Initial coarsening and microstructural evolution of fast-fired and MgO-doped Al{sub 2}O{sub 3}

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1997.tb03208.x· OSTI ID:556441

Lin, F J.T.; Jonghe, L.C. De ^[1]; Rahaman, M N ^[2]

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1. Lawrence Berkeley National Lab., CA (United States). Materials Science Div.
2. Univ. of Missouri, Rolla, MO (United States). Dept. of Ceramic Engineering

The effect of an initial coarsening step (50--200 h at 800 C) on the subsequent densification and microstructural evolution of high-quality compacts of undoped and MgO-doped Al{sub 2}O{sub 3} has been investigated during fast-firing (5 min at 1,750 C) and during constant-heating-rate sintering (4 C/min to 1,450 C). In constant-heating-rate sintering of both the undoped and MgO-doped Al{sub 2}O{sub 3}, a refinement of the microstructure has been achieved for the compact subjected to the coarsening step. A combination of the coarsening step and MgO doping produces the most significant refinement of the microstructure. In fast-firing of the MgO-doped Al{sub 2}O{sub 3}, the coarsening step produces a measurable increase in the density and a small refinement of the grain size, when compared with similar compacts fast-fired conventionally (i.e., without the coarsening step). This result indicates that the accepted view of the deleterious role of coarsening in the sintering of real powder compacts must be reexamined. Although extensive coarsening after the onset of densification must be reduced for the achievement of high density, limited coarsening prior to densification is beneficial for subsequent sintering.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 556441
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 11 Vol. 80; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
BULK DENSITY
DOPED MATERIALS
GRAIN SIZE
HEATING RATE
MAGNESIUM OXIDES
MICROSTRUCTURE
SINTERING
TEMPERATURE RANGE 1000-4000 K