Determination of the thermodynamic properties of liquid <Emphasis Type="Italic">n</Emphasis>-hexadecane from the measurements of the velocity of sound

The density, the isobaric expansion coefficient, the specific heats at constant pressure and constant volume, and the isothermal compressibility coefficient of liquid n-hexadecane have been calculated in the range of temperatures 298–433 K and pressures 0.1–140 MPa from the data on the velocity of sound. The coefficients of the Tate equation in the above parametric range have been determined. The table of the thermodynamic properties of n-hexadecane has been presented. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 150–156, January–February, 2009.     

Influence of rotational motion of nitrogen molecules on the thermal expansion of solid solutions of Ar−N2: A new effect

The thermal expansion coefficient of solid Ar and of solid solutions of¹⁴N₂ in Ar (0.51; 2.24; 4.89 mol.%¹⁴N₂) has been investigated in the temperature range 1–16 K. Two new effects have been discovered for the behaviour of the impurity contribution Δα to the linear expansion coefficient, i.e., negative values of Δα atT<4.3 K for the solution with a nitrogen concentration of 0.51%, and independence of Δα on impurity content for two more concentrated solutions below 7 K. An explanation of the peculiarities mentioned is given. The comparison of the results obtained with the theoretical predictions has been made.     

On the calculation of deformation curves for two-phase cermets

Analytical algorithms for the construction of tensile and compression stress-strain diagrams of two-phase cermets are proposed, which are based on the concept of mean stresses in the phase volume and physical equations of the theory of small elastoplastic strains. The deformation properties and strength of cermet are supposed to depend on such parameters of its microstructure as mean size and coefficient of variation of solid phase grain-size distribution, contiguity coefficient of solid phase grains, and mean thickness of the metal phase inter-layers. A numerical analysis of the characteristic parameters of deformation curves for WC-Co hard metals has been carried out over a wide range of cobalt concentration and carbide grain size. A good agreement between the theoretical values of ultimate tensile and compression strength and known experimental values has been established. The constructed model deformation curves for hard metals may be regarded as alternatives to the corresponding experimental curves of stress against relative change in specimen length. __________ Translated from Problemy Prochnosti, No. 3, pp. 99–111, May–June, 2006.     

Influence of the concentration of a dispersed phase and of the magnetic field on the attenuation of ultrasonic waves in magnetic fluids

The regularities of the propagation of elastic waves of ultrasonic range in magnetic fluids have been experimentally established. The influence of relaxation processes — nonlocal heat exchange and viscous dissipation — on the coefficient of attenuation of sound has been revealed and a comparison to the existing theoretical data has been made. The dependences (anisotropic in form) of the attenuation of the wave’s amplitude on the value and direction of the magnetic field have been determined and an interpretation of the results obtained has been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 133–140, September–October, 2007.     

Special features of the dynamics of heating of moving media by electromagnetic radiation

The dynamics of temperature waves in moving media heated by high-frequency electromagnetic radiation has been studied by the methods of numerical simulation with allowance for the dependence of the viscosity and the absorption coefficient of the radiation on temperature. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 5, pp. 939–944, September–October, 2000.     

Determination of the nonlinear heat-conductivity coefficient of tubular bodies by the method of functional identification

The problem on determination of the nonlinear heat-conductivity coefficient of a body in the cylindrical coordinate system by the method of functional identification has been considered. Computational experiments are described and calculation results are discussed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 23–30, November–December, 2006.     

Thermal Expansion of Ni–W,Ni–Cr,and Ni–Cr–W Alloys Between Room Temperature and 800 °C

The thermal expansion of Ni–W, Ni–Cr, and Ni–Cr–W alloys has been measured by quartz dilatometry for the 20 °C to 800 °C temperature range. It is found that substitution of nickel by tungsten leads to a considerable decrease of the thermal expansion coefficient (TEC), while chromium has only a small influence on the TEC of the alloy.     

Acoustic and thermodynamic properties of the binary liquid system <Emphasis Type="Italic">n</Emphasis>-dodecane+<Emphasis Type="Italic">n</Emphasis>-hexadecane

By the method of direct measurement of the pulse-passage time, the velocity of sound in a binary liquid mixture n-dodecane+n-hexadecane has been investigated in the temperature range 298–433 K and in the pressure range 0.1–100.1 MPa. The maximum measurement error is 0.1%. Experimental data on the velocity of sound for the investigated mixture have been obtained for the first time. On the basis of the data on the velocity of sound, we have determined the density, the isobaric expansion coefficient, the isobaric and isochoric heat capacities, and the isothermal compressibility coefficient of a mixture of three compositions in the 298–433 K temperature range and in the 0.1–100.1 MPa range of pressures. The coefficients of the Tate equations in the above range of parameters have been calculated. A table of thermodynamic properties of the mixture is presented.     

