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Silicon nitride containing rare earth silicate intergranular phases

Conference ·
OSTI ID:10125876
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:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC05-84OR21400
OSTI ID:
10125876
Report Number(s):
CONF-921101--81; ON: DE93006624
Country of Publication:
United States
Language:
English