Premium
Effect of β‐to‐α Phase Transformation on the Microstructural Development and Mechanical Properties of Fine‐Grained Silicon Carbide Ceramics
Author(s) -
Zhan GuoDong,
Xie RongJun,
Mitomo Mamoru,
Kim YoungWook
Publication year - 2001
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.1151-2916.2001.tb00773.x
Subject(s) - materials science , annealing (glass) , microstructure , silicon carbide , equiaxed crystals , ceramic , sintering , metallurgy , phase (matter) , composite material , chemistry , organic chemistry
Ultrafine β‐SiC powders mixed with 7 wt% Al 2 O 3, 2 wt% Y 2 O 3 , and 1.785 wt% CaCO 3 were hot‐pressed and subsequently annealed in either the absence or the presence of applied pressure. Because the β‐SiC to α‐SiC phase transformation is dependent on annealing conditions, the novel processing technique of annealing under pressure can control this phase transformation, and, hence, the microstructures and mechanical properties of fine‐grained liquid‐phase‐sintered SiC ceramics. In comparison to annealing without pressure, the application of pressure during annealing greatly suppressed the phase transformation from β‐SiC to α‐SiC. Materials annealed with pressure exhibited a fine microstructure with equiaxed grains when the phase transformation from β‐SiC to α‐SiC was <30 vol%, whereas materials annealed without pressure developed microstructures with elongated grains when phase transformation was >30 vol%. These results suggested that the precise control of phase transformation in SiC ceramics and their mechanical properties could be achieved through annealing with or without pressure.