V. I. Kushch*, V. G. Kulych
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*vkushch56@gmail.com
Rheological properties of thermoplastic slip for forming blanks of large-sized thin-walled products from silicon carbide ceramics (pp. 3-14)
An experimental and computational method for studying the rheological properties of thermoplastic slip has been developed, which consists in parallel conducting laboratory and computational experiments and determining viscosity parameters from the condition of agreement of calculated and experimental data. The experimental part of the method uses the penetrometry method, which is simple to implement and does not require special equipment. The computational part consists in analyzing the model boundary value problem for the Navier–Stokes equations by the finite element method or using the analytical model developed in the work. The determined viscosity characteristics of the slip based on paraffin and polydisperse SiC powder make it possible to predict the process of slip casting of large-sized thin-walled silicon carbide ceramic blanks.
Keywords: viscoplasticity, slip casting, rheology, Herschel–Bulkley model, penetrometry, computer modeling.
UDC 549.548.211
V. M. Kvasnytsya
M. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
kvasnytsya@ukr.net
Analysis of goniometry of sculptures on the faces of natural diamond crystals (pp. 15-28)
The data of the goniometric study of the most common sculptures on the surface of natural diamond crystals are summarized. These sculptures are composed of flat microplanes that arise during the growth or dissolution of diamond crystals. They are an integral part of their surface and are directly involved in the creation or destruction of diamond crystal faces. The results of goniometry of trigonal and ditrigonal hatching at the location of octahedron edges, directly and inversely parallel triangular and hexagonal depressions on octahedron faces, quadrilateral depressions on cube faces, drop-shaped tubercles and cavities on dodecahedron faces are considered. It is shown that the most common microplanes of sculptures crystallographically correspond to simple forms, which often have large symbols and form clusters mainly around the most important structural forms of diamond.
Keywords: diamond, crystallomorphology, goniometry, growth and dissolution sculptures, simple forms.
UDC 549.211:548.736.15
Khyati Upadhyay1, Abhay Dasadia1, *, Jordan Moshcovitis2
1Faculty of Science, A. D. Patel Institute of Technology, The C.V.M University, New Vallabh Vidhyanagar-388 121, Gujarat, India
2MMC Research PTY LTD, Melbourne, VIC 3000, Australia
*abhaydasadia@adit.ac.in
Assessment of Nitrogen Concentration and Related Defects in Single Crystal Diamonds for Technological Applications (pp. 29-37)
Single crystal diamond is a material of great interest for a wide range of advanced applications due to its unique properties. Despite the potential of diamond-based devices, their commercialization is hampered by significant technological challenges, in particular the need for high-quality, technological-grade materials to fully realize their benefits. It is generally accepted that high-quality single-crystal diamonds grown by microwave plasma chemical vapor deposition are of type IIa, meaning that their nitrogen concentration is less than 1 ppm. This study attempted to grow high-quality single-crystal diamonds with nitrogen impurities of less than 1 ppm using a welding material to maintain an optimal substrate temperature. The quality and defects associated with nitrogen were evaluated by studying the optical properties using Raman, ultraviolet and infrared spectroscopy. Raman spectroscopy confirmed the presence of pure diamond phase in the spectra of the sample, a peak was observed at 1332.5 cm–1 with a full width at half maximum of 1.5 cm–1, and IR spectroscopy showed a nitrogen concentration of less than 1 ppm, ultraviolet spectroscopy at 502 nm revealed the presence of the H3 defect, quantified at 206 parts per billion (ppb). The results of the study showed a strong dependence of the controlled growth parameters on the nitrogen concentration in the process of synthesis of single-crystal diamonds.
Keywords: single-crystal diamonds, microwave plasma chemical vapor deposition, welding material, optical absorption, nitrogen-vacancy centers.
UDC 621.921.34:666.792.3:544.431.7:621.793.16
He Zhao1, *, Yanhong Wang2, Yitong Luo3, Baoyan Liang3
1School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, P.R. China
2School of Chemical Engineering and Technology, North University of China, Taiyuan, P.R. China
3Materials and Chemical Engineering School, Zhongyuan University of Technology, Zhengzhou, P.R. China
*zhaohe2022@126.com
Rapid Deposition of Metal Carbides on the Surface of Diamond Particles Induced by Thermal Explosion Reaction (pp. 38-45)
It is shown that vacuum heat treatment of a mixture of metal powders (Ti, Cr or W) and diamond particles using high temperature resulting from the thermo-explosive reaction of Ni–Al compact, promoted rapid sublimation of metal powders with formation of carbide coating. Metal elements quickly evaporated and deposited on the surface of diamond particles after thermal explosion, and a heterogeneous carbide coating was formed on the surface of diamond particles. Carbides formed in the coating were nano-sized or submicron-sized. The mechanism of coating formation is explained taking into account the thermodynamic reaction and saturated vapor pressure.
Keywords: metal, coating, diamond, thermo-explosive reaction, carbide.
