On the Possible Nature of Armchair-Zigzag Structure Formation and Heat Capacity Decrease in MWCNTs

Ponomarev, A. N.; Egorushkin, Valeriy; Bobenko, Nadezhda; Barabashko, M. S.; Rezvanova, A. E.; Belosludtseva, Anna

doi:10.3390/ma15020518

Cited by 9 publications

(5 citation statements)

References 40 publications

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“…[ 36 , 57 ]. The MWCNTs probably decrease the thermal gradients in the ceramics during the sintering due to the better thermal and electrical conductivity of MWCNTs [ 58 , 59 , 60 ].…”

Section: Resultsmentioning

confidence: 99%

Young’s Modulus and Vickers Hardness of the Hydroxyapatite Bioceramics with a Small Amount of the Multi-Walled Carbon Nanotubes

et al. 2022

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The Vickers hardness and Young’s modulus of the hydroxyapatite (HA) bioceramics with a small amount of the multi-walled carbon nanotubes (MWCNTs) were studied by using ultramicrotester Shimadzu for dynamic tests DUH-211. Small concentrations of MWCNTs were from 0.05 to 0.5 wt.%. The argon inert atmosphere and vacuum condition were taken for the prevention of the MWCNTs oxidation. The Brunauer–Emmett–Teller (BET) surface area SBET of the HA-MWCNTs composites was determined by thermal adsorption-desorption of nitrogen. It was found that for HA-MWCNTs sintered in the Ar atmosphere, an increase in the concentration of nanotubes up to 0.5 wt.% leads to a decrease in porosity near 3 times in comparison to HA without MWCNTs additives. The small amount of additives of multi-walled carbon nanotubes leads to an increase in hardness of 1.3 times and compression strength of composite and compression strength of composite that is comparable in absolute values with the literature data of enamel hardness (3–5 GPa) and compression strength (95–370 MPa). The absolute values increase close to linearly with the increase of nanotube concentrations. The Young’s modulus of sintered composite slightly changes with the variation of concentrations of nanotubes and close to the enamel (75–100 GPa). The ratio of plastic work to total work and the ratio of elastic (reversible) work to the total work of deformation of composite HA/MWCNTs are practically constant at a studied range of MWCNTs concentration. The additives of the multi-walled carbon nanotubes lead to both an increase in the elasticity index of ~1.5 times and an increase in the resistance to plastic deformation of ~3 times, which improved the tribological performance of the surface. Plastic and elastic (reversible) work slightly changed.

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“…[ 36 , 57 ]. The MWCNTs probably decrease the thermal gradients in the ceramics during the sintering due to the better thermal and electrical conductivity of MWCNTs [ 58 , 59 , 60 ].…”

Section: Resultsmentioning

confidence: 99%

Young’s Modulus and Vickers Hardness of the Hydroxyapatite Bioceramics with a Small Amount of the Multi-Walled Carbon Nanotubes

et al. 2022

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“…The HA powder was calcinated at the temperature 850 • C for 1 h in wet atmosphere and then mixed with the MWCNTs powder [6,21,22]. MWCNTs with the mean diameter 18 nm were prepared using the chemical vapor deposition (CVD) method [23,24] and characterized by the calorimetric, scanning electron microscopy (SEM), Energy Dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy [25][26][27]. The MWCNTs powder contains a small amount of the Co/Fe catalyst (less than 0.3 wt.%) and has a high-quality surface with a small number of defects and other impurities.…”

Section: Ha-mwcnts Compositesmentioning

confidence: 99%

Composite hydroxyapatite-multi-walled carbon nanotubes: study of porosity by terahertz time domain spectroscopy

Rezvanova,

Kudryashov,

Ponomarev

et al. 2023

Nanosystems: Phys. Chem. Math.

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Optical properties of a ceramic biocomposite material based on hydroxyapatite (HA) with the additives up to 0.5 wt.% of multi-walled carbon nanotubes (MWCNTs) have been studied by terahertz timedomain spectroscopy in the frequency range 0.25 -1.1 THz. It was found that the refractive index of the composite varies between 2.6 and 2.8 depending on the porosity of the material. The absorption coefficient decreases with increasing of MWCNTs concentration in the ceramic biocomposite. The values of the refractive index and the absorption coefficient of our ceramics close to those for cortical bone, dentine and enamel. The absorption curves show frequency peaks whose positions correspond to the macrocrystallite sizes. The size of macrocrystallites decreases with increasing concentration of MWCNTs, which leads to an increase in microhardness according to the Hall-Petch equation. The time delay of the terahertz signal through the sample increases for higher concentration of MWCNTs. This indicates that nanotubes embedded into the HA matrix fill the pores and decrease the area of the pore space, which increases the density of the ceramic composite and decreases its porosity.

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“…Тип (кресло, зигзаг), размер и ориентация кристаллитовважнейшая характеристика структурного беспорядка нанотрубок [2][3][4]. В [5] Работа выполнена в рамках государственного задания ИФПМ СО РАН, FWRW-2022-0002.…”

Section: институт физики прочности и материаловедение со ран томскunclassified

THE KEY ROLE OF MICRODEFORMATIONS IN THE FORMATION OF THE DOMAIN STRUCTURE OF MWCNTs

Belosludtseva¹,

Bobenko²,

Егорушкин³

et al. 2022

Physical Mesomechanics of Materials. Physical Principles of Multi-Layer Structure Forming and Mechanisms of Non-Linear Behavior

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On the Possible Nature of Armchair-Zigzag Structure Formation and Heat Capacity Decrease in MWCNTs

Cited by 9 publications

References 40 publications

Young’s Modulus and Vickers Hardness of the Hydroxyapatite Bioceramics with a Small Amount of the Multi-Walled Carbon Nanotubes

Young’s Modulus and Vickers Hardness of the Hydroxyapatite Bioceramics with a Small Amount of the Multi-Walled Carbon Nanotubes

Composite hydroxyapatite-multi-walled carbon nanotubes: study of porosity by terahertz time domain spectroscopy

THE KEY ROLE OF MICRODEFORMATIONS IN THE FORMATION OF THE DOMAIN STRUCTURE OF MWCNTs

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