Silicon nitride containing rare earth silicate intergranular phases

Conference · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6859186

Nunn, S D; Tiegs, T N; Ploetz, K A; Walls, C A; Bell, N

Si[sub 3]N[sub 4] ceramics prepared with refractory grain boundary phases to improve high temperature properties are difficult to density by conventional sintering methods. Gas-pressure sintering may be used to promote densification and development of acicular grains for improved fracture toughness. The current study examined rare earth silicate sintering aids with the composition M[sub 2]Si[sub 2]O[sub 7], where M is a trivalent cation (Y, La, Nd). M[sub 2]O[sub 3] and SiO[sub 2] additions were varied to develop a number of compositions in the Si[sub 3]N[sub 4]-Si[sub 2]N[sub 2]O-M[sub 2]Si[sub 2]O[sub 7] ternary phase field. Pressureless sintering and gas-pressure sintering were used to density the samples. Densification, microstructure development, oxidation resistance, and mechanical properties were evaluated and compared with respect to compositional variations and processing conditions.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6859186
• Report Number(s): CONF-921101-81; ON: DE93006624
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ADDITIVES
DENSITY
FABRICATION
FRACTURE PROPERTIES
LANTHANUM COMPOUNDS
LANTHANUM SILICATES
MECHANICAL PROPERTIES
NEODYMIUM COMPOUNDS
NEODYMIUM SILICATES
NITRIDES
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
RARE EARTH COMPOUNDS
SILICATES
SILICON COMPOUNDS
SILICON NITRIDES
SINTERING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM SILICATES