Hydrothermal synthesis of boehmite and a-alumina from Bayer’s alumina trihydrate

Panda, PK and Jaleel, VA and Ushadevi, S (2006) Hydrothermal synthesis of boehmite and a-alumina from Bayer’s alumina trihydrate. Journal of Materials Science, 41 . pp. 8386-8389. ISSN 0022-2461

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    Abstract

    a-Alumina (Al2O3) is a ceramic material used widely due to its versatile properties such as high temperature stability, high strength at high temperature, high hardness with higher wear resistance, good thermal shock resistance etc [1, 2]. In addition, it is available abundantly at relatively low cost, therefore, is a popular material for fabrication of structural components, electronic substrates etc. a-Al2O3 is generally prepared by Bayer’s process [3], pyrolysis of suitable salts [4], freeze drying [5], plasma evaporation process [6], sol–gel processing [7–9], molten salt [10], hydrothermal [11–14] and solvothermal [15] techniques. Inoue et al. [16] obtained microcrystalline a-Al2O3 by glycol-thermal treatment of gibbsite under nitrogen blanket. Generally, the powder characteristics such as purity, particle size distribution, grain morphology, surface area etc. are influenced by the processing methods used for its preparation. For example, powders prepared by hydrothermal route are known to generate pure and crystalline oxide powders with relatively narrow size distribution. Hydrothermal reactions are carried out at low temperatures and the precursors in the form of metal powders [17] or metal salt solutions [18, 19] are used. The characteristics of the powders influence the sintering and grain growth process, thereby, influence the properties of the final products [20]. For examples, powders prepared by hydrothermal route are excellent for sintering to near theoretical density at relatively low temperature because of their fine and narrow size distribution, highly crystalline nature, high reactivity due to their synthesis at low temperature. In our earlier studies, a- Al2O3 and boehmite were synthesised from Al metal blocks [21, 22]. Other groups have also been studied [23–27] mainly by using aluminium as the precursor. It is known that aluminium metal is the final product of Bayer’s process, which uses cheap bauxite as the precursor. Alumina tri hydrate (ATH) is an intermediate product of the Bayer’s process, which is much cheaper than aluminium metal. Therefore, in our present study, an attempt has been made to prepare a-Al2O3 from the cheap alumina tri-hydrate (ATH) by hydrothermal synthesis.

    Item Type: Journal Article
    Additional Information: Copyright to this article belongs to M/s. Springer-Verlag
    Uncontrolled Keywords: Hydrothermal synthesis;Hydrothermal alumina;Ceramic material;Alumina trihydrate
    Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
    Division/Department: Materials Science Division, Materials Science Division, Materials Science Division
    Depositing User: Ms. Alphones Mary
    Date Deposited: 31 Oct 2012 09:50
    Last Modified: 31 Oct 2012 09:50
    URI: http://nal-ir.nal.res.in/id/eprint/11333

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