An approach of direct bonding of SiC wafers of differing polytypes has been implemented in order to create a template for cubic 3C-SiC homo epitaxy. Hetero epitaxial 3C-SiC layers grown by chemical vapor deposition were transferred onto a hexagonal 6H-SiC wafer. The results of structural characterization showed that the quality of 3C-SiC sublimation epitaxy on the templates is comparable to the level of epitaxy of cubic silicon carbide by chemical vapor deposition method. It was confirmed that the 3C-SiC layer transferred onto the 6H-SiC substrate plays the role of a crystalline “seed” that determines cubic polytype of the overgrown SiC layer.

The mechanism of structure transformation in Cr/4H-SiC UV photodetectors, which is responsible for the cyclic gettering of radiation defects, under repeated proton irradiation, is proposed in this work.

The mechanism of structure transformation in Cr/4H–SiC UV photo detectors, which is responsi-ble for the cyclic gettering of radiation defects, under repeated proton irradiation, is proposed in this work.

The uneven heating of the bed is the main reason for changing the angular position of the grinding wheels in double-sided face grinders, which leads to an increase in the machining error. The nodes of the face grinder when idling and when working under a thermal load are heated differently. The ends of the spindle heads and the bed have the highest temperatures when the machine tool is idling. Parts of the frame and the ends of the spindle heads facing the grinding zone have the greatest heating when working under thermal load. The least heated are the end walls and the lower part of the frame. These features of the thermal behavior of the machine tool structure made it possible to consider some measures to improve the thermal characteristics of the machine tool, which can lead to a decrease in the thermal deformations of the machine tool. Four schemes for the redistribution of heat fluxes were implemented. The implementation of the first three schemes under thermal load did not reveal significant changes in thermal characteristics. The implementation of the fourth scheme made it possible to reduce changes in the angular position of the grinding wheels.

Abstract. The results of the effect of irradiation with Ar ions on the structural, electrophysical and optical characteristics of the ultraviolet Cr/4H-SiC photodetectors in the spectral range of 200−400 nm are presented. After a single irradiation with 53MeV Ar ions with a fluence of 1 · 1010 cm−2, the quantum efficiency of the photodetectors practically remained at the level of the initial samples due to the "gettering effect“ of simple radiation defects by cluster formations. The observed effect promoted a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a consequence, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After repeated irradiation of the photodetectors with Ar ions with a total fluence of 2 · 1010 cm−2, the decay of clusters was observed, the formation of a significant number of simple defect centers, which led to a decrease in the lifetime of current carriers and, as a consequence, to a decrease in photoconductivity of Cr/4H-SiC photodetectors.

The paper presents a technique for numerical simulation of the thermal deformation behavior of the load-bearing system of a double-sided face grinder using the Ansys. The machine tool is considered in two modes of its operation: at idle and working strokes. Spindle bearings, heat fluxes from cutting fluid, heat fluxes from main engines are presented as the main heat sources. Basic data for convective and heat fluxes were taken according to the methods used in the calculations of machine tools. To obtain adequate models, the values ​​of heat and convective fluxes were refined from experimental data for temperatures and temperature displacements. Convective heat transfer in the thermal model of the machine tool was set for 450 surfaces. Heat fluxes were specified for 161 surfaces. The simulation of the thermal behavior of the machine tool was carried out for 6 h of its operation in the Ansys. The ten-node Solid227 element was used as a typical finite element. The problem of thermoelasticity was solved in a coupled formulation. The error in calculating thermal characteristics did not exceed 0.5 ℃, the error in calculating temperature displacements did not exceed 5 µm. The results of computer simulation confirmed the experimental relationships characteristic of this group of machine tools in the positions of the left and right grinding wheel. At idle, the mutual position of the grinding wheels can be attributed to the type of deformation as “below is wider”. On the working stroke, this deformation state can be represented as “below is narrowly”.

The paper presents a method for predicting the thermal characteristics of machine tools using a feedforward neural network. The method was based on the results of full-scale and computational tests. Experimental modal analysis is a feature of the proposed mathematical description of the thermal behavior model of the machine tool. This made it possible to use an analytical description for the thermal characteristics of the machine tool and analytically link the values of the input vector and the predicted values of the thermal characteristics. The conducted research on predicting the thermal characteristics of machine tools using neural networks revealed the multivariance of the predictive characteristics. To select one solution, it was proposed to use two criteria for the discrepancy between the predicted and calculated values of thermal characteristics. The results of the machine experiment are presented for four variants of the varied parameters of the mathematical model. The use of a feedforward neural network to predict the thermal characteristics of machine tools has shown high efficiency in reducing the duration of a full-scale experiment.

