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32 results on '"Khmyrov, Roman"'

1. Structure formation and thermal conduction in polymer-based composites obtained by fused filament fabrication

Author

Smirnov, Anton, Pinargote, Nestor Washington Solis, Khmyrov, Roman, Babushkin, Nikolai, Gridnev, Mikhail, Kuznetsova, Ekaterina, and Gusarov, Andrey

Subjects
Condensed Matter - Materials Science
Abstract

Fused filament fabrication (FFF) is widely used to obtain polymer-based composites with improved mechanical and thermal conduction properties. The effective properties of the composites are sensitive to its structure including the shape, distribution, and orientation of inclusions in the matrix and FFF-specific defects. The present work aims to study the formation of composite structure and relate it to the measured effective thermal conduction properties. Polymer flow in the hot end and the structure of printed samples are studied by metallography. The effective thermal diffusivity is measured by the laser flash method and analyzed by the Maxwell Garnett theory. Fibers in a polymer-matrix composite visualize polymer flow in the hot end of the FFF printer. In the nozzle, fibers are generally oriented parallel to the flow direction while gas bubbles may locally disturb flow and disorient fibers. Printed composite Carbon fiber/TPU inherits preferential orientation of fibers observed in the filament. Disorientation of fibers relative to the alignment direction increases after printing. In the printed Al2O3/PA composite, there is a lattice of triangle-based cylindrical pores parallel to the extrusion direction. Al2O3 particles are of irregular shape and approximately equiaxed. No segregation or agglomeration are observed. Significant anisotropy of thermal diffusivity is observed in the printed samples of 5%vol. Carbon fiber/TPU composite. The measured effective thermal diffusivity of printed Al2O3/PA composites is essentially isotropic and significantly increases with the volume fraction of inclusions. In the studied FFF-printed composites, the effective thermal diffusivity is proportional to the thermal diffusivity of polymer matrix, which is sensitive to its structure formed in non-equilibrium conditions of rapid quenching from liquid phase.

Published
2023

4. Study of the thermal diffusivity of a ceramic-polymer material based on polyamide with the inclusion of varishaped aluminum oxide, obtained by the FFF method.

Author

Smirnov, Anton, Khmyrov, Roman, Kuznetsova, Ekaterina, and Kurmysheva, Alexandra

Subjects
*THERMAL diffusivity, *THERMAL conductivity, *THERMAL properties, *POLYAMIDES, *ALUMINUM oxide
Abstract

The article is focused on studying Fused Filament Fabrication (FFF) of alumina-filled polymer objects and their thermal properties. To track influence of inclusion type on thermal diffusivity of 3D printed samples with equiaxed and needle-like Al2O3 particles were made. The difference between the microstructure of needle and equiaxed compositions was evaluated using Phenom G2Pro (Phenom-World BV, Eindhoven, The Netherlands). The tests of thermal diffusivity were carried out on LFA 467 HT HyperFlash setup (NETZSCH Inc., Germany). It was found that the addition of 20 vol. % of ceramic particles in polyamide (PA12) increases its thermal conductivity, and the shape and location of inclusions play an important role in heat flow processes. It is shown that specimens with alumina needle-like inclusions demonstrated the highest values of thermal diffusivity. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Correction: Smirnov et al. Experimental and Statistical Modeling for Effect of Nozzle Diameter, Filling Pattern, and Layer Height of FDM-Printed Ceramic–Polymer Green Body on Biaxial Flexural Strength of Sintered Alumina Ceramic. J. Compos. Sci. 2023, 7, 381

Author

Smirnov, Anton, primary, Nikitin, Nikita, additional, Peretyagin, Pavel, additional, Khmyrov, Roman, additional, Kuznetsova, Ekaterina, additional, and Solis Pinargote, Nestor Washington, additional

Published
2024
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10. Phase Composition, Microstructure and Mechanical Properties of Zr 57 Cu 15 Ni 10 Nb 5 Alloy Obtained by Selective Laser Melting.

Author

Khmyrov, Roman S., Korotkov, Andrey, Gridnev, Mikhail, Podrabinnik, Pavel, Tarasova, Tatiana V., and Gusarov, Andrey V.

