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Potentials of nanostructured WC-Co hardmetal as reference material for Vickers hardness

: Fabijanić, Tamara Aleksandrov; Alar, Željko; Pötschke, Johannes


International journal of refractory metals and hard materials 50 (2015), pp.126-132
ISSN: 0263-4368
Journal Article
Fraunhofer IKTS ()
Vickers hardness; nanostructured WC–Co hardmetal; Sinter-HIP; reference material; hardness uniformity

The potential of nanostructured WC–Co hardmetal as reference material for Vickers hardness was researched in this paper. Preliminary reference Vickers hardness blocks were developed from a WC 9–Co mixture. The WC powder used was nanoscaled and had a grain size of 150 nm and a specific surface area of 2.5 m2/g. Hardness blocks were consolidated using the Sinter-HIP process. Properties of the sintered material were obtained by using standard measurement techniques like magnetic properties or the SEM analysis of microstructure. Special emphasis was placed on hardness uniformity of the test surface as it is the most important property placed on reference hardness blocks. Hardness uniformity was tested by analysis of variance, ANOVA, for single factor in order to determine if significant hardness variations across the block surface were present. From the conducted research it was concluded that hardness distribution over the whole test surface was uniform. The achieved superior properties of the material, such as full densification, nanosized homogeneous microstructure, high hardness and good fracture toughness, influenced the metrological characteristics of the reference Vickers hardness block. Hardness non-uniformity is nearly two times lower when compared to commercially available standard reference material made of ultra-fine WC–Co. Material response does not involve chipping, cracking or any other imperfections. The research opens a new area of application for nanostructured WC–Co hardmetals as reference material for Vickers hardness for high hardness range.