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Effect of Liquid Phase Sintering on Microstructure and Mechanical Properties of Yb 2 O 3 ‐AlN Containing SiC‐Based Ceramics
Author(s) -
Izhevskyi V. A.,
Bressiani A. H. A.,
Bressiani J. C.
Publication year - 2005
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.1551-2916.2005.00212.x
Subject(s) - materials science , sintering , microstructure , ceramic , phase (matter) , grain growth , composite material , silicon carbide , flexural strength , fracture toughness , grain size , chemistry , organic chemistry
A series of silicon carbide‐based ceramics with different sintering additives were liquid‐phase sintered to high densities. Yb 2 O 3 in combination with AlN was used as the additive, instead of the commonly used Y 2 O 3 –AlN, to improve the refractoriness of the secondary phase. Thermo‐chemical decomposition of AlN was sufficiently suppressed with the use of nitrogen overpressure and reasonable weight loss was achieved in the different additive containing SiC ceramics without a reactive powder bed. Use of the heavier rare‐earth element modified the liquid phase formed during sintering and reduced the phase transformation controlled grain growth rate, compared with Y 2 O 3 doped materials. It also permitted microstructure tailoring through post‐sintering heat treatments in nitrogen. Materials with self‐reinforced microstructures, formed as a result of anisotropic grain growth, were obtained. Improved fracture toughness (4.5–5 MPa/m 1/2 ) and good flexural strength retention up to 1400°C were also observed.