UDC 666.792.3:621.78
Zixun Huang1, 2, Liangbiao Wang1, *, Shunkai Wang1, Tinghai Yang2, Xiaokai Song1, Tao Mei3
1School of Chemistry and Chemical Engineering, Jiangsu University of Technology, Changzhou, Jiangsu, P.R. China
2School of Resources and Environmental Engineering, Jiangsu University of Technology, Changzhou, Jiangsu, P.R. China
3Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Key Laboratory
of Polymer Materials, School of Materials Science and Engineering, Hubei University, Wuhan, P.R. China
*lbwang@jsut.edu.cn
Simple preparation of vanadium carbide nanoparticles by thermal reduction method (pp. 46-50)
Vanadium carbide nanoparticles were synthesized by lithium-thermal reduction process at 600 °C in a stainless steel autoclave. The product was investigated by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The X-ray diffraction patterns showed that the obtained product is a cubic phase of vanadium carbide.
Keywords: chemical synthesis, X-ray diffraction, carbide, nanoparticles.
UDC 621.923.7
Yu. D. Filatov1, *, A. Yu. Boyaryntsev2, O. V. Kolesnikov2, S. M. Galkin2, V. O. Novgorodtsev2, Ya. I. Polupan2, O. I. Pylypenko2, V. I. Sidorko3, S. V. Kovalev1
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Institute of Scintillation Materials, NAS of Ukraine, Kharkiv, Ukraine
3State Enterprise “Engineering and Production Center ALKON” NTAK (ALKON) NAS of Ukraine, Kyiv, Ukraine
*filatov2045@gmail.com
Polishing of optical components from semiconductor materials (pp. 51-63)
As a result of the study of the mechanism of removal of the processed material and wear of particles of the dispersed phase of the dispersed system during the polishing of semiconductor materials, it was established that the formation of sludge nanoparticles and wear nanoparticles of polishing powder is a consequence of QD-FRET – Förster resonance energy transfer mediated by quantum dots that form on the surfaces of the processed material and polishing powder particles. It is shown that the energy transferred between the particles of the polishing powder and the treated surface, as well as the energy of the nanoparticles of sludge and nanoparticles of wear of the polishing powder, parabolically depend on their most probable sizes, which are interconnected with the effective band gap width of quantum dots (QDs). It is established that the material removal rate and the wear intensity of the polishing powder exponentially decrease with an increase in the effective band gap width of QDs on the corresponding surfaces, and their ratio, which characterizes the effectiveness of using a dispersed system of micro- and nanopowders for polishing semiconductor materials, increases linearly with a decrease in the ratio of the effective band gap widths characteristic of QDs on the treated surface and on the surface of the polishing powder particles. It is shown that the results of the theoretical calculation of the material removal rate are in good agreement with the experimental determination of the polishing performance of InSb, SiC and Ge crystals with a deviation of 4–5%.
Keywords: polishing, semiconductors, quantum dots, QD-mediated Förster resonance energy transfer (QD-FRET), material removal rate, polishing powder wear intensity.
UDC 621.9.025.77:615.46:616.728
S. V. Sokhan*, V. V. Vozny, V. G. Sorochenko, O. A. Mykyshchenko
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*svsokh@gmail.com
Diamond grinding of ceramic balls with changing geometric parameters of the process (pp. 64-80)
For diamond grinding of ceramic balls made of silicon nitride with plane-based and circular feed with oscillation, the results of an experimental study of the influence of geometric parameters of the grinding process on the accuracy of the shape of the balls and the shape of the worn surface of the diamond wheel are presented. The indicators of the accuracy of the shape of the polished balls were the inconsistency of the ball diameter and the form factor of the circular shape, and the shape of the worn surface of the circle was the angle of inclination of the surface profile line in the radial direction and the rate of change of this angle. The specified influence is described by adequate linear functions of the process indicators in d is the ratio of the number of balls on the circles of their location and the eccentricity of the location of the ball trajectory field from the axis of rotation of the diamond wheel with a constant overlap of the axis of rotation of the circle with the outer circle of the location of the balls. The values of the geometric indicators are given, under which the application of the studied ball grinding scheme is expedient.
Keywords: ceramic balls made of silicon nitride, diamond grinding, geometric parameters of the process, inconstancy of the ball diameter, form factor of the ball circular shape, shape of the worn surface of the wheel.
