Synthesis and physicomechanical properties of B4C-VB2 composites

Grigor'ev, O. N.; Kovalchuk, Vitalii; Zaporozhets, O. I.; Bega, N. D.; Galanov, Boris A.; Prilutskii, É. V.; Kotenko, V. A.; Kutran, T. N.; Dordienko, N.A.

doi:10.1007/s11106-006-0041-x

Cited by 22 publications

(18 citation statements)

References 14 publications

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“…Neither B 4 C nor TiB 2 can be obtained as a monophasic full density material, despite many methods that have been applied, such as pressure-less sintering at 2423 K [12,29], HP (Hot Pressing) [8,14,18,20,30], SPS (Spark Plasma Sintering), reaction sintering [7,14,30] etc. The combination of two different highly refractory materials i.e .…”

Section: Introductionmentioning

confidence: 99%

TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

Ziemnicka-Sylwester

2013

Materials

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TiB2-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm.

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Section: Introductionmentioning

confidence: 99%

TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

Ziemnicka-Sylwester

2013

Materials

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“…Free carbon may be present in the charge because the charge composition deviates from the optimal one as new phases form during hot pressing. Small amounts of free carbon are known to activate sintering in the system in question and to promote composites with higher mechanical properties, which is evidenced by [15]. Similar phase transformations (but without TiB 2 ) occur in the B 4 C-AlN-Si powder mixture in reaction sintering under pressure (Table 1).…”

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confidence: 84%

Production and properties of impact-resistant composites based on boron carbide and aluminum nitride

Grigor'ev

Kotenko

Shcherbina

et al. 2010

Powder Metall Met Ceram

Self Cite

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The dependence of the phase constitution and strength of B 4 C-AlN composites on the initial charge formulation and hot pressing temperature is studied. It is established that new reinforcing phases are synthesized during reaction sintering under pressure. The optimum conditions for producing B 4 C-AlN composites are determined. The composites have quite high strength margin and may be used as components of armor protection in military equipment.Boron carbide B 4 C and aluminum nitride AlN are promising refractory compounds for impact-resistant ceramic composites. The properties of B 4 C and AlN result from their constitution and electronic structure: chemical resistance, low thermal expansion coefficient, high heat conductivity, and mechanical strength. Note that boron carbide has higher hardness and brittleness than aluminum nitride [1-3].The plastic properties of materials are assessed from their hardness commonly determined by elastoplastic indentation (under small loads on the intender). For this purpose, the well-known Tabor law is used, which relates Meyer hardness (HM) to yield stress (σ s ): HM = Cσ s , where the proportionality coefficient C for ceramics varies from 1.5 to 3 depending on the ratio of HM to elastic modulus E (HM/E) [4].When the load on the indenter increases up to the maximum values at which hardness can still be measured, the hardness of brittle materials substantially decreases due to fracture in the contact area. Under this local loading, the hardness characterizes strength rather than plastic properties of ceramics.The papers [5-9] describe new contact indentation methods that have been developed to assess the quality of brittle ceramics from the hardness, size, and nature of the fractured indentation area and, thus, to examine their strength and determine important characteristics such as wear, erosion, and impact resistance [9, 10].

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“…In the literature, there are some reported fracture toughness values for the boride-based composites: spark plasma sintered NbB 2 -B 4 C composites containing 60 mol% NbB 2 have the fracture thoughness of 7.2 ± 1.2 MPa.m 1/2 calculated by Anstis method [43]. Hot-pressed B 4 C-VB 2 composites with a variable amount of VB 2 was found to have the highest fracture toughness value of 8 MPa.m 1/2 [63]. Also, the fracture toughness value of hot-pressed TiB 2 -2.5 wt.% MoSi 2 composites was reported as about 6 MPa.m 1/2 [61].…”

Section: Mechanical Properties Of the Sintered Productsmentioning

confidence: 99%

Effect of sintering techniques on the microstructure and mechanical properties of niobium borides

Balcı

Ağaoğulları

Muhaffel

et al. 2016

Journal of the European Ceramic Society

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a b s t r a c tThis study reports on the consolidation of niobium boride powders by cold pressing/pressureless sintering (PS, with or without Co addition) and spark plasma sintering (SPS) techniques. Niobium boride powders (containing NbB, Nb 3 B 4 and NbB 2 phases) which were mechanochemically synthesized from Nb 2 O 5 , B 2 O 3 and Mg blends and purified by HCl leaching were used as precursor material. The effects of different sintering techniques on the consolidation behaviour, microstructure, densification rate and mechanical properties (microhardness, wear characteristics, elastic modulus, indentation response and fracture toughness) of the bulk products were investigated. PS with Co addition resulted in superior properties than those yielded after PS without Co addition and SPS. Bulk niobium boride products having relative density of 93-98%, microhardness of 24-28 GPa, wear volume loss of 2.8-4.5 × 10 −4 mm 3 , elastic modulus of 508-552 GPa and fracture toughness of 4.05-4.74 MPa m 1/2 were obtained by Co (2 or 5 wt.%) activated PS at 1500 • C.

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Synthesis and physicomechanical properties of B4C-VB2 composites

Cited by 22 publications

References 14 publications

TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

Production and properties of impact-resistant composites based on boron carbide and aluminum nitride

Effect of sintering techniques on the microstructure and mechanical properties of niobium borides

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