Effect of ZrO sub 2 addition and nonstoichiometry on sintering and physical property of magnesium aluminate spinel
Thesis/Dissertation
·
OSTI ID:7162535
Addition of ZrO{sub 2} was found to be beneficial for the spinel formation reaction possibly by increasing the cation vacancy concentrations. Effect of nonstoichiometry on initial spinel formation reaction was insignificant in extent. Nonstoichiometric Mg-rich spinel experienced high sintering rate possibly because of increased concentration of oxygen vacancies. Non-stoichiometric Al-rich spinel possessed slower sintering rate because of decreased oxygen vacancy concentrations. Addition of ZrO{sub 2} resulted in retarded grain boundary mobility in Mg-rich spinel and ZrO{sub 2} particles were found to act as grain growth inhibitors. Grain size was reduced after ZrO{sub 2} addition and samples made from MgAl{sub 2}O{sub 4} starting powder exhibited extensive presence of abnormally grown large grains because of agglomerates in starting powder. Addition of ZrO{sub 2} assisted in growth of Al{sub 2}O{sub 3} precipitates from Al-rich spinel aged at 1,300 C. Precipitation of {alpha}-Al{sub 2}O{sub 3} precipitates from Al-rich spinel followed a nucleation and growth process, revealing an apparent incubation time period. Equations for calculating the volume fraction of m-ZrO{sub 2} phase were suggested.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (United States)
- OSTI ID:
- 7162535
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
360606 -- Other Materials-- Physical Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
FABRICATION
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALLURGICAL EFFECTS
MINERALS
NONMETALS
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
SINTERING
SPINELS
TRANSITION ELEMENT COMPOUNDS
VACANCIES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES
360601* -- Other Materials-- Preparation & Manufacture
360606 -- Other Materials-- Physical Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
FABRICATION
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALLURGICAL EFFECTS
MINERALS
NONMETALS
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
SINTERING
SPINELS
TRANSITION ELEMENT COMPOUNDS
VACANCIES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES