Application of controlled interfacial pore structures to pore perturbation and pore drag in alumina
A new technique has been developed which allows generation of intergranular pore structures with pores of almost any size, spacing, shape and number. This method is based on photolithographic techniques, ion beam etching and hot pressing. The material studied is alumina; the purpose of the investigation is a simulation of various aspects of sintering. If an etched sapphire wafer is bonded to an unetched sapphire disk, bicrystals with well-defined pore geometries are produced. These samples are utilized to monitor the evolution of initially instable pore structures such as pore channels and flat cracks. The behavior of these features is found to depend strongly on the crystallographic orientation of the bonding plane, and in the case of pore channels, also depends strongly on the channel direction. As a byproduct, metastable and stable faceted pore geometries as a function of orientation in the bicrystal can be monitored. If an etched sapphire wafer is bonded to a dense polycrystalline matrix (undoped and MgO-doped alumina), grain growth under the influence of pore drag can be studied. In the same experiment, the conditions for pore-boundary separation can be defined. Grain growth in a dense matrix and grain boundary migration of basal plane sapphire into alumina have been measured. The applicability of this method to pore coarsening and pore elimination has been shown. 145 refs., 83 refs., 4 tabs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6565901
- Report Number(s):
- LBL-26211; ON: DE89004586
- Country of Publication:
- United States
- Language:
- English
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360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BEAMS
CHALCOGENIDES
CRYSTAL STRUCTURE
EQUATIONS
ETCHING
FABRICATION
FRACTURE MECHANICS
GRAIN BOUNDARIES
GRAIN GROWTH
GRAIN SIZE
HOT PRESSING
INTERFACES
ION BEAMS
KINETICS
MATERIALS WORKING
MATHEMATICAL MODELS
MECHANICS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
POROSITY
PRESSING
SINTERING
SIZE
SURFACE FINISHING