Section Of Diagram Research Articles

Thermodynamics of Vaporization in the Li2O–Ta2O5 system: The Standard Enthalpies of Formation of Lithium Tantalates

Vaporization in the Li2O–Ta2O5 system is studied using the Knudsen effusion method in combination with mass-spectrometric analysis of the gas phase in the temperature range of 1570–1860 K. Saturated vapor above the system is found to consist of lithium atoms, oxygen molecules, and lithium oxide Li2O molecules over the entire range of condensed phase compositions. The absolute partial pressures are calculated, and a p–x section of the complete p–T–x phase diagram at T = 1753 K is constructed. The experimental data made it possible to calculate the standard enthalpies of a number of heterophase reactions and the standard enthalpies of formation of lithium tantalates using the second and third laws of thermodynamics: $${{\Delta }_{f}}H_{{{\text{298}}}}^{^\circ }$$ (Li3TaO4) = –2074.6 ± 62.9 kJ/mol, $${{\Delta }_{f}}H_{{{\text{298}}}}^{^\circ }$$ (LiTaO3) = –1403.5 ± 57.4 kJ/mol, and $${{\Delta }_{f}}H_{{{\text{298}}}}^{^\circ }$$ (LiTa3O8) = –3466.4 ± 47.3 kJ/mol. Activities of the components at T = 1473 K and the standard enthalpy of formation of lithium heptatantalate ( $${{\Delta }_{f}}H_{{{\text{298}}}}^{^\circ }$$ (Li7TaO6) = –3383.0 kJ/mol) are estimated from the p–x section of the phase diagram.

MELT PROPERTIES OF THE FOUR SALT SYSTEM AlF3-KF-NaF-ZrF4

The fusibility of salt mixtures in the anhydrous quadruple AlF3-KF-NaF-ZrF4 system was studied. The direction of lowering the melting point of substances in the tetrahedron of the composition of the quadruple system, the influence of complexation on lowering the melting point of salt mixtures, were clarified.
 The fusibility of salts in the ternary AlF3-NaF-ZrF4 system was investigated experimentally by methods of thermal phase analysis. The diagram of fusibility to the isotherm of 900 °C is constructed. Primary crystallization fields are represented by the phases of the initial salts (AlF3, KF, ZrF4) of the compounds that were formed in binary subsystems (2KF∙ZrF4, 7NaF∙6ZrF4, 3NaF∙4ZrF4, 5NaF∙3AlF3) and Na3AlF6-Na3ZrF7 solid solutions. The minimum melting point was 466 ° C in a triple eutectic.
 The fusibility of salt mixtures was experimentally studied in the subsystem K2ZrF6-Na2ZrF6-KAlF4-NaAlF4, which was a section of the tetrahedron of the composition of the quadruple system AlF3-KF-NaF-ZrF4. The fusibility diagram of this subsystem was constructed. A triple point with a melting point of 450 °C was found. Primary crystallization fields are represented by compounds K2ZrF6, Na2ZrF6 and solid solutions KAlF4-NaAlF4.
 The low-melting region of the compositions in the tetrahedron of the composition of the quadruple system was shifted to the faces NaF-KF-ZrF4 and AlF3-KF-ZrF4. The intense chemical interaction of the starting materials of the quadruple system with the formation of complex compounds and the extensive formation of solid solutions complicated the determination of crystallizing solid phases and the establishment of monovariant equilibria in quadruple mixtures.
 Quadruple eutectic in the four component system was formed by the merger of four monovariant lines. To calculate the composition of the quadruple eutectic by the melting temperature and the composition of the eutectic of the triple subsystems, the coordinates of the four triple points are necessary. The characteristic of two triple points was obtained as a result of an experimental study of the fusibility diagrams of auxiliary sections of a tetrahedron of the composition: K2ZrF4-Na2ZrF6-KAlF4-NaAlF4 and KZrF6-NaAlF4-(0,5NaF+0,5ZrF4)-KAlF4, which were located near the quadruple eutectic.

