| 1. |
- Bushlya, V., et al.
(författare)
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On chemical and diffusional interactions between PCBN and superalloy Inconel 718 : Imitational experiments
- 2019
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219. ; 39:8, s. 2658-2665
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Tidskriftsartikel (refereegranskat)abstract
- During a metal cutting process, chemical wear can become the dominant mechanism of tool degradation under the high temperatures and contact pressures that arise between the tool and the metal workpiece. This study focuses on the chemical and diffusional interactions between superalloy Inconel 718 and cubic boron nitride (cBN) tool material with and without TiC binder. It covers thermodynamic modeling and experimental tests in the pressure range of 0.1 Pa to 2.5 GPa at temperatures up to 1600 °C. The methods used include diffusion couples under both vacuum and high pressure, transmission electron microscopy (TEM) analysis and in-situ synchrotron observations. It is shown that cBN is prone to diffusional dissolution in the metal and to reactions with niobium, molybdenum, and chromium from Inconel 718. Adding TiC binder changes the overall degradation process because it is less susceptible to these interaction mechanisms.
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| 2. |
- Dub, S. N., et al.
(författare)
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Theoretical shear strength and the onset of plasticity in nanodeformation of cubic boron nitride
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:2, s. 88-98
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Tidskriftsartikel (refereegranskat)abstract
- The nanoindentation in the continuous stiffness measurement mode was used to investigate the onset of plasticity at the nanodeformation of cubic boron nitride (cBN). This technique allows us to reveal an elastic-plastic transition in the contact and to measure the yield strength of cBN at the nanoscale. An abrupt elastoplastic transition (a pop-in) was observed in the (111) cBN single crystal as a result of a homogeneous or heterogeneous nucleation of dislocations in the previously dislocations-free region under the contact. The analysis of the data obtained at the homogeneous nucleation of dislocations in the contact region made it possible to experimentally estimate the theoretical shear strength of cBN and its ideal (elastic) hardness. In a sample of the fine-grained cBN with a nanotwinned substructure a smooth elastoplastic transition was observed in consequence of the propagation and multiplication of already existing dislocations in the contact region.
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| 3. |
- Kolabylina, T., et al.
(författare)
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Superhard pcBN tool materials with Ti3SiC2 MAX-phase binder : Structure, properties, application
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:3, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Superhard cutting tool materials were sintered in cBN–(Ti3SiC2–TiC) system via high pressure–high temperature method. Sintering was performed under the pressure 8 GPa in the 1400–2400°C temperature range. The initial mixtures of three compositions were chosen with 90, 80 and 60 vol % cBN. The mixtures were prepared by mixing cBN (1–3 μm) and Ti3SiC2–TiC (< 2 μm). It was found, that upon sintering, the compositions of the obtained samples differed from the initial mixtures in all cases as a result of chemical reactions. Microstructure observations, phase composition estimation, and mechanical properties of the obtained tool materials were carried out. The results indicate that both the varying cBN content and the applied sintering conditions have a direct effect on the structure, properties, and kinetics of reactions.
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| 4. |
- Kryzhanivskyy, V., et al.
(författare)
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Modelling and Experimental Investigation of Cutting Temperature when Rough Turning Hardened Tool Steel with PCBN Tools
- 2015
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Ingår i: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 489-495
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Konferensbidrag (refereegranskat)abstract
- In this study the cutting tool temperature that develops during rough turning of hardened cold-work tool steel is modelled on the basis of experimental data. The data obtained from a series of thermocouples, placed on a PCBN insert, into an anvil, and into a toolholder, were used as the input for the model. An inverse problem was solved, where the heat fluxes and heat transfer coefficients were computed and where the developed temperature field was reconstructed from the experimental readings. The temperature was modelled for the case of new tools, as well as for the case of its development in the course of tool wear. The machining case involved utilization of a high-cBN content and a binderless PCBN grade, both possessing high thermal conductivity of 110 and 190 W/m K respectively. (C) 2015 The Authors. Published by Elsevier B.V.
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| 5. |
- Slipchenko, K. V., et al.
(författare)
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Особливості формування структури та фазового складу в процесі реакційного спікання кубічного нітриду бору зі сполуками Ti, Cr, V
- 2018
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Ingår i: Metallofizika i Noveishie Tekhnologii. - : National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka). - 1024-1809. ; 40:8, s. 1081-1091
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Tidskriftsartikel (refereegranskat)abstract
- Influence of sintering temperature on both phase composition and structure of ceramic matrix composites based on cubic boron nitride with binders in a form of Al and the Ti, Cr, V carbides are investigated by methods of physical materials science. As the object of study, three cBN–TiC–Al, cBN–Cr3C2–Al, cBN–VC–Al compositions containing 60% vol. cBN are selected. The composites are obtained by high-pressure high-temperature (HPHT) sintering in high-pressure apparatus AVTT-30 in the temperature range of 1600– 2450°C under pressure of 7.7 GPa. In the process of HPHT sintering of composites in the cBN–TiC–Al and cBN–Cr3C2–Al systems, the formation of titanium and chromium diborides is found at the temperatures of sintering Тsint ≥ 1850°С and Тsint ≥ 2150°С, respectively, simultaneously with the formation of alu-minium nitride.
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| 6. |
- Turkevych, Dmytro, et al.
(författare)
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HP-HT sintering, microstructure, and properties of B6O- and TiC-containing composites based on cBN
- 2015
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Ingår i: Journal of Superhard Materials. - 1934-9408. ; 37:3, s. 143-154
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Tidskriftsartikel (refereegranskat)abstract
- The article presents a study of the potential for the use of B6O superhard boron suboxide as a binder in composite materials with a low cBN content. Superhard B6O is characterized by higher mechanical properties than TiC widely used in commercial materials today. Composites containing 60 vol % cBN and different binder compositions that included B6O and TiC have been sintered in a toroid-type high-pressure apparatus at a pressure of 7.7 GPa in a temperature range from 1500 to 2000 A degrees C. The microstructure, phase and elemental composition of the sintered materials have been examined via electron microscopy and X-ray diffraction analysis. Mechanical properties have been analyzed via indentation techniques. The performance of the cutting tools produced from the sintered composites has been evaluated in turning hardened cold work tool steel.
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