UDC 620.22:621.921
V. I. Kushch, V. G. Kulych
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
vkushch56@gmail.com
Theoretical estimates of packing density of two-component powder systems: review and comparative analysis (pp. 3-18)
A review and comparative analysis of approaches and methods known in the literature for predicting packing density of two-component powder systems is carried out. A theoretical model of a binary mixture is proposed, which provides spline approximation of calculated and experimental data with proper accuracy. The parameters of the model are physical quantities, the comparison of the values of which for different binary systems allows us to assess both the influence of the formation method on the packing density and the degree of correspondence of the existing theoretical models to real powder materials.
Keywords: powder material, two-component system, packing, density, empirical model, physical model.
UDC 549.211
V. M. Kvasnytsya
Institute of Geochemistry, Mineralogy and Ore Formation named after M. P. Semenenko, NAS of Ukraine, Kyiv, Ukraine
kvasnytsya@ukr.net
Synthetic NRNT diamonds as pseudo-indicators of diamond content of rocks (pp. 19-27)
A comparison of synthetic NRNT and natural diamonds was made and a significant difference between them was shown. The main indicator features of synthetic NRNT diamonds were highlighted, by which their findings in natural objects can be recognized. The reliability of NRNT diamond findings in rocks of the Ukrainian Crystalline Shield was considered. Findings in samples of concentrates from crystalline and terrigenous rocks of diamonds similar to their synthetic NRNT crystals are pseudo-indicators of diamond content of rocks and require detailed study.
Keywords: synthetic NRNT diamond, natural diamond, indicator features.
UDC 661.657.5/.665:539.89:621.762.5
Xiangxiang Yin1, 2, Peicheng Mo3, *
1Hydrochina Chengdu Engineering Corporation Limited, Chengdu, P.R. China
2College of Water Conservancy and Hydropower, Hohai University, Nanjing, P.R. China
3China Nonferrous Metal (Guilin) Geology and Mining Co., Ltd., Guilin, P.R. China
*2393707540@qq.com
Effect of sintering pressure on the properties of PcBN carbide inserts (pp. 28-36)
PcBN carbide inserts (polycrystalline cubic boron nitride) were synthesized using cBN/Zr/Al as raw materials under high temperature and pressure. The effect of synthesis pressure on the interfacial morphology, wear resistance, microhardness and flatness of PcBN carbide insert was investigated. The test results showed that with the increase of synthesis pressure, the interfacial bond of the composite became denser and more uniform, and the bond strength between the cBN layer and the alloy substrate was higher. The density, microhardness and abrasion resistance of PcBN carbide insert were improved. Under ultra-high pressure, the thickness deviation of PcBN carbide insert gradually decreased, the thickness distribution became uniform, and the flatness of the samples was better.
Keywords: high pressure, polycrystalline cubic boron nitride, interfacial bonding, wear resistance.
UDC 621.921.34:546.26-162: 621.785
Danhui Han1, *, Junlong Liu1, Chong Peng1, Baoyan Liang2
1State Key Laboratory for High Performance Tools, Zhengzhou Research Institute for Abrasives & Grinding Co., Ltd, Zhengzhou, P.R. China
2Materials and Chemical Engineering School, Zhongyuan University of Technology, Zhengzhou, P.R. China
*zwxlby@126.com
Creation of the structure of the diamond/graphene composite by low-temperature heat treatment method (pp. 37-47)
The diamond/graphene composite was obtained using graphene oxide (GO). The resulting composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The effects of different particle sizes and diamond content on the phase composition and microstructure of the products were studied. The results indicate that OG is significantly reduced at a temperature of ~ 200 °C. Most of the OG materials were reduced to graphene. They increased in size, exfoliated, and acquired an organ-like shape. A graphene coating was formed on the surface of the diamond particles by simple heat treatment of mixtures of diamond and OG powders. The coating effect of large diamond particles was weak due to their high inertness. The quasi-core-shell structure of the diamond/graphene composite can be obtained using fine-grained diamonds.
Keywords: thermal recovery, graphene, diamond, composite.
