UDC 539.5:661.657
E. Kishor, N. Swaminathan*
Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India
*n.swaminathan@iitm.ac.in
A molecular dynamics based comparison of the mechanical properties of three polytypes of cubic BC3 (p. 3–21)
In this work molecular dynamics simulations are employed to compare the mechanical properties and hardness of three polytypes of cubic BC3. Firstly, two interatomic Tersoff potentials, with different parameterizations, were identified from the literature for the boron–carbon system. Based on cohesive energies and structural properties from existing ab-initio studies, the suitability of the two potentials for predicting the properties of BC3 was analyzed. Secondly, using the better interatomic potential, more detailed molecular dynamics simulations were conducted to estimate and compare the elastic, yield, post-yield behavior and hardness of the three polytypes. The elastic constants compare well with existing ab-initio values and vary by at most by 15% among the three polytypes. Response to indentation showed considerable qualitative differences in yield and post-yield response. One of the polytypes showed lower yield strength and seemed more ductile than the other two. The hardness also showed a complex dependence on both the material and the indentation depths. A peculiar, indenter-size dependent pile-up behavior was also seen. Specifically, for lower radii, pile-up was seen on indentation. As the radius of the indenter was increased, pile-up was seen only on retracting the indenter. The higher volume occupied by the indentation-amorphized material was found to be the reason for pile-up on retracting the indenter.
Keywords: superhard materials, elastic constants, hardness, molecular dynamics, boron-doped diamond.
UDC 661.657.5/636:537.533.35
V. L. Solozhenko1, *, V. Bushlya2
1LSPM–CNRS, Université Paris Nord, Villetaneuse, France
2Division of Production and Materials Engineering, Lund University, Lund, Sweden
*vladimir.solozhenko@univ-paris13.fr
Mechanical properties of boron phosphides (pages 22–28)
Microstructure and mechanical properties of bulk polycrystalline boron phosphides (cubic BP and rhombohedral B12P2) have been studied by scanning electron microscopy and micro- and nanoindentation. The obtained data on hardness, elastic properties and fracture toughness clearly indicate that both phosphides belong to a family of hard phases and can be considered as prospective binders for diamond and cubic boron nitride.
Keywords: boron phosphides, hardness, elastic moduli, fracture toughness.
UDC 539.23:620
A. A. Onoprienko*, V. I. Ivashchenko, A. O. Kozak, A. K. Sinelnichenko, T. V. Tomila
Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Kyiv, Ukraine
*onopr@ipms.kiev.ua
Deposition and characterization of thin Si–B–C–N films by dc reactive magnetron sputtering of composed Si/B4C target (p. 29–38)
The effect of the gas mixture composition on the structure, chemical bond character and hardness of Si–B–C–N films was systematically studied. A series of Si–B–C–N films was deposited by reactive dc magnetron sputtering of the target composed of Si disc with B4C chips placed in the sputtering zone of the disc. The films were deposited with nitrogen fractions 30-to-70% in Ar/N2 gas mixture and annealed in a vacuum at temperatures up to 1200°C. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, indentation tests. Addition of nitrogen in the gas mixture up to 60% led to an increase of hardness from 13.4 up to 17.8 GPa. With further increase in nitrogen content in gas mixture the film hardness decreased. The latter is caused by the formation of the weak B–N bonds as well as C–C and C=C bonds that are characteristic for h-BN-like phase and graphite phase, respectively.
Keywords: Si–B–C–N films, reactive magnetron sputtering, N2 content, structure, chemical bonding, hardness.
UDC 620.178.16:621.921.34-488:621.793.3
Kong Dejun*, Zhao Wen, Zhang Ling
School of Mechanical Engineering, Changzhou University, Changzhou, China
*kong-dejun@163.com
Friction-wear behaviors of chemical vapor deposited diamond films at high temperatures (p. 39–48)
A diamond film was deposited on a YT14 hard alloy cutting tool using a chemical vapor deposition. The coefficients of friction and wear behaviors of the obtained diamond films at 500, 600, and 700 °C were investigated using a high-temperature tribological tester. The results show that the C of diamond film is fully released at 700 °C, generating CO and CO2. The (220) plane of diamond film is oxidized fully at 500 °C, while the (110) plane of diamond film is oxidized at 700 °C. The average coefficients of friction of diamond film at 500, 600 and 700 °C are 0.55, 0.49, and 0.48, respectively, the wear mechanism is primarily oxidation wear, adhesive wear and abrasive wear, accompanied with fatigue wear.
Keywords: chemical vapor deposition (CVD), diamond film, coefficient of friction, high temperature, friction and wear, wear mechanism.