Phase equilibria in Ho-Fe-Sn ternary system at 670 K

Interaction between the components in the Ho-Fe-Sn ternary system was studied using X-ray diffractometry, metallography and electron microprobe analysis. Isothermal section of the phase diagram was constructed at 670 K over the whole concentration range. Component interaction in the Ho-Fe-Sn system at 670 K results in the existence of one ternary compound HoFe6Sn6 which crystallizes in the YCo6Ge6 structure type (space group P6/mmm, a=0.53797(2), c= 0.44446(2) nm). The interstitial-type solid solution HoFexSn2 (up to 8 at.% Fe) based on the HoSn2 (ZrSi2-type structure) binary compound was found. Solubility of Sn in the HoFe2 binary (MgCu2 structure type) extends up to 5 at. %.

Phase equilibria, thermodynamic analysis and electrical properties of the Li2O–Y2O3–B2O3 system

Abstract Phase equilibria in the Li2O–Y2O3–B2O3 system are studied via the methods of thermodynamic, differential thermal analysis and X-ray diffractometry. The physico-chemical characteristics of the previously mentioned intermediate compounds with the compositions 2Li2O⋅Y2O3⋅5B2O3, 6Li2O⋅Y2O3⋅3B2O3, 3Li2O⋅2Y2O3⋅3B2O3 are clarified. T–x diagrams of polythermal sections, isothermal section at 25 °C, and liquidus surface projection for the Li2O–Y2O3–B2O3 system were constructed. The temperature dependencies for electrical conductivity of compounds of the Li2O–Y2O3–B2O3 system are studied. It has been shown that the conductivity of these compounds in polycrystalline form exponentially increases with increasing temperature. This indicates the semiconductor nature of the conductivity of the studied samples. The activation energies of the conductivity for these samples are determined.

The Influence of Tooth Surface Wear on Dynamic Characteristics of Gear-Bearing System Based on Fractal Theory

Abstract In this paper, the influence of tooth surface wear on dynamic characteristics of the gear-bearing system is discussed. The gear-bearing system considering the factors of tooth surface friction, time-varying meshing stiffness, backlash and et al. is established. Based on the Fractal theory and the Archard theory, the tooth surface wear is calculated, and it is substituted into the calculation of backlash and stiffness to obtain the time-varying backlash and the time-varying meshing stiffness. The Runge–Kutta method is used to solve the dynamic differential equation of the gear system, then the phase diagrams, the Poincare section diagrams and the bifurcation diagrams of the system are obtained. The results show that compared with the constant backlash and normal-distribution backlash under the wear condition, the wear backlash calculated by the Fractal theory and the Archard theory can better show the influence of wear on the system response. With the increasing of the accumulated wear on the tooth surface, the decrement of the time-varying meshing stiffness increases, and the system is more unstable. As the friction coefficient decreases, the regions of periodic and quasi-periodic motion state increase, and the boundaries between the periodic and quasi-periodic motion state become clear. Therefore, friction mainly plays a hysteretic role on the gear-bearing system.

Er-Cr-Ge Ternary System

The isothermal section of the phase diagram of the Er–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. The interaction between the elements in the Er−Cr−Ge system results in the formation of two ternary compounds: ErCr6Ge6 (MgFe6Ge6-type, space group P6/mmm, Pearson symbol hP13; a = 5.15149(3), c = 8.26250(7) Ǻ; RBragg = 0.0493, RF = 0.0574) and ErCr1-хGe2 (CeNiSi2-type, space group Cmcm, Pearson symbol oS16, a = 4.10271(5), b = 15.66525(17), c = 3.99017(4) Ǻ; RBragg = 0.0473, RF = 0.0433) at investigated temperature. For the ErCr1-xGe2 compound, the homogeneity region was determined (ErCr0.28-0.38Ge2; a = 4.10271(5)-4.1418(9), b = 15.6652(1)-15.7581(4), c = 3.99017(4)-3.9291(1) Ǻ).

