Microstructure of alumina reinforced with tungsten carbide |
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Authors: | Wilson Acchar Cordt Zollfrank Peter Greil |
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Affiliation: | (1) Department of Physics, Federal University of Rio Grande do Norte, Natal-Rio Grande do Norte, CEP 59072-970, Brazil;(2) Department of Materials Science (III), Glass and Ceramics, University of Erlangen-Nürnberg, D-91058 Erlangen, Germany |
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Abstract: | Carbides and nitrides reinforced alumina based ceramic composites are generally accepted as a competitive technological alternative
to cemented carbide (WC-Co). The aim of this work was to investigate the effect of dispersed tungsten carbide (WC) on the
microstructure and mechanical properties of alumina (Al2O3). Micron size alumina and tungsten carbide powders were mixed in a ball mill and uniaxially pressed at 1600°C under 20 MPa
in an inert atmosphere. The hardness of WC reinforced alumina was 19 GPa and fracture toughness attained up to 7 MPa m1/2. It was demonstrated by TEM analysis that coarse, micrometersized tungsten carbide grains were located at grain boundaries
of the alumina matrix grains. Additionally, sub-micrometer tungsten carbide spheres were found inside the alumina particles.
Crack deflection triggered by the tungsten carbide at the grain boundaries of the alumina matrix is supposed to increase fracture
toughness whereas the presence of intergranular and intragranular hard tungsten carbide particles are responsible for the
increase of the hardness values of the investigated composite materials. |
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