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2018 год

Gusarov A.V.

Journal of Heat Transfer


Foams, three-dimensional (3D)-printed cellular and honeycomb structures, and very oblate particles dispersed in a matrix are the examples of heterogeneous media with thin-wall morphology. Phase boundaries can also be considered by this approach. Statistical description is proposed to estimate the effective radiative properties of such media. Three orientation models are studied: (i) isotropic, (ii) surface elements parallel to a plane, and (iii) surface elements parallel to an axis. Radiative transfer equations (RTEs) are obtained and analyzed in the framework of the homogeneous phase approach (HPA) and the multiphase approach (MPA). Analytical expressions are obtained for the absorption, extinction, and scattering coefficients, the scattering phase function, and the radiative thermal conductivity for very oblate particles dispersed in an absorbing scattering matrix. The reflective properties of the platelets and their preferential orientation can be used to optimize the radiative thermal conductivity.


A.V. Gusarov, S.N. Grigoriev, M.A. Volosova, Y.A. Melnik, A. Laskin, D.V. Kotoban, A.A. Okunkova

Journal of Materials Processing Technology


One of the most perspective methods of additive manufacturing is selective laser melting. It allows producing the parts directly from 3D-model to 3D-object from metallic powders and alloys. Nowadays the method has very low productivity, which limits its extensive use and possible application to solve a modern design problem by introducing direct and fast metal production. The solution of its productivity would allow receiving metallic 3D-objects with complex geometry in short production period.

The method was improved by the installation of laser beam profiling and online monitoring systems on the developed experimental setup. The profiler contributes to obtaining the alternative power density distributions of the laser beam. The CoCrMo powder was chosen because of its excellent melting qualities, and the initial powder was pre-treated with the purpose to get the diameter of the particles less than 20 μm. During the experiments, 3D-samples were obtained by the improved method of selective laser melting with parameters of two process windows for each of the laser beam spot. The 3D-samples were studied for the revelation of common material defects of the microstructure.

The chemicalanalyses of the samples were implemented by scanning electronic microscopy. The analyses showed that the samples of each laser beam spot had defects related to the formation of a solid solution. Application of Inverse Gaussian laser beam spot into the SLM-machine for production of 3D-objects allows producing the pieces with the values of the parameters exceeding the value for Gaussian laser beam spot in several times. The typically recommended parameters for production of the piece on the modern SLM-machine are less than 100 W for laser source power and less than 30 mm/s for scanning speed. The analytical data, presented in the article demonstrated the field of process parameters, which can give a possibility to obtain 3D-object with the parameters up to 1 kW for laser source power and up to 0.3 m/s for scanning speed. The analyses of microstructure give a possibility to conclude about no visible difference between the formation of the objects with different laser beam spots. The online video-monitoring shows that with the application of laser beam profiling system the negative effects of the selective laser melting reduces visibly.

I. Zhirnov, D.V. Kotoban, A.V. Gusarov

Applied Physics A


Selective laser melting is the method for 3D printing from metals. A solid part is built from powder layer-by-layer. A continuum-wave laser beam scans every powder layer to fuse powder. The process is studied with a high-speed CCD camera at the frame rate of 104 fps and the resolution up to 5 µm per pixel. Heat transfer and evaporation in the laser-interaction zone are numerically modeled. Droplets are ejected from the melt pool in the direction around the normal to the melt surface and the powder particles move in the horizontal plane toward the melt pool. A vapor jet is observed in the direction of the normal to the melt surface. The velocities of the droplets, the powder particles, and the jet flow and the mass loss due to evaporation are measured. The gas flow around the vapor jet is calculated by Landau’s model of submerged jet. The measured velocities of vapor, droplets, and powder particles correlate with the calculated flow field. The obtained results show the importance of evaporation and the flow of the vapor and the ambient gas. These gas-dynamic phenomena can explain the formation of the denudated zones and the instability at high-energy input.

system the negative effects of the selective laser melting reduces visibly.

Tarasova T.V., Gvozdeva G.O., Stefen Nowotny, Ableyeva R.R., Dolzhikova E.Yu.

ARPN Journal of Engineering and Applied Sciences. 2018. Vol.3. №4. Р. 1438-1442.


The laser build-up cladding is a well-known technique for repair, coatings and additive manufacturing tasks. Modern equipment for the laser cladding enables material to be deposited with the lateral resolution of about 100 μm and to manufacture miniature precise parts. However, the micro cladding regimes are unknown. Determination of these regimes is an expensive task as a well-known relation between laser cladding parameters and melt pool dimensions are changing by technology micro-miniaturization. These relations cannot be more used for the laser micro cladding parameters determination. In this paper the formation of single clad track on a Al-alloy substrate by coaxial laser micro cladding using Yb: YAG continuous laser was studied both from a theoretical and experimental point of view. The theoretical analysis concentrated on the laser beam energy transfer using a simple model of heat transfer to the substrate. This approach provides laser micro cladding parameter values required for the formation of desired width clad track to be predicted. For an appropriate experimental analysis of the main process parameters involved, a method based on a gradual change of a single processing parameter was examined. Correlations between the main micro cladding parameters and geometrical characteristics of a single clad track have been found.

Tarasova T. V., Gvozdeva G.O., Ableyeva R. R.

 MATEC Web of Conferences. 2018. Vol.224. P. 1-6.


The laser build-up cladding is a well-known technique for additive manufacturing tasks. Modern equipment for the laser cladding enables material to be deposited with the lateral resolution of about 100 μm and to manufacture miniature parts. In this paper the laser micro cladding process was investigated to produce miniature thin-wall parts of Al-based composites. Thin walls formation process by subsequent single tracks overlapping with vertical increment was investigated. The influence of the cladding parameters on the minimal width and the quality of the fabricated thin walls was examined. The thin walls with the minimal width of 140 μm and surface roughness Ra 1,5 μm were generated. Laser micro cladding potential to manufacture lattice-shaped structures of Al-Si composites was shown. Fabricated thin-wall structures can have application in different fields e.g. aviation, automotive and tooling industries.

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