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Churkin V, Kulnitskiy B, Zinin P, Blank V, Popov M. The Effect of Shear Deformation on C-N Structure under Pressure up to 80 GPa. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:828. [PMID: 33804921 PMCID: PMC8063801 DOI: 10.3390/nano11040828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/14/2021] [Accepted: 03/20/2021] [Indexed: 11/25/2022]
Abstract
We studythe effect of shear deformation on graphitic g-C3N4 under pressures of up to 80 GPa at room temperature. g-C3N4 samples are transformed from initial amorphous flakes into onion-like structures, in which the nitrogen content in the quenched samples decreases with increasing pressure (from 42% in the initial conditions to 1% at 80 GPa). The concentration of the sp2 bonds also decreases from 1 (the initial sample) to 0.62 with increasing pressure to 80 GPa. This transformation of the sample is due to the fact that in the pressure range of 55-115 GPa, the equilibrium phase is not a diamond, but instead, carbon onions cross-linked by sp3 bonds, which are denser than diamonds. The results of our study show that the presence of nitrogen in sp3-bonded structures at pressures of higher than 55 GPa reduces the density and, accordingly, carbon structures without nitrogen become thermodynamically favorable.
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Affiliation(s)
- Valentin Churkin
- Technological Institute for Superhard and Novel Carbon Materials, Centralnaya Str. 7a, Troitsk, 142190 Moscow, Russia; (V.C.); (B.K.); (V.B.)
- Moscow Institute of Physics and Technology State University, Institutskiy per. 9, Dolgoprudny, 141700 Moscow, Russia
| | - Boris Kulnitskiy
- Technological Institute for Superhard and Novel Carbon Materials, Centralnaya Str. 7a, Troitsk, 142190 Moscow, Russia; (V.C.); (B.K.); (V.B.)
- Moscow Institute of Physics and Technology State University, Institutskiy per. 9, Dolgoprudny, 141700 Moscow, Russia
| | - Pavel Zinin
- Scientific and Technological Center of Unique Instrumentation, Russian Academy of Sciences, Butlerova str. 15, 117342 Moscow, Russia
| | - Vladimir Blank
- Technological Institute for Superhard and Novel Carbon Materials, Centralnaya Str. 7a, Troitsk, 142190 Moscow, Russia; (V.C.); (B.K.); (V.B.)
- Moscow Institute of Physics and Technology State University, Institutskiy per. 9, Dolgoprudny, 141700 Moscow, Russia
- Research Centre, National University of Science and Technology MISiS, Leninskiy prospekt 4, 119049 Moscow, Russia
| | - Mikhail Popov
- Technological Institute for Superhard and Novel Carbon Materials, Centralnaya Str. 7a, Troitsk, 142190 Moscow, Russia; (V.C.); (B.K.); (V.B.)
- Moscow Institute of Physics and Technology State University, Institutskiy per. 9, Dolgoprudny, 141700 Moscow, Russia
- Research Centre, National University of Science and Technology MISiS, Leninskiy prospekt 4, 119049 Moscow, Russia
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Electrical Discharge Machining of Oxide Nanocomposite: Nanomodification of Surface and Subsurface Layers. JOURNAL OF MANUFACTURING AND MATERIALS PROCESSING 2020. [DOI: 10.3390/jmmp4030096] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The work is devoted to the research of the changes that occur in the subsurface layer of the workpiece during electrical discharge machining of conductive nanocomposite based on alumina with the use of a brass tool. The nanocomposite of Al2O3 + 30% of TiC was electroerosively machined in a water and hydrocarbon oil. The process of electrical discharge machining is accompanied by oscillations that were registered by diagnostic means. The obtained surface of the samples was researched by the means of scanning electron microscopy and X-ray photoelectron spectroscopy. The observed surface and subsurface changes provide grounding for the conclusions on the nature of processes and reactions that occur between two electrodes and nanomodification of the obtained surfaces that can be an advantage for a series of applications.
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