The states of condensed phase of two-component substances under laser heating

A self-similar problem, which has an exact analytical solution, is used as an example for analyzing possible states of the condensed phase of two-component materials under surface heating to temperatures in excess of the temperatures of phase transitions. It is demonstrated that the disruption of initially uniform distribution of concentration of components in the material, which is caused by non-congruent phase transitions, results in formation of a complex structure dependent on the thermal properties and consisting of alternating regions with different single-phase and two-phase states of material, namely, liquid-vapor, liquid, liquid-solid, and solid. All of these regions may exist in the condensed phase simultaneously.     

Necessary conditions of attainable superheating of the surface of nonvolatile condensed systems under intense heating

The values of heat flux and other parameters of the process of thermal destruction of nonvolatile condensed systems are determined, at which the temperature of the surface being heated reaches the upper limit of the phase state.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 928–937.Original Russian Text Copyright © 2004 by O. F. Shlenskii.     

Deposition of ZnO on the surface of Al metal particles by esterification reaction under solvothermal conditions

ZnO nanoparticles were synthesized by esterification reaction between zinc acetate and absolute ethanol under solvothermal conditions. The influences of reaction parameters and different surfactants on the size and morphology of synthesized ZnO nanoparticles were studied. As the application of this reaction, ZnO particles were deposited on the surface of Al particles using the same solvothermal process. The deposition reaction time and amount of reactants to the distribution density of deposited ZnO nanoparticles were studied. X-ray diffraction and transmission electron microscopy were used to characterize the synthesized ZnO nanoparticles and ZnO/Al composite particles.     

Heating of condensed particles in a gas flow

A solution is obtained for the heating of condensed particles in a gas flow, from which one derives an expression for the temperature reduction and rate of cooling of the gas.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 6, pp. 1050–1053, December, 1972.     

A model of bumping of dielectric liquids under laser heating of their surface

A theoretical investigation is performed of the evaporative mode of interaction between laser radiation and matter. It is demonstrated that a periodically explosive pattern of boiling is possible in dielectric liquids in the presence of free surface, if the depth of radiation absorption exceeds the size of the region of thermal diffusion. Analytical expressions are obtained for the period of bumping and for the size of surface layer destroyed by fluctuation vapor bubbles. Calculation is performed of the degree of attenuation of radiation intensity at the surface of liquid due to absorption of a part of radiation in the vapor-droplet mixture being formed.     

Reduction of fine polydisperse particles in a once-through reactor under conditions of gas suspension

The article presents the theoretical and experimental results of the process of reduction of a polydisperse system of particles for the quasisteady regime in a once-through reactor.Translated from Inzhenero-Fizicheskii Zhurnal, Vol. 58, No. 3, pp. 512–517, March, 1990.     

Calculation of the heating of polydisperse particles in a gas

The problem of the heating of polydisperse particles in a gas is solved with allowance for the temperature field inside a particle and the variation of the gas temperature.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 3, pp. 485–489, March, 1980.     

Nonstationary heating of two-dimensional metal nanoparticles by laser radiation

A numerical solution of the problem of nonstationary heating of a two-dimensional nanoparticle by laser radiation in the approximation of a constant temperature over the nanoparticle volume is presented. The asymptotes to the heating temperature for long times and for maximum heating of a nanoparticle at long durations of laser radiation have been obtained. It is shown that the temperatures of heating of silver and gold nanoparticles subjected to laser radiation at a resonance wavelength of plasmons are appreciable and may reach the boiling temperature of water. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 936–943, September–October, 2008.     

Carburization of iron surface induced by laser heating

The solid state carbon diffusion on an iron surface coated by graphite dag and heated by a continuous wave laser beam has been studied. Experimental values of the diffusion paths have been compared with those calculated by a mathematical model of the thermal cycle induced by laser heating. Case layers have been obtained of about 0.2 mm, with a bainitic structure.     

Engineering method of computing the radiation flux to a permeable surface under aerodynamic heating conditions

Formulas are proposed for the computation of the radiation heat transfer at the frontal point of an axisymmetric blunt body with a carbon-based destructible coating around which a hypersonic air stream flows.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 5, pp. 763–767, November, 1988.     

The concentration effect at nonisothermal nucleation under conditions of solid-solution heating

The influence of the heating rate of a solid solution up to the temperature of isothermal annealing on the distribution of CuCl particles by radii has been studied using the example of a solid solution of CuCl in glass. The study of changes in the distribution of particle radii in the CuCl phase has been performed using exciton-thermal analysis. It has been found that, with slow (60 min) heating of the sample to 650°C, the concentration of nucleates in the CuCl phase first increases rapidly and, then, the concentration decreases. The decrease in concentration is explained by the rapid growth of the critical radius with temperature and depletion of the solution. As follows from numerical simulation, the nucleation in a solution of CuCl in glass under conditions of slow heating is in good agreement with the experimental data.     

