Borides of the IVb Group

Makarenko, G. N.

doi:10.1007/978-3-642-66620-9_18

Cited by 22 publications

(7 citation statements)

References 42 publications

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“…In Fig. 3a, 3b, 3c our experimental results are given in comparison with literature data [1,2,[3][4][5][6][7][8][9][10][11][12][13][14][15] where the spread is significant especially for σ = 13 at.%. Such spread is not typical for crystals of covalent bonds.…”

Section: Resultsmentioning

confidence: 72%

“…Boron carbide (structural type B 4 C) is a phase of variable composition with wide range of homogeneity (8-20 at.%) [1,2] that corresponds to B 11.5 C -B 4 C. A wide spread in B/C ratio means that structural type remains uncharged and ordering of carbon atoms can take place in a different fashion which sufficiently influences boron carbide properties especially electrical and temperature ones [1].…”

Section: Introductionmentioning

confidence: 99%

“…The first data on crystal structure obtained by Xray diffraction [3,4] showed that boron carbide has a hexagonal system (space group R 3 m) consisting of icosahedra В 12 and linear groups C-C-C [3] or C-B-C [4] in its structure. Later, structural and spectral investigations showed that boron carbide is a phase of variable composition and its properties is a function of carbon content (σ) that can vary between 8 and 20 at.% [1,2]. Figure 1 presents a wide data spread in values reported by various authors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the largest inconsistence was for σ ≈ 10-13 at.%.…”

Section: Introductionmentioning

confidence: 99%

“…Later, structural and spectral investigations showed that boron carbide is a phase of variable composition and its properties is a function of carbon content (σ) that can vary between 8 and 20 at.% [1,2]. Figure 1 presents a wide data spread in values reported by various authors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the largest inconsistence was for σ ≈ 10-13 at.%.…”

Section: Introductionmentioning

confidence: 99%

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XRD Investigation of SHS-Produced Boron Carbide

et al. 2013

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Boron carbide with compositions corresponding to the homogeneity region in its phase diagram was obtained by self-propagating high temperature synthesis (SHS). The received samples were characterized by X-ray diffraction (XRD) analysis, lattice parameters and half-width of reflections have been investigated. The lattice parameters of boron carbide reported in the literature exhibit a too wide spread in their values for equal carbon content. It is unusually for covalent compounds such as boron carbide which has strong chemical bonds. The largest spread in lattice parameters was observed at 13.2 % (atomic) of carbon in boron carbide. In other hand, for SHS-produced samples the spread was minimal. Using XRD analysis cell parameters of boron carbide in our experiments was found to depend on carbon concentration in non-linear way. Lattice parameter was found to reach the unusually high value of 12.31 Å. The half-widths of boron carbide diffraction lines were found to depend on carbon concentration and reach their maximum values at 13.2 atomic % of carbon when the lattice is most disordered. The structure analysis allows to associate it with the process of crystal structure ordering caused by replacement of boron atoms by carbon ones during formation of boron carbide structure. The carbon atoms can be incorporated into different positions in both the linear groups and the icosahedra. In other words, some certain composition can correspond to different structure. Therefore, both experimental data and crystal-chemical considerations allow to conclude the possibility of different kinds of ordering in boron carbide structure, resulting in instability of lattice parameters and consequently in properties.

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Section: Resultsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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XRD Investigation of SHS-Produced Boron Carbide

et al. 2013

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“…Lightweight heat‐ and abrasion‐resistant materials contribute to the high‐speed operation of production machines, resulting in the enhancement of productivity. As a lightweight and heat‐resistant material, boron carbide (B 4 C) has been widely used due to its excellent mechanical properties and its low density of 2.52 Mg/m 3 . B 4 C bulk ceramics are usually prepared by sintering at high temperature above 2000 K with and without pressures of around 30 MPa …”

Section: Introductionmentioning

confidence: 99%

NaB₅C–B₅/C Composite Ceramics Prepared by Reaction Sintering in Na Vapor

2016

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Reaction sintering of sodium carbaboride (NaB 5 C) was performed by heating compacts of mixtures of amorphous boron (B) and carbon black (C) powders (B/C molar ratio, 5/1) at 1173 K in Na vapor. The ceramics obtained from the compacts of B 5 /C powder mixed with a ball mill (compact density, 1.67 Mg/m 3 ) were the composites of NaB 5 C (74 mass%) and unreacted B 5 /C (26 mass%). The bulk density and bending strength of the composite ceramics were 2.04 AE 0.03 Mg/m 3 and 320.9 AE 10.4 MPa, respectively. Transmission electron microscope observation revealed that nanometer-size amorphous grains of B or C were included in the matrix of NaB 5 C.

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