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Fine‐Grained Silicon Carbide Ceramics with Oxynitride Glass
Author(s) -
Kim YoungWook,
Mitomo Mamoru
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.tb02149.x
Subject(s) - materials science , silicon oxynitride , flexural strength , microstructure , sintering , reducing atmosphere , ceramic , fracture toughness , silicon carbide , composite material , equiaxed crystals , phase (matter) , carbide , metallurgy , silicon , silicon nitride , chemistry , organic chemistry
By using an oxynitride glass composition from the Y‐Mg‐Si‐Al‐O‐N system as a sintering additive, the effect of atmosphere on densification was investigated during the liquid‐phase sintering of SiC, and the resulting microstructure and mechanical properties of the sintered and subsequently annealed materials were investigated. SiC ceramics that were densified with 10 wt% oxynitride glass showed higher sinterability in a nitrogen atmosphere. Oxynitride glass enlarged the stability region of β‐SiC and suppressed β→ alpha phase transformation, which resulted in an equiaxed microstructure. Grain growth of fine‐grained SiC in some extent (up to ∼300 nm) was beneficial in improving both room‐temperature strength and toughness. The best results were obtained when the ceramics were hot‐pressed at 1800°C for 1 h in a nitrogen atmosphere and subsequently annealed at 1900°C for 3 h in an argon atmosphere. The room‐temperature flexural strength and fracture toughness of the material were 847 MPa and 3.5 MPa·m 1/2 , respectively.