| 1. |
- Prikhna, T., et al.
(författare)
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Effects of high pressure on the physical properties of MgB2
- 2011
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 24:5, s. 137-150
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of MgB2-based materials under high pressure gave the possibility to suppress the evaporation of magnesium and to obtain near theoretically dense nanograined structures with high superconducting, thermal conducting, and mechanical characteristics: critical current densities of 1.8-1.0×106 A/cm2 in the self-field and 103 A/cm2 in a magnetic field of 8 T at 20 K, 5-3×105 A/cm2 in self-field at 30 K, the corresponding critical fields being Hc2=15 T at 22 K and irreversible fields Hirr=13 T at 20 K, and Hirr=3.5 T at 30 K, thermal conduction of 53±2 W/(m{dot operator}K), the Vickers hardness HV=10.12±0.2 GPa under a load of 148.8 N and the fracture toughness K1 C=7.6±2.0 MPa{dot operator}m0.5 under the same load, the Young modulus E=213 GPa. Estimation of quenching current and AC losses allowed the conclusion that high-pressure-prepared materials are promising for application in transformer-type fault current limiters working at 20-30 K.
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| 2. |
- Rumiantseva, Yu Yu, et al.
(författare)
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Electrical Characteristics of Thermobarically Sintered cBN–NbN Composite
- 2020
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 42:2, s. 126-128
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Tidskriftsartikel (refereegranskat)abstract
- The structure, phase composition, and temperature dependence of electrical resistivity of the thermobarically sintered cBN–NbN composite are presented. The semiconductor character of the change in resistivity from 2.5 to 1.8 Ohm cm in the range of 300–700 K is revealed.
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| 3. |
- Rumiantseva, Yu, et al.
(författare)
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Influence of cBN content, Al2O3 and Si3N4 additives and their morphology on microstructure, properties, and wear of PCBN with NbN binder
- 2020
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842. ; 46:14, s. 22230-22238
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline cubic boron nitride (PCBN) tool materials with NbN binder without additives and PCBN with Al2O3 or Si3N4 micropowder and whisker additives were manufactured and compared. PCBN materials with Si3N4 whisker reinforcement have the best mechanical properties of all the evaluated materials. Composites reinforced with Al2O3 whiskers have the lowest fracture toughness. However, Al2O3 whisker-reinforced tools outperform both commercial and Si3N4 reinforced tools when machining hardened steel. Thus Al2O3 whisker-reinforced PCBN materials are promising for industrial applications, likely due to their higher resistance to oxidation and diffusional wear mechanisms during cutting operations.
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| 4. |
- Slipchenko, K. V., et al.
(författare)
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Sintering of BN Based Composites with ZrC and Al under High Temperatures and Pressures
- 2020
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 42:4, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The sintering of cubic boron nitride (cBN) based ceramic matrix materials with zirconium carbide and aluminum has been carried out under high pressures and temperatures. The performed study has revealed that the interaction between mixture components with the formation of a new phase, namely, zirconium diboride (ZrB2) occurs at sintering temperatures above 1750°C and an applied pressure of 7.7 GPa. A further increase in the sintering temperature leads to a growth in the volume ZrB2 content and reduces the microhardness and crack toughness of the studied materials. The flank wear of specimens under the conditions used for the processing of AISI316L stainless steel (vc = 300 m/min, t = 300 s) grows with an increase in the sintering temperature to attain the critical value VB = 325 µm, when the specimen sintered at temperature of 2300°C is used, and VB = 200 µm for the specimen sintered at 1750°C.
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| 5. |
- Slipchenko, K. V., et al.
(författare)
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Sintering of cBN Based Materials with a TaC Binder for Cutting Tool Application
- 2020
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 42:2, s. 51-57
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Ceramic matrix composites based on cubic boron nitride with a TaC binder phase are sintered under conditions of high pressure and high temperature. The sintering is carried out in a high-pressure apparatus of the toroid type in the temperature range of 1450–2450°C. It is shown that a chemical reaction between components of the mixture with the formation of TaB2 takes place at a sintering temperature above 2150°C. The microhardness of the composites increases with an increase in the sintering temperature and reaches a maximum value (34 GPa) at 2150°C. The composites show high resistance to mechanochemical wear when used for high-speed machining of nickel-based alloy Inconel 718.
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| 6. |
- 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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| 7. |
- Stratiіchuk, D. A., et al.
(författare)
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Sintering of Superhard cBN-Based Materials with Ti4WC5
- 2020
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 42:6, s. 371-376
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The physicomechanical properties and structure of superhard cBN–Ti4WC5–Al materials were studied. The materials were sintered under a pressure of 7.7 GPa within a broad range of temperatures (1600–2450°C). The formation of a dense material with high physicomechanical properties was found at a sintetring temperature of 1800°C. A further increase in the sintering temperature had a negligible effect on the properties of sintered materials. The formation of titanium diboride and a slight increase in the unit cell parameters of Ti4WC5 were revealed at sintering temperatures above 2000°C. According to X-ray diffraction analysis, this might be due to the diffusion of Al into the Ti4WC5 lattice. Cutting performance in the longitudinal turning of stainless steel AISI 316L correlated with the sintering temperature, and the average tool wear was ranged within 60–82 µm.
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| 8. |
- 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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| 9. |
- Bushlya, V., et al.
(författare)
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Sintering of binderless cubic boron nitride and its modification by β-Si3N4 additive for hard machining applications
- 2020
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Ingår i: International Journal of Refractory Metals and Hard Materials. - : Elsevier BV. - 0263-4368. ; 86
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Tidskriftsartikel (refereegranskat)abstract
- This study present the results of HP-HT sintering, microstructure, properties, and performance of binderless cBN tool material. Within the investigated sintering temperature range of 1900–2600 °C the optimum was found to be 2200–2300 °C. Lower temperature results in incomplete diffusion bonding between cBN grains, while higher temperature results in high degree of recrystallization of initial structure, grain growth, and even formation of hexagonal boron nitride in triple joints. Introduction of stress-inducing β-Si3N4 minor inclusions resulted in high overall mechanical and thermal properties: HK = 41 GPa; KIC = 12.6 MPa·m1/2; λ = 180 W/(m·K). Machining experiments in roughing of hardened tool steels show that binderless cBN material provides high performance in terms of resistance to tool cratering, chipping, and tool fracture.
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| 10. |
- 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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