Liquid phase assisted densification of superhard B6O materials

Herrmann, Matthias; Raethel, Jan; Bales, Axel; Sempf, Kerstin; Sigalas, Iakovos; Hoehn, Mandy

doi:10.1016/j.jeurceramsoc.2009.03.002

Cited by 29 publications

(26 citation statements)

References 14 publications

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“…XRD pattern of the densified materials showed the formation of CoB as a secondary phase by the additives [23]. In the materials, borides are formed independently if cobalt metal, oxide or boride was added [23]. This means that the boride is in equilibrium with B 6 O, and is liquid under the sintering conditions thus being able to accelerate the sintering process.…”

Section: Resultsmentioning

confidence: 99%

“…The resulting sintered materials had improved fracture toughness (3-5 MPa m 1/2 ) and only a slight reduction in Vickers microhardness (31 GPa under 500 g load) in comparison to pure B 6 O materials (34 GPa) [16][17][18]23,26]. The investigation of the microstructure reveals that the material was densified predominantly by liquid phase sintering.…”

Section: Introductionmentioning

confidence: 99%

“…The investigation of the microstructure reveals that the material was densified predominantly by liquid phase sintering. Herrmann et al [23] have shown that different transition metals can also be suitable sintering additives. Independently if the additives are oxides or metals they will be converted during sintering into borides according to reactions:…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Boron suboxide materials with Co sintering additives

Johnson

Sigalas

Ogunmuyiwa

et al. 2010

Ceramics International

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Boron suboxide materials with Co sintering additives

Johnson

Sigalas

Ogunmuyiwa

et al. 2010

Ceramics International

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“…An example is the full densification of boron suboxide (B 6 O) showing very high-hardness values of up to 45 GPa achieved in graphite dies by FAST/SPS whereas the synthesis in HP requires expensive hexagonal BN dies. [51] Additional thermal effects in FAST/SPS are related to high local temperature gradients or non-uniform temperature distribution as well as macroscopic temperature fields creating thermal stresses. [52] Temperature gradients in the sample can be evaluated by Finite-Element Modeling, as shown in Section 4.…”

Section: Thermal Effectsmentioning

confidence: 99%

Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

et al. 2014

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Field-assisted sintering technology/Spark plasma sintering is a low voltage, direct current (DC) pulsed current activated, pressure-assisted sintering, and synthesis technique, which has been widely applied for materials processing in the recent years. After a description of its working principles and historical background, mechanical, thermal, electrical effects in FAST/SPS are presented along with the role of atmosphere. A selection of successful materials development including refractory materials, nanocrystalline functional ceramics, graded, and non-equilibrium materials is then discussed. Finally, technological aspects (advanced tool concepts, temperature measurement, finite element simulations) are covered.

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“…13)19) In addition, another advantage of SPS is that controversial spark or spark plasma effects are generated between particles to facilitate the sintering process and aid in the elimination of surface impurities, leading to enhanced sintering and consolidation. 20) 25) Recently, Herrmann and coworkers 26) To overcome the problem of low fracture toughness while maintaining the high hardness of the B 6 O material, two approaches were proposed in this study. In the first approach, B 6 OB 4 C composites were fabricated to prevent the formation of B 2 O 3 -triple junctions and to simultaneously assist the formation of high-hardness B a C b phases.…”

Section: )8)mentioning

confidence: 99%

Synthesis of B6O powder and spark plasma sintering of B6O and B6O–B4C ceramics

Solodkyi

Xie

Zhao

et al. 2013

J. Ceram. Soc. Japan

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Hard boron suboxide (B 6 O) is a difficult-to-consolidate ceramic material that requires extreme processing conditions to achieve sintering activation and is only consolidated readily at high pressures above 4 GPa. In this contribution, for the first time, we report the consolidation of hard and tough laboratory-synthesized B 6 O by the spark-plasma sintering (SPS) technique. The density of SPS-sintered specimens of >= 98% is reported, and an optimal combination of 34 GPa hardness and 4 MPa·m 1/2 fracture toughness is achieved by controlling the amount of glassy phase boron oxide (B 2 O 3 ) with an appropriate SPS set up. The effects of the type of protection used, i.e., graphite die lined only with graphite foil, BN coating, or tantalum foil, on the phase compositions and properties of bulk were studied. Finally, composites of boron suboxide and boron carbide, B 6 OxB 4 C (x = 0, 3, 5, 10, 20, 40 wt %) were fabricated by SPS, and a significant improvement in the mechanical properties was achieved. Results showed that dense B 6 O10 wt %B 4 C composite material with a hardness above 40 GPa and a fracture toughness of 4.8 MPa·m 1/2 were obtained.

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Liquid phase assisted densification of superhard B6O materials

Cited by 29 publications

References 14 publications

Boron suboxide materials with Co sintering additives

Boron suboxide materials with Co sintering additives

Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

Synthesis of B<sub>6</sub>O powder and spark plasma sintering of B<sub>6</sub>O and B<sub>6</sub>O–B<sub>4</sub>C ceramics

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