Subjects
SELECTIVE laser melting, COPPER, METALLIC glasses, MICROSTRUCTURE, ALLOYS, WEAR resistance
Abstract

Zr57Cu15Ni10Nb5 (more known as Vit-106) is a promising zirconium-based alloy with a high glass-forming ability, and belongs to the so-called bulk metallic glasses (BMG). Workpieces with a size of around one centimeter in all three dimensions can be obtained from a BMG alloy by casting. However, further increasing the cast size decreases the cooling rate and thus induces crystallization. Selective laser melting (SLM) is a well-known technique to overcome size limitations for BMGs because a workpiece is built by the addition of multiple melt portions in which the cooling rate is kept above the critical one. Currently, BMG parts obtained by SLM suffer from partial crystallization. The present work studies the influence of SLM process parameters on the partial crystallization of Vit-106 by metallography and the influence of the microstructure on mechanical properties by microhardness and wear resistance testing. Submicron crystalline inclusions are observed in an amorphous matrix of a Vit-106 alloy obtained by SLM. The size and the concentration of the inclusions can be controlled by varying the laser scanning speed. It is shown that submicron crystalline inclusions formed in the amorphous matrix during SLM can favorably affect microhardness and wear resistance. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Granulation of Silicon Nitride Powders by Spray Drying: A Review

Author

Grigoriev, Sergey N., primary, Soe, Thet Naing, additional, Malakhinsky, Alexander, additional, Makhadilov, Islamutdin, additional, Romanov, Vadim, additional, Kuznetsova, Ekaterina, additional, Smirnov, Anton, additional, Podrabinnik, Pavel, additional, Khmyrov, Roman, additional, Solís Pinargote, Nestor Washington, additional, and Kurmysheva, Alexandra Yu., additional

Published
2022
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21. Development of Al2O3 and PLA ceramic-polymer filament for 3D printing by fused deposition modelling method.

Author

Smirnov, Anton, Podrabinnik, Pavel A., Babushkin, Nikolay N., Kuznetsova, Ekaterina V., Pristinskiy, Yuri O., and Khmyrov, Roman S.

Subjects
FUSED deposition modeling, THREE-dimensional printing, POLYLACTIC acid, ALUMINUM oxide, FIBERS, DISTILLED water
Abstract

The authors discuss the process of ceramic-polymer filament obtaining based on aluminum oxide (Al2O3) and polylactide (PLA) for its use in 3D printing technology by fused deposition modeling method (FDM). They consider ceramic polymer compositions with the following component ratio: 30% PLA and 70% Al2O3; 40% PLA and 60% Al2O3; 50% PLA and 50% Al2O3. The compositions were obtained by the colloidal method on a ball mill in distilled water, followed by drying in a vacuum oven and sieving. The microstructure and elemental composition of the mixtures have been studied. The modes of extrusion of the obtained ceramic-polymer compositions are selected. The most advantageous composition of a ceramic-polymer mixture of 40% PLA and 60% Al2O3 has been determined for further use in creating three-dimensional objects by FDM. Experimental samples of products from the produced ceramic-polymer filament were printed. [ABSTRACT FROM AUTHOR]

Published
2022
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22. Influence of the conditions of selective laser melting on evaporation

Author

Khmyrov Roman S., Protasov Cyrill E., and Gusarov Andrey V.

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

The paper presents the results of optical diagnostics of evaporation and displacement of powder fractions during the formation of a single track in the process of selective laser melting. The velocity of the powder fractions is estimated. It was defined, that an increase in the scanning speed leads to an decrease in the particle coming out rate from the molten pool and the rate at which they are attracted. The results allow evaluating the kinetics of the mass-transfer process during selective laser melting. It was clearly shown the material quality properties after the selective laser melting are strongly influenced by the formed thermal field in the laser-irradiated zone.

Published
2018
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30. Interferometry of Gas-Phase Flows during Selective Laser Melting.

Author

Podrabinnik, Pavel A., Shtanko, Alexander E., Khmyrov, Roman S., Korotkov, Andrey D., and Gusarov, Andrey V.

Subjects
LASER interferometry, HIGH power lasers, INTERFEROMETRY, LASERS, LASER beams, RADIATION absorption
Abstract

Gas-phase flows occurring in a plume in a processing zone during selective laser melting (SLM) can significantly affect the quality of the process. To further enhance SLM performance, the characteristics of the flows should be considered. In this article, the vapor-gas jet emerging from the laser processing zone was studied. It was visualized by interferometry to evaluate flow velocity, geometry and changes in refractory index depending on laser power. The velocity and pressure fields of the vapor jet and the entrained ambient gas were estimated by mathematical modeling. It was shown that the increase of laser power led to higher jet velocity and greater change in its refractory index. The latter also was used to evaluate the content of metal vapor in the plume and its influence on the absorption of laser radiation. [ABSTRACT FROM AUTHOR]

Published
2020
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