Nonequilibrium processes of power and enviromental resistance of reinforced concrete structures to progressive collapse

The problems of calculating the parameters of non-equilibrium power and environmental resistance of reinforced concrete elements of a structural system under special effects are considered. A static-dynamic diagram of the deformation of corrosion-damaged concrete during overlimit impact caused by the sudden removal of a supporting structure is constructed. The section of this diagram is described by the analytical dependence for change in the strength of loaded and corrosion-damaged concrete from time, which takes into account, on the one hand, the process of the increasing strength of “healthy” concrete in time (theory of concrete aging), and on the other, the process of the degradation of an aggressive environment on concrete. A section of the dynamic deformation diagram is described by the Kelvin-Voigt model in a version of the theory of plasticity of concrete G.A. Genius, which corresponds to the conditions of deformation of concrete as an elastic-viscous-plastic material. The dynamic tensile strength of corrosion-damaged concrete is taken into account by the coefficient of increase in the dynamic strength of the material based on the two-element model of its deformation.

Precise modeling of complex tooth surface microtopography and multi-degree-of-freedom nonlinear friction dynamics for high-performance face gear.

Face gear transmission is a kind of space-meshing mechanism that is mainly used in the field of aviation. Compared with traditional transmission, it has the advantages of stability, reliability, low noise, and strong carrying capacity. However, owing to its complex tooth surface, there are no means to accurately model the face gear. Likewise, research based on the geometry is difficult. Therefore, the tooth surface equation of the face gear is derived in this article based on the meshing theory. Based on the equations, the point cloud of the face gear tooth surface is calculated, the complex tooth surface is generated, and the face gear is accurately modeled. Moreover, taking tooth surface friction excitation into consideration, a multi-degree-of-freedom nonlinear dynamic model of face gear transmission system is established, using the adaptive variable step length Runge-Kutta method. As shown in the results, the bifurcation diagram, phase diagram, time history diagram, and Poincaré section diagram are combined to analyze the influence of tooth surface friction and meshing frequency on the dynamic characteristics of the system.

Effects of oxygen partial pressure on the thermodynamics of CaO–SiO2–VOx system at 1873 K

AbstractIn this study, two aspects concerning with the thermodynamics of CaO–SiO2–VOx system were investigated. One aspect is about the effects of oxygen partial pressure on the phase relationships in CaO–SiO2–VOx system at 1873 K, and the other is the measurement of the standard Gibbs energy of formation of the vanadium compounds. In the first aspect, the phase relationships in CaO–SiO2–VOx system at 1873 K under oxygen partial pressure of 1.7 × 10−9 atm were determined, and the isothermal section diagram was constructed. Furthermore, by comparing this diagram with that under 6.9 × 10−11 atm, the effects caused by oxygen partial pressure on this system were elucidated. With the increase in oxygen partial pressure, the compound CaV2O4 that exists stably under 6.9 × 10−11 atm is oxidized to V2O3 and CaVO3. The solubility limit of V2O3 in liquid phase also increases remarkably, which results in the enlargement of the single liquid area. In the second aspect, the standard Gibbs energy of formation of CaV2O4, CaVO3, V2O3, and Ca2Si1−δVδO4 (0 < δ < 0.1) at 1873 K were measured. The determined values for CaV2O4 and CaVO3 are −1 259 468.9 ± 5090.5 J/mol and −963 479.8 ± 3298.6 J/mol, respectively. Then, the limit of oxygen partial pressure for CaV2O4 existing stably at 1873 K is determined to be 4.4 × 10−10 atm.

Influence of Se on Properties of As-S-Se-I Glass for Immersion Mid-IR Leds Lenses

The study of glass components influence on the physical and chemical properties of As–S–Se–I glasses has the potential to help design glasses with the required properties. A change of certain glass properties upon the introduction of selenium into AsSI glass was demonstrated. Non-stoichiometric compounds along the As2S3-AsI3-Se diagram section were investigated by differential thermal analysis, ultrasonic measurements, dilatometric measurements. It has been shown that the introduction of selenium decreases the glass solubility in water. Change in the glass properties with the change in the short-range structure studied by Raman spectroscopy was shown. These glasses can be used for creation of immersion lenses and optical adhesives which change radiation characteristics of mid-IR LEDs.

