UDC 621.762.5:539.26
M. P. Bezhenar, G. S. Oleinik, S. A. Bozhko, T. O. Garbuz, S. M. Konoval (m. Kiev)
Structure of composites of the cBN–Al–ZrN system, spliced under high pressure
Using electron microscopy methods, the structure of composites of the cBN-Al-ZrN system, fused under high pressure, was investigated. Based on the analysis of the morphological features of the warehouse composite – products of chemical interaction in the system, it is shown that such interaction can occur as part of a rare phase (crystallization from melting Al), so and in case of non-median contact of refractory storage systems.
Key words: cubic boron nitride, composite, high pressure, reaction adhesiveness, structure, electron microscopy.
UDC 66.094.3.097:662.613.13
V. Ya. Zabuga, G. G. Tsapyuk, T. V. Kartashova, E. V. Ishchenko, V. K. Yatsimirsky (Kiev)
Soot oxidation in the presence of Cu—Co—Fe oxide catalyst
The kinetics of oxidation of ashless soot grade K354 in the initial state, after its modification with concentrated nitric acid and subsequent introduction of a catalytically active additive into it were studied. The kinetic parameters of the soot oxidation process with the catalyst were obtained. It was shown that the rate constant of the catalytic reaction is three orders of magnitude greater than that of the oxidation reaction of soot treated with nitric acid.
Keywords: transition metal oxides, catalytic oxidation of soot.
UDC 544.473-039.63
O. V. Ishchenko, P. M. Silenko, T. M. Zakharova, A. V. Yatsimirsky, A. M. Shlapak (m. Kiev)
Kinetic patterns of CO oxidation on oxide catalysts based on 3d metals deposited on β-SiC and SiC nanofibers
The kinetic regularities of the CO oxidation reaction on oxide Cu—Co—Fe catalysts applied to powdered β-SiC and SiC nanofibers have been established. A kinetic scheme has been proposed, which is similar to the experimental one.
Key words: transition metal oxides, CO oxidation, silicon carbide, silicon carbide nanofibers.
UDC 621.922.079
V. I. Kushch, Y. A. Podoba (Kyiv)
Prediction of yield strength and shrinkage under pressure of a diamond-containing composite with a porous matrix
A developed theoretical model is presented to estimate the yield strength of a granular composite material with a porous matrix. A parametric analysis of the model was performed, the influence of the loading type, porosity of the matrix material and volume content of hard inclusions on the macroscopic yield strength of the composite was studied. An expression for the plasticity potential for a composite with a porous matrix was obtained, which provides satisfactory agreement with the results of the numerical analysis of the model over the entire range of changes in structural parameters. The applicability of the developed approach to the study of the process of pressure molding of blanks of products from composite materials was shown.
Keywords: composite, plasticity, porous material, yield strength, structural model, finite element method.
UDC 519.688:536.2:669.018.25
N. V. Litoshenko (Kyiv)
Evaluation of residual thermal stresses in polycrystalline aggregates of carbide grains of WC-Co hard alloy
An algorithm for calculating residual thermal stresses in polycrystalline WC aggregates of WC-Co hard alloy is presented. The algorithm is based on the equations of thermoelasticity. The stresses in the polycrystal arising due to the anisotropy of thermal expansion of single-crystal grains and misorientation of the crystallographic axes of neighboring grains, as well as the stresses transmitted to the aggregate from the surrounding hard alloy, are calculated. The results are comparable with the experimental data.
Keywords: WC-Co hard alloy, residual thermal stresses, tungsten monocarbide crystal, polycrystalline aggregate of WC carbide grains.
UDC 548.74:681.723:621.9.02
O. G. Lysenko (Kyiv)
Application of a scanning probe microscope with a diamond tip as a nanotechnological tool The experimental results of using a scanning probe microscope for mechanical surface treatment with nanometer resolution are presented. The device features a tip made of a boron-doped single crystal diamond and an electromagnetic system for measuring nano-interactions between the tip and the sample surface. Three-dimensional images of gold and silicon surfaces after nanocleaning and nano-scratching operations are demonstrated. The possibilities of using a diamond nanotool for the manufacture of nanoelectronics elements are discussed.