UDC 621.315:666.3.017:546.2
V. I. Chasnyk1, *, D. V. Chasnyk2, O. M. Kaydash3, **
1State Enterprise Scientific Research Institute “Orion”, Kyiv, Ukraine
2Ukrainian Scientific Research Institute of Special Equipment and Forensic Examinations of the Security Service of Ukraine, Kyiv, Ukraine
3V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*vassiliyiv@gmail.com
Activation energy of electrical conductivity and peculiarities of microwave radiation absorption in AlN–SiC composite (pp. 48-55)
Semiconductor composite materials of the AlN–50% SiC–Y3Al5O12 system with high with a microwave absorption level of 4.6 dB/mm. For the obtained composites, the values of the activation energy of electrical conductivity EA in the temperature range 20–800 °C were calculated, which are 0.120–0.075 eV for temperatures close to room temperature of 20–150 °C and increase to 0.270–0.275 eV in the case of increasing the temperature to 350–800 °C. The determined values of the energy of electromagnetic wave photons in the frequency range from 1 to 100 GHz are from 4.13·10–6 to 4.13·10–4 eV. Based on quantum electrodynamics at the atomic level, the process of absorption of microwave radiation in semiconductor composites of the AlN–SiC system is described. Low-energy photons of electromagnetic waves falling on the surface of the AlN–SiC composite transfer their energy to the conduction electrons of the surface layers of the SiC phase and are absorbed by them. After 10–8 s, the conduction electrons emit photons at the same frequency of the electromagnetic wave, mainly into the same SiC grains. As a result of such interaction, electromagnetic radiation is absorbed, and, as a result, wave energy is dissipated, after which the entire composite is heated: first the particles of the SiC phase, and then the AlN grains.
Keywords: aluminum nitride, silicon carbide, absorption of microwave radiation, electrical resistance, activation energy of electrical conductivity, energy of electromagnetic wave photons.
UDC 666.539.3/6 (045)
A. G. Dovgal*, L. B. Priymak, V. V. Varyukhno, O. M. Bilyakovych
National Aviation University, Kyiv, Ukraine
*andrii.dovhal@npp.nau.edu.ua
The influence of steel grinding on the structure and mechanical properties of SiC–Al2O3 composites (pp. 56-66)
The influence of steel grinding on the structure of the SiC–Al2O3 composite obtained in steel drums with steel grinding media was studied. The following physical and mechanical properties of the obtained samples were studied, such as bending strength and hardness. The optimal values of these characteristics were established in relation to the composition and technological modes of obtaining.
Keywords: ceramics, composite, grinding, strength, hardness, density, porosity.
UDC 621.923.7
Yu. D. Filatov
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv Kyiv, Ukraine
filatov2045@gmail.com
Quantum mechanism of optical glass polishing (pp. 67-79)
As a result of the study of the mechanism of optical glass polishing using dispersed systems of cerium dioxide powders, it was found that glass removal occurs by removing sludge nanoparticles from the treated surface during its interaction with polishing powder particles, which occurs in an open microresonator formed by the surfaces of the treated material and polishing powder particles, as a result of Förster resonance energy transfer between the energy levels of the polishing powder particles and the treated material. It is shown that in a two-mode system with a discrete spectrum of natural frequencies, the number of sludge nanoparticles generated in the system of the treated surface–dispersed system–lapping surface increases with increasing volumetric wear coefficient, lifetime of the excited state of clusters of the treated surface, and Q factor of the microresonator. A method for calculating the removal rate of the treated material and the roughness parameters of polished surfaces has been developed and it has been established that the deviation of the calculated polishing productivity from the experimental data does not exceed 2%, the errors in calculating the arithmetic mean Ra and the root mean square deviation Rq of the polished surface profile are 10%, and the calculated value of the maximum profile height Rmax is underestimated in comparison with the experimental data by 40–50%.
Keywords: polishing, optical glass, Förster resonance energy transfer, material removal rate, polished surface roughness.
