Direct synthesis of fine boron carbide powders using expanded graphite

Gubernat, Agnieszka; Pichór, Waldemar; Zientara, Dariusz; Bućko, Mirosław M.; Zych, Łukasz; Kozień, Dawid

doi:10.1016/j.ceramint.2019.07.227

Cited by 11 publications

(14 citation statements)

References 28 publications

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“…The hardness of the commercial boron carbide is up to 35 GPa. [ 53 ] For all the compositions, there is a clear tendency of the hardness increase with the increase in the used additive. The lowest hardness values were recorded for the boron‐enhanced composites; for 20% B addition, the hardness equaled 29.4 GPa.…”

Section: Resultsmentioning

confidence: 99%

Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering

et al. 2022

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Composites based on boron carbide (B 4 C) have drawn attention due to their outstanding physical and chemical properties. Herein, the effect of adding boron, titanium, and both titanium and boron, on the B 4 C-based material, is investigated. In addition, the additives' influence on the temperature of composite synthesis and the whole sintering process is evaluated. The Ti-B 4 C composites are prepared by two different methods: pressureless sintering and hot pressing. The presence of Ti, B, and C as dominant additives in the sintered composites is confirmed by X-ray diffraction and scanning electron microscopy (SEM). The SEM examination reveals that TiB 2 particles formed during the composite process synthesis are distributed homogeneously in the B 4 C matrix. Mechanical properties, such as hardness, Young's modulus, and fracture toughness are tested, along with the composites' density and porosity. All the sintered samples, regardless of the incorporated additives, are characterized by high mechanical properties, reaching outstanding values in a few cases. The obtained results allow us to state that the usage of a boron and titanium mixture significantly improves the sintering process of composites due to the reactive sintering phenomenon occurring during the composites' preparation. The Ti-B 4 C composites are classified as ultrahigh-temperature ceramics materials.

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Section: Resultsmentioning

confidence: 99%

Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering

et al. 2022

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“…On the other hand, however, [46] proposes another mechanism for the synthesis of boron carbide using a specific form of carbon (i.e., expanded graphite). The work [47] proposed a mechanism for the synthesis of boron carbide using expanded graphite in a layered system. Basing on the experiments, it was concluded that the transport of carbon towards boron and thus the process of carbon incorporation into the rhombohedral structure of boron is very likely.…”

Section: Discussionmentioning

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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“…Boron carbide powders are rarely prepared via direct synthesis from the elements. Such synthesis is more efficient and can occur in the temperature range of 1200-1500 • C if reactive carbon forms, such as carbon nanotubes [14], amorphous carbon [15], or expanded graphite [16], are used as carbon substrates or when advanced synthesis techniques, such as CVD [17] or mechanical alloying [18], are used. Good results, especially for the synthesis of boron-rich fine nanoparticles, are obtained from the application of amorphous boron and soot in the form of loose beds where the transfer of both reagents through a gas phase occurs.…”

Section: Introductionmentioning

confidence: 99%

Boron-Rich Boron Carbide Nanoparticles as a Carrier in Boron Neutron Capture Therapy: Their Influence on Tumor and Immune Phagocytic Cells

et al. 2021

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The aim of the work was to study the interaction between boron-rich boron carbide nanoparticles and selected tumor and immune phagocytic cells. Experiments were performed to investigate the feasibility of the application of boron carbide nanoparticles as a boron carrier in boron neutron capture therapy. Boron carbide powder was prepared by the direct reaction between boron and soot using the transport of reagents through the gas phase. The powder was ground, and a population of nanoparticles with an average particle size about 80 nm was selected by centrifugation. The aqueous suspension of the nanoparticles was functionalized with human immunoglobulins or FITC-labeled human immunoglobulins and was then added to the MC38 murine colon carcinoma and to the RAW 264.7 cell line of mouse macrophages. Flow cytometry analysis was used to determine interactions between the functionalized boron carbide nanoparticles and respective cells. It was shown that B4C–IgG nanoconjugates may bind to phagocytic cells to be internalized by them, at least partially, whereas such nanoconjugates can only slightly interact with molecules on the cancer cells’ surface.

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Direct synthesis of fine boron carbide powders using expanded graphite

Cited by 11 publications

References 28 publications

Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering

Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering

Effect of Expanded Graphite on the Reaction Sintering of Boron Carbide

Boron-Rich Boron Carbide Nanoparticles as a Carrier in Boron Neutron Capture Therapy: Their Influence on Tumor and Immune Phagocytic Cells

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Direct synthesis of fine boron carbide powders using expanded graphite

Cited by 11 publications

References 28 publications

Effect of Additives on the Reactive Sintering of Ti–B4C Composites Consolidated by Hot Pressing and Pressureless Sintering

Effect of Additives on the Reactive Sintering of Ti–B4C Composites Consolidated by Hot Pressing and Pressureless Sintering

Effect of Expanded Graphite on the Reaction Sintering of Boron Carbide

Boron-Rich Boron Carbide Nanoparticles as a Carrier in Boron Neutron Capture Therapy: Their Influence on Tumor and Immune Phagocytic Cells

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Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering

Effect of Additives on the Reactive Sintering of Ti–B₄C Composites Consolidated by Hot Pressing and Pressureless Sintering