Heat treatment of nanocrystalline Al{sub 2}O{sub 3}-ZrO{sub 2}

Book · Mon Sep 01 04:00:00 EDT 1997

OSTI ID:522324

Smyser, B M; Connelly, J F; Sisson, Jr, R D ^[1]; Provenzano, V ^[2]

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1. Worcester Polytechnic Inst., MA (United States). Dept. of Materials Engineering
2. Naval Research Lab., Washington, DC (United States)

The effects of grain size on the phase transformations in nanocrystalline ZrO{sub 2}-Al{sub 2}O{sub 3} have been experimentally investigated. Compositions from 10 to 50 vol% Al{sub 2}O{sub 3} in ZrO{sub 2} were obtained as a hydroxide gel. The powders were then calcined at 600 C for 17 hours and heat treated at 1,100 C for 24 and 120 hours and at 1,200 C for 2 hours. The phase distribution and grain size were determined using x-ray diffraction and transmission electron microscopy. The initial grain size after calcining was 8--17 nm. It was determined that the critical ZrO{sub 2} grain size to avoid the tetragonal to monoclinic phase transformation on cooling from 1,100 C was between 17 and 25 nm. Samples containing 50% Al{sub 2}O{sub 3} maintained a grain size below the critical size for all times and temperatures. The 30% Al{sub 2}O{sub 3} samples showed the same behavior in all but one heat treatment. The remainder of the samples showed significant grain growth and at least partial transformation to the monoclinic phase.

• OSTI ID: 522324
• Report Number(s): CONF-961202--; ISBN 1-55899-361-4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CONCENTRATION RATIO
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
GRAIN SIZE
HEAT TREATMENTS
MONOCLINIC LATTICES
TETRAGONAL LATTICES
ZIRCONIUM OXIDES