Hydrothermal Oxidation of Aluminum

Aluminum surfaces were oxidized under hydrothermal conditions over a pressure range of up to 40,000 psi and temperatures to 500C. The oxidized surfaces were examined by X-ray diffraction, soft X-ray emission spectroscopy, and scanning electron microscopy (SEM). Crystalline product phases formed on t...

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Bibliographic Details
Main Authors: Dachille,Frank, White,Eugene W, Gigl,Paul D
Format: Report
Language:English
Subjects:
ALUMINATES
ALUMINUM
BOEHMITE
CORROSION
CORUNDUM
ELECTRON MICROSCOPY
HYPERBARIC CONDITIONS
OXIDATION
Properties of Metals and Alloys
SCIENTIFIC RESEARCH
SURFACE CHEMISTRY
SURFACE PROPERTIES
X RAY DIFFRACTION
X RAY SPECTROSCOPY
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Summary:Aluminum surfaces were oxidized under hydrothermal conditions over a pressure range of up to 40,000 psi and temperatures to 500C. The oxidized surfaces were examined by X-ray diffraction, soft X-ray emission spectroscopy, and scanning electron microscopy (SEM). Crystalline product phases formed on the surfaces over the p-t range were bayerite, boehmite, and corundum, each in a fairly well defined region. Along the 10,000 psi isobar bayerite formed up to 150C, boehmite from 150C to 425C, and corundum above 425C, and along the 30,000 psi isobar the temperatures are higher by 25C in each case. SEM revealed the formation of dense mat surfaces, amorphous to X-rays, in early stages of treatment in the bayerite and boehmite reaction regions, with those formed in the bayerite region being denser and of finer texture. Preliminary tests have shown that films formed under the bayerite conditions are more resistant to corrosive attack then 'boehmite' type films. (Author)