Stability and chaotic dynamics of forced $$\phi ^8$$ generalised Liénard systems

This work studies a forced generalised Lienard oscillator with $$\phi ^8$$ potential with order 8 dissipation. The fixed points and their stability have been analysed for autonomous and non-dissipative Lienard oscillator. The system can exhibit three, five or seven fixed points and the corresponding stability diagram is checked and analysed. The effect of restoring parameters on the potential is also studied. Periodic, multiperiodic and chaotic monostable and bistable attractors and their coexistence have been checked through the bifurcation diagram, Lyapunov exponent, phase space and Poincare section using the fourth-order Runge–Kutta algorithm. The results obtained by the analytical methods are validated and complemented by the numerical simulations.

Phase Equilibria in the Cu2Se−SnSe−CuSbSe2 System

Phase equilibria in the Cu2Se−SnSe−CuSbSe2 system were studied by differential thermal and X-ray powder diffraction analyses. Alloys were obtained by alloying of the preliminarily synthesized and identified initial compounds in a vacuum with subsequent annealing at 650 K for 500 h. Characteristic plots describing this system were constructed, namely, the polythermal sections SnSe−Cu3SbSe3, Cu2Se−[A], and CuSbSe2−[B], where [A] and [B] are the alloys of the compositions (SnSe)0.5(CuSbSe2)0.5 and (Cu2Se)0.5(SnSe)0.5, respectively; the isothermal section of the phase diagram at 300 K; and the projection of the liquidus surface. It was shown that this system is a quasi-ternary section of the quaternary system Cu−Sn−Sn−Se and is characterized by invariant equilibria: a transient one and a eutectic one. Fields of primary crystallization of phases and the types and coordinates of in- and monovariant equilibria were found. Wide regions of solid solutions based on SnSe and CuSbSe2 were revealed.

Phase Equilibria in the Sm2O3–CaO–NiO and Sm2O3–NiO–CoO Systems

Phase equilibria in the 1/2 Sm2O3–CaO–NiO and 1/2 Sm2O3–NiO–CoO systems are systematically studied at 1100°C in air. The formation of two types of solid solutions Sm2– yCayNiO4 – δ (0.5 ≤ y ≤ 0.55) and SmCo1– xNixO3 – δ (0 < x ≤ 0.15) crystallized in the K2NiF4-type structure and perovskite structure, respectively, is detected. The oxygen content in the samples within the temperature range 25–1100°C in air is determined by means of high temperature thermogravimetry and dichromatometric titration. Isobaric isothermal cross sections of the phase diagrams for the 1/2 Sm2O3–CaO–NiO and 1/2 Sm2O3–NiO–CoO systems at 1100°C and $${{p}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ = 0.21 atm are proposed.

Interaction of the Components in the {Ce, Gd}-{Ti, Zr}-Sb Systems

The phase equilibria in the ternary systems {Ce, Gd}–{Ti, Zr}–Sb were investigated by means of X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The isothermal sections of the phase diagrams at 600°C were constructed. The formation of three ternary compounds (Ce2Ti7Sb12, Ce3TiSb5, and Gd2Ti11Sb14) was confirmed in the {Ce, Gd}–Ti–Sb systems and no more ternaries were found. The investigation of the {Ce, Gd}–Zr–Sb systems revealed several new ternary compounds and confirmed the known ones. The crystal structure of the new compound Ce0.08(3)Zr1.92(3)Sb was determined from X-ray powder diffraction data. The other new compounds in the Ce–Zr–Sb system were found to have compositions close to ~CeZrSb4and ~Ce2Zr3Sb5. In the Gd–Zr–Sb system the existence of a large homogeneity range was established for the GdZrSb compound along the isoconcentrate 33.3 at.% Sb: Gd1-xZr1+xSb (x= 00.905(18) at 600°C), and a new compound, ~Gd3Zr3Sb14, was discovered. The crystal structures at the boundary compositions of the Gd1-xZr1+xSb phase were refined from X-ray powder diffraction data.

