Specific signatures of α-alumina powders prepared by calcination of boehmite or gibbsite

Boumaza, A.; Djelloul, A.; Guerrab, Fahima

doi:10.1016/j.powtec.2010.03.036

Cited by 61 publications

(32 citation statements)

References 16 publications

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“…Meanwhile, there is no obvious information of Si-O bonds, which may conclude that the thickness of the layers is enough to shield Si-O groups. In addition, it is noteworthy that the bands at *640, *590, 447 are in agreement with the characteristic absorption peaks of a-Al 2 O 3 for AS-EnP and AS-EnM, which is related to heat treatment at 1200°C [28]. It is identified that Al-Si alloy particles render the component of a-Al 2 O 3 on their surfaces.…”

Section: Ftir and Xrd Investigationsupporting

confidence: 70%

“…It can be ascertained that neither the pre-oxidation layers of AS-P nor modified layers by KH560 of AS-M is sufficient to conceal the information of Si-O bonds. The absorption at 2306 cm -1 for AS-P is due to CO 2 molecular presence in air [28]. Third, the curves of AS-EnP and ASEnM reveal the same FTIR spectrum characteristic, which may predicate that the same core/shell structures are both obtained by the two synthetic methods.…”

Section: Ftir and Xrd Investigationmentioning

confidence: 75%

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Comparison of structure and phase change characteristic of microencapsulated core/shell Al–Si alloy microparticles synthesized by two methods

Sui

et al. 2015

J Sol-Gel Sci Technol

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Pre-oxidation process and modification with silane coupling agent (SCA) of original Al-Si alloy particles were selected to synthesize inorganic microencapsulated core/shell Al-Si alloy microparticles based on the sol-gel technology, respectively. The microstructure and phase change characteristic were measured and investigated by means of Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, thermogravimetry and differential scanning calorimeter. These two methods can both realize the microencapsulation and form stable dense a-Al 2 O 3 shell. It is speculated that the microencapsulated reason is mainly attributed to the change in surface electric behaviors of Al-Si alloy particles according to the results of zeta potential measure. The latent heats are 416.92 and 307.21 kJ/kg for specimens treated by pre-oxidation and the modification of SCA, respectively. The latter renders thicker and more uniform shell layer. Graphical Abstractalumina gel particles

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Section: Ftir and Xrd Investigationsupporting

confidence: 70%

Section: Ftir and Xrd Investigationmentioning

confidence: 75%

Comparison of structure and phase change characteristic of microencapsulated core/shell Al–Si alloy microparticles synthesized by two methods

Sui

et al. 2015

J Sol-Gel Sci Technol

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“…(b). The accompanied continuous weight loss of about 2 wt% is probably due to the elimination of residual hydroxyls …”

Section: Resultsmentioning

confidence: 99%

Self‐Assembled 3D Hierarchically Structured Gamma Alumina by Hydrothermal Method

Cheng

et al. 2013

J. Am. Ceram. Soc.

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Self‐assembled γ‐Al2O3 with hierarchical structure was successfully obtained via thermolysis of γ‐boehmite (γ‐AlOOH) particles, which was hydrothermally derived from aluminum ammonium sulfate hydrate (NH4Al(SO4)2·12H2O), urea, poly‐glycol (PEG)‐2000, and deionized water. SEM observations indicate that the as‐synthesized γ‐AlOOH has hierarchical flower‐like structure, composing of needle‐like building blocks. After calcinations at 800°C, it converts to cubic γ‐Al2O3 with hierarchical structure retained by a topotactical process. N2 adsorption and desorption reveal that the obtained γ‐Al2O3 has a BET surface area of 101 m2/g with a narrow mesoporous size of about 13 nm and a broad macroporous‐size distributions of 200–500 nm, respectively. The as‐generated γ‐Al2O3 with hierarchical structure shows good capacities for removing Congo red from wastewater, indicating that 3D hierarchical structure has excellent adsorption ability.

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“…The unit cell parameters found for h by Rietveld refinement compare well with those found by Willson et al 7 . This difference on crystallographic parameters has been attributed by Boumaza et al 38 to microstructural changes that frequently accompany phases transformations. This difference on crystallographic parameters has been attributed by Boumaza et al 38 to microstructural changes that frequently accompany phases transformations.…”

Section: Resultsmentioning

confidence: 85%

Characterization of the Aluminas Formed During the Thermal Decomposition of Boehmite by the Rietveld Refinement Method

Jiménez¹,

Padilla²,

López‐Delgado³

et al. 2014

Int J Applied Ceramic Tech

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Boehmite synthesized through a sol‐gel route from a nonconventional raw material, as an aluminum waste, was calcined at temperatures between 500 and 1500°C. Quantification of crystalline phases was performed by the Rietveld refinement of the XRD patterns. γ‐Al2O3 is formed at 500°C, and up to 1000°C, is the dominant phase. At temperatures ranging from 1000 to 1400°C, it was observed the appearance of a four‐phase region. The complete transformation into α‐Al2O3 lasts until 12 h at 1400°C or at higher temperatures. The presence of an amorphous phase in calcined samples was confined by direct comparison with a standard of pure α‐Al2O3.

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Specific signatures of α-alumina powders prepared by calcination of boehmite or gibbsite

Cited by 61 publications

References 16 publications

Comparison of structure and phase change characteristic of microencapsulated core/shell Al–Si alloy microparticles synthesized by two methods

Comparison of structure and phase change characteristic of microencapsulated core/shell Al–Si alloy microparticles synthesized by two methods

Self‐Assembled 3D Hierarchically Structured Gamma Alumina by Hydrothermal Method

Characterization of the Aluminas Formed During the Thermal Decomposition of Boehmite by the Rietveld Refinement Method

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