Wear resistance of polycrystalline diamond cutters for drill bits

In the present work, the wear resistance of GES 1313 polycrystalline diamond (PCD) cutters (produced by E6), which are cylindrical in form (diameter 13.44 mm, height 13 mm), in turning granite and abrasive wheels at different speeds is investigated. The optimal cutting speed is determined, and comparative data are obtained for the cutting of Mansurovsk granite and 64C (SiC) abrasive wheels, so as to develop recommendations regarding the test conditions for PCD cutters. The wear resistance is characterized in two ways: as the ratio of the loss of volume of the diamond layer to the volume of machined material removed (when it is a dimensionless number); or by the quantity of machined material removed with a fixed degree of cutter wear (when it is expressed in cm³ with respect to 1-mm wear of the rear surface). In cutting granite, the cutting speed varies from 80 to 320 m/min; in cutting abrasive wheels, the cutting speed is 500 m/min. To calculate the volume of the PCD cutters, 3D models of the worn sections are constructed by means of Kompas 3D software, and a calibration curve for determining the volume of material removed by wear at the rear surface of the PCD cutters is plotted. The cutting angle is–22°. The change in volume of the worn section of the PCD cutter with change in the cutting angle from–20 to–25° is less than the measuring precision of the wear area up to 0.8-mm blunting. Increase in speed from 80 to 160 m/min in cutting granite reduces the wear resistance of the PCD cutters by a factor of 12. The relative wear of the PCD cutters in cutting granite is (0.01–0.02) × 10–6, which is 20 times less than in cutting 64C abrasive wheels. The relative wear of the PCD cutters in cutting abrasive wheels does not depend on the blunting of the rear surface up to values of 1.4 mm. This method may be recommended for rapid determination of the wear resistance of PCD. The proposed method of calculating the worn volume of the PCD by means of Kompas 3D or other appropriate software may be used to assess the relative wear resistance of abrasives and cutting materials.     

Field-assisted sintering of effective materials for alternative power engineering

The process of field-assisted sintering of nanostructured thermoelectrics for the formation of effective materials for alternative power engineering has been numerically simulated. Functionally graded thermoelectrics and segmented thermoelement branches have been sintered in a temperature-gradient field. Modified die tooling elements are proposed that allow the desired thermal conditions to be created for the sintering of inhomogeneous effective materials.     

Investigation of the oxidative resistance of high-temperature coating on a SiC material under exposure to high-enthalpy flow

The method, procedure, and results of the investigation of a high-speed air plasma flow effect on the structure of an ultrahigh-temperature coating made for a composite silicon carbide material are considered. The coating is based on hafnium diboride, silicon carbide, and oxides of hafnium, yttrium, and zirconium. The effect of a high-speed plasma flow on the samples was studied in a VAT-104 wind tunnel (Central Aerohydrodynamic Institute); this facility enables simulation of the conditions of high-velocity flight in the upper atmosphere. During the tests, the main parameters of the plasma flow were recorded, and the temperature distribution of the sample was measured. The weight loss of the samples was determined. Using the results of numerical parametric simulation of flow past and heat transfer of the samples, the catalytic activity of the coating was determined. After testing in a high-enthalpy flow, X-ray diffraction analysis and X-ray phase analysis of the samples were performed, and their surface microstructure was analyzed.     

Self-propagating high-temperature synthesis of Lu<Subscript>2</Subscript>O<Subscript>3</Subscript> powders for optical ceramics

A technique has been developed for the self-propagating high-temperature synthesis of lutetium oxide (Lu₂O₃) powders using citric acid, glycine, and lutetium acetate as fuels. We have carried out thermodynamic analysis of synthesis conditions and examined the effect of the nature of the fuel on the properties of the resultant powders. Using vacuum sintering at a temperature of 1780°C and powders prepared with glycine as a fuel and containing 25 mol % yttrium oxide and 5 mol % lanthanum oxide as sintering aids, we have obtained transparent lutetium oxide-based ceramics.     

Molecular-Beam Epitaxy of Two-Dimensional GaSe Layers on GaAs(001) and GaAs(112) Substrates: Structural and Optical Properties

Semiconductors - The results of studies of the structural and optical properties of two-dimensional GaSe layers grown by molecular-beam epitaxy on GaAs(001) and GaAs(112) substrates using a valve...     

Discomfort of Visual Perception in Virtual and Mixed Reality Systems

Programming and Computer Software - The importance of the topic of this paper is caused by the rapid development of virtual, mixed, and augmented reality systems. A problem in designing virtual...     

Creating an Atmosphere within Spacecraft

Russian Engineering Research - In space flight, the creation of an artificial atmosphere for those on board represents a serious challenge. New approaches produce environmentally and...     

Information Science in Occupational Safety Management

Russian Engineering Research - Approaches to information technology in occupational safety management at industrial enterprises are considered. Obstacles to such uses of information technology are...