Chemical oxygen-iodine laser: aerooptics and gas dynamics

We have investigated the interaction of regular and irregular structures — systems of shock waves, rarefaction waves, and turbulent layers — in a chemical oxygen-iodine laser.     

Motion of particles through the interface of different-density metal specimens under the conditions of superdeep penetration

The parameters of motion of particles in a thin layer of material adjacent to the plane boundary of two semi-infinite specimens of different densities under the conditions of superdeep penetration are calculated on the basis of the hydrodynamic model. Results of the calculations are checked experimentally. The efficiency of superdeep penetration for different-density materials (aluminum, steel, copper) and their combinations is determined. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 5, pp. 1050–1055, September–October, 2000.     

Gas-phase ignition of a film of liquid condensed substance by a metal particle heated to high temperatures under mixed-convection conditions

The process of ignition of a mixture of air and a kerosene vapor by a steel wire heated to high temperatures has been modeled numerically. The investigations have been carried out on a model allowing for the combination of heat- and mass-transfer processes (evaporation of the flammable liquid, diffusion and convection of the fuel vapor in air, heat conduction, and oxidation of the fuel vapor in air). The values of the delay time of ignition of the vapor-gas mixture have been determined and the scale of influence of the initial temperature and dimensions of the wire, the distance between the heating source and the kerosene surface, and the temperature and humidity of air on the inertia of the ignition process have been established.     

The temperature field of a thin plate under conditions of monotonic heating

An approximate solution is given for the heat-conduction equation for the temperature field under conditions of monotonie heating. The solution is obtained by linearization according to the small parameter method.     

Investigation of thermomechanical responses in ultrafast laser heating of metal nanofilms

The present work uses two-temperature model and Cattaneo's constitutive model to study the thermomechanical responses and the size effect on energy transport during ultrafast laser heating of Au nanofilms. It is shown that the grain size effects on thermophysical properties, heat transport and thermal stresses are rather evident when the average grain diameter is less than the electron mean free path. The study on heat transport shows that there are two heat waves propagating in the lattice during nonequilibrium heating of films. It is found that the classical thermoelastic theory can not reveal the generation of the ultrafast thermal stresses during nonequilibrium heating; however, it can approximately describe the stress evolution in the stage of thermal equilibrium.     

Raising the fatigue strength of a construction by local laser heating

A method is proposed for raising the fatigue strength of a construction by inducing residual stresses by local heating with a high-power pulsed laser. Fatigue failure can be slowed or eliminated, as can the formation of fatigue defects, if a pattern of compressive residual stresses is produced in the most readily damaged zones. Experiments have been done on how laser heating affects the fatigue strengths of planar specimens and fatigue crack growth. Finite-element calculations have been used to examine the effects of the heating parameters on the residual stresses.Translated from Problemy Prochnosti, No. 4, pp. 10–17, April, 1995.     

The effect of flux density on the formation of temperature field in alumina under conditions of heating by concentrated laser radiation

A numerical investigation is performed of the effect of the density of a flux of heating concentrated radiation of CO₂ laser on the formation of temperature field in the process of heating and melting of a plane layer of alumina. A mathematical model of unsteady-state radiative-conductive heat transfer is used for considering the process of heating in rigorous formulation in view of the dependence of the thermophysical properties of the solid phase on temperature and of the optical properties—on temperature and wavelength, including the generalized approach to the problem of phase transition in melting in view of formation of an extended two-phase zone. In so doing, the evaporation from the melt surface is taken into account. The presented results relate to flux densities in the range from 200 to 3000 W/cm². It is demonstrated that the special features of formation of temperature fields are due both to the contribution of volumetric radiation and absorption of fluxes of outer and self-radiation and to the specific nature of alumina for which the absorption coefficients of melt and of solid phase in the energetically important spectral region may differ by as much as two orders of magnitude.     

Heat transfer mechanisms during short-duration laser heating of thin metal films

A perturbation technique is used to simplify the generalized governing equations of the parabolic two-step model. The generalized form of the two-step model contains diffusion terms in both electron and lattice energy equations and assumes that incident laser radiation is absorbed by both electron gas and solid lattice to account for the thermal behavior of semiconducting and impure materials. The simplified perturbation technique is used to eliminate the coupling between the electron and the lattice energy equations when the temperature difference between the electron and the lattice is a small perturbed quantity, which is true in materials exhibiting high coupling factors. A mathematical criterion is derived to determine the conditions under which electron and lattice are in thermal equilibrium. It is found that five dimensionless parameters control the state of thermal equilibrium between the lattice and the electron.