Synthesis of boron suboxide (B6O) with alkaline earth metal oxide materials with improved properties

Journal article

Authors / Editors

Ogunmuyiwa, Enoch

Research Areas

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Publication Details

Author list: Ogunmuyiwa EN, Johnson OT, Sigalas I

Publisher: Taylor and Francis Group

Place: PHILADELPHIA

Publication year: 2019

Journal: Particulate Science and Technology (0272-6351)

Journal acronym: PARTICUL SCI TECHNOL

Volume number: 37

Issue number: 1

Start page: 60

End page: 67

Number of pages: 8

ISSN: 0272-6351

eISSN: 1548-0046

Languages: English-Great Britain (EN-GB)

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Abstract

The pure boron suboxide (B6O) powder admixed with 1.08 vol% of MgO, CaO, and CaCO3 (corresponding to 1.5, 1.4, and 0.7 wt%, respectively) were synthesized by hot-pressing and the mechanical properties were evaluated. Pure B6O powders were sintered at a temperature of 1900 degrees C, while the B6O-alkaline earth metal oxide admixed powders were sintered at a temperature of 1850 degrees C. All sintering was done under an applied load of 80 MPa in an argon environment. The microstructures and phase analyses were studied by scanning electron microscopy and X-ray diffraction techniques, respectively. The addition of the alkaline earth metal oxide additives resulted in the formation of boride and borate phases, depending on the oxide used. The mechanical properties of the hot-pressed materials were characterized based on their density, hardness, and fracture toughness. Between 95 and 98% of the theoretical densities were achieved and the result indicate a good combination of hardness (between 31.6 and 32.1 GPa) and fracture toughness (between 6.1 and 6.8 MPa.m(0.5)) in the B6O-alkaline earth metal oxide materials. The introduction of the additive enhances the fracture toughness of the pure B6O-materials, while the fracture mode observed in the sintered materials is mainly transgranular.

Keywords

Alkaline earth metal oxide, Boron suboxide, Fracture toughness, transgranular

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