Oxidation of Cr/sub 2/O/sub 3/ in the highly dispersed oxide system Al/sub 2/O/sub 3/-Cr/sub 2/O/sub 3/
Journal Article
·
· Inorg. Mater. (Engl. Transl.); (United States)
OSTI ID:5973116
The study of oxidation of Cr/sub 2/O/sub 3/ in the Al/sub 2/O/sub 3/-Cr/sub 2/O/sub 3/ system of highly dispersed oxides showed that Cr/sub 2/O/sub 3/ is oxidized when heated in air in the 670-870 K range. Hexavalent chromium ions located on the surface and in the crystal layer near the surface are the product of oxidation. Oxidation of hydrated chromium oxide Cr(OH)/sub 3/ after annealing is more than one order of magnitude greater than for Cr/sub 2/O/sub 3/. In combined annealing of highly dispersed Cr/sub 2/O/sub 3/ and Al/sub 2/O/sub 3/, the concentration of Cr/sup 6+/ ions is determined by the annealing temperature and increases with an increases in the specific surface area of the oxides and the degree of its hydration. During storage of annealed Al/sub 2/O/sub 3/ + Cr/sub 2/O/sub 3/ mixtures, Cr/sup 6+/ is reduced to Cr/sup 3+/. It was hypothesized that the process of oxidation and reduction of chromium ions in a system of oxide in a highly dispersed state are due to dehydration and hydration of the surface of the Cr/sub 2/O/sub 3/ and Al/sub 2/O/sub 3/ crystals.
- Research Organization:
- Institute of Chemistry, Ural (USSR)
- OSTI ID:
- 5973116
- Journal Information:
- Inorg. Mater. (Engl. Transl.); (United States), Journal Name: Inorg. Mater. (Engl. Transl.); (United States) Vol. 24:7; ISSN INOMA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANNEALING
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DEHYDRATION
DIFFRACTION
EFFICIENCY
HEAT TREATMENTS
HYDRATES
HYDRATION
OXIDATION
OXIDES
OXYGEN COMPOUNDS
REDUCTION
SCATTERING
SOLVATION
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VALENCE
X-RAY DIFFRACTION
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANNEALING
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DEHYDRATION
DIFFRACTION
EFFICIENCY
HEAT TREATMENTS
HYDRATES
HYDRATION
OXIDATION
OXIDES
OXYGEN COMPOUNDS
REDUCTION
SCATTERING
SOLVATION
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
VALENCE
X-RAY DIFFRACTION