UDC 66925/27.539
M. M. Prokopiv, O. V. Kharchenko*
Institute of Superhard Materials named after V. M. Bakul, NAS of Ukraine, Kyiv, Ukraine
*keramtex@ukr.net
**injenner214@bigmir.net
Features of the influence of sintering conditions of fine-grained hard alloy WC–10Co on its structure, physical-mechanical and operational characteristics (pp. 49–58)
The results of the study of the influence of the environment during sintering of fine-grained hard alloy WC–10Co on its structural characteristics and physical-mechanical properties, as well as the operational stability and wear mechanisms of cutting inserts made of this alloy during impact cyclic turning of parts made of 40X steel are presented. It is shown that sintering of hard alloy in vacuum, compared to sintering in a methane-hydrogen environment, reduces the residual microporosity of its structure, increases the physical-mechanical properties and operational stability of cutting inserts made of it. A new phenomenon has been discovered – the formation of continuous chips under conditions of intermittent turning of parts made of 40X steel and welding it to the working part of the cutting insert made of hard alloy WC–10Co, sintered in vacuum, and the absence of such a phenomenon for the alloy sintered in a methane-hydrogen environment.
Keywords: sintering, methane-hydrogen environment, vacuum, hard alloy, operational stability, cyclic turning, wear, gas desorption.
UDC 620.22:669.018.25
S. A. Davydenko
Institute of Superhard Materials named after V. N. Bakulya NAS of Ukraine, Kyiv, Ukraine
snesha@.ism.kiev.ua
On the stability of isolated pores in sintered hard alloys (Ti,W)C–WC–Co (pp. 59–64)
Studies of the sintered hard alloy (Ti,W)C–WC–Co are presented. It has been proven that in this alloy, during the period of liquid-phase sintering, stable isolated pores can appear that are not filled with molten cobalt. The condition under which the isolated pores are filled with molten cobalt is determined, which guarantees the production of non-porous hard alloys.
Key words: sintered hard alloys, structure, isolated pore.
UDC 621.941
L. N. Devin*, N. THERE ARE. Stakhnyv, A. WITH. Antoniuk, S. IN. Rychev, V. N. Nechiporenko
Institute of Superhard Materials named after IN.N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*ldevin@ism.kiev.ua
Effect of cutting speed on temperature and cutting force during finishing turning of titanium alloy VT1-0 with a cutter with a diamond-hard alloy plate (pages 65–73)
The regularities of changes in temperature, cutting force, and roughness of the machined surface depending on the cutting speed during finishing turning of titanium alloy VT1-0 with a cutter with a diamond-hard alloy plate are established. The optimal cutting modes are substantiated.
Key words: turning, titanium alloy, diamond carbide plate, cutting temperature, cutting force, roughness.
UDC 621.9: 621.923
IN. AND. Lavrinenko
Institute of Superhard Materials named after V.M. Bakulya National Academy of Sciences of Ukraine, m. Kyiv, Ukraine
lavrinenko@ism.kiev.ua
Porosity and water absorption of composites for instrumental purposes as factors for increasing the wear resistance of grinding wheels with NTM. Communication 1. Abrasive composites with NTM (pp. 74–82)
The conditions for using the porosity of abrasive composites from superhard materials in the process of water absorption are determined for the first time. It is shown how the physical and mechanical properties (hardness, strength indicators, electrical conductivity) of composites change under the influence of water absorption, the duration of this effect is determined, and the conditions for increasing their wear resistance in a grinding tool are investigated.
Keywords: abrasive composites with NTM, water absorption effect, porosity, composite properties, wear resistance.
UDC 621.658.012.531
S. S. Samotugyn1, V. I. Lavrinenko2, *, O. A. Khristenko1, Yu. WITH. Samotugina1
1Priazov State Technical University, Pryazovsky State Technical University, Mariupol, Ukraine
2Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*lavrinenko@ism.kiev.ua
Increasing the durability of carbide thread cutters by plasma surface modification (p. 83–90)
The results of calculations and durability tests of threaded profile cutters with brazed carbide plates after plasma surface modification are presented. A 2.15–2.5 times increase in the resistance of the cutters compared to the initial state was established (according to the criteria of optimal and equal wear). After regrinding, the durability of the cutters decreases due to a decrease in the hardness of the cutting edges, remaining significantly higher compared to the original cutters.
Key words: cutter, threading, plasma, hardening, hard alloy.
UDC 546.27.18:544.225
B. A. Kulnitskiy1, 2, I. A. Perezhogin1, 2, 3, V. D. Blank1, 2, V. A. Mukhanov4, V. L. Solozhenko 4, *
1Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Russia
2Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
3International Laser Center, Lomonosov Moscow ow State University, Moscow, Russia
4LSPM–CNRS, Université Paris Nord, Villetaneuse, France
*vladimir.solozhenko@univ-paris13.fr
Nanotwinning in boron subphosphide B12P2 (pages 91–94)
Microstructure of boron subphosphide B12P2 produced by self-propagated high-temperature synthesis has been studied by high-resolution transmission electron microscopy. Two systems of twins have been found i.e. conventional twins on the (0003)h plane and nanotwins resulting from duplication of the rhombohedral unit cell of B12P2 along one of the basic vectors.
Keywords: boron subphosphide, transmission electron microscopy, nanotwinning.