Formation of micron-sized and nanometer-sized single crystal alumina whiskers by displacement reactions

Ng, Dickon H. L.; Ma, Ning; Lo, CM; Kwok, W. Y.; Yau, M.Y.; To, C.Y.; Li, T.K.; Deng, Chengji

doi:10.1016/j.jeurceramsoc.2005.03.233

Cited by 10 publications

(3 citation statements)

References 31 publications

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“…The growth of the fibers/whiskers was found to be mostly in the [0 0 1] direction through the VLS mechanism [10][11][12][13][14][15]18 or through a mechanism that is analogous to Ostwald ripening. 16,17 Both of these mechanisms are categorized as tip growth models, resulting in characteristic round droplets or slight sharp curvatures on the tips of the fibers/whiskers. A similar method (basal growth) of growing ␣-Al 2 O 3 whiskers in an aluminum-based MMC has been reported using an internal oxidation reaction between aluminum and molybdenum oxide (MoO 3 ) at 850 • C. 19 The ␣-Al 2 O 3 whiskers obtained were, on average, 1 m in diameter and 10 m in length.…”

Section: Introductionmentioning

confidence: 99%

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Yang

Tsai

et al. 2011

Journal of the European Ceramic Society

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Section: Introductionmentioning

confidence: 99%

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Yang

Tsai

et al. 2011

Journal of the European Ceramic Society

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“…This sample showed not only the SiC whiskers, but also the formation of submicrometer-sized single-crystal alumina whiskers (3 ~ 6 μm in length and 0.2 ~ 1.2 μm in diameter), as presented in Figure 4F. The specific mechanism for the alumina whiskers has been revealed by Ng et al 27 According to their theory, the remaining liquid aluminum would react with SiO vapor to form Al 2 O 3 precursors through Reaction 7. When the newly formed Si enters the molten Al, the viscosity of the melt would be decreased, favoring the nucleation and growth of whiskers.…”

Section: Phases and Microstructure Evolutionmentioning

confidence: 58%

Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles

Bao

Bao³

et al. 2019

Int J Applied Ceramic Tech

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With the aim to achieve the application of low carbon Al2O3‐C refractory as submerged entry nozzle (SEN) materials, a comprehensive study on the microstructure, thermo‐mechanical properties, as well as application performance during use in the continuous casting was carried out by comparing with the traditional one. Both hot and cold modulus of ruptures of the low carbon Al2O3‐C refractory were superior to the traditional one, and its thermal shock resistance still kept in an acceptable level. The increase in the amount of SiC whiskers and the enhancement in the sintering are considered as the strengthening mechanism. In the industrial trial, the rapid loss of graphite caused by the large level fluctuation made the traditional Al2O3‐C refractory more susceptible to flux corrosion. For the low carbon Al2O3‐C refractory, however, the dense structure and the adhesion of viscous slag layer suppressed the slag penetration. Besides, the remaining SiC phases were also difficult to be wetted and dissolved by the flux. As a consequence, a better corrosion resistance was obtained, achieving a decrease of 27.6% in the average depth of the corrosion groove after working for 8 hous.

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“…Simultaneously, at 800°C, reactions of Al with CO or O2 form various gaseous Al2O, AlO, and AlO2 [15,16]. The Al2O gas is vital for whisker formation since this species is responsible for mass transport in the vapor phase.…”

Section: Mgalon Whiskermentioning

confidence: 99%

Whisker Bond: From Findings to Concept in Refractories

Guo,

Wei

2024

Recent Prog Mater

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Ceramic bonds are conventionally formed during the burning of refractory bricks and by using pre-fabricated blocks or monolithic lining, which is characterized as the coalescence of the particles by liquid sintering. However, the whisker bond was discovered with the outstanding performance of unburnt periclase–spinel–Al bricks while substituting magnesia–chrome bricks in the chromium-free campaign of refractory lining of RH degassers. Thanks to the prominent effect of the whisker bond, such a refractory material demonstrates ultrahigh hot strength, high resistance to slag penetration, and thermomechanical stress. Investigations reveal the initial melting of metal Al at the melting point of 660°C, aluminum liquid rims around the cavities formed before ~800°C, gaseous AlN yielded and distributed throughout the matrix with increasing temperature, gaseous Mg reduced from ~1000°C, and MgAlON whiskers eventually formed in the matrix. Microstructure observations show a dense interwoven whiskers bonded matrix in most residual parts of the used periclase–spinel–Al bricks. The whisker network in the matrix is made up of straight columns of 1–5 µm in diameter and 20–40 µm in length, which is different from birdnesting, nano-size curly whiskers observed in the past. The findings suggest a whisker-bond concept in terms of the bond mode of the whisker network and the process of the vapor-solid forming mechanism.

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Formation of micron-sized and nanometer-sized single crystal alumina whiskers by displacement reactions

Cited by 10 publications

References 31 publications

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles

Whisker Bond: From Findings to Concept in Refractories

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Formation of micron-sized and nanometer-sized single crystal alumina whiskers by displacement reactions

Cited by 10 publications

References 31 publications

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Growth mechanism of single-crystal α-Al2O3 nanofibers fabricated by electrospinning techniques

Microstructure, properties, and application of low carbon Al2O3‐C refractories used as submerged entry nozzles

Whisker Bond: From Findings to Concept in Refractories

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Product

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Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles