Influence of atmosphere on the final-stage sintering kinetics of ultra-high-purity alumina

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb07761.x· OSTI ID:6078648

Thompson, A M; Harmer, M P ^[1]

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1. Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering and Materials Research Center

The influence of sintering atmosphere on the final-stage sintering of ultra-high-purity alumina has been investigated. Model final-stage microstructures were tailored via a latex sphere impregnation and burnout technique. Critical experiments have been conducted to quantitatively examine the influence of the oxygen partial pressure on the final-stage sintering kinetics. Samples were sintered at 1850 C in either dry hydrogen or wet hydrogen and their microstructures were characterized as a function of sintering time. Sintering in dry hydrogen decreased the susceptibility of the final-stage microstructure to pore/boundary break-away. In the kinetic analysis, the variation in the number of pores per grain, N[sub g], was taken into account. It was found that in both atmospheres, the densification rate was controlled by grain boundary diffusion, and that the grain growth rate in both atmospheres was controlled by the rate of surface diffusion of matter around the pores and that sintering in dry hydrogen enhanced the grain growth rate by a factor of 5.6. The overall effect of the dry hydrogen atmosphere was that it enhanced the coarsening rate relative to the densification rate by a factor of 2.5, and consequently shifted the grain size-density trajectory to much lower densities for a given grain size.

• OSTI ID: 6078648
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:9; ISSN 0002-7820; ISSN JACTAW
• 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
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
FABRICATION
GRAIN BOUNDARIES
GRAIN GROWTH
GRAIN SIZE
MATERIALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
SINTERED MATERIALS
SINTERING
SIZE