Reactivity of aluminum sulfate and silica in molten alkali-metal sulfates in order to prepare mullite

Ouatib, Rachida El; Guillemet, Sophie; Durand, Bernard; Samdi, A.; Rakho, Lahcen Er; Moussa, Rédouane

doi:10.1016/j.jeurceramsoc.2003.12.002

Cited by 34 publications

(21 citation statements)

References 29 publications

(25 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Particle size of the amorphous silica, quartz and fused silica powders was 20-30 m. First, Al2(SO4)3·18H2O were calcined at 300 • C for 3 h to obtain Al2(SO4)3. According to the former research results that the Si-rich composition is beneficial for needlelike mullite grains formation [15,16], the constant composition [Al2(SO4)3:SiO2 = 2.5:1(wt%)] was employed in all samples. For the samples with various Na2SO4 contents, Al2(SO4)3 and Na2SO4 by weight percentage (wt%) as 2.5:14, 2.5:7, 2.5:3.5, and 2.5:1.75 were used and present by solid circles in Al2(SO4)3-Na2SO4 phase diagram [17] (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…However, the morphology of the whiskers was observed to be different in K 2 SO 4 and Na 2 SO 4 flux. Ouatib et al prepared mullite whiskers by reaction of aluminum sulfate and amorphous silica in molten eutectic (Na 0.8 ,K 0.2 ) 2 SO 4 [15]. While the effect of molten salts on morphology of mullite whiskers has been demonstrated, the influence of raw materials was scarcely reported.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Zhang

Liu

et al. 2009

Journal of Alloys and Compounds

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Zhang

Liu

et al. 2009

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…It is well known that dissolved chemical reagents present in the molten salt system can easily react with each other and transform via precipitation [18]. According to the Al 2 (SO 4 ) 3 −Na 2 SO 4 phase diagram, the eutectic point of this system is 650°C.…”

Section: Formation Mechanism Of Mullite Nanowhiskers Using Different mentioning

confidence: 99%

Molten salt synthesis of mullite nanowhiskers using different silica sources

Yang

Qiu

Zhang

et al. 2015

Int J Miner Metall Mater

View full text Add to dashboard Cite

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.

show abstract

“…The images show the needle-like appearances of mullite whiskers clusters with diameters in the range of 100-200 nm and lengths in the range of 2-5 μm. And the micrographs also reveal the presence of two kinds of particles: plate-like crystals and clusters of smaller angular crystals [10]. When the R value is 3 (Fig.…”

Section: Ft-ir Analysismentioning

confidence: 93%

“…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

View full text Add to dashboard Cite

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).

show abstract

Reactivity of aluminum sulfate and silica in molten alkali-metal sulfates in order to prepare mullite

Cited by 34 publications

References 29 publications

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

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

Molten salt synthesis of mullite nanowhiskers using different silica sources

Mullite whiskers prepared by molten salt method using Si powders

Contact Info

Product

Resources

About