Detection of interphase instability from luminescence of reaction products

The reaction between chlorine and an alkaline solution of hydrogen peroxide is suggested for the investigation of chemothermocapillary convection [1].Vitebsk Branch of the Institute of Solid State and Semiconductors Physics, Academy of Sciences of Belarus, Vitebsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 1, pp. 30–33, January, 1994.     

High-frequency sintering of multilayer ceramic capacitors

Results of sintering multilayer ceramic capacitors by a high-frequency field are presented. It is shown that half-finished multilayer ceramic capacitors subjected to a high-frequency field are sintered in 5–15 min instead of the several hours taken in the conventional method. Possibilities of using high-frequency fields for sintering ceramic materials and electronic products are discussed.Vitebsk Branch of the Institute of Solid State and Semiconductor Physics, Academy of Sciences of Belarus, Vitebsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 143–145, January–February, 1995.     

Effect of the concentration of zirconium dioxide on the fracture resistance of Al2O3-ZrO2 ceramics

We analyzed structural changes and physicomechanical properties of Al₂O₃-ZrO₂ ceramics as functions of the chemical composition of highly dispersed powders (synthesized by using plasmochemical methods based on the original technology) and sintering conditions. It was established that compositions with 10–15% wt. % ZrO₂ are characterized by the best physicomechanical properties and the highest fracture resistance. Ceramics with optimal structure were obtained by sintering powders at a temperature of 1700°C for two hours.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Institute of Inorganic Chemistry, Latvian Academy of Sciences, Riga, Latvia. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 5, pp. 52–57, September – October, 1995.     

Enhancement of the crack resistance of Si3N4−Y2O3 ceramics and its structural and metallurgical aspects

We experimentally establish quantitative characteristics of the influence of the technological procedure of sintering of Si₃N₄−10 wt % Y₂O₃ ceramic compositions on their mechanical properties, crack resistance, and micromechanisms of fracture. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv; Institute of Inorganic Chemistry, Latvian Academy of Sciences, Riga, Latvia. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 33, No. 3, pp. 65–71, May–June, 1997.     

Influence of thermal conductivity of a material on an unsteady heat removal parameter

In preparing [1] the authors additionally studied the influence of the thermophysical properties of a material on its unsteady breakdown. They found that the unsteady heat removal parameter d₀ depends logarithmically on the thermal conductivity.Institute for High Temperatures, Academy of Sciences of the USSR, Moscow. Institute for Development of Materials, Ukrainian Academy of Sciences, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 4, pp. 546–551, April, 1992.     

Relationship of the structural and physicomechanical characteristics in porous SHS materials based on titanium carbide

Structural and physicomechanical characteristics of the porous SHS materials TiC_stoich, TiC_0.9, and TiC_0.8 based on titatium carbide with a porosity of 55–58% are investigated. It is shown that as the combustion temperature increases, the compressive and breaking strength decreases monotonically and a smooth coarsening of the porous stucture occurs. Introduction of nickel into the carbide improves the strength and ductility of the porous SHS material. There is an optimum initial temperature (500–600°C) ensuring maximum strength when nickel is introduced.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Institute for Problems of Superductility of Metals, Russian Academy of Sciences, Ufa. Translated from Inzhenerno-Fizicheskii Zhurnal. Vol. 65, No. 4, pp. 466–470, October, 1993.     

The effect of a constant electric field on the combustion wave of self-propagating high-temperature synthesis. a model of a medium of interacting diffusion pairs

The study was carried out to investigate the effect of a constant electric field (CEF) on the parameters of the combustion wave of self-propagating high-temperature synthesis. A model of a medium that consists of interacting diffusion pairs is used. It is found that the combustion rate increases with an increase in the CEF (Joule heat is neglected); the combustion temperature remains unchanged under the action of the CEF. The possibility of experimental detection of the effect of a CEF is discussed. Institute of Engineering Acoustics, Academy of Sciences of Belarus, Vitebsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 5, pp. 790–794, September-October, 1997. Original article submitted September 22, 1994.     

