Influence of silica sources on morphology of mullite whiskers in Na2SO4 flux

Zhang, Pengyu; Liu, Jiachen; Du, Haiyan; Li, Zhongqiu; Li, Shun; Chen, Chao

doi:10.1016/j.jallcom.2009.04.138

Cited by 24 publications

(21 citation statements)

References 19 publications

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“…1(b)) reveals that it is composed of Si and O with an atomic ratio of O:Si of 2:1. Therefore, mullite clusters with undissolved silica enwrapped in the center are formed using common silica as the silica source, which is consistent with a previous study [21].…”

Section: Phase and Microstructure Characterizationsupporting

confidence: 91%

“…A similar phenomenon has been reported in the literature for mullite synthesis through a solid-state reaction [21]. However, the formation mechanism for the MSS method has not been reported up to now.…”

Section: Formation Mechanism Of Mullite Nanowhiskers Using Different supporting

confidence: 82%

“…However, the previous studies mainly focused on the preparation of mullite using different molten salt systems. It was pointed out that silica with different crystal structures plays an important role in determining the morphology of mullite whiskers [21], but no further study has been reported.…”

Section: Introductionmentioning

confidence: 99%

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Molten salt synthesis of mullite nanowhiskers using different silica sources

Yang

Qiu

Zhang

et al. 2015

Int J Miner Metall Mater

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Mullite nanowhiskers with Al-rich structure were prepared by molten salt synthesis at 1000°C for 3 h in air using silica, amorphous silica, and ultrafine silica as the silica sources. The phase and morphology of the synthesized products were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. A thermogravimetric and differential thermal analysis was carried out to determine the reaction mechanism. The results reveal that the silica sources play an important role in determining the morphology of the obtained mullite nanowhiskers. Clusters and disordered arrangements are obtained using common silica and amorphous silica, respectively, whereas the use of ultrafine silica leads to highly ordered mullite nanowhiskers that are 80−120 nm in diameter and 20−30 μm in length. Considering the growth mechanisms, mullite nanowhiskers in the forms of clusters and highly ordered arrangements can be attributed to heterogeneous nucleation, whereas disordered mullite nanowhiskers are obtained by homogenous nucleation.

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Section: Phase and Microstructure Characterizationsupporting

confidence: 91%

Section: Formation Mechanism Of Mullite Nanowhiskers Using Different supporting

confidence: 82%

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Molten salt synthesis of mullite nanowhiskers using different silica sources

Yang

Qiu

Zhang

et al. 2015

Int J Miner Metall Mater

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“…By repeating this oxidation-dissolution cycle, the active Si has been etched completely and the inert mullite whiskers has been grown continuously. This repeated oxidationdissolution mechanism is different from the commonly accepted mechanism of mullite whiskers formation [13], raw material Si powders could be oxidized by SO 3 which originated from the decomposition of Al 2 (SO 4 ) 3 . Thus, mullite nuclei form in the mixture molten salts and mullite whiskers could grow continuously depending on oxidation-dissolution cycle.…”

Section: Formation Mechanism Of Mullite Whiskersmentioning

confidence: 80%

“…As a new ceramic powder synthesis method, molten salt synthesis has been employed to synthesize ceramic powders because it decreases reaction temperature and gives powders of homogeneous morphology [8]. Mullite whiskers formation in molten salts system has been extensively studied [9][10][11][12][13]. But earlier studies focused on utilizing SiO 2 as raw material, there was no report about the preparation of mullite whiskers from Si powders by molten salt synthesis.…”

Section: Introductionmentioning

confidence: 99%

Mullite whiskers prepared by molten salt method using Si powders

Wang

Guo

et al. 2012

J Adv Ceram

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Mullite whiskers were prepared from Si powders in molten Al 2 (SO 4 ) 3 -Na 2 SO 4 mixture salts with different Al/Si molar ratio (R) of raw materials. The resulting mullite whiskers, had been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and infrared spectroscopy analysis (FT-IR). Mullite phase was obtained in molten salts when the temperature reached at 850 ℃. SEM and EDS results revealed that two kinds of microstructures were formed in the final product, Al-rich mullite pellets and clusters of tiny mullite crystals, and the content of Al-rich mullite pellets increased with the higher Al/Si molar ratio (R) adopted in raw materials. A new oxidation-dissolution mechanism was proposed to explain mullite whiskers growth. According to thermodynamic analysis, mullite phase might be spontaneously formed as the temperature reached the decomposition temperature of aluminum sulfate (1023 K).

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Preparation of mullite whiskers and their enhancement effect on ceramic matrix composites

Zhang

Zhang³

et al. 2013

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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Influence of silica sources on morphology of mullite whiskers in Na2SO4 flux

Cited by 24 publications

References 19 publications

Molten salt synthesis of mullite nanowhiskers using different silica sources

Molten salt synthesis of mullite nanowhiskers using different silica sources

Mullite whiskers prepared by molten salt method using Si powders

Preparation of mullite whiskers and their enhancement effect on ceramic matrix composites

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