An approach of direct bonding of SiC wafers of differing polytypes has been implemented in order to create a template for cubic 3C-SiC homoepitaxy. Heteroepitaxial 3C-SiC layers grown by chemical vapor deposition were transferred onto a hexagonal 6H-SiC wafer. The results of structural characterization showed that the quality of 3C-SiC sublimation epitaxy on the templates is comparable to the level of epitaxy of cubic silicon carbide by chemical vapor deposition method. It was confirmed that the 3С-SiC layer transferred onto the 6H-SiC substrate plays the role of a crystalline "seed" that determines cubic polytype of the overgrown SiC layer.

The results of the effect of irradiation with Ar ions on the structural, electrophysical, and optical characteristics of ultraviolet Cr/4H-SiC photodetectors in the spectral range 200 to 400 nm are presented. After a single irradiation with Ar ions with an energy of 53 MeV with a fluence of 1 × 1010 cm–2 the values of the quantum efficiency of photodetectors practically remain at the level of the initial samples due to the “gettering effect” of simple radiation defects by cluster formations. This effect contributes to a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a result, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After the repeated irradiation of photodetectors with Ar ions with a total fluence of 2 × 1010 cm–2 the decay of clusters and the formation of a significant number of simple defect centers are observed, which lead to a decrease in the lifetime of the current carriers and photoconductivity of Cr/4H-SiC detectors.

Abstract. The results of the effect of irradiation with Ar ions on the structural, electrophysical and optical characteristics of the ultraviolet Cr/4H-SiC photodetectors in the spectral range of 200−400 nm are presented. After a single irradiation with 53MeV Ar ions with a fluence of 1 · 1010 cm−2, the quantum efficiency of the photodetectors practically remained at the level of the initial samples due to the "gettering effect“ of simple radiation defects by cluster formations. The observed effect promoted a decrease in the number of simple radiation defects of the vacancy type, an increase in the lifetime of current carriers, and, as a consequence, unchanged values of the photoconductivity of Cr/4H-SiC photodetectors. After repeated irradiation of the photodetectors with Ar ions with a total fluence of 2 · 1010 cm−2, the decay of clusters was observed, the formation of a significant number of simple defect centers, which led to a decrease in the lifetime of current carriers and, as a consequence, to a decrease in photoconductivity of Cr/4H-SiC photodetectors.

Heavily doped 3C-SiC films based on semi-insulating 6H-SiC substrates were obtained by sublimation epitaxy. The structural perfection of the obtained samples was monitored by X-ray diffractometry. The measurements of the photoluminescence and Hall effect spectra have confirmed the rather high perfection of the obtained epitaxial layers.

The paper presents a description of the experimental thermal characteristics of a double-sided face grinding machine. Thermal characteristics in the form of time dependences of temperatures and displacements were obtained when the machine was idling, as well as under load. The analysis of experimental studies showed that for a face grinding machine, the thermal characteristics differ significantly at idle and when operating under thermal load. First of all, this is due to different heating of the machine components during idling and when operating under thermal load. It was experimentally found that the highest temperatures during idling are at the faces of the spindle heads and the bed. When working under a thermal load, the greatest heating was recorded for structural elements of the bed located near the fence of the grinding zone, as well as for the faces of the spindle heads facing the grinding zone. The design features of the machine led to a significant difference in the magnitude of the thermal displacements of the right and left grinding wheels. The grinding wheels moved in the direction “wider at the bottom” under the influence of thermal deformations when the machine was idling. When working under heat load, the relative position of the grinding wheels gradually changed from “it is wider at the bottom” to “it is narrower at the bottom.” Changing the position of the grinding wheels led to distortions in the relative position of the grinded faces of the workpiece on the machine.

The aim of the study was to develop a methodology for measuring the structural and geometric parameters of a straight bull-nose cutter. To test the effectiveness of the developed methodology for measuring the structural and geometric parameters of the cutter, a full-scale experiment was conducted. During the experiment, all the structural and geometric parameters of the straight bull-nose cutter were measured using handheld measuring tools and a coordinate measuring machine Wenzel XOrbit 55 (Germany). A comparative analysis of the results of measurements using a universal handheld measuring tool and coordinate measuring machine showed: all the geometrical parameters of the cutter can only be measured using a coordinate measuring machine; the results of measuring geometric parameters using a universal handheld measuring tool do not allow making unambiguous organizational decisions on the further operation of the cutting tool, since the measurement error is comparable with the current size tolerances; however, for such design parameters as length, height, width of the cutter due to large tolerances, the use of a universal handheld tool is sufficient. The practice of measurements using a coordinate measuring machine has shown that, when conducting critical measurements, the use of coordinate measuring machines is not only accurate, but also more productive in comparison with the use of handheld measuring tools.

Heavily doped 3C-SiC films based on semi-insulating 6H-SiC substrates were obtained by sublimation epitaxy. The structural perfection of the obtained samples was monitored by X-ray diffractometry. The measurements of the photoluminescence and Hall effect spectra have confirmed the rather high perfection of the obtained epitaxial layers.

