TEM study of boehmite gels and their transformation to α-alumina

X. Yang; A. C. Pierre; D. R. Uhlmann

doi:10.1016/0022-3093(88)90048-8

TEM study of boehmite gels and their transformation to α-alumina

X. Yang, A. C. Pierre, D. R. Uhlmann

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Abstract

The transformations of boehmite gels during heat treatments at temperatures up to 1150°C have been studied using transmission electron microscopy. Specific attention is directed to the evolution of porosity during the transformations, with isolated small pores seen in λ-Al₂O₃, aligned small pores in θ-Al₂O₃, and large cylindrical pores in α-Al₂O₃. The results are compared with the previous observations of Wilson and Stacey of the transformations which occur on heating boehmite monocrystals. The observed evolution of porosity is related to the results of Kumagai and Messing on the effects of seeding alumina gels with small α-Al₂O₃ particles, where dense α-Al₂O₃ structures were obtained at 1200°C. It is suggested that such seeding avoids the formation of wormy crystalline structures with large intragranular pores. Also discussed is the approach of developing alumina sols which will form smectic structures on approaching the leatherhard point during drying of the gels.

Original language	English (US)
Pages (from-to)	371-377
Number of pages	7
Journal	Journal of Non-Crystalline Solids
Volume	100
Issue number	1-3
DOIs	https://doi.org/10.1016/0022-3093(88)90048-8
State	Published - Mar 1988

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Condensed Matter Physics
Materials Chemistry

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@article{b87fa5c2c8f848ea880c1a7fda88f83e,

title = "TEM study of boehmite gels and their transformation to α-alumina",

abstract = "The transformations of boehmite gels during heat treatments at temperatures up to 1150°C have been studied using transmission electron microscopy. Specific attention is directed to the evolution of porosity during the transformations, with isolated small pores seen in λ-Al2O3, aligned small pores in θ-Al2O3, and large cylindrical pores in α-Al2O3. The results are compared with the previous observations of Wilson and Stacey of the transformations which occur on heating boehmite monocrystals. The observed evolution of porosity is related to the results of Kumagai and Messing on the effects of seeding alumina gels with small α-Al2O3 particles, where dense α-Al2O3 structures were obtained at 1200°C. It is suggested that such seeding avoids the formation of wormy crystalline structures with large intragranular pores. Also discussed is the approach of developing alumina sols which will form smectic structures on approaching the leatherhard point during drying of the gels.",

author = "X. Yang and Pierre, {A. C.} and Uhlmann, {D. R.}",

note = "Funding Information: Financial support for the presentw ork was provided by the Air Force Office of Scientific Research. This support is gratefully acknowledged.",

year = "1988",

month = mar,

doi = "10.1016/0022-3093(88)90048-8",

language = "English (US)",

volume = "100",

pages = "371--377",

journal = "Journal of Non-Crystalline Solids",

issn = "0022-3093",

publisher = "Elsevier B.V.",

number = "1-3",

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T1 - TEM study of boehmite gels and their transformation to α-alumina

AU - Yang, X.

AU - Pierre, A. C.

AU - Uhlmann, D. R.

N1 - Funding Information: Financial support for the presentw ork was provided by the Air Force Office of Scientific Research. This support is gratefully acknowledged.

PY - 1988/3

Y1 - 1988/3

N2 - The transformations of boehmite gels during heat treatments at temperatures up to 1150°C have been studied using transmission electron microscopy. Specific attention is directed to the evolution of porosity during the transformations, with isolated small pores seen in λ-Al2O3, aligned small pores in θ-Al2O3, and large cylindrical pores in α-Al2O3. The results are compared with the previous observations of Wilson and Stacey of the transformations which occur on heating boehmite monocrystals. The observed evolution of porosity is related to the results of Kumagai and Messing on the effects of seeding alumina gels with small α-Al2O3 particles, where dense α-Al2O3 structures were obtained at 1200°C. It is suggested that such seeding avoids the formation of wormy crystalline structures with large intragranular pores. Also discussed is the approach of developing alumina sols which will form smectic structures on approaching the leatherhard point during drying of the gels.

AB - The transformations of boehmite gels during heat treatments at temperatures up to 1150°C have been studied using transmission electron microscopy. Specific attention is directed to the evolution of porosity during the transformations, with isolated small pores seen in λ-Al2O3, aligned small pores in θ-Al2O3, and large cylindrical pores in α-Al2O3. The results are compared with the previous observations of Wilson and Stacey of the transformations which occur on heating boehmite monocrystals. The observed evolution of porosity is related to the results of Kumagai and Messing on the effects of seeding alumina gels with small α-Al2O3 particles, where dense α-Al2O3 structures were obtained at 1200°C. It is suggested that such seeding avoids the formation of wormy crystalline structures with large intragranular pores. Also discussed is the approach of developing alumina sols which will form smectic structures on approaching the leatherhard point during drying of the gels.

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JO - Journal of Non-Crystalline Solids

JF - Journal of Non-Crystalline Solids

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ER -

TEM study of boehmite gels and their transformation to α-alumina

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