Crystal Chemistry of Ternary Rare Earth Transition Metal Carbides: Studies of the Tb-Fe-C System at 800°C

The isothermal section of the phase diagram of Tb–Fe–C system at 800 °C was studied in the full concentration range using powder X-ray phase and structure analyses, and energy-dispersive X-ray spectroscopy. Six ternary compounds Tb1.88Fe14C, Tb13Fe10C13, TbFeC2, Tb15Fe8C25, Tb5.64Fe2C9, Tb2FeC4 and a limited solid solubility of carbon in the crystal structure of the binary parent compound Tb2Fe17Cх (0≤ х ≤0.8) have been found to exist at 800 °C. The crystal structures of two new ternary carbides have been determined by means of powder X-ray diffraction: Tb15Fe8C25 with structure type Er15Fe8C25, space group P321, a = 11.9706(3) Å, c = 5.1733(2) Å, RB(I) = 0.07, RP = 0.06, RPw = 0.08, and Tb13Fe10C13 with structure type Gd13Fe10C13, space group P3121, a = 9.1800(9) Å, c = 23.703(5) Å, RB(I) = 0.04, RP = 0.16. Both compounds are representatives of the carbometalate class of complex carbides. Tb15Fe8C25 displays an itinerant ferro-or ferrimagnetic ordering of the Fe 3d-moments below TM ≈ 50 K while Tb 4f-moments remain essentially paramagnetic at least down to about 10 K.

Lu-V-{Ge, Sn} ternary systems

&#x0D; The isothermal sections of the phase diagrams of the Lu–V–Ge and Lu-V-Sn ternary systems were constructed at 870 K over the whole concentration range using X-ray diffraction and EPM analyses. In the Lu-V-Ge system a formation of the substitutional solid solution Lu5Ge3-xVx based on the Lu5Ge3binary compound (Mn5Si3 structure type) was found up to 6 at. % V. Insertion of the V atoms in the structure of the LuGe2 binary germanide (ZrSi2structure type, up to 5 aт. % V) results in the formation of the LuV0,15Ge2 ternary phase (CeNiSi2 structure type, space group Cmcm, a=0.40210(4),b=1.5661(1), c=0.38876(3) nm), which corresponds to the limit composition of the interstitial solid solution LuVxGe2. The interaction between the elements in the Lu-V-Sn system results in the formation of one ternary compound LuV6Sn6 (SmMn6Sn6-type, space group P6/mmm, a=0.5503(2), c=0.9171(4) nm) at investigated temperature.&#x0D;

Dynamics analysis of fractional-order permanent magnet synchronous motor and its DSP implementation

In this paper, dynamics of the fractional-order permanent magnet synchronous motor (FOPMSM) model is investigated. The numerical solution of the FOPMSM system is derived based on Adomian decomposition method (ADM) that is a computationally efficient and high accurate method, and its dynamical behaviors are observed by means of phase diagrams, bifurcation diagrams, Lyapunov exponent spectra (LEs), Poincaré section and chaos diagram based on spectral entropy (SE) complexity. Comparison with some reported studies, the simulation results show that it has more rich dynamical characteristics. The lowest order for the existence of chaos is 2.115 that demonstrated by 0–1 test, which is lower than that existing result (2.85). Finally, the FOPMSM system is implemented by digital signal processor (DSP), which verifies the correctness of the solution algorithm and the physical feasibility of this system. It indicates that the FOPMSM system has broad application prospect.

