Shock induced melting of sapphire Ostrik, A; Nikolaev, D
Journal of physics. Conference series,
01/2022, Volume:
2154, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
The method for calculation the melting curves of crystalline bodies based on the Debye model of heat capacity and the Lindemann melting rule is proposed. Hugoniot shock adiabate, determined ...in dynamic experiments and thermophysical characteristics of the substance under normal conditions are used as input data. Mathematically, the calculation of the melting curveis reduced to the Cauchy problem for a system of ordinary differential equations. This system is solved numerically by the Runge-Kutta method. Using the proposed method, the melting curves of copper, silver, gold, and sapphire at high pressures are calculated. The results obtained for copper, silver and gold were compared with available calculated and experimental data to validate the method. Experiments on shock compression of transparent sapphire sampleswere performed, using a Mach-type cumulative explosive generators. Investigated pressure range (280-1350 GPa) covered a region of shock-induced melting. The temperature of shock front was registered by fast optical pyrometer together with shock velocity. Particle velocity andpressure were obtained by impedance matching technique. Satisfactory agreement of calculatedand experimental data on temperature of melting behind the shock wave front in sapphire was obtained.
The article describes a method for producing semi-finished products from a copper alloy of the Cu–Ni–Cr–Si system for electrical purposes through the radial-shear rolling (RSR). From the Cu–Ni–Cr–Si ...alloy by hot deformation, rods with a diameter of 20 mm were obtained, which were then heat treated with quenching and aging. A detailed analysis of the microstructure and properties (mechanical and electrical) of the obtained samples was carried out after RSR and after heat treatment (HT). After RSR, material hardening occurs due to shear deformations forming a gradient structure with grain sizes varying from 8.22 μm to 15.95 μm between the surface and the center of the rod. The microstructure and mechanical property analysis showed that after heat treatment, the alloy is thermally hardened due to the precipitation of Ni2Si and Cr3Si particles uniformly distributed in the sample volume in the form of fine inclusions with an average size of 0.56–0.65 μm. After heat treatment, the alloy enhanced its mechanical properties (ultimate tensile strength (UTS) ~ 700–750 MPa, yield strength (YS) ~ 557–606 MPa, and elongation between 17 and 22%) and its electrical conductivity of 45.17% IACS from the 30.52% IACS of the RSR material. The improved mechanical properties of the heat-treated material are due to the different strength contributions mainly coming from dislocations and precipitates. The electrical conductivity improvement after the heat treatment is related to the dislocation density reduction and the increase in grain boundary misorientation due to the recrystallization phenomenon giving rise to a lower number of boundaries but with a twinning character. Thus, the RSR method offers a new industrial alternative for the production of semi-finished products from a Cu–Ni–Cr–Si alloy in the form of rods with diameters ranging from 10 to 55 mm.
•Radial shear rolling can produce copper rods of different diameters at an industrial scale.•The thermomechanical process using radial shear rolling gives rise to a heterogeneous material.•Aging treatment after radial shear rolling produces a remarkable combination of strength, ductility, and electrical conductivity.•Dislocations annihilation and grain boundaries misorientation change help to improve the material electrical conductivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The response of a graphene-based humidity sensor is considered as a function of film structures. Analysis of the resistance changes due to water molecule adsorption on the graphene or multi-layer ...graphene (MLG) surface is performed for films with different structures and resistivities from hundreds of ohms/sq to hundreds of kilo-ohms/sq. The results revealed possible increase, decrease and non-monotonous behavior of resistance with changes in film structure. Adsorption of water molecules at grain boundary defects is assumed to lead to an increase in film resistivity due to the donor property of water and the p-type conductivity of graphene. Another type of conductive center with a higher capture cross-section is realized in the case of water molecule adsorption at edge defects in MLG films (the formation of conductive chains with ionic conductivity). If these chains form a continuous network the film resistivity decreases. The result of the competition between the opposite effects of the conductivity compensation and formation of the water-based conductive chains depends on the film structure and determines the response of humidity sensors. Sensor sensitivity is found to increase when only one type of defect determines water adsorption (edge defects or grain boundary defects).
