UDC 621.315.592:621.91:620.181
A. M. Kovalchenko (Kyiv)
Studies of the plastic mode of cutting brittle materials (review)
Theoretical and experimental studies of the plastic mode of cutting brittle materials (semiconductors, ceramics, and glass) are considered. The plastic mode of cutting is based on the implementation of phase transitions under pressure in the processed material with subsequent cutting of the transformed amorphous layer, which allows to avoid the formation of cracks. Works on the study of phase transitions in brittle materials during indentation, scratching, friction, and cutting are considered. It is shown that the depth of cut, the radius of rounding of the cutter edge, the thickness of the formed chip, the angle of inclination of the cutting face of the cutter, the crystallographic orientation of the processed material and the diamond tool, the type of lubricating and cooling liquid are the determining parameters for the implementation of the plastic mode of cutting.
Key words: phase transformations under pressure, plastic mode of cutting, semiconductors, ceramics, glass.
UDC 532.64:669.046
THERE ARE. IN. Sukhovaya (Dnipropetrovsk)
A structural approach to the creation of wear-resistant composite materials
The influence of the initial structure of filler alloys on the process of structuring of interfaces of the solution-diffusion type in macro-heterogeneous composite materials with a metallic bond is studied. It is shown that by combining in the structure of the filler phases that differ in resistance to the action of the molten bond during impregnation, it is possible to ensure increased wear resistance of composite materials under the conditions of dry friction, abrasive, gas-abrasive and corrosive wear.
Key words: macroheterogeneous composite materials, interface, dissolution processes, wear resistance.
UDC 538.911, 538.97, 539.381, 548.74
M. D. Borcha, S. IN. Balovsiak, I. M. Fodchuk, V. Yu. Khomenko, O.P. Kroitor (Chernivtsy)
IN. N. Weaver (Kyiv)
Local deformations in diamond crystals determined by Fourier transformation of Kikuchi patterns
A new technique for determining local deformations in crystals based on diffraction patterns of back-reflected electrons (Kikuchi patterns) using a discrete two-dimensional Fourier transform is proposed. This technique was tested in the study of diamond samples synthesized under various conditions. The obtained results are in good agreement with the data of other methods.
Key words: synthesized diamonds, diffraction of reflected electrons, Kikuchi lines, deformations, Fourier transform.
UDC 669.621
Ya. A. Kryl, P. M. Prysyazhnyuk (Ivano-Frankivsk)
Structure formation and properties of NbC–Hadfield steel cermets
The structure and properties of cermets based on NbC with a Hadfield steel binder were studied. Cermets were obtained by impregnating NbC steel frameworks at 1450 °C in an argon environment. The obtained materials have a two-phase structure: manganese austenite and NbC grains. The optimal set of mechanical properties is achieved with a content of 55–60% (by volume) of the carbide phase.
Keywords: cermets, Hadfield steel, niobium carbide, impregnation.
UDC 621.922.025:661.657.5
V. K. Starkov (Moscow)
Highly porous cubic boron nitride wheels for grinding without cooling
The influence of the composition of highly porous cBN grinding wheels on the efficiency of the grinding process of hardened steel with oil mist cooling and without cooling is considered. Experimental studies and statistical analysis of the obtained results established that the energy consumption of the material removal process, the heating of the part and the roughness of its treated surface depend on the content of cBN, pore-forming fillers and ceramic bond in the composition of the abrasive mass.
Key words: highly porous cBN grinding wheels, composition of the abrasive mass, cubic boron nitride, dry grinding.
UDC 621.623
Yu. D. Filatov, A. G. Vetrov, V.I. Sydorko, A. Yu. Filatov, S. IN. Kovalev (Kyiv)
Regularities of finishing diamond-abrasive processing of monocrystalline silicon carbide
As a result of studies of the regularities of the finishing diamond-abrasive processing of monocrystalline silicon carbide based on a generalized model of the formation and removal of sludge particles and removal of the processed material, it was shown that the use of the reduced transfer energy as a criterion for evaluating the efficiency of the processing process made it possible to substantiate the expediency of using boron carbide and titanium dioxide powders for fine grinding and chromium oxide, aluminum oxide, cerium dioxide and diamond micropowders AFM 2/1 for superfine grinding.
Key words: diamond-abrasive processing, sludge particle, transfer energy, removal of the processed material.
UDC 621.9:621.928.4
IN. I. Lavrynenko, G. D. Ilnytskaya, G. AND. Petasiuk, V. N. Tkach, V. IN. Smokvina, V. WITH. Shamraeva, I. N. Zaitseva (Kyiv)
D. G. Muzychka (Dneprodzerzhinsk)
The influence of physical and mechanical characteristics of synthetic diamond powders of the AS6 brand on the wear resistance of a grinding tool cop
The physical and mechanical characteristics of AC6 grade abrasive powders based on diamonds synthesized in the Ni–Mn–C and Fe–Si–C systems are discussed.Such diamonds differ in magnetic properties, mechanical characteristics, and the content of impurities and intracrystalline inclusions.The possibilities of using the results of the study of the morphometric characteristics of diamond powders for their effective use in grinding tools are shown. The relationship between these characteristics and the wear resistance of the grinding tool during diamond grinding has been established.
Key words: physical and mechanical characteristics, synthetic diamond powders, magnetic properties, morphological characteristics, wear resistance.
UDC 621.921.34-492.2
Yu. IN. Sirota, V. I. Kush (Kyiv)
Statistical analysis of the compressive strength of individual grains of STM powders and improvement of the method of its evaluation
A new approach to assessing the strength of diamond powder is proposed, based on the statistical theory of extreme values and providing prediction of strength properties on a small sample. A comparative statistical analysis of a number of batches of powder was carried out. It is shown that the strength of the powder grains in the entire studied range of grain sizes and grades is satisfactorily approximated by the Weibull distribution, the relationship between the Weibull parameters and the average strength is investigated. The convergence of empirical statistics is studied, the criterion of the sufficiency of the sample volume is formulated for estimating the average compressive strength of grains. The possibility of reducing the number of tests has been established, which allows to significantly reduce time, reduce the wear of anvils and thereby reduce the cost of research. The presented results are the theoretical basis for improving existing and developing new methods of quality control of STM powders.
Key words: STM powders, strength assessment, statistical theory, Weibull distribution, quality control.
UDC 621.921.34:621.921.34–413:621.923.4:662.23.05
THERE ARE. THERE ARE. Ashkinazy (Moscow)
AND. AND. Shulzhenko, V.G.Gargin, A.N.Sokolov, L.And Alexandrova, V.N. Weaver (Kyiv)
IN.G.Ralchenko, V. And Konov, A. P. Bolshakov, S. G. Ryzhkov (Moscow)
R.K.Bohdanov, A.P.Zakora, M. IN. Suprun (Kyiv)
Diamond polycrystalline composite material with a dispersion-strengthening additive based on nickel
At high pressure and temperature, with the use of nickel, cobalt powders and nanopowder of tungsten carbide as sintering process activating additives, a diamond polycrystalline composite material with improved physical and mechanical characteristics was obtained. Samples of this material, reinforced at high pressure and temperature with polycrystalline CVD diamond, were made.
Keywords: nanopowders, composite material, sintering, nickel, tungsten carbide, CVD diamond.