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Processing and properties of Al 2 O 3 /SiC nanocomposites
Author(s) -
BORSA C. E.,
JIAO S.,
TODD R. I.,
BROOK R. J.
Publication year - 1995
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1995.tb03561.x
Subject(s) - materials science , sintering , nanocomposite , intergranular corrosion , scanning electron microscope , composite material , grain size , grain boundary , transmission electron microscopy , matrix (chemical analysis) , flexural strength , homogeneous , intergranular fracture , microstructure , nanotechnology , physics , thermodynamics
Summary Alumina/SiC nanocomposites were produced by mechanical mixture of commercial powders. The preparation steps involved the vigorous mixing of the powders and drying under conditions where the homogeneous mixture was kept stable. Pressureless sintering of die‐pressed powders achieved reasonable densities (∼97% theoretical density) for 2·5wt% of SiC on sintering at 2073 K. Higher SiC contents strongly reduced the sintered density. The use of a more reactive alumina (finer matrix powder) gave similar results. Hot pressing at 1973 K/1 h/25 MPa produced high‐density materials for SiC contents as high as 20 wt%. Transmission and scanning electron microscopy analysis showed that the SiC particles were well distributed and were situated both inside the grains and on the grain boundaries of the alumina matrix. The SiC strongly inhibited grain growth in the matrix in keeping with the Zener model. The bend strength increased as the SiC content increased, a result partly explained by the grain size refinement. The strength improvement of 20% over monolithic was explained in terms of the change to an intergranular fracture mode.