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We have studied the effect of the ratio of the macrocomponents of magnesium oxide- and yttrium oxide-based composite ceramics on their microstructure and optical and mechanical properties over the ...entire composition range. The ceramics were produced under identical conditions by hot-pressing nanopowders prepared by self-propagating high-temperature synthesis. The composition of the ceramics has been shown to have a significant effect on their optical transmission, average grain size, and density, whereas their microhardness is essentially independent of composition. Composite ceramics with a magnesium oxide to yttrium oxide volume ratio of 50 : 50 are optimal for most practical applications.
The isotope–geochronological and geochemical data on the age and composition of rocks of the Butugol Block, located in the eastern part of the Tuva–Mongolian microcontinent of the Central Asian ...Orogenic Belt, have been obtained. It has been established that the protolith for gneisses is, in one case, volcanic rocks with an age of 1009 ± 8 Ma, and in the other case, potassium meta-sedimentary rocks accumulated in continental marginal basins. The protolith of metavolcanogenic rocks of this complex were formed at the turn of the Mesoproterozoic and Neoproterozoic on the already formed crust, while the metasedimentary rocks were formed owing to the Mesoproterozoic, more rarely Paleoproterozoic and Archean, continental provenances. It has been established that the development of the Butugol metamorphic complex (Butugol Block) differs from the development of other blocks of the Earth’s crust included in the composite Tuva–Mongolian microcontinent.
•New governing equation for the hydrogen concentration dynamics in alloys.•Role of nonlinearities of different nature on the concentration wave.•Polarity of the input affects the localized wave of ...concentration.
New governing equation is obtained for nonlinear modeling of dynamics of hydrogen concentration in alloys. An influence of the nonlinear terms on the dynamics of hydrogen concentration is studied. A particular case is found when the governing equation admits exact kink-shaped traveling wave solution. Numerical simualtion reveals different influence of the nonlinear terms arising in the equation due to different physical reasons. Qualitatively different effects such as arising of the tail behind the localized wave and formation of the counterpart wave are found. An influence of the polarity of the input on behavior of the localized wave of concentration is described.
The objects of this study are petroleum road bitumen and polymeric bituminous binder for road surfaces obtained by polymer materials. The subject of the study is monitoring the polymer-bitumen binder ...quality changes as a result of varying the bitumen modification process. The purpose of the work is to identify the patterns of the modification process and build a mathematical model that provides the ability to calculate and select technological equipment. It is shown that the polymer-bitumen binder production with specified quality parameters can be ensured in apparatuses with agitators in turbulent mode without the colloidal mills use. Bitumen mix and modifying additives limiting indicators which can be used as restrictions in the form of mathematical model inequalities are defined. A mathematical model for the polymer-bitumen binder preparation has been developed and its adequacy has been confirmed.
The relation between microstructural and magnetic properties of thin obliquely deposited films has been studied by means of numerical techniques. Using our developed simulation code based on ...ballistic deposition model and Fourier space approach, we have investigated dependences of magnetometric tensor components and magnetic anisotropy parameters on the deposition angle of the films. A modified Netzelmann approach has been employed to study structural and magnetic parameters of an isolated column in the samples with tilted columnar microstructure. Reliability and validity of used numerical methods is confirmed by a good agreement of the calculation results with each other, as well as with our experimental data obtained by the ferromagnetic resonance measurements of obliquely deposited thin Ni80Fe20 films. The combination of these numerical methods can be used to design a magnetic film with a desirable value of uniaxial magnetic anisotropy and to extract the obliquely deposited film structure from only magnetic measurements.
•We present a simulation approach to study a relation between structural and magnetic properties of oblique films.•The calculated dependence of magnetic anisotropy on a deposition angle accords well with the experiment.•A modified Netzelmann approach is proposed.•It allows for the computation of magnetic and structural parameters of an isolated column.•Proposed approach can be used for theoretical studies and for characterization of oblique films.