Keywords: Nanotechnology, semiconductor diamond, scanning probe microscopy.
UDC 621.922.029:661.65
V. S. Ptashnikov (St. Petersburg, Russia)
Increasing the peripheral speed of a part as a way to improve the ergonomics of round counter grinding with cubic boron nitride tools
For the first time, it was experimentally established that increasing the actual peripheral speed of a part in a wide range of round counter center grinding in the area of elastic wear and linear wear of tools and from cubic boron nitride with different characteristics on machines of different (8.3 and 12.0 N/μm) static rigidity at a wheel speed of 32-91 m/s invariably unambiguously reduces roughness, i.e. the thickness of the cut, which indicates an improvement in the ergonomics of the process. A comparative assessment of grinding processes at regulated and controlled levels of forced oscillations at idle speed showed that the weakening of the positive influence of the speed effect with an increase in the actual speed of the part and/or the speed of the wheel on the roughness and thickness of the cut is caused by vibration suppression – an increasing range of radial vibration displacements of the wheel-part at the rotation frequencies of the wheel, part and other elements of the SPID system. Recommendations are given for improving the ergonomics of round counter grinding with cubic boron nitride tools by increasing the actual speed of the part. Keywords: cubic boron nitride, cylindrical counter grinding, ergonomics, peripheral speed, roughness.
UDC 66.046.51:661.865.5:621.9.025.7
Q. Zou, W. Gong, X. Zeng, Y. Wu, J. Liu, Sh. Zou (Wuhan, Hubei, P. R. China)
Doping Fe-based diamond tool matrix composites with a rare-earth element
The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10—62 ‰ and about 5 &8240;, as compared to composites free of rare-earth elements.
Rare-earth diamond tool matrix composites where Co was replaced with Fe, which provides a good practical service performanc, and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured.
Keywords: doping cerium, matrix materials, flexural strength, impact ductility, metallized diamond tools.
UDC 621.921.34-2:622.24.05
N. V. Novikov, G. P. Bogatyreva, R. K. Bogdanov, G. D. Ilnitskaya, A. M. Isonkin (Kyiv)
The influence of the strength characteristics of diamond grinding powders on the performance of drilling tools
The results of the study of the influence of the strength characteristics (strength, homogeneity in strength, thermal stability) of diamond powders on the wear of impregnated drill bits and energy costs during the destruction of rock by them are presented. The influence of the strength characteristics of powder grains on the performance of drilling tools is experimentally confirmed. The conducted production tests showed that with an increase in the strength characteristics of diamonds, the average penetration per bit and the mechanical drilling speed increase.
Keywords: diamond grinding powders, drilling tool, strength, strength homogeneity, thermal stability, impregnated drill bit, bit penetration, mechanical drilling speed.
UDC 621.923:666.3:621.922
M. M. Yakhutlov, B. S. Karamurzov, U. D. Batyrov, M. M. Oshkhunov, M. R. Kardanova (Nalchik, Russia)
Stress-strain state of the grain-matrix system of a diamond tool under force disturbances
The stress-strain state of the grain-matrix system of a diamond tool on a carbide matrix is estimated by numerical modeling. It is shown that the most stressed part of the bond is the contact (transition) layer with diamond. Regularities of stress changes in this area with a change in the direction of the cutting force, the properties of the matrix and the transition layer are obtained. The analysis of stresses depending on the degree of immersion of grain into the matrix is carried out; critical parameters of immersion are determined for different grain shapes and Poisson’s ratios of the bond.
Keywords: stress-strain state, diamond tool, force disturbances, carbide matrix, numerical modeling, grain shape, Poisson’s ratio.