The key feature of optically variable elements is the appearance and disappearance of high saturation colors during shooting under different angles. The accuracy of color saturation measurement ...algorithms is limited by the automatic white balance correction subsystem, which uncontrollably changes the color characteristics of the image from frame to frame. In this paper, the possibility of using a priori information about color consistency of the document area to compensate for distortion of the white balance is considered using examples of document owner monochrome photographs. The proposed method of color correction increases the contrast of color saturation between the unprotected areas of the photograph and the areas covered by visually variable image on the protective film. The method is tested on reference data obtained with a mobile device.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The present paper discusses methods and tools for solving problems in color perception, providing an objective description of what is seen in the act of vision. A number of illustrative examples of ...the task of specifying low-parameter spectral descriptions providing a formal connection between radiation spaces and sensor responses are addressed. These structures are called spectral models. These are described and explained using specific examples (with analysis of the advantages and disadvantages) of their principal variants and within-type modifications. Limitations to the physical optical characteristics of scenes recorded by sensors and variants of approximations to spectral descriptions of its elements are given, along with the appropriate motivations for developing these variants, ensuring the solvability of the reverse problem thus simplified but which in the general case has no solution. In the context of the requirements for spectral models, the challenges that arise in modeling the phenomena of color constancy, as well as in setting the task of calibrating cameras, are considered. The advantages of using Gaussian spectral models (both nonlinear and multiplicatively closed) in this are discussed in comparison with optimal linear models, and three of its modifications are described which expand the color gamut, as the original version does not reproduce colors in the magenta segment. In terms of the Gaussian model with transition to the optimizing properties of the von Mises model, a method for estimating the chromaticity of a source from the color pattern of internal reflections (interreflexes) in a set of differently colored folded samples is described and shown as a result of numerical experiments (using “real” spectral data). The text combines an analysis of theoretical positions with a discussion of the results of computer simulations and physical experiments.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The article of the methods for coordinates determination of the object coordinates are reviewed. The advantages of a passive method with the using of the direction finder are noted. The problems ...arising from the transmission of signals in the direction finder method are determined. The construction for the signal transmission of the fiber optic communication line is presented. It is established that the greatest influence on the error in determining the coordinates of the object by direction finder has a phase shift in the optical fiber during a change the temperature. The chart of the phase shift at the temperature for various cases of optical fiber placement are investigated. The obtained data of the experimental investigations are presented.
Computing-experimental method of verification of operability of composite porous package for protection of thin-walled constructions from non-stationary one-sided loadings is proposed. A set of ...explosive devices for generate loads of the required space-time distributions is described. Two new explosive devices for generation of low-pulse loads of microsecond duration with low difference in loading time at the surface of the tested composite constructions are considered. Time deformation profiles of glass-plastic cylindrical shell under low-impulse load of microsecond duration are given. It is received that use of wire or foil sensors for measurement of deformations give close results when the shell stage of deformation of glass-plastic thin-walled constructions is investigated.
The article examines the literary-critical and journalistic reception of I.S. Shmelev’s works in the USSR, along with the history of publication and interpretation of his works in the pre-war period. ...The subject of the analysis is the corpus of articles, essays, and reviews published in the newspapers “Pravda,” “Izvestiia,” “Literaturnaia Gazeta,” the journals “Pechat’ i Revoliutsiia,” “Krasnaia Nov,” “Prozhektor,” “Biulleten’ Knigi,” etc., collections of works by Shmelev, adstracts dedicated to him in the “Histories of Russian Literature” by V.L. Lvov- Rogachevsky, V.E. Evgeniev-Maksimov, B.V. Mikhailovsky, and others mentions of the writer’s name in the central Soviet press. Shmelev actively published until 1929, despite the writer’s anti-Soviet position in emigration. The negative reviews that began to appear in the USSR after the publication of the “Solntse Mertvykh” did not delete Shmelev’s name from the history of literature and the modern literary process. He was still considered one of the most significant Russian writers and even included in the study program of universities.
The article examines the American period of V.I. Ryndzyun's life and his work as an American writer and journalist. Vladimir Ryndzyun began publishing in Russia before the Revolution, and in the ...early 1920s he became famous under the pen-name “A. Vetlugin” thanks to publications in Russian émigré newspapers and books published in Paris and Berlin. He arrived in the USA in 1923 with Sergey Yesenin and Isadora Duncan and decided to stay there. He contributed to American journalism and American cinema as Voldemar Vetluguin, and to American literature as Frederick Van Ryn. In the fall of 1933, his essay “There's No Repealing Tastes”, signed with the pen-name Frederick Van Ryn was published in the first issue of Esquire magazine along with the works of Ernest Hemingway, John Dos Passos, Erskine Caldwell, etc. In 1934 he became an editor of RedBook Magazine as Voldemar Vetluguin. In 1936 he started to contribute in this pulp fiction magazine as Frederick Van Ryn as if he decided to separate his work as an editor and his literary works. Under the name of Frederick Van Ryn, he also collaborated with other magazines: a number of his publications appeared in the 1940s in Liberty; all of them have to do with cinema. His new pen-name made it possible for him to develop the author’s strategy in the USA, but in general it fits into the system of author’s masks / projections, which are typical for V.I. Rynzdyun’s / Voldemar Vetluguin’s works and self-fashioning.
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