ISSN:
1573-4897
Keywords:
boehmite
;
hydrothermal process
;
morphology
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract In the metal matrix composite field, both fine (〈0.5 µm) and coarse, crystalline, calcined aluminas with narrow or broad particle size distributions, are being used as reinforcement phase. The effect was studied of the preparation method of fine boehmite (γ-AlOOH), precursor of the γ-Al2O3, on the product morphology. The material was produced by heating three kinds of hydrothermal precursors at different pH, and for 2 h at 200°C, using constant stirring. Under the conditions investigated (i.e., 0.12 mol/dm3 of Al(OH)3 and only diluted NaOH and HNO3 solutions used to adjust the pH of slurry), the pH of hydrothermal slurry influenced the product morphology; in contrast, the three different hydrothermal precursors, namely dry aluminum hydroxide gel, fresh aluminum hydroxide precipitate and gibbsite reagent powders, had only a little effect on the product morphology. The dehydration/transformation mechanism from Al(OH)3 to γ-AlOOH is believed to be dissolution/reprecipitation rather than a direct dehydration.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00567195
Permalink