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Spark‐Plasma Sintering of Silicon Carbide Whiskers (SiC w ) Reinforced Nanocrystalline Alumina
Author(s) -
Zhan GuoDong,
Kuntz Joshua D.,
Duan RenGuan,
Mukherjee Amiya K.
Publication year - 2004
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.1151-2916.2004.tb07510.x
Subject(s) - materials science , spark plasma sintering , nanocrystalline material , ball mill , sintering , fracture toughness , scanning electron microscope , silicon carbide , whiskers , grain size , composite material , cermet , vickers hardness test , grain growth , nanocomposite , metallurgy , ceramic , microstructure , nanotechnology
The combined effect of rapid sintering by spark‐plasma‐sintering (SPS) technique and mechanical milling of γ‐Al 2 O 3 nanopowder via high‐energy ball milling (HEBM) on the microstructural development and mechanical properties of nanocrystalline alumina matrix composites toughened by 20 vol% silicon carbide whiskers was investigated. SiC w /γ‐Al 2 O 3 nanopowders processed by HEBM can be successfully consolidated to full density by SPS at a temperature as low as 1125°C and still retain a near‐nanocrystalline matrix grain size (∼118 nm). However, to densify the same nanopowder mixture to full density without the benefit of HEBM procedure, the required temperature for sintering was higher than 1200°C, where one encountered excessive grain growth. X‐ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that HEBM did not lead to the transformation of γ‐Al 2 O 3 to α‐Al 2 O 3 of the starting powder but rather induced possible residual stress that enhances the densification at lower temperatures. The SiC w /HEBMγ‐Al 2 O 3 nanocomposite with grain size of 118 nm has attractive mechanical properties, i.e., Vickers hardness of 26.1 GPa and fracture toughness of 6.2 MPa·m 1/2 .