On estimating fracture toughness of cemented carbides from Palmqvist crack sizes

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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Comment on "Indentation Fracture Toughness of Sintered Silicon Carbide in the Palmqvist Crack Regime"

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1991.tb06949.x ◽

1991 ◽

Vol 74 (4) ◽

pp. 887-888 ◽

Cited By ~ 7

Author(s):

Sreeram Srinivasan ◽

Ronald O. Scattergood

Keyword(s):

Fracture Toughness ◽

Silicon Carbide ◽

Indentation Fracture ◽

Indentation Fracture Toughness ◽

Palmqvist Crack ◽

Sintered Silicon

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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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Fracture Indentation on AISI 1018 Borided Steels

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.449.9 ◽

2010 ◽

Vol 449 ◽

pp. 9-14 ◽

Cited By ~ 2

Author(s):

Ivan Campos-Silva ◽

M. Ortíz-Domínguez ◽

E. Hernández-Sánchez ◽

D. Bravo-Bárcenas ◽

O. Bravo-Bárcenas ◽

...

Keyword(s):

Fracture Toughness ◽

Exposure Time ◽

Boride Layer ◽

Crack Model ◽

Iron Boride ◽

Fracture Testing ◽

Experimental Parameters ◽

Two Temperatures ◽

Boriding Process ◽

Palmqvist Crack

Fracture indentation was applied to estimate the fracture toughness of AISI 1018 borided steels. The Fe2B hard layers were formed using the powder-pack boriding process for two temperatures with 4 and 8 h of exposure times. The fracture toughness of the iron boride layer of the AISI 1018 borided steels was estimated using a Vickers microindentation induced-fracture testing at distances of 15 and 30 m from the surface, applying four loads (0.49, 0.98, 1.96 and 2.9 N). The microcracks generated at the corners of the Vickers microindentation were considered as experimental parameters, which are introduced in a Palmqvist crack model to determine their corresponding fracture toughness KC. As a result, the experimental parameters, such as exposure time and boriding temperature are compared with the resulting fracture toughness of the borided phase.

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Microstructure and Mechanical Properties of Sintered Fibrous Monolith Cemented Carbide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.815.233 ◽

2013 ◽

Vol 815 ◽

pp. 233-239

Author(s):

Xue Quan Liu ◽

Cun Guang Ding ◽

Chang Hai Li ◽

Yi Li ◽

Li Xin Li ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Crack Propagation ◽

Fracture Energy ◽

Bending Strength ◽

Extrusion Process ◽

Cemented Carbide ◽

Cemented Carbides ◽

Microstructure And Mechanical Properties

A fibrous monolith cemented carbide with WC-6Co as cell and WC-20Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, bending strength and fracture toughness of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and SEM. The results showed that the bending strength and fracture toughness of the fibrous monolith cemented carbides was remarkably improved 71.91% and 45.7% respectively, while the hardness was slightly decreased 1% compared with WC-6Co composites. It is the reason that the tougher shell WC-20Co with higher bending strength and fracture toughness can absorb more fracture energy, which can slow down and prevent the crack propagating from brittle core WC-6Co.

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