Study of Reaction-Bonded Boron Carbide Properties

Golubeva, N. A.; Plyasunkova, L. A.; Kelina, I. Yu.; Antonova, E. S.; Журавлев, А. А.

doi:10.1007/s11148-015-9736-1

Cited by 15 publications

(4 citation statements)

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“…Some notable boron carbide crystal structures are tetragonal, including B 50 C 2 , B 50 C, B 48 C 3 , B 51 C, and B 49 C 3 [ 9 , 10 ]. Several theoretical and experimental studies have suggested that, as the boron to carbon ratio varies, the atomic bonding, electron density, mechanical properties, and lattice constants of boron carbide change significantly [ 11 , 12 , 13 , 14 , 15 ]. Thermodynamically, the most stable forms of boron carbide are the α-tetragonal and rhombohedral crystal structures [ 11 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

et al. 2020

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Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness.

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Section: Introductionmentioning

confidence: 99%

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

et al. 2020

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“…Phase diagrams based on alkali metal halides, metaborates and carbonates are of practical interest from the point of view of boron carbide synthesis [1][2][3], which is used for the manufacture of grinding and abrasive materials [4][5][6][7], chemical glassware, protective plates of body armor, in electronics and nuclear industry [8][9][10], in thermonuclear installations [11,12]. On the other hand, it is of interest to synthesize oxide tungsten bronzes (OTB) of alkali metals in melts of metaborates, carbonates and alkali metal halides [13], widely used as electrochromic indicators, displays, optical modulators -"smart windows", exhibiting high corrosion resistance, thermal stability in a wide temperature range, metallic and semiconductor n-type electrical conductivity.…”

Section: Introductionmentioning

confidence: 99%

Four-Component Mutual System Na, K//Cl, BO2, CO

Kochkarov¹,

Khubaeva²,

Asueva³

et al. 2019

Proceedings of the International Symposium "Engineering and Earth Sciences: Applied and Fundamental Research" Dedicated to the

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The phase diagram of a four-component reciprocal system Na, K‖Cl, BO2, CO3 into simplexes was triangulated, the main dominant chemical exchange reactions were revealed. It is shown that in a four-component reciprocal system, Na, K ‖ Cl, BO2, CO3, continuous rows of solid solutions based on sodium and potassium metaborates NaхК1-хBO2, sodium and potassium carbonates NaхК1-хСO3 are stable and do not disintegrate with the formation of eutectic. The phase diagram of the stable NaBO2-Na2СO3-КBO2-К2СO3-КCl pentatope of a four-component reciprocal system Na, К‖Cl, BO2, and CO3 was studied for the first time using the method of differential thermal analysis. It is shown that melts of a four-component reciprocal system Na, K ‖ Cl, BO2, CO3 can be used as media for the synthesis of oxide tungsten bronzes.

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“…Several theoretical and experimental studies have suggested that the atomic bonding, electron density, mechanical properties, and lattice constants of boron carbide change significantly with boron/carbon ratios. ,,− The (B 11 C) icosahedron in B 4 C satisfies Wade’s rule , (26 e within icosahedron) by transferring one electron from the C–B–C chain to form a formal C-(B+)-C closed shell chain . This seems unlikely for boron-rich boron carbide.…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains

Yang

Goddard

2018

J. Phys. Chem. C

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The atomic structures of boron carbide in the regime below ~13.3 at.% C (known as boron-veryrich boron carbide, BvrBC) have not previously been reported due to the complexity of the structure and bonding. We report here the atomistic crystal structures for stoichiometry B 14 C, with only 6.7 at.% C, predicted using quantum mechanics (QM) at the PBE level. We find that B 14 C consists of one B 12 icosahedral cluster and one C-B-B chain per unit cell. The C-B-B chain can be linear or bent, leading to two different space groups for (B 12 )CBB. Our bonding analyses show that both structures satisfy the electron counting rule (Wade's rule). However, the bent CBB chain which has lower crystal symmetry leads to an energy substantially more stable (0.315 eV per molecular unit) than the linear CBB chain structure, which has high crystal symmetry. This is because the bent CBB chain structure requires only one three-center−two-electron (3c-2e) bond while linear CBB chain structure requires three 3c-2e bonds. We predicted the mechanical properties of both structures from QM simulations. We found that shearing the linear CBB chain structure transforms first to the bent CBB chain structure under both pure and biaxial shear deformations. As the shear proceeds the icosahedra deconstruct due to the interaction of the CBB chains with the icosahedra. This suggests that the bent CBB structure is responsible for the failure processes of B 14 C.

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Study of Reaction-Bonded Boron Carbide Properties

Cited by 15 publications

References 1 publication

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

Four-Component Mutual System Na, K//Cl, BO2, CO

Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains

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Study of Reaction-Bonded Boron Carbide Properties

Cited by 15 publications

References 1 publication

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

Four-Component Mutual System Na, K//Cl, BO2, CO

Structure and Properties of Boron-Very-Rich Boron Carbides: B12 Icosahedra Linked through Bent CBB Chains

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Structure and Properties of Boron-Very-Rich Boron Carbides: B₁₂ Icosahedra Linked through Bent CBB Chains