Experimental determination of solid–liquid interfacial energy for succinonitrile solid solution in equilibrium with the succinonitrile–(D) camphor eutectic liquid

The equilibrated grain boundary groove shapes for Succinonitrile (SCN) solid solution in equilibrium with the Succinonitrile (SCN)–D Camphor (DC) eutectic liquid were directly observed. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficient and solid–liquid interface energy for SCN solid solution in equilibrium with the SCN–DC eutectic liquid has been determined to be (5.39 ± 0.27) × 10⁻⁸ K m and (7.88 ± 0.79) × 10⁻³ J m⁻² with present numerical method and Gibbs–Thomson equation, respectively. The grain boundary energy of SCN rich phase of the SCN–DC eutectic system has been determined to be (14.95 ± 1.79) × 10⁻³ J m⁻² from the observed grain boundary groove shapes. Thermal conductivity ratio of the liquid phase to the solid phase for SCN–0.16 mole % DC alloy has also been measured.     

Analytical solution of the problem on thermal slip of second order for molecular gases

Results obtained using exact analytical methods in the problem on thermal slip of second order for molecular gases with allowance for the rotational degrees of freedom of molecules have been presented. Numerical calculations of the thermal-slip coefficient for a number of molecular gases have been carried out. The dependence of the velocity of thermal slip of second order of a molecular gas on the Prandtl number has been shown. The found value of the coefficient of thermal slip of second order theoretically confirms the existence of negative (in the direction of the temperature gradient) thermophoresis for molecular gases. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 190–194, May–June, 2006.     

Influence of the laser-processing parameters on the adhesion strength of adhesive Fe-Cr-B-Si-system coatings

The influence of the laser-processing parameters on the adhesion strength of the Fe-Cr-B-Si-system coating has been investigated. The characteristics of a change in the adhesion strength of coatings, as well as in the amounts of iron borides as functions of the velocity of travel, diameter of a laser beam, and coefficient of overdropping have been studied. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 155–159, November–December, 2006.     

Development of Certain Aspects of the A. V. Luikov Heat- and Mass-Transfer Theory

It has been proposed that A. V. Luikov's system of heat- and mass-transfer equations be supplemented with balance differential equations of change in the temperature and degree of saturation of a medium with its motion in the material for an a priori unknown character of their change. The approach to determination of the relative coefficient of thermal diffusion, the criterion of phase transition, and the value of the Fo number for the beginning of the stage of a regular regime of a one- and two-dimensional plate and to evaluation of the notion of the “soft” and “hard” processes of drying has been refined. The method of allowance for the multidimensionality of a body has been developed. The practical absence of the influence of moisture exchange on heat exchange in drying has been proved. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 102–107, July–August, 2005.     

Unsteady 3D nonlinear Kutta-Joukovski condition for thin lifting surfaces

Considering unsteady potential flows, the fluid velocity regularity condition at a wake shedding edge – often referred to as the Kutta-Joukovski condition – has been clarified in the 2D nonlinear and 3D linearized cases only, and the usual nonlinear direct numerical approaches, as they are built on an already discretised view of the problem, skip over the theoretical question. A nonlinear Kutta-Joukovski condition is proposed here for unsteady 3D flows around thin airfoils, for which the body and its trailing-edge-shed wake are represented by double layers. The fluid velocity field, deriving from the potential function, is expressed using the two usual terms, relating to the edge of the sheet and its surface. Removing the singularity for the first term leads to the well-known condition for the potential jump across the shedding edge to be continuous from the body to the wake. For the second, works by Legras, for the steady case – and readily extendible to the unsteady one – exhibit its logarithmic singular behavior and allow to derive a regularity condition that deals with the surface gradient of the potential jump across the shedding edge. Lastly, implemented in a general non linearized situation, these conditions lead to an expression relating the geometric and doublets distribution characteristics of the two surfaces (wing and wake). Received 29 July 1997     

