Effect of grain growth of [beta]-silicon nitride on strength, Weibull modulus, and fracture toughness

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb06670.x· OSTI ID:6351487

Hirosaki, Naota; Akimune, Yoshio ^[1]; Mitomo, Mamoru ^[2]

---

1. Nissan Motor Co., Ltd., Yokosuka (Japan). Materials Research Lab.
2. National Inst. for Research in Inorganic Materials, Ibaraki (Japan)

[beta]-Si[sub 3]N[sub 4] powder containing 1 mol% of equimolar Y[sub 2]O[sub 3]-Nd[sub 2]O[sub 3] was gas-pressure sintered at 2,000C for 2 h (SN2), 4 h (SN4), and 8 h (SN8) in 30-MPa nitrogen gas. These materials had a microstructure of in-situ composites'' as a result of exaggerated grain growth of some [beta]-Si[sub 3]N[sub 4] grains during firing. Growth of elongated grains was controlled by the sintering time, so that the desired microstructures were obtained. SN2 had a Weibull modulus as high as 53 because of the uniform size and spatial distribution of its large grains. SN4 had a fracture toughness of 10.3 MPa[center dot]m[sup 1/2] because of toughening provided by the bridging of elongated grains, whereas SN8 showed a lower fracture toughness, possibly caused by extensive microcracking resulting from excessively large grains. Gas-pressure sintering of [beta]-Si[sub 3]N[sub 4] powder was shown to be effective in fostering selective grain growth for obtaining the desired composite microstructure.

• OSTI ID: 6351487
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:7; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
CHALCOGENIDES
CRACK PROPAGATION
DATA
DISTRIBUTION
ELONGATION
EXPERIMENTAL DATA
FABRICATION
FRACTURE PROPERTIES
GRAIN GROWTH
INFORMATION
MECHANICAL PROPERTIES
MICROSTRUCTURE
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
NITRIDES
NITROGEN COMPOUNDS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
POWDERS
RARE EARTH COMPOUNDS
SILICON COMPOUNDS
SILICON NITRIDES
SINTERING
SPATIAL DISTRIBUTION
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES