Oxidation resistance of B6O-materials with different additives

Herrmann, Matthias; Thiele, Maik; Jaenicke-Roessler, K.; Freemantle, C.S.; Sigalas, Iakovos

doi:10.1016/j.jeurceramsoc.2011.03.029

Cited by 18 publications

(8 citation statements)

References 21 publications

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“…These light elements have the ability to form covalently bonded 3D networks with a high atomic density and extreme resistance to external shear. B 6 O is a particularly promising material system for light‐weight armor applications as it has a high hardness, low density, high mechanical strength, high oxidation resistance (<1200°C), and chemical inertness . However, unlike other high‐performance ceramics, B 4 C and B 6 O display low fracture toughness and a reduction in shear strength under extreme high temperature and pressure environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

2015

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The structural, electronic, and elastic properties of pristine and carbon‐doped boron suboxide (B6O) are calculated using density functional theory. The results indicate that it is energetically preferable for a single carbon atom to substitute into an oxygen site rather than a boron site. The lattice parameters and cell volume increase to relieve the residual stress created by the carbon substitution. The interstitial position is not favorable for a single atom substitution. However, if two carbon atoms substitute for two neighboring oxygen atoms, then it becomes energetically favorable to dope an interstitial oxygen, boron, or carbon atom along the C–C chain. If the interstitial dopant is either boron or carbon, a local B4C‐like structure with either a C–B–C or C–C–C chain is created within the boron suboxide unit cell. The resulting structure shows improvements in the bulk modulus at the expense of the shear and Young's moduli. The moduli further improve if an additional carbon is substituted within a polar or equatorial site of the neighboring B12 icosahedron. Based on these calculations, we conclude that carbon doping can either harden or soften B6O depending on the manner in which the substitutions are populated. Furthermore, as B6O samples are often oxygen deficient, C doping can occupy such sites and improve the elastic properties.

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Section: Introductionmentioning

confidence: 99%

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

2015

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“…Moisture content was also shown to influence reactions and evaporation involving B 2 O 3 . 19) Considering the above observations, in our case it is probable that different quality of the raw powders and of their mixture when compared with literature and also specific unconventional features of SPS mentioned in Introduction are responsible for the observed effects.…”

Section: Low Temperature In-situ Reactive Spsmentioning

confidence: 62%

B6O ceramic by in-situ reactive spark plasma sintering of a B2O3 and B powder mixture

Solodkyi

Borodianska

Zhao

et al. 2014

J. Ceram. Soc. Japan

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A mixture of B 2 O 3 and amorphous B with the mole ratio of 1:14 is shown to react and form B 6 O ceramic under in-situ spark plasma sintering (SPS) conditions. The optimum SPS temperature and time to obtain phase B 6 O are 1250°C and 30 min, respectively, and Rietveld refinement of the XRD patterns indicates that the oxygen occupancy of B 6 O x is reasonably high at x = 0.89(99). However, to reach high density above 98%, SPS temperatures of 17001800°C are necessary and a one-step twotemperature in-situ reactive SPS was designed and applied. As-prepared B 6 O dense ceramic has Vickers hardness (36.7 « 1.2 GPa) and fracture toughness (K 1c = 4.2 « 0.15 MPa.m 1/2) comparable with the highest values reported in literature for the bulks obtained by processing routes of already reacted B 6 O powders (ex-situ routes).

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“…Therefore, the evaporation of B 2 O 3 is not fast enough to prevent the transformation. Additionally, the evaporation of B 2 O 3 strongly depends on the moisture content [ 49 , 50 ].…”

Section: Discussionmentioning

confidence: 99%

On the Stability of c-BN-Reinforcing Particles in Ceramic Matrix Materials

2018

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Cubic boron nitride (c-BN) composites produced at high pressures and temperatures are widely used as cutting tool materials. The advent of new, effective pressure-assisted densification methods, such as spark plasma sintering (SPS), has stimulated attempts to produce these composites at low pressures. Under low-pressure conditions, however, transformation of c-BN to the soft hexagonal BN (h-BN) phase can occur, with a strong deterioration in hardness and wear. In the present work, the influence of secondary phases (B2O3, Si3N4, and oxide glasses) on the transformation of c-BN was studied in the temperature range between 1100 °C and 1575 °C. The different heat treated c-BN particles and c-BN composites were analyzed by SEM, X-ray diffraction, and Raman spectroscopy. The transformation mechanism was found to be kinetically controlled solution–diffusion–precipitation. Given a sufficiently low liquid phase viscosity, the transformation could be observed at temperatures as low as 1200 °C for the c-BN–glass composites. In contrast, no transformation was found at temperatures up to 1575 °C when no liquid oxide phase is present in the composite. The results were compared with previous studies concerning the c-BN stability and the c-BN phase diagram.

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Oxidation resistance of B6O-materials with different additives

Cited by 18 publications

References 21 publications

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

Carbon Doping in Boron Suboxide: Structure, Energetics, and Elastic Properties

B<sub>6</sub>O ceramic by <i>in-situ</i> reactive spark plasma sintering of a B<sub>2</sub>O<sub>3</sub> and B powder mixture

On the Stability of c-BN-Reinforcing Particles in Ceramic Matrix Materials

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