UDC 549.21:539.4.015
S. M. Dub1, *, A. S. Nikolenko2, P. M. Lytvyn2, S. O. Ivakhnenko1, V. V. Strelchuk2, O. M. Suprun1, V. V. Lysakovsky1, I. M. Danylenko2
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2V. E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine
*lz@ism.kiev.ua
Shear metallization on the (001) and (111) facets of diamond during hardness testing
Shear metallization on the (001) face of diamond single crystals of types Ib, IIa and IIb during hardness testing has been studied for the first time. The study was conducted using Vickers and Berkovich indenters on single crystals of diamond grown by the temperature gradient method. In the Raman spectra for impressions on the (001) face of diamond, complex-shaped intense photoluminescence was detected, which complicates the identification of phonon bands of the sp2-phase of carbon. It was possible to reliably detect the sp2-phase of carbon in impressions on the (001) face only for type IIb diamond when using the Berkovich indenter. It was found that for type IIb diamond, graphitization during hardness tests on the (001) face is significantly weaker than on the (111) face. The recorded photoluminescence signal with a maximum of ~ 510 nm may be evidence of the formation of a mixed sp2/sp3-phase of amorphous carbon at the initial stage of graphitization in impressions on the (001) face of diamond.
Keywords: diamond, hardness, Mott transition, diamond metallization, Raman spectroscopy.
UDC 666.798.3:621.762.5
Zeynep Aygüzer Yaşar1, Richard A. Haber2,*
1Present Address: Department of Metallurgical and Materials Engineering, Hitit University, Corum, Turkey
2Department of Material Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, USA
*rich.haber@rutgers.edu
Effect of sintering temperature and applied pressure on the properties of boron carbide and silicon carbide composites
A spark plasma sintering method was used to obtain high-density silicon carbide composites. The mixtures 50B4C–1.5C–48.5SiC (% (wt)) were sintered at different (1800, 1850, 1900, 1950 °C) temperatures and a pressure of 50 MPa and at different (20, 30, 40 and 50 MPa) pressures and a constant temperature of 1950 °C. The boron carbide–silicon carbide composites reached full (> 99 %) density at a temperature of 1950 °C and a pressure of 50 MPa. The samples were characterized using SEM, XRD and ultrasonic analysis. The density, Vickers and Berkovich hardness and fracture toughness were also evaluated. Ultrasonic analysis showed that increasing the sintering temperature and applied pressure increases the elastic, shear and full compression moduli of the composites. The samples compacted at 1950 °C and 50 MPa had elastic moduli of 409 GPa, shear moduli of 176 GPa, and overall compressive moduli of 203 GPa. With increasing sintering temperature and pressure, the hardness and fracture toughness of the composites also increased. The Vickers hardness values increased sharply from 17.55 GPa (1800 °C) to 30.78 GPa (1950 °C) with increasing sintering temperature. The highest (37.37 GPa) Berkovich hardness value was obtained in the sample sintered at 1950 °C and 50 MPa. However, the highest calculated fracture toughness value was 2.64 MPa×m1/2.
Keywords: silicon carbide, boron carbide, spark plasma sintering, mechanical properties, microstructure.
UDC 621.762.4
V. V. Ivzhenko1,*, E. S. Gevorkyan2, T. O. Kosenchuk1
1V.M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Ukrainian State University of Railway Transport, Kharkiv, Ukraine
*ivv@ism.kiev.ua
Sintering and properties of materials based on silicon, boron and titanium carbides obtained by the method of electric spark sintering
The features of electric spark sintering of materials based on silicon carbide with additives of boron and titanium carbides were studied. The titanium carbide impurity activates the process of densification of silicon carbide and deactivates the process of densification of a mixture of silicon and boron carbides at the initial stage of sintering. The structure and physical and mechanical properties of materials of the SiC–В4С–(0–15% (by weight))ТiС systems have been studied. Titanium carbide inhibits the growth of silicon carbide grains by approximately 3 times, which increases the crack resistance of silicon carbide with impurities of boron and titanium carbides by 40–45%. A material with a crack resistance of 6.3 MPa·m1/2 and increased wear resistance was obtained.
Keywords: silicon carbide, boron carbide, titanium carbide, electric spark sintering, temperature, densification, structure, porosity, crack resistance, wear resistance.
UDC 666.798.2:621.762.4:621.9.025.7
Bin Fang*, Zhonghang Yuan, Liying Gao, Depeng Li, Yuanbin Zhang
School of Mechanical & Automotive Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
*fb@qlu.edu.cn
Microstructure and mechanical properties of (Ti,W)C-based cermet tool materials reinforced with c-BN
The effect of c-BN addition on the microstructure and mechanical properties of (Ti,W)C-based cermet tool materials manufactured by hot pressing was investigated. With the addition of c-BN, the mode of The composite structure changes from intergranular to transgranular. The main strengthening mechanism is the overlapping of particles, deflection and bifurcation of cracks, which improve the fracture toughness of the metal-ceramic tool material. Proper addition of c-BN can improve the mechanical properties of the composites. When the c-BN content is 1.5% (wt%), the (Ti,W)C-based metal-ceramic tool materials achieve optimal comprehensive mechanical properties. The hardness, bending strength and fracture toughness are 19.78 GPa, 987 MPa and 9.44 MPa·m1/2, respectively.
Keywords: c-BN, carbide, hot pressing, mechanical properties, microstructure.
