Fracture toughness of cemented carbides: Testing method and microstructural effects

In this paper, WC-10Ni3Al cemented carbides were prepared by the powder metallurgy method, and the effects of ball-milling powders with two different organic solvents on the microstructure and mechanical properties of cemented carbides were studied. We show that the oxygen in the organic solvent can be absorbed into the mixed powders by ball-milling when ethanol (CH3CH2OH) is used as a ball-milling suspension. This oxygen leads to the formation of α-Al2O3 during sintering, which improves the fracture toughness, due to crack deflection and bridging, while the formation of η-phase (Ni3W3C) inhibits the grain growth and increases the hardness. Alternatively, samples milled using cyclohexane (C6H12) showed grain growth during processing, which led to a decrease in hardness. Therefore, the increase of oxygen content from using organic solvents during milling improves the properties of WC-Ni3Al composites. The growth of WC grains can be inhibited and the hardness can be improved without loss of toughness by self-generating α-Al2O3 and η-phase (Ni3W3C).

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Novel rock fracture toughness testing method: Cracked-Chevron-Notched Brazilian Disc method

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts ◽

10.1016/0148-9062(91)91120-g ◽

1991 ◽

Vol 28 (4) ◽

pp. A264

Keyword(s):

Fracture Toughness ◽

Rock Fracture ◽

Brazilian Disc ◽

Fracture Toughness Testing ◽

Testing Method ◽

Rock Fracture Toughness ◽

Toughness Testing

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Properties of Cryogenic Treated Cemented Carbides (WC-Co)

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.403.75 ◽

2020 ◽

Vol 403 ◽

pp. 75-89

Author(s):

Vojtěch Průcha ◽

David Bricín ◽

Antonín Kříž ◽

Zdeněk Jansa

Keyword(s):

Fracture Toughness ◽

Cryogenic Treatment ◽

The Other ◽

Coarse Grained ◽

Cemented Carbides ◽

Polished Surface ◽

X Ray Diffraction ◽

Deep Cryogenic Treatment ◽

Fine Grained ◽

Disk Test

The present paper explores the effects of deep cryogenic treatment (DCT) on the properties of WC-Co cemented carbides. The investigation involved four different cemented carbide (CC) grades. Two of them were coarse-grained WC with grain sizes larger than 6 μm and binder fractions of 10 and 15 wt. %. The other two were fine-grained with WC grains of 0.5-0.8 μm and the same binder fractions of 10 and 15 wt. %. Their specimens were ground and polished to prepare them for DCT. In each specimen, one half of this polished surface was used for testing the properties of the CC before cryogenic treatment. The post-DCT properties were then determined on the other half. Properties of the cemented carbides prior to and after DCT were studied using optical and scanning electron microscopy, X-ray diffraction, hardness testing according to Vickers scale followed by calculation of fracture toughness KIC and a ball-on-disk test of the wear resistance of the surface. One of the findings was that cryogenic treatment led to a decrease in residual stresses and to lower fracture toughness KIC in the CC.

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