UDC 621.744:666.798.2
N. V. Novikov, V. V. Ivzhenko, A. A. Leshchuk, V. A. Popov, G. F. Sarnavskaya, A. P. Antonyuk (Kyiv)
Experimental Research and Modeling of Injection Molding of Complex-Shaped Products from Technical Ceramics
The article presents the results of technological studies of injection molding of products from thermoplastic masses based on ceramic and metal-ceramic powders. Computer modeling of heat transfer processes during injection molding of complex-shaped products from thermoplastic masses based on silicon nitride, aluminum nitride, tungsten carbide containing paraffin was performed.
UDC 546.26-419
M. A. Serga, A. A. Budyak, S. A. Ivakhnenko, O. A. Zanevsky (Kyiv)
Resistive properties of dispersed-composite materials based on graphite
The method of mathematical modeling was used to calculate the electrical conductivity values of dispersed-composite materials made of GMZ grade graphite and finely dispersed particles of lower electrical conductivity at various ratios. To obtain dispersed-composite materials in compact form, GMZ graphite, stabilized ZrO2 powder and binders based on liquid glass, synthetic rubber and polyvinyl alcohol were used. Experimental data showed the effect of the binder on the electrical resistance of dispersed-composite materials.
UDC 539.89:621.762.5:621.921.34-492.2
A. A. Bochechka, V. S. Gavrilova, A. M. Kutsay, V. N. Tkach, A. N. Lutsenko, L. A. Romanko (Kiev)
The influence of thermal, chemical and vacuum treatments on the surface condition and impurity composition of diamond nanopowders of detonation and static synthesis
Nanodispersed diamond powders that underwent thermal, chemical and vacuum treatments and their non-combustible residues were studied using IR spectroscopy, mass spectral analysis and X-ray diffraction. It was found that the main impurities on the surface of nanoparticles are functional groups that include boron, nitrogen, silicon, hydrogen and oxygen. Powder treatment with hydrofluoric acid reduces the amount of compounds containing nitrogen and silicon. Thermal treatment in an inert gas environment almost completely removes carbonyl groups, and heating in a vacuum removes hydroxyl groups. The number of boron-carbon bonds remains almost unchanged during these treatments.
UDC 621.921
E. A. Pashchenko, O. V. Lazhevskaya, Ya. L. Silchenko, N. G. Klimenko (Kiev)
Diamond-abrasive composites based on complex metal derivatives
The article presents the results of using complex metal derivatives to modify oligomeric binders of diamond-abrasive tools. The processes of destruction of particles of copper, nickel, chromium, and aluminum complexes in polymer matrices are studied. The possibility of alloying the surface layers of the processed materials with metals from the composition of metal complexes introduced into diamond-abrasive composites is shown, which allows to significantly improve the functional characteristics of ground surfaces and sharpened cutting edges of products for structural and tool purposes.
UDC 539.89: 62-987
P. A. Balabanov (Kiev)
The effect of high pressure and temperature on the microstructure and mechanical properties of steel matrices of high-pressure devices
The effect of high pressure and temperature on the microstructure and mechanical properties of the matrices of high-pressure devices, for the manufacture of which rolled products and ingots obtained by the method of electroslag remelting from high-speed steel P6M5 were used, is studied. It is shown that matrices made of cast blanks are softened during high-temperature heating to a lesser extent than those made of rolled products, which contributes to an increase in their durability in the synthesis of superhard materials.
UDC 553.82:535.1
I. Kh. Abdukadirova (Tashkent)
Study of radiation effects in leucosapphire single crystals
The effect of high doses of damaging radiation on the stability of optical properties and structure of leucosapphire single crystals was studied. In particular, the dynamics of the crystal lattice in the region of fundamental vibrations for samples irradiated with a set of neutron fluences was tracked by infrared spectroscopy. The dose dependence of the parameters of the unit cell of the crystal was established, and a nonlinear change in some structural parameters was detected. A parallel was drawn with the features of fluctuations of the spectral characteristics of the fundamental modes in irradiated crystals. An assumption was made about the main mechanism of partial damage to leucosapphire single crystals by very high doses of radiation.
UDC 620.22:66.067.124
E.S. Gevorkyan (Kharkov)
Porous ceramic filters made of silicon carbide
The technology for producing a ceramic filter based on self-bonded silicon carbide is described. The filter has a relatively low electrical resistance and can operate effectively when passing direct electric current at low voltage. During operation, the filter itself can heat up to a temperature of 1000°C. This allows it to be used for cleaning diesel exhaust wasps (soot), since the filter is regenerated when direct current is passed.
UDC 621.922.4
P. G. Matyukha, N. V. Azarova (Donetsk)
The influence of radial vibrations of a grinding wheel on the shape of a cut and the number of contacting grains
Based on the developed mathematical model of flat plunge grinding with vibrations, the influence of radial vibration parameters on the number of contacting grains and the shape of individual cuts was studied.
UDC 669.312.621.97
T. G. Afrikyan (Gavar, Republic of Armenia)
Performance of extruded diamond grinding wheels
A technological process for the manufacture of diamond grinding wheels of a straight profile by sequential extrusion of the diamond-bearing layer and the wheel body is proposed. Optimized extrusion parameters, the implementation of which allows for the orientation of needle-shaped diamond grains in the extrusion direction when using them. In comparative tests of performance, the extruded wheels showed high results in terms of specific diamond consumption and surface cleanliness.
UDC 621.922.029:661.65
V. S. Ptashnikov (St. Petersburg)
Physical and Normative Hardness of Abrasive Tools Made of High-Hardness and Superhard Materials. Part 2. Normative Hardness of Abrasive Tools
Based on the scientifically substantiated concept of the physical hardness of abrasive tools, a conceptual analysis of the standard system for measuring their normative hardness was conducted for the first time in domestic practice. An ambiguous and sharply inadequate reproducibility of readings from all five standard methods was established as a consequence of a violation of the inversion principle when measuring and using physically incorrect hardness indicators. It is proved that the normative hardness, as immanent to the measurement method, does not express physical hardness, and the use of all five methods is physically incorrect. It is concluded that the system of state standards for measuring hardness, as contradicting the practice of abrasive processing and the basic principles of metrology to ensure the uniformity of measurements, requires radical reform based on the concept of physical hardness with subsequent integration into the international system.