Some features of the chemical transformation of a highly exothermic ore concentrate-based mixture in a combustion wave

Use of inexpensive ore concentrates as initial components in SHS metallurgy [1–3] brings about some specific features in the process and the properties of the materials obtained. Ore reagents contain a considerable amount of impurities (Al₂O₃, SiO₂, Fe₂O₃) that decrease the energetics of SHS systems and the temperature and the rate of combustion and create the limits of combustion and phase separation. In addition, the impurities participate in chemical reactions and enter the desired product. In many cases the presence of silicon, iron, and aluminum in a cast product does not prevent use of this product for practical purposes.Institute of Metallurgy, Academy of Sciences of the Republic of Georgia, Tbilisi. Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 613–616, November, 1993.     

Optical study of localization in theab-plane conductivity of single crystals of YBa2Cu3O6.95 induced by ion damage

We studied the changes in the dc resistivity, Raman scattering, and IR conductivity of single crystals of YBa₂Cu₃O_6.95 induced by damage from low-energy He⁺ ion bombardment. It appears thatT _c , transport properties, and optical conductivity are strongly affected by modest irradiation doses whereas the chemical composition of the sample is not modified. Carrier localization is evidenced by the frequency dependence of the optical conductivity in the strongly damaged crystal and is used to explain the suppression of both the superfluid density andT _c upon irradiation. The temperature dependence of the superfluid density is in agreement with the theoretical predictions for ad-wave superconductor. We also show that the intrinsic residual losses in the FIR are dramatically reduced in the disordered crystal.On leave from P. N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow, Russia.This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Institute for Advanced Research. One of us (A.P.) is grateful to the Ontario Center for Materials Research for financial support.     

Determination of quasistationary material surface destruction rate from linear entrainment measurements in the nonstationary regime

A method is proposed for determining the quasistationary linear entrainment rate396-1 and the nonstationary entrainment parameter d₀ from measurements of the thickness of the entrained layer during the nonstationary period of the destruction of the surface of a material.Institute of Problems in Material Science, Academy of Sciences of Ukraine. Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 4, pp. 552–554, April, 1992.     

Strength criteria for a solid body taking into account the size effect and the influence of the environment

We develop a procedure for the evaluation of the surface γ and interphase γ _m energy of deformed solid bodies subjected to atomic irradiation or placed in a liquid metal. The characteristic of the surfaces γ _m appears in the Griffith, Griffith-Orowan, Kamdar-Westwood, and Kontorova-Frenkel fracture mechanics criteria and their modifications for the case of the size strength effect. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 2, pp. 80–85, March–April, 1999.     

Thermal destruction of superconductivity of YBa2Cu307−x thin films under various conditions of heat removal

The volt-ampere characteristics of thin films of YBa₂Cu₃0_7–x with different heat removals from a specimen are experimentally determined. The influence of boiling of liquid nitrogen on the destruction dynamics of the superconducting state in thin HTSC-films loaded with the carrier current is investigated.Institute of Thermal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 64, No. 5, pp. 588–593, May, 1993.     

The Effect of Radiation on the Spatial Distribution of the Temperature of Subsonic Flows of Induction Plasma

Results are given of measurements of the temperature characteristics of subsonic flows of air and oxygen plasma, generated by a VGU-4 100-kW induction plasmatron developed at IPM RAN (Institute of Problems of Mechanics of the Russian Academy of Sciences). The values of absolute intensity of spectral lines of oxygen and nitrogen atoms are used to measure the average (over the plasma jet diameter) temperature of atomic level populations (hereinafter referred to as atomic temperature) as a function of the parameters of the mode of generation, namely, the gas pressure in the range from 25 to 200 GPa and the power of anode supply within 29–72 kW. The distributions of the atomic temperature of plasma (T _a ) along the jet are obtained for some modes of generation. The radial distributions of the atomic temperature are obtained for some modes of generation of air and oxygen plasma. Their comparison with the temperature profiles obtained by the calculation of flows of equilibrium plasma in a discharge channel reveals a divergence for values of temperature on the flow axis exceeding 8000 K.     