In this paper, modal analysis is proposed to building simulation models of thermal processes in machine tools. The technique of building simulation models in Simulink in three ways is described. The first way of modeling uses an analytical solution of the thermal conductivity equation. The second way of modeling uses built-in tools for solving differential equations. The third way of modeling uses the apparatus of transfer functions. An analysis of the structures of the generated simulation models was carried out to solve two typical tasks: building the thermal characteristics of the machine tool under zero and nonzero initial conditions. The first way to build simulation models, based on the use of analytical solutions of the thermal conductivity equation, allows you to build the most compact simulation models of the running machine tools. A feature of building invariant S-models is the formation of modeling parameters in Matlab M-file. For multimodal thermal characteristics of machine tools based on experimental modal analysis, a new algorithm for building them under nonzero initial conditions is proposed. It is based on the redistribution between several modes of the thermal displacement level formed in a previous section of the machine diagrammatic work. From full-scale and computational experiments, it was shown that this uniquely made it possible to increase the accuracy of prediction.

Abstract The paper presents the results of a study of the effect of irradiation with heavy Ar ions on the structural and optical characteristics of 4H-SiC. It has been shown that as a result of already single irradiation with Ar ions with an energy of 53 MeV with a fluence of 1٠1010 cm-2, at least 2 powerful local regions with negative deformation prevail in the structure of silicon carbide. Along with this, a region with positive deformation is also observed in the structure. The formation of localized clusters with negative and positive deformations, along with the undisturbed matrix, is accompanied by the formation of linear type defects that partially relieve stresses in the structure. It is assumed that the resulting complex defect structure upon irradiation with Ar ions provides the effect of gettering of point defects and leads to the quantum efficiency of 4H-SiC UV photodetectors at the level of the initial samples.

Coordinate measuring machines make it possible to measure the geometric parameters of precision parts, the measuring of which is not feasible with a universal hand tool. The purpose of the study was to develop a methodology for measuring the design and geometric parameters of a straight bull-nose turning tool. To test the effectiveness of the developed methodology for measuring the design and geometric parameters of the cutting tool, a full-scale experiment was conducted. During the experiment, the measurement of all the structural and geometric parameters of the cutting was carried out using hand-held measuring tools and the Wenzel XOrbit 55 coordinate measuring machine. A comparative analysis of the results of the measurements showed the folowing: all the geometric parameters of the cutting can only be measured using a coordinate measuring machine; geometric parameters measurements using a universal hand tool do not allow you to make unambiguous organizational decisions on the further operation of the cutting tool, since the measurement error is comparable to the current size tolerances, however, for such design parameters as length, height, and width of the cutting, due to the large tolerances, it is sufficient to use a universal hand measuring tool. The measurement practice using a coordinate measuring machine has shown that when performing critical measurements, the use of coordinate measuring machines, in manual mode, is not only accurate, but also more productive in comparison with a universal hand measuring tools.

The paper presents the original design of a special tap for cutting precise threads. Distinctive design features of the tap are: the presence of the rear threaded guide, which together with the copier threaded sleeve of appliance perceives the axial forces and provides the tap axial feed strictly corresponding to the step of the thread being cut, excluding its breaking under the action of axial forces; the presence of a smooth front guide part with the direction on the cut hole, to reduce the influence of radial forces that lead to an increase in the diameter of the thread due to the radial vibrations of the tap; the presence of the chamfer that implements the most technological cutting scheme such as flank infeed. A prototype of a special tap made on a turning and milling machine tool is presented, confirming the manufacturability of the proposed tool design. Research conducted in the field of engineering analysis with the CAE-system Ansys showed a significant increase in structural rigidity, as well as a significant increase in natural frequencies.

The article presents new technical solutions aimed at improving the performance of the installation for the molding of wood-concrete slabs. Calculation and design of rotary wheel racks which provide movement of installation in two mutually perpendicular directions is made; the proportioning bunker; conveyor that distributes and discharges the ready mortar into the formwork with two pneumatic cylinders; frames of plate forming installation. The study of the frames of plate forming installation, proportioning bunker and conveyor. Engineering analysis was carried out in CAE system ANSYS. Engineering analysis included five types of calculations: calculation of stiffness with rigid and elastic grip conditions, modal analysis, dynamic calculation, thermal and thermal-deformation calculations. The obtained results of the engineering analysis allowed us to conclude that the deformation of the frames is insignificant, that is, their rigidity provides the required accuracy of the manufacture of plates and the accuracy of the position of the proportioning bunker relative to the conveyors. The carried out measures on modernization of plate forming installation provided increase in productivity approximately in 2 times.

Results of an epitaxial growth of 3C-SiC epilayers on hexagonal 6H-SiC, 4H-SiC substrates are described. The study of the obtained epitaxial layers grown on 6H substrates was made by photoluminescence and optical microscopy. Also, an image analysis of the interface of 3C-SiC epitaxial layers with 6H, 4H, and 15R substrates obtained by Transmission Electron Microscopy (TEM) are presented. Difference between the layers on the Si and C faces are discussed.