Property of SiO&lt;sub&gt;2&lt;/sub&gt;-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Powders Prepared from Metal Alkoxide

Hirata, Yoshihiro; Minamizono, Hiroshi; Shimada, Kinji

doi:10.2109/jcersj1950.93.46

Cited by 18 publications

(12 citation statements)

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“…The band at 1384cm -1, probably due to nitrate or ammonium [20], is also present as a result of the aluminium nitrate or NHgOH solution used in the co-precipitated process. After decomposition, the infrared spectrum obtained is similar to that of the mixture of 7-A1203 and amorphous SiO 2 [17]. Okada and Otsuka [21] reported that if A120 3 were substituted for SiO 2 in the amorphous solid, it would result in a shift of the Si-O vibration band from 1100 cm -1 towards 1000cm -1.…”

Section: Infrared Spectroscopy and Temsupporting

confidence: 54%

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Characteristics of mullite prepared from co-precipitated 3Al2O3·2SiO2 powders

Lee¹,

Yu²

1992

J Mater Sci

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Diphasic gels were prepared by a precipitated process from the mixed solutions of colloidal silica and aluminium nitrate. High-purity stoichiometric mullite powders were produced by calcination of the products of these gels, with an exothermic reaction occurring at 1300~ The chemical and structural evolutions, as a function of thermal treatment, have been characterized by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, infrared spectroscopy, and electron microscopy. The components of the co-precipitated gels react independently with increasing temperature up to the formation of mullite. The composition of mullite also varies with the temperature of thermal treatment. The calcined powders treated by ball-milling could be sintered into a high-density body, in spite of the occurrence of a small amount of glassy phase during sintering.

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Section: Infrared Spectroscopy and Temsupporting

confidence: 54%

“…The lattice parameters of this sample are ao =0.7542nm, b o = 0.7691 nm and c o --0.2883 nm. Cameron [16] and Hirata et al [17] reported that the value of a o is dependent on the alumina content of mullite. Hence, the A120 3 concentration in mullite can also be estimated using the lattice parameters.…”

Section: 2mentioning

confidence: 99%

Characteristics of mullite prepared from co-precipitated 3Al2O3·2SiO2 powders

Lee¹,

Yu²

1992

J Mater Sci

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“…At pH 8.3 the xerogel is as pseudoboehmite (Fig. 2), it appears at a pH value slightly lower than that obtained by Hirata et al [11]. In Hirata's work the products at pH < 9.1 were amorphous aluminium hydroxides.…”

Section: 1 Phase Transformationmentioning

confidence: 64%

“…The absence of nordstrandite throughout this study may have resulted from the lower pH used, the interference caused by the existence of silicon compounds, or the insufficient aging period. Hirata [11], however, found that the nordstrandite was present at pH values greater than 10.9. The silicon hydroxide in the xerogels exists as the amorphous phase under all conditions in this study.…”

Section: 1 Phase Transformationmentioning

confidence: 91%

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Characterization of co-precipitated Al2O3−SiO2 gels

1989

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Aluminum nitrate and tetraethyl orthoxysilane were used as starting materials. They were mixed at different ratios ranging from 1.8 to 4.8 (AI3+/Si 4+) and dissolved in ethyl alcohol. The pH of the reaction solution was also varied by the addition of ammonium hydroxide at a range of 8.3 to 10.4. Experiments were carried out at 25 and 60°C. In each case the materials were hydrolysed to a colloidal solution which was then filtrated and the resulting colloids retained on the filter as a gel which after drying at 110 ° C became a xerogel. The xerogels then were characterized by BET, SEM/TEM, and XRD/XRF.Of all the factors studied the pH of the reaction mixture was found to have the greatest affect on the morphology of the crystalline phase in the xerogels. Fibrous pseudoboehmite was found at the lower pH values of 8.3 and bayerite was present at pH value greater than 9.5 and became the predominant species at pH values greater than 10.4. The AI3+/Si 4+ ratios and the reaction temperature both affected the crystallinity of the xerogels but to a much lesser degree than did the pH.

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Preparation of SiO2-Al2O3 glass powders by the sol-gel process for dental applications

Taira

Yamaki

1995

J Mater Sci: Mater Med

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SIO2-AI203 binary glass powders with AI203 contents up to 50 wt% have been synthesized by the sol-gel process. The starting solution (sol) consisted of 1 mole of tetraethoxysilane, 50 moles of water containing aluminum nitrate, 10 moles of ethyl alcohol and 0.02 moles of HCI catalyst. The sol was converted into gel by heating at 85 °Cand suction by running water. The sintering process was analysed by DTG thermal analysis. The fired powders were examined by XRD. It was confirmed that the gels were converted into the glass structure without crystallization. The measurements of refractive index and powder size of fired powders revealed that these powders could be used as refractive-index-adjustable fillers for dental composite resins. The other potential usage of the SiO2-AI203 powders obtained might be in the production of powders for dental cements.

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Property of SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> Powders Prepared from Metal Alkoxide

Cited by 18 publications

References 0 publications

Characteristics of mullite prepared from co-precipitated 3Al2O3·2SiO2 powders

Characteristics of mullite prepared from co-precipitated 3Al2O3·2SiO2 powders

Characterization of co-precipitated Al2O3−SiO2 gels

Preparation of SiO2-Al2O3 glass powders by the sol-gel process for dental applications

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