The normal and oblique impact of three types of wet granules

Impact tests against a hardened steel plate have been carried out to obtain the coefficient of restitution of three types of spherical granules. The dominant elastic γ-Al₂O₃, the elastic-plastic zeolite 4A and the dominant plastic sodium benzoate have been chosen as granule samples. An electromagnetic canon has been constructed to accelerate the granules and to measure the normal coefficient of restitution. The moisture content of the granules has been varied so that the pore saturation ranges between of S = 0–1. Thereby, the influence of the moisture content on the normal coefficient of restitution could be determined. A free fall apparatus, on which the impact angle is changeable in the range of Θ_A = 0–80°, has been used to investigate the tangential coefficient of restitution. A high speed digital camera has been used to record the events of impact and rebound. The record frequency of the camera has been varied between 4,000 and 8,000 frames per second.     

PTCR barium titanate ceramics obtained from oxalate-derived powders with varying crystallinity

Barium titanate powders with average crystallite sizes of 68–2000 nm have been prepared by the calcination of barium titanyl oxalate (BTO) at temperatures of 700–1150 °C. The morphology and recrystallization kinetics of the powders have been studied using the SEM and X-ray methods. Samples of PTCR (BaCaPb)TiO₃ ceramics have been made from these powders and their microstructure and electrical properties have been investigated. It has been found that the increase of the crystallinity of the starting powders suppresses recrystallization of the ceramics, leading to growth in resistivity and significantly influencing on the resistance jump and breakdown strength of the ceramics. An optimal temperature range for the calcination of BTO has been found to ensure maximum breakdown strength of the PTC thermistors with the resistance of 31 Ω. At this temperature range the barium titanate powders had crystallite sizes of ~200 nm.     

Refractive index of Al<Subscript>3</Subscript>C<Subscript>2</Subscript>B<Subscript>48</Subscript> aluminum borocarbide crystals

Aluminum borocarbide single crystals have been grown from an Al-based solution melt. The crystal lattice parameters have been determined, the dispersion of the refractive index in a 0.55–1.3 μm wavelength interval has been studied, and the temperature coefficient of the refractive index in a 300–600 K range has been measured. The crystals are characterized by a high refractive index in the visible spectral range in combination with at a high hardness, which makes them of interest for jewelry, as well as for both traditional and X-ray optics.     

Optical properties of TlInS2 layered single crystals near the absorption edge

The sample thickness effect on the optical properties of TlInS₂ layered crystals has been investigated at room temperature. The absorption coefficient of the samples calculated from the experimental transmittance and reflectance in the photon energy range of 1.10–3.10 eV has two absorption regions. The first is a long-wavelength region of 1.16–1.28 eV. The second region lies above 2.21 eV with a thickness-dependent indirect band gap. The energy gap decreases from 2.333 to 2.255 eV as the sample thickness increases from 27 to 66 μm. The differential spectra of absorption coefficient demonstrates the existence of a thickness-dependent impurity level being lowered from 2.360 to 2.307 eV as sample thickness increases from 27 to 66 μm.     

First-Principles Calculation of the Air–Water Second Virial Coefficient

Recent theoretical work has produced quantitatively accurate potential-energy surfaces for water with common gases. These pair potentials have been used to calculate second interaction virial coefficients with an accuracy superior to that obtained by most experiments. In this work, results for water–nitrogen, water–oxygen, and water–argon are combined to calculate an effective second virial coefficient for water with air. The results are in agreement with the existing experimental data, but they cover a wide range of temperatures while the experimental data extend only from 253 to 348 K. These results will be useful for humidity standards and other applications requiring thermodynamic properties of moist air.     

An automated setup for investigation of the thermal diffusion and mutual diffusion of gas mixtures

We present a block diagram of a setup for determining the thermal-diffusion factor and the coefficient of mutual diffusion of gas mixtures. The procedure of the experiment is described. Experimental results on the temperature and concentration dependence of α _t and D₁₂ for He-Ar and Ar-CO mixtures are given. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 1, pp. 182–188, January–February, 1998.     

Application of the parameter-expansion method to calculation of two-phase flows in channels with injection

Velocity and concentration distributions of the condensed phase have been obtained based on the parameter-expansion method. The characteristics of two-phase flows in channels with strong and weak injections have been investigated. The factors exerting an influence on the velocity of nonequilibrium phase motion have been determined; the range of applicability of the solution obtained has been established and its qualitative behavior has been elucidated; the possibility of applying such a solution to calculation of the concentration of the condensed phase has been shown. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 119–127, November–December, 2006.