Better sintering through green-state deformation processing

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb05263.x· OSTI ID:5764196

Cameron, C P; Raj, R ^[1]

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1. Cornell Univ., Ithaca, NY (USA). Dept. of Materials Science and Engineering

Aqueous colloidal suspensions of alumina were precessed in the dispersed state and the flocculated state by controlling the double-layer interactions between the particles. Repulsive particle forces led to high packing densities but the green bodies were mechanically so weak that they were unable to retain their shape (the dispersed case). Attractive forces led to good green strength but the packing density was low and the particles were agglomerated (the flocculated case). The agglomerated structure of the flocced specimens could be fragmented by mechanical deformation of the green compact; the deformation was carried out under a superimposed hydrostatic pressure of less than 1 MPa. The flow stress of the flocculated structures depended on the deformation rate, and on the magnitude of the superimposed hydrostatic pressure. The flow stress was 2.5 kPa at a strain rate of 0.1 s{sup {minus}1}. Deformation processing of the flocced structures increased the green (relative) density from 0.51 to 0.62. The sintering behavior of undeformed and deformation-processed flocced structures was studied. Deformation-processed green bodies sintered more rapidly and yielded a final grain size that was smaller and more uniform than that obtained from the undeformed specimens. The ability to homogenize and density the packing of flocculated structures by deformation processing suggests new opportunities in green-state processing.

• OSTI ID: 5764196
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:7; ISSN 0002-7820; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COLLOIDS
CRYSTAL STRUCTURE
DEFORMATION
DENSITY
DISPERSIONS
FABRICATION
GRAIN SIZE
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SINTERING
SIZE