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Fracture Strength and Microstructure of β‐SiAlON with Hafnia Addition
Author(s) -
Goto Yasuhiro,
Komatsu Michiyasu
Publication year - 1999
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.1151-2916.1999.tb01943.x
Subject(s) - microstructure , sialon , materials science , hafnia , amorphous solid , composite material , ceramic , phase (matter) , flexural strength , monoclinic crystal system , fracture (geology) , sintering , mineralogy , crystallography , crystal structure , cubic zirconia , chemistry , organic chemistry
The influence of HfO 2 addition on the fracture strength and microstructure of ß‐SiAlON ceramics sintered from Si 3 N 4 and Al 2 O 3 powders was investigated. The strength was increased by the addition of HfO 2 , from ∼500 MPa to 700 MPa, and was almost constant from ambient temperature to 1300°C. Monoclinic HfO 2 grains that were distributed in the SiAlON grain boundaries had a flat shape (∼20 nm thick) and were surrounded by an amorphous phase. The aluminum concentration in ß‐SiAlON in the samples with an Al 2 O 3 starting composition of 15 wt% was decreased by the addition of HfO 2 . The amount of secondary phases was very small at grain boundaries between the SiAlON grains; amorphous phases were observed infrequently at the triple points but were very small (∼20 nm). The effects of HfO 2 addition on the mechanism of the microstructure development and fracture strength are discussed.