The possibility of laser cutting plasma-sprayed refractory products made of aluminum oxide is investigated. An industrial laser complex KS-5VDM1-3 Navigator (VNITEP, Russia), equipped with an LS-3 ...ytterbium fiber laser with a power of 3 kW, is used in order to develop cutting conditions. It is established that immediately after completion of the plasma spraying process, article material phase composition is a collection of various modifications of aluminum oxide, and subsequent material heating leads to a series of polymorphic transformations accompanied by changes in item material volume and density. The process is complete when all aluminum oxide polymorphic modifications are transferred into the only stable phase α-Al
2
O
3
(corundum). It is shown that laser cutting of plasma-sprayed aluminum oxide products is only possible when transition of all its phase modifications to corundum is completed. In the opposite case, a sharp change in product material volume, due to polymorphic transformations occurring under conditions of a high temperature gradient that occurs during laser cutting, leads to product destruction. A plasma-sprayed article, whose material is entirely the α-modification of aluminum oxide (corundum), withstands high temperature gradients and is easily laser cut without destruction. Cutting technology of plasma-sprayed refractory products made of aluminum oxide is assimilated at the Scientific and Educational Center for the Implementation of Laser Technologies at Vladimir State University.
Abstract
The article is devoted to the analysis of the effect of laser surface modification on the hardness and wear resistance of steel SHX15SG used in the manufacture of roller screw mechanisms. ...Experiments on laser surface modification were performed on the Russian domestic SVAROG-1-5DR laser system. to get the maximum hardness value. When laser processing without melting the surface of steel SHX15SG, the laser radiation power should be in the region of 5 kW, which corresponds to the maximum power for the installation used. The speed of movement of the laser beam relative to the treated surface should be equal to 25 mm/s, and the focal length should be at least 60 mm. In the case of laser treatment with surface reflow, higher hardness values are obtained at a power of 2 kW. Increasing the power of laser radiation to 5 kW leads to a decrease in hardness. In this case, the speed value should be equal to 25 mm/s, and the focal length should be close to 85 mm. When the focal length is reduced to 60 mm, laser treatment no longer causes melting of the surface of the material under study.
The importance of jet noise for prospective supersonic transport (SST) in takeoff and climb modes dictates the need to develop methods for reducing jet noise and their subsequent validation in large- ...and full-scale tests. This paper presents the results of Russia’s first ground acoustic tests of a rectangular nozzle with a noise suppression system, installed on a subsonic aircraft engine to demonstrate the technology. The authors studied a rectangular beveled nozzle with an ejector and screens—elements of the SST airframe. The test results were compared for three nozzle geometries: a round nozzle corresponding to measurements for the original engine without modifications, a rectangular nozzle without screens, and a rectangular nozzle with screens. It was found that when the rectangular nozzle without screens is used, there two opposite effects occur: noise amplification compared to the round nozzle for angles of observation close to the jet axis, and noise attenuation at angles of observation close to the fan rotation plane. Installing screens increases noise up to 5 dB in the low-frequency region below 150 Hz and reduces noise by 2 dB for frequencies higher than 250 Hz. Estimation of community noise in the EPNL metric showed that this rectangular nozzle with the noise suppression system has the effect of reducing community noise in comparison with the baseline round nozzle.
Thin magnetic films with periodic surface topography are of special interest for microwave applications as their static and dynamic magnetic characteristics can be readily adjusted. In this paper, we ...explore the capabilities of a simple method for producing large-area periodically patterned films by creating regularly spaced grooves on a substrate using a diamond cutter. For 110-nm-thick films, it was found that the substrate-topography-induced magnetic anisotropy was inversely proportional to the pattern period, which in experimental samples varied from 5 to 20 μm. Based on the Netzelmann theory, analytical expressions for demagnetization tensor components were obtained, which accord well with the experimental data. The measurements of the natural ferromagnetic resonance spectra demonstrated that the increase of the topography-induced magnetic anisotropy with the decrease of the pattern period led to the increase of the resonance frequency from 0.65 to 1.86 GHz, and to a decrease of the linewidth and effective damping parameter.
•A simple technique to fabricate parallel microgrooves on substrates was used.•Grooved substrates transform the properties of permalloy films deposited on them.•The grooves period controls magnetic anisotropy and ferromagnetic resonance frequency.•The Netzelmann approach was used to calculate magnetic anisotropy of grooved films.•The grooves also control the magnetization damping parameter.
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