Pressure sintering and creep deformation: a joint modeling approach. Progress report, January 1, 1977--December 31, 1977
The joint modeling of creep deformation and pressure sintering, previously developed for the final and intermediate stages, has now been refined to include a ''transition stage'' that accounts for a decreasing ''connectivity'' for the cylindrical-open porosity and a smooth transition to spherical porosity as pinch-off occurs. As in the final and intermediate stages, this transition stage takes into account three major contributions to densification: lattice diffusional flow, grain boundary flow, and power law deformation; effects of grain growth have also been included. The model has been extensively tested and compared to experimental results on hot-pressed CoO, and is now being tested against earlier experimental data that we have obtained on MgAl/sub 2/O/sub 4/. Work has continued on creep studies of NiO and CoO, comparing the similarities and differences in creep behavior and relating these to dislocation structures observed in TEM. Finally, work has been completed on the grain growth of CoO as a function of porosity level, and also the effects of impurities (Cr, Li) on the creep and densification rates of CoO and NiO. These studies have provided specific information required for the intermediate stage modeling. They have also led to initial work on grain boundary segregation effects studied by STEM that we hope to continue and extend to a quantitative approach during the next year.
- Research Organization:
- Lehigh Univ., Bethlehem, Pa. (USA)
- DOE Contract Number:
- EY-76-S-02-2408
- OSTI ID:
- 7285995
- Report Number(s):
- COO-2408-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COBALT COMPOUNDS
COBALT OXIDES
CREEP
DEFORMATION
ELASTICITY
FABRICATION
GRAIN GROWTH
IMPURITIES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
NICKEL COMPOUNDS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
POROSITY
SINTERED MATERIALS
SINTERING
TENSILE PROPERTIES
THERMOELASTICITY
TRANSITION ELEMENT COMPOUNDS