Exploitation of Mold Flux for the Ti-bearing Welding Wire Steel ER80-G

AbstractIn order to improve the surface defects of strand, the mold flux is exploited for the Ti-bearing welding wire steel ER80-G. The composition of mold flux is designed by analyzing the solidification characteristics of ER80-G and the slag system isothermal section diagram, simulating by the FactSage thermodynamics software. The Ti-bearing welding wire steel ER80-G belongs to the peritectic steel. The melting point range of the newly designed mold flux system is from 1030∘C to 1129∘C, the melting rate range is from 58 s to 64 s, the viscosity range at the temperature of 1300∘C is from 0.33 Pa·s to 0.50 Pa·s, the crystallization temperature range is from 1160∘C to 1293∘C, the crystalline fraction range is from 34% to 85%. The surface defects of strand which transverse depression, longitudinal depression, slag runner and so on were obviously improved when the newly design mold flux F3, F5, F9 were used to the production respectively. Those results suggest that 0.9 basicity with 28.4%-CaO, 31.6%-SiO2,3%-MgO, 10%-Na2O, 10%-CaF2, 6%-Al2O3, 1%-Fe2O3, 10%-Tcand all groups with 1.0 and 1.1 basicity show the best properties for Ti-bearing welding wire steel ER80-G.

Chaotic motion of piezoelectric material hyperbolic shell under thermoelastic coupling

Piezoelectric material, which exhibits excellent electro-mechanical conversion properties, is widely used in smart sensors and structures for sonar systems, weather detection and remote sensing. Hyperbolic shell structure made of piezoelectric material is liable to break down when it is used in high temperature environment, which is caused by the unexpected chaotic dynamic motion under the coupling effect of thermal filed and force field. Therefore, the chaotic nonlinear dynamic vibration of simply-supported piezoelectric material hyperbolic shell is studied under the combined action of temperature field and simple harmonic excitation. Based on the theory of finite deformation, the non-linear vibration equation and coordination equation of the hyperbolic shell are established. The non-linear dynamic equation of the structure is obtained by the Bubnov-Galerkin principle. The corresponding undisturbed Hamilton system has a homoclinic orbit. Using Melnikov function, the chaotic motion condition of the dynamic system under the criterion of Smale-horseshoe transformation is obtained. Furthermore, the mathematical model is established by Simulink software and the numerical simulations are performed by the fourth-order Runge-Kutta method. The simulation results accord well with those from the Melnikov method. The bifurcation diagram, the Lyapunov exponent diagram, the phase diagram and Poincaré section diagram are acquired to analyze the influence of temperature field on the non-linear characteristic of piezoelectric material hyperbolic shell system. When the temperature is close to 32℃ and 41℃, the Lyapunov index is less than 0 and the corresponding movement of the system is in the periodic zone, which is the same as that for a temperature range from 36℃ to 37℃. When the Lyapunov index is greater than 0, the corresponding movement of the system is in chaos zone. Therefore, the change of temperature has an additional effect on the stiffness of the system which affects the vibration of the system. The chaos and periodic zones of the system alternate with the increase of temperature and the vibration characteristics of the system can be controlled by changing the temperature field. Therefore, adjusting the temperature field can control the motion state of the system, which helps to improve reliability of the structure.

Nonlinear Dynamic Analysis of Rotor Rub‐Impact System

A dynamic model of a double‐disk rub‐impact rotor‐bearing system with rubbing fault is established. The dynamic differential equation of the system is solved by combining the numerical integration method with MATLAB. And the influence of rotor speed, disc eccentricity, and stator stiffness on the response of the rotor‐bearing system is analyzed. In the rotor system, the time history diagram, the axis locus diagram, the phase diagram, and the Poincaré section diagram in different rotational speeds are drawn. The characteristics of the periodic motion, quasiperiodic motion, and chaotic motion of the system in a given speed range are described in detail. The ways of the system entering and leaving chaos are revealed. The transformation and evolution process of the periodic motion, quasiperiodic motion, and chaotic motion are also analyzed. It shows that the rotor system enters chaos by the way of the period‐doubling bifurcation. With the increase of the eccentricity, the quasi‐periodicity evolution is chaotic. The quasiperiodic motion evolves into the periodic three motion phenomenon. And the increase of the stator stiffness will reduce the chaotic motion period.