RECRYSTALLIZATION AND SINTERING OF OXIDES. Progress Report for September 1, 1959 to August 31, 1960

Technical Report · Wed Aug 31 04:00:00 EDT 1960

OSTI ID:4126881

Three important problems have come under intensive study during the past year: (1) rate of shrinkage of powder compacts of alumina, (2) electrical conductivity of singlecrystal and polycrystalline alumina, and (3) growth of sapphire seeds in sintered alumina. A fourth problem concerning the kinetics of grain growth in sintered magnesia and sintered calcia was exploratory treatment. Inc reased accuracy of shrinkage measurement has shown areas of divergence and areas of convergence between theory and experiment. Measurement of rates of shrinkage show promise of yielding accurate determinations of selfdiffusion constants. Electrical conductivity of alumina in polycrystalline and single- crystal form is electronic and not ionic. All evidences for ionic conductivity can be traced to surface impurities. Leakage through the gaseous atmosphere surrounding the sample is the most serious experimental problem in high- temperature conductivity measurement. Alumina compacts seeded with sapphire crystals show growth that is approximately uniform in all dimensions but is not uniform with respect to time. For a second reheating the rate of growth is smaller. Magnesia and calcia show continuous grain growth that conforms to the equations utilized to describe the grain growth of metals. (auth)

• Research Organization: Utah. Univ., Salt Lake City. Inst. for the Study of Rate Processes
• NSA Number: NSA-14-025865
• OSTI ID: 4126881
• Report Number(s): TID-6572
• Country of Publication: United States
• Language: English

Related Subjects

ALUMINUM OXIDES
CALCIUM OXIDES
COMPACTS
CRYSTALS
DEFORMATION
DIFFUSION
ELECTRIC CONDUCTIVITY
ELECTRONS
EXPANSION
GASES
GRAIN SIZE
HIGH TEMPERATURE
IMPURITIES
IONS
LEAKS
MAGNESIUM OXIDES
MATHEMATICS
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
POWDERS
RECRYSTALLIZATION
SINTERING
SURFACES
TRACER TECHNIQUES