Effects of boron addition on some properties of hard-type carbons

Hagio, Tsuyoshi; Ogawa, Ichitaro; Kobayashi, Kazuo

doi:10.1007/bf01106521

Cited by 3 publications

(3 citation statements)

References 10 publications

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“…B 4 C was not dissolved with 7N HNO 3 , but dissolved with molten sodium carbonate . In addition, boron substituted in the MWCNTs was not dissolved with molten sodium carbonate . The pulverized sample was dissolved with molten sodium carbonate in a platinum crucible to remove boron substituted in the MWCNTs.…”

Section: Methodsmentioning

confidence: 99%

“…The boron atom enters the graphite lattice in the high temperature range of 1800 to 2350 °C, which results in a substitution in natural graphite with a maximum substitution of 2.35 at% (2.12 wt %) at 2350 °C in a vacuum . Additionally, boron promotes the graphitization of carbon materials and acts as a sintering agent at a temperature of at least 2000 °C when the mixture of carbon materials and boron sources such as boron, , boron carbide (B 4 C), , or boric acid (H 3 BO 3 ) is sintered by a heating and pressing treatment under atmospheric pressure using an inert gas. Endo’s results are quite intriguing because DWCNTs reacted with boron to change into a new structure while keeping the nanotube within the moderate temperature range of 1400–800 °C, suggesting that the reactivity of the nanotube surface with a large curvature is higher than that of graphite , and that a moderate temperature prevents the DWCNT from undergoing phase transition to graphite under ordinary pressure.…”

Section: Introductionmentioning

confidence: 99%

“…13 In addition, boron substituted in the MWCNTs was not dissolved with molten sodium carbonate. 6 The pulverized sample was dissolved with molten sodium carbonate in a platinum crucible to remove boron substituted in the MWCNTs. The cake in the crucible was dissolved with distilled water.…”

Section: ' Introductionmentioning

confidence: 99%

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Boron-Assisted Transformation to Rod-Like Graphitic Carbons from Multi-Walled Carbon Nanotubes in Boron-Mixed Multi-Walled Carbon Nanotube Solids

Sato

Nishizaka

Motomiya

et al. 2011

ACS Appl. Mater. Interfaces

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We produced boron-mixed multi-walled carbon nanotube solids (B-mixed MWCNT solids) by heating and pressing the powder of purified MWCNTs mixed with 1, 5, and 10 wt % boron in the temperature range 1400-1800 °C every 200 °C under a constant pressure of 20 MPa in vacuo, and investigated the influence of boron addition on nanotube structure and the mechanical and electrical properties of the resulting B-mixed MWCNT solids. The structure of the prepared material was characterized by scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy-electron energy loss spectroscopy, Raman scattering spectroscopy, and X-ray diffraction, and their mechanical properties and conductivity were measured using a mechanical and Vickers indentation tester and an electric resistor, respectively. It is notable that part of the nanotubes in the B-mixed MWCNT solids solidified at 1800 °C had dramatically changed into rod-like graphitic carbons (RLGCs). The occupancy distribution of RLGCs increased with increasing boron contents. However, boron was not detected in the energy-loss near-edge structure spectrum of RLGCs. Furthermore, RLGCs were not observed in the boron-unmixed sample treated with the same solidified condition, indicating that adding boron causes a remarkable ability to transform the phase of MWCNT. Transformation from MWCNTs to RLGCs resulted in increased specific bending strength and modulus, Vickers hardness, and electrical conductivity of B-mixed MWCNT solids with increasing boron content and solidified temperature.

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Section: Methodsmentioning

confidence: 99%