconductor with 2Δ(0)/kBTC = 4.35, where the zero-temperature energy gap (2Δ(0)) obtained from the Eliashberg calculations is 3.15 meV. The critical temperature TC was recently reported to be 8.4 K and this paper confi rms the Coulomb pseudopotential repulsions (μBlack star) to be equal to 0.123. Moreover, the free energy difference between the superconducting and the normal state has been calculated. On the basis of the obtained results, the specific heat for the superconducting and the normal state, as well as the thermodynamic critical field, have been determined. It has been also proved that the electron effective mass is high and reaches its maximum equal to 2.46me for the critical temperature. © 2014 The Royal Swedish Academy of Sciences.

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