The melting of boron carbide and the homogeneity range of the boron carbide phase

Bouchacourt, M.; Thévenot, F.

doi:10.1016/0022-5088(79)90007-9

Cited by 49 publications

(20 citation statements)

References 5 publications

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“…Formation of additional intermediate phases with crystal symmetry other than

R \overset{true¯}{3} m

, such as a monoclinic modification of B 13 C 2 , has also been reported. These variations have been reflected in several versions of the B–C phase diagram reported in the literature; Fig. shows examples of the two more commonly used phase diagrams .…”

Section: Atomic Structure Stoichiometry and Polytypismmentioning

confidence: 99%

Boron Carbide: Structure, Properties, and Stability under Stress

et al. 2011

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Boron carbide is characterized by a unique combination of properties that make it a material of choice for a wide range of engineering applications. Boron carbide is used in refractory applications due to its high melting point and thermal stability; it is used as abrasive powders and coatings due to its extreme abrasion resistance; it excels in ballistic performance due to its high hardness and low density; and it is commonly used in nuclear applications as neutron radiation absorbent. In addition, boron carbide is a high temperature semiconductor that can potentially be used for novel electronic applications. This paper provides a comprehensive review of the recent advances in understanding of structural and chemical variations in boron carbide and their influence on electronic, optical, vibrational, mechanical, and ballistic properties. Structural instability of boron carbide under high stresses associated with external loading and the nature of the resulting disordered phase are also discussed.

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“…Formation of additional intermediate phases with crystal symmetry other than

R \overset{true¯}{3} m

Section: Atomic Structure Stoichiometry and Polytypismmentioning

confidence: 99%

Boron Carbide: Structure, Properties, and Stability under Stress

et al. 2011

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“…Boron carbide rhombohedral phase exists over a large range of stoichiometry: the literature reports boron carbides from 8.6 to 18.8 at.%C [27,28] even if precise boundaries are still under debates [29]. These stoichiometry changes in boron carbide are thought to be accomodated thanks to local disorder in the structure [30].…”

Section: Computational Detailsmentioning

confidence: 99%

The influence of irradiation induced vacancies on the mobility of helium in boron carbide

Gillet

Roma

Crocombette

et al. 2018

Journal of Nuclear Materials

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Boron carbide, used as a neutron absorber, undergoes nuclear reactions producing relevant quantities of He. The understanding of He kinetics at the atomic scale in the material is still in its infancy, in spite of decades of experimental work devoted to the characterization of He containing, irradiated, boron carbide samples. The interplay of He itself with intrinsic defects created by irradiation on kinetics is still almost completely unknown. In this paper we present an exhaustive study of vacancies and substitutional helium impurities in boron carbide using Density Functional Theory. Analyzing the stability and mobility of these defects allows us to consider diffusion mechanisms other than the known interstitial mechanisms. We find that vacancies trap He interstitials, raising the activation energy of 2D diffusion to approximately 2 eV. The trapping mechanism is different according to the charge state of the vacancy : in p-type conditions, when vacancies are neutral or positive, He diffuses via a dissociative mechanisms and is trapped in a substitutional position; in n-type conditions, negative vacancies trap He atoms traveling in an adjacent {111} plane by a charge transfer driven distorsion. No favorable vacancy assisted diffusion mechanism was identified for substitutional He atoms, except the dissociative one previously mentioned. Other possible vacancy diffusion mechanisms, which we also analyzed, are hindered by the high activation energy of vacancy self-diffusion.

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“…Figure 1 shows a B-C phase diagram with a homogeneity range of 8.8-20% at. C [1,[4][5][6][7][8][9] and a diagram including low-temperature phases (i.e., boron rich boron carbides) [6]. Due to its attractive properties, it can be used in many advanced industries, which may include nuclear power, military industry, or medicine [1,4,5,[10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Effect of Expanded Graphite on the Reaction Sintering of Boron Carbide

et al. 2022

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This paper presents novel results of research focused on reaction sintering of a mixture of expanded graphite and amorphous boron. It has been shown that as a result of combining the synthesis from the elements with sintering under pressure, dense boron carbide polycrystals (95% TD) can be obtained in which stable structures dominate, i.e., boron carbides of stoichiometry B13C2 and B4C. Sintering was carried out on boron excess systems, and reaction mixtures with the following mass ratios (B:C = 5:1; 10:1; and 15:1) were used. Boron excess systems were used due to the presence of additional carbon during sintering since the matrix, reactor lining, and heating elements were made of graphite. 1850 °C was considered to be the optimum reaction sintering temperature for all of the systems tested. This shows that a reduction in the sintering temperature of 200–300 °C was observed with respect to traditional sintering techniques. Micro-cracks are present in the sinters, the presence of which is most likely due to the difficulty in removing the gaseous products which accompany the boron carbide synthesis reaction. The elimination of these defects of sintering requires further research.

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The melting of boron carbide and the homogeneity range of the boron carbide phase

Cited by 49 publications

References 5 publications

Boron Carbide: Structure, Properties, and Stability under Stress

Boron Carbide: Structure, Properties, and Stability under Stress

The influence of irradiation induced vacancies on the mobility of helium in boron carbide

Effect of Expanded Graphite on the Reaction Sintering of Boron Carbide

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