UDC 620.22-621.921.34
B. T. Ratov1, V. A. Mechnyk2,, M. O. Bondarenko2, V. M. Kolodnitsky2,*, M. O. Kuzin3, E. S. Gevorkyan4, V. A. Chyshkala5
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
3Lviv Branch of Dnipro National University of Railway Transport named after Acad. V. Lazaryan, Lviv, Ukraine
4Ukrainian State University of Railway Transport, Kharkiv, Ukraine
5Kharkiv National University named after V. N. Karazin, Kharkiv, Ukraine
*vlad.me4nik@ukr.net
**vasylkolod56@gmail.com
The influence of VN additive on the structure and strength characteristics of diamond-containing composites based on the Fe‒Cu–Ni–Sn matrix, formed by cold pressing with subsequent vacuum hot pressing
By the method of cold pressing with subsequent vacuum hot pressing, samples of composite diamond-containing materials with a diameter of 10 mm and a thickness of 8 mm were developed based on the matrix 51Fe–32Cu–9Ni–8Sn (% (by weight)) with different (from 0 to 10%) vanadium nitride content, the physical and mechanical properties of which depend on the composition of the metal matrix. The optimal (CVN = 4 %) concentration of vanadium nitride in the matrix of composites sintered in the temperature range of 20‒1000 °C at a pressure of 30 MPa for 5 min was established, at which the indicators of the physical and mechanical properties of the composites (Rbm = 1110 MPa and Rcm = 1410 MPa) are the highest due to the dispersion mechanism of strengthening and modification of the structure (reduction of the average grain size, disappearance of pores, formation of clusters of the inhibitor phase at the interphase boundaries) and the phase composition of the composites. In addition, all sintered samples containing VN powder additives in the composition of the charge are characterized by a more uniform phase distribution and a more dispersed structure compared to the sample not containing VN powder additives in the composition. It is shown that the structure of composites containing the VN additive consists of a solid solution of nitrogen and vanadium in α-iron and a mixture of Fe, Cu, Ni, Sn phases, primary and secondary dispersed phases of vanadium nitride.
Keywords: composite, iron, copper, nickel, tin, composition, vanadium nitride, concentration, vacuum hot pressing, structure, properties.
UDC 621.623
Yu. D. Filatov, V. I. Sidorko, S. V. Kovalev, V. A. Kovalev
Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
*filatov@ism.kiev.ua
The influence of the structure of the processed material on the polishing performance of optical surfaces
As a result of studying the regularities of the influence of the structure of the processed material on the polishing performance and roughness of polished surfaces of optical parts and elements made of glass, sieves, optical and semiconductor crystals, it was found that the removal performance of the processed material increases linearly with an increase in the size of the slurry particles. It is shown that the volumetric wear coefficient with an increase in the transfer energy decreases significantly during the polishing of optical and semiconductor crystals and decreases slightly during the polishing of optical glass and sieves. It is shown that the roughness parameters of polished surfaces increase linearly with an increase in the distance between the layers of molecular fragments or interplanar distances in the processed material. It was established that the ratio η/Ra does not depend on the distance between the layers of molecular fragments in amorphous materials and increases linearly with increasing interplanar distance in crystals.
Keywords: polishing, structure, polishing performance, surface roughness.
UDC 621.923
V. I. Lavrinenko1, *, O. O. Pasichny1, V. G. Poltoratsky1, V. Yu. Solod2, **, V. L. Dobroskok3, ***, E. V. Ostroverkh3
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
2Dnipro State Technical University, MES of Ukraine, Kamianske, Ukraine
3National Technical University “Kharkiv Polytechnic Institute” MES of Ukraine, Kharkiv, Ukraine
*lavrinenko@ism.kiev.ua
**v_solod@ukr.net
***vldob314@gmail.com
Features of the relationship between the roughness parameters of the treated surface under the condition of grinding with wheels made of a mixture of NTM grinding powders with a modified grain surface
Features of the relationship between the main height parameters of roughness Rmax and Ra, between the step Sm and the height parameter Ra during end grinding were investigated grinding wheels made of superhard materials, as well as the conditions under which deviations from the established ratios Rmax and Ra and Sm and Ra occur. It is shown that the ratio Rmax and Ra is almost not affected by the change in the grain composition of the working layer of the wheel, and the ratio Sm and Ra depends on the presence of a mixture of NTM grains in the working layer or on the modification of their surface. It is found that under standard conditions the average step of irregularities Sm increases with an increase in the parameter Ra in all studied cases. The conditions of forced influence on the cutting layer of the wheel to reduce the step of irregularities Sm with an increase in the parameter Ra are given.
Keywords: surface roughness, roughness parameters, grinding powders of superhard materials, modified surface of grains.
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
Oxidation resistance of solid boron chalcogenides B6X and B12X (X = S, Se)
The oxidation resistance of new boron chalcogenides, orthorhombic B6X and rhombohedral B12X (X = S, Se), was studied using thermal analysis (TG-MS). It was found that in air, boron sulfides remain stable up to ~ 580 °C, while boron selenides begin to oxidize already at a temperature of ~ 550 °C.
Keywords: boron chalcogenides, oxidation resistance, thermal analysis.
UDC 548.736.15:531.748
P. M. Lytvyn1, V. V. Strelchuk1, S. O. Ivakhnenko2, A. S. Nikolenko1, T. V. Kovalenko2,*1V. E. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine
2V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*tetiana.v.kovalenko@gmail.com
Using digital micro-photogrammetry to analyze the morphology of grown single crystals of HPHT-diamond
The possibility of using digital micro-photogrammetry to analyze and model the habit and sectoral structure of single crystals of diamond with a size of up to 20 mm, which was obtained at high pressures and temperatures (HPHT-diamond crystals), is considered. The prospects of such a method for developing cutting maps for cutting single-sector samples and their further use are shown.
Keywords: close-range photogrammetry, diamond single crystals, sectorial structure, morphology.