UDC 620.22-621.921.34:539.422.25
B. T. Ratov1, V. A. Mechnyk2, *, E. S. Gevorkyan3, M. O. Bondarenko2, V. M. Kolodnitsky2, **, N. S. Akhmetova1, D. L. Korostyshevsky2, R. U. Bayamirova4
1NAO “Kazakh National Research Technical University named after K. I. Satpayev”, Almaty, Kazakhstan
2Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
3Kazimierz Pułaski University of Technology and Humanities in Radom, Poland
4Sh. Yesenov Caspian University of Technology and Engineering, Radom, Poland Aktau, Kazakhstan
*vlad.mechnik2019@gmail.com
**vasylkolod56@gmail.com
Study of wear resistance of impregnated crowns based on composites of the Salmaz‒(WC‒Co)‒ZrO2 system in the case of granite drilling (pp. 80-90)
The dependence of the wear rate of diamond impregnated crowns made of composite diamond-containing materials (CBMs) 25Salmaz–70.5WC–4.5Co and 25Salmaz–68.62WC–4.38Co‒2ZrO2 by the spark-plasma sintering method in the temperature range of 20‒1350 °C at a pressure of 30 MPa for 3 min on the rotation speed and axial load in the case of granite drilling was established. It is shown that the addition of ZrO2 nanopowder in an amount of 2% (by weight) to the composition of KAM 25Salmaz–70.5WC–4.5Co leads to a threefold decrease wear rate. The wear resistance of diamond impregnated crowns made of KAM 25Salmaz–70.5WC–4.5Co and 25Salmaz–68.62WC–4.38Co‒2ZrO2 is highest at a rotation speed of 250 rpm and an axial load of 900 kg, and the lowest at a rotation speed of 750 rpm and an axial load of 1250 kg. It was found that the increase in wear resistance of the diamond impregnated bit made of KAM 25Salmaz–68.62WC–4.38Co‒2ZrO2, compared to the bit made of KAM 25Salmaz–70.5WC–4.5Co, is due to the grinding of the grains of the main WC phase, an increase in the relative density, tensile strength during compression and bending, an increase in fracture toughness and the formation of a strong and reliable bond of diamond grains with the hard alloy matrix. The results obtained on the wear resistance of diamond impregnated bit in combination with the fine-grained structure of the hard alloy matrix and high diamond retention allow them to be used for the manufacture of new tools with increased performance properties for drilling hard rocks.
Keywords: diamond impregnated crown, composite, tungsten carbide, cobalt, zirconium dioxide, wear resistance, spark-plasma sintering.
UDC 621.923
V. I. Lavrinenko1, *, V. G. Poltoratsky1, O. O. Pasichny1, V. Yu. Solod2, **
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Dnipro State Technical University, MES of Ukraine, Kamianske, Ukraine
*lavrinen52@gmail.com
**v_solod@ukr.net
Performance performance of a grinding tool with cubic boron nitride grains with combined wear-resistant coatings (pp. 91-97)
The effect of the surface coating of cubic boron nitride (cBN) grains on the tool wear resistance and machining performance was studied. In the case of low (50 mm3/min) machining performance, the wear resistance increase coefficient is 1.66 for the B2O3 + CeO2 coating, and for higher (200 mm3/min) machining performance, the wear resistance increase coefficient is 1.13 for the B2O3 + B4C coating. It is shown that with such processing performance, in terms of the roughness parameter of the processed surface Ra, the best coating of the surface of cBN grains with a combination of oxide and carbide (B2O3 + SiC) is both in terms of wear resistance of the grinding wheel and roughness of the processed surface. It is established that in the case of increased grinding performance, any coating of the surface of cBN grains reduces the parameter t50 and, as a result, the holding capacity of the rough surface obtained during grinding with such wheels decreases.
Keywords: combined wear-resistant coatings, grinding tool, cubic boron nitride grains, operational indicators.
UDC 661.657:536.421.1:539.89
V. L. Solozhenko
LSPM–CNRS, Université Sorbonne Paris Nord, Villetaneuse, France
vladimir.solozhenko@univ-paris13.fr
On the melting of boron arsenide under pressure (pp. 98-100)
The melting of cubic boron arsenide (BAs) was investigated at pressures up to 8 GPa using in situ electrical resistance measurements. It was found that above 2.5 GPa BAs melts congruently, and the melting curve has a negative slope (53±5 K/GPa), indicating a higher melt density compared to the solid phase. The melting point of BAs at atmospheric pressure is 2410(30) K.
Keywords: boron arsenide, melting, high pressure, high temperature.
UDC 621.921.343
D. A. Stratiychuk*, L. M. Devin, S. V. Rychev, V. Z. Turkevich, Y. Y. Rumyantseva
V. M. Bakuly Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*d_strat@ukr.net
The influence of wSiC and wSi3N4 microfibers on the dynamic tensile strength limit for BL group cBN composites (pp. 101-103)
The influence of wSiC and wSi3N4 microfibers on the dynamic tensile strength limit (Rmd) for BL group superhard cBN composites obtained in the cBN–NbN–Al and cBN–NbN–Al2O3 systems is considered. It is demonstrated that the Rmd has a range of values from 182 to 333 MPa and depends on the nature of the filler. It is noted that the addition of wSiC microfibers to the initial charge increases the Rmd of the sintered ceramic by an average of 10–15%, while the presence of Al2O3 leads to a slight decrease in the strength of the material.
Keywords: wSiC and wSi3N4 microfibers, dynamic tensile strength, BL-group cBN ceramics, high pressures, hardness.