Phase relationships in the Si{sub 3}N{sub 4}-SiC-La{sub 2}O{sub 3}-Y{sub 2}O{sub 3} system under high pressure gas processing

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:518607

Perera, D S; Moricca, S ^[1]; Liddell, K ^[2]

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1. Australian Nuclear Science and Technology Organisation, Manai, New South Wales (Australia)
2. The Univ., Newcastle Upon Tyne (United Kingdom); and others

SiC-reinforced Si{sub 3}N{sub 4} ceramics, with La{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and SiO{sub 2} as sintering aids, have been sintered and hot isostatically pressed in the same cycle (sinter/HIP) at 1750{degrees}C under different pressures up to 100 MPa in a nitrogen atmosphere. The materials consist of {alpha} and {beta} Si{sub 3}N{sub 4}, SiC and minor phases. The minor phases formed-such as lanthanum yttrium silicon oxynitrides-are dependent on the temperature, pressure and time of the sinter/HIP process. A phase similar to Y{sub 2}Si{sub 3}N{sub 6} that was observed in this system has been indexed on a hexagonal unit-cell. Phase relationships are discussed with respect to the gas pressure applied and optimum processing conditions.

• OSTI ID: 518607
• Report Number(s): CONF-960367--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
LANTHANUM OXIDES
PHASE DIAGRAMS
PHASE STUDIES
SILICA
SILICON CARBIDES
SILICON NITRIDES
SINTERING
TIME DEPENDENCE
YTTRIUM OXIDES