Premium
Effect of Grain Growth of β‐Silicon Nitride on Strength, Weibull Modulus, and Fracture Toughness
Author(s) -
Hirosaki Naoto,
Akimune Yoshio,
Mitomo Mamoru
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb06670.x
Subject(s) - materials science , weibull modulus , microstructure , fracture toughness , sintering , grain growth , composite material , grain size , silicon nitride , flexural strength , toughness , mineralogy , chemistry , layer (electronics)
β‐Si 3 N 4 powder containing 1 mol% of equimolar Y 2 O 3 –Nd 2 O 3 was gas‐pressure sintered at 2000°C 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 β Si 3 N 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‐m 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 β‐Si 3 N 4 powder was shown to be effective in fostering selective grain growth for obtaining the desired composite microstructure.