Influence of chemical nonequilibrium on the characteristics of power units operating on a chemically reactive gas

Flux parameter calculation features in the circuit of power units operating on a chemically-reactive N₂O₄ mixture are reviewed in this paper. It was observed that, contrary to chemically inert heat-transfer agents, a change in the state of a chemically-reactive gas under the influence of external action depends both on the total magnitude of the action and on its specific value. The effect of chemical reaction kinetics on the thermodynamic characteristics of similar type units has been qualitatively and quantitatively analyzed.Institute for Nuclear Power Engineering of Belarus Academy of Sciences, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 6, pp. 825–830, June, 1992.     

State of the art with plasma current interruptors

The state of research is considered for high-power pulse generators based on inductive energy stores and plasma interruptors. The main attention is given to plasma interruptors in which the low-resistance state lasts about 10^–6 sec. Basic features are indicated and characteristic components in the theory with an indication of problems in using the devices and particular examples of existing equipment.High-Current Electronics Institute, Siberian Division, USSR Academy of Sciences, Tomsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 5, pp. 720–722, May, 1992.     

On inversive maximal period polynomials over finite fields

Over finite field GF(q) withq a power of an odd primep, we characterize inversive maximal period polynomials in terms of polynomials of orderq + 1, and then we study some properties of polynomials of orderq + 1.This paper was written while the author was visiting the Institute of Information Processing, Austrian Academy of Sciences, AustriaThe author would like to thank the Institute of Information Processing, Austrian Academy of Sciences, Austria, for its hospitality and for using its facilities     

Heat transfer of HTSC-ceramic cooled by liquid hydrogen

An experimental investigation of heat transfer and crises of bubble and film boiling of hydrogen on the YBa₂Cu₃O₇ HTSC-ceramic is described. Heat transfer characteristics obtained at pressures from 17 to 100 kPa and heat flux densities from 0.1 to 120 kW/m² are compared with well-known results for hydrogen boiling on metal heaters.Physicotechnical Institute of Low Temperatures, Academy of Sciences of the Ukraine, Khar'kov. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 179–183, September–October, 1994.     

Fracture toughness anisotropy of partially stabilized ZrO2 crystals in the plane (001)

Partially stabilized ZrO₂ crystals doped with Tb₂O₃ exhibit fracture toughness anisotropy in the plane (001) in Vickers indentation. The anisotropy is determined over a range of loads that give rise to fully developed radial cracks around the indenter impression. Extensive lateral cracking and surface chipping obscure the observed anisotropy of fracture toughness at relatively high loads. Institute of Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 5, pp. 86–95, September–October, 1999.     

Measurement of vibrational temperatures in the working chamber of a technological electric-discharge CO2 laser

Results are given for the reconstruction, based on spectral distributions of the amplification factor of the active medium, of the progressive temperature and the upper laser level temperature in the working chamber of a 1.2-kV technological CO₂ laser. The obtained data on the temperature distribution in the zone of excitation of the medium enabled us to formulate requirements on organizing the process of laser energy removal and to assess the efficiency of the resonator devices used.Academic Scientific Complex A. V. Luikov Institute of Heat and Mass Transfer, Minsk. Institute of Flow Machines, Academy of Sciences of Poland, Gdansk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 281–286, September–October, 1994.     

Thermal model of local ultrasound heating of biological tissue

Possibilities of creation of controlled temperature fields in deep-seated biological tissue with the use of an endocavity ultrasound applicator with surface cooling are considered. Mathematical models are proposed and calculated that make it possible to construct acoustic and thermal fields in biotissues depending on the thermophysical and ultrasound characteristics of the medium being irradiated and to reveal situations and effects that are important for solving problems of practical medicine in the field of local ultrasound hyperthermia and thermotherapy of tissue. Kiev Polythechnical Institute, Kiev, Ukraine. Institute of Experimental Pathology, Oncology, and Radiobiology, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 779–784, September–October, 1996.