UDC 621.9.025.7
V. I. Hrytsyna1, K. I. Koshevy1, O. A. Opalev1, O. M. Reshetnyak1, V. E. Strelnytsky1, A. O. Lyamtseva2, A. O. Chumak2, S. A. Klymenko2, *, O. O. Bochechka2, O. I. Chernienko2
1National Scientific Center “Kharkiv Institute of Physics and Technology” of the National Academy of Sciences of Ukraine, Kharkiv, Ukraine
2V. M. Bakul Institute of Superhard Materials of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
*atmu@meta.ua
Cutting tool equipped with a polycrystal of synthetic diamond with a polycrystalline diamond CVD coating (pp. 81-91)
A thin protective polycrystalline diamond CVD coating for cutting tools equipped with a polycrystalline material of synthetic diamond obtained by the HP-HT method is proposed. The coating deposition modes in a glow discharge plasma stabilized by a magnetic field are worked out. The coating was synthesized in a hydrogen-methane mixture at a partial pressure of CH4 within (2.2–2.7)·102 Pa. The effect of the temperature of the polycrystalline diamond substrate during deposition on the structure of the synthesized coating is studied. It is shown that at temperatures within 1060–1150 °C, diamond crystals in the coatings are clearly faceted with rectangular or triangular facets of micrometer size. Further increase in the synthesis temperature leads to the formation of less ordered small components on the surface of the formed large diamond crystals. At a deposition temperature of 1110–1150 °C, a pilot batch of cutting inserts obtained from polycrystalline diamond material with a CVD coating of polycrystalline diamond 30 μm thick was manufactured and the effect of the coating on the operational properties of tools equipped with these inserts during finish impact-free turning of aluminum alloy AK12M2MgN and technical ceramics MK90 was studied. It is shown that the presence of a coating on the tool during the processing of aluminum alloy allows to obtain processed surfaces with less roughness, and during the processing of technical ceramics to increase the wear resistance of tools by 1.52–1.75 times, which expands the area of use and ensures increased efficiency of the tool equipped with diamond polycrystals. The temperature limit for the synthesis of coatings is set to 1175 °C, exceeding which contributes to the formation of a coating with worse operational properties.
Keywords: diamond, CVD coating, polycrystal, turning, tool wear.
UDC 621.923
G. D. Ilnytska, V. V. Smokvina, V. I. Lavrinenko, O. B. Loginova, S. O. Lysovenko, V. V. Belorusets, S. P. Staryk*
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*s.starik@ukr.net
Content and composition of intracrystalline inclusions and impurities in low-strength diamond grinding powders (pp. 92-104)
The surface condition of low-strength diamond grinding powders obtained in the Ni–Mn–C system was investigated, the content and composition of their intracrystalline inclusions and impurities were determined before and after thermochemical treatment in an alkaline melt. It was established that the non-combustible residue of diamond powders is dominated by elements of the carbon solvent alloy, they make up from 93.6 to 58.5% of the total amount. In the initial fractions in the composition of inclusions and impurities of diamond powders, the ratio between Ni and Mn remains at the level characteristic of the composition of the growth medium, but after thermochemical treatment, the non-combustible residue in magnetic fractions contains more Mn. The content of carbon solvent alloy elements (Mn + Ni) is reduced in the initial fraction by almost two times, in the magnetic fraction by 2%, and in the non-magnetic fraction by approximately 17%. According to the data of X-ray spectral microanalysis, after treatment at a temperature of 800 °C, inclusions containing Ni and a small amount of Mn appear first on the surface of diamond crystals, followed by inclusions of the solvent alloy enriched in Mn. The appearance of such inclusions and the sequence of their appearance on the surface are explained by the peculiarity of the distribution of components in the phases of Ni–Mn–C system alloys and the phenomenon of capillary extrusion, which after annealing is also observed on the surface of diamond crystals obtained in other growth media. It is shown that after thermochemical treatment in an alkaline melt due to the dissolution of the selected inclusions, the content of the unburned residue decreases by approximately 2 times and the magnetic properties of diamond powders weaken by 1.4 times. Diamond crystals containing a smaller amount of intracrystalline impurities and inclusions have greater strength. The total content of inclusions and impurities in the unburned residues of diamond grinding powders before and after thermochemical treatment decreases by 2.4 times, and the content of t of alloy elements of carbon solvent – 1.6 times. It is possible to determine the content and composition of intracrystalline inclusions in samples of diamond grinding powders more accurately after thermochemical treatment.
Keywords: diamond, grinding powders, intracrystalline inclusions, impurities, thermochemical treatment, strength, unburned residue, ratio between Ni and Mn, capillary extrusion.
UDC 546.22/.27:620.193:666.3-135
V. L. Solozhenko
LSPM–CNRS, Université Sorbonne Paris Nord, Villetaneuse, France
vladimir.solozhenko@univ-paris13.fr
On the melting of boron chalcogenides B6S and B6Se under pressure (pp. 105-107)
The melting of new boron chalcogenides, orthorhombic B6S and B6Se, was investigated at pressures up to 8 GPa using in situ electrical resistance measurements. It was found that above 2.5 GPa both chalcogenides melt congruently, and the melting curves have a negative slope (–61(5) K/GPa for B6S and –80(2) K/GPa for B6Se), indicating a higher density of the melts compared to the solid phases. The melting points at atmospheric pressure were estimated to be 2190(30) K for B6S and 2347(12) K for B6Se.
Keywords: boron chalcogenides, melting, high pressure, high temperature.