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Sintering of Nanophase γ‐Al 2 O 3 Powder
Author(s) -
Wu Shun J.,
Jonghe Lutgard C.,
Rahaman Mohamed N.
Publication year - 1996
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1996.tb08962.x
Subject(s) - sintering , materials science , compaction , relative density , inert , shrinkage , particle size , dispersion (optics) , metallurgy , inert gas , grain size , composite material , chemical engineering , chemistry , physics , organic chemistry , optics , engineering
The sintering of ultrafine γ‐Al 2 O 3 powder (particle size ∼10–20 nm) prepared by an inert gas condensation technique was investigated in air at a constant heating rate of 10°C/min. Qualitatively, the kinetics followed those of transition aluminas prepared by other methods. Measurable shrinkage commenced at ∼ 1000°C and showed a region of rapid sintering between ∼1125° and 1175°C followed by a transition to a much reduced sintering rate at higher temperatures. Starting from an initial density of ∼0.60 relative to the theoretical value, the powder compact reached a relative density of 0.82 after sintering to 1350°C. Compared to compacts prepared from the as‐received powder, dispersion of the powder in water prior to compaction produced a drastic change in the microstructural evolution and a significant reduction in the densification rate during sintering. The incorporation of a step involving the rapid heating of the loose powder to ∼1300°C prior to compaction (which resulted in the transformation to α‐Al 2 O 3 ) provided a method for significantly increasing the density during sintering.