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Microstructure Characterization of Gas‐Pressure‐Sintered β‐Silicon Nitride Containing Large β‐Silicon Nitride Seeds
Author(s) -
Hirosaki Naoto,
Akimune Yoshio,
Mitomo Mamoru
Publication year - 1994
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.1151-2916.1994.tb07277.x
Subject(s) - microstructure , materials science , silicon nitride , sintering , nitride , silicon , core (optical fiber) , precipitation , composite material , gas pressure , characterization (materials science) , aluminium , metallurgy , nanotechnology , layer (electronics) , physics , meteorology , petroleum engineering , engineering
Fine β‐Si 3 N 4 powders with or without the addition of 5 wt% of large β‐Si 3 N 4 particles (seeds) were gas‐pressure sintered at 1900°C for 4 h using Y 2 O 3 and Al 2 O 3 as sintering aids. The microstructures were examined on polished and plasmaetched surfaces. These materials had a microstructure of in situ composites with similar small matrix grains and different elongated grains. The elongated grains in the materials with seeds had a larger diameter and a smaller aspect ratio than those in the materials without seeds. A core/rim structure was observed in the elongated grains; the core was pure β‐Si 3 N 4 and the rim was β‐SiAION. These results show that the large β‐Si 3 N 4 particles acted as seeds for abnormal grain growth and the rim was formed by precipitation from the liquid containing aluminum.