Influences of the preparation methods of WC–Co powders on the sintering and microstructure of coarse grained WC–8Co hardmetals

Su, Wei; Sun, Yexi; Jiao, Feng; Liu, Jue; Ruan, Jianming

doi:10.1016/j.ijrmhm.2014.10.012

Cited by 33 publications

(7 citation statements)

References 25 publications

(37 reference statements)

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“…In the review of García et al [57], it is shown that for 7.5 wt.% cobalt, the Vickers hardness varies between 1400 and 1800 HV 30 depending on the grain size (5-1 µm). Moreover, the literature shows that non-recycled WC-7.5Co and WC-8Co have been sintered by conventional process with lower mechanical properties [59][60][61]. The results found in this paper are comprised between 1700 and 1850 HV 30 .…”

Section: Discussionmentioning

confidence: 69%

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Mégret

Vitry

Delaunois

2021

J. Sustain. Metall.

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Cemented carbide tools suffer from many issues due to the use of tungsten and cobalt as raw materials. Indeed, those are listed by the European Commission as “critical raw materials” since 2011 and by the US Department of Interior as “critical minerals” in 2018. To remain competitive with the conventional high-speed steels, less performant but cheaper, WC–Co tools can be recycled. In the present paper, a WC–7.5Co powder, recycled by the “Coldstream” process, has been sintered with vacuum sintering. As preliminary experiments have shown that the sinterability of the powder is low, the sintering temperature was set at 1500 °C to achieve full density. In parallel, the influence of ball milling conditions (rotation speed and milling medium) on the reactivity of the recycled powder has been studied in terms of grain size distribution, hardness, and fracture toughness. The optimized milling conditions were found to be 6 h wet milling, leading to a hardness of about 1870 HV30 and a toughness of about 10.5 MPa√m after densification. The recycled powder can thus totally compete with conventional powders, opening avenues for the recycling of cemented carbide tools. Graphical Abstract

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Section: Discussionmentioning

confidence: 69%

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Mégret

Vitry

Delaunois

2021

J. Sustain. Metall.

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“…These wear resistant MMCs may also be prepared as coatings by various thermal spray methods, including HVOF, plasma spray, cold spray and others. For all of these processes, the feedstock powders play a role in optimizing the process and the properties of the MMCs [3,5]. Several types of WC powder are used for the surface coating process, among which cast WC and agglomerated WC-Co or Ni powders are most often the materials of choice [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Effect of WC morphology on dry sliding wear behavior of cold-sprayed Ni-WC composite coatings

Alidokht

Yue

Chromik

2019

Surface and Coatings Technology

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Cold spray is a relatively new method used to deposit WC reinforced composite coatings, where its low temperature is advantageous for avoiding oxidation and carbide decomposition.Previous studies demonstrated that using agglomerated WC resulted in higher WC retention within the Ni matrix, as compared to that of cast WC. However, the influence of the morphology of the starting powders on the coating's microstructure, properties, and wear performance is not well understood. Here we report cold spray deposition of Ni with two types of WC particles, i.e. cast and agglomerated. In both cases, ~30vol.% WC was retained in coatings, allowing for a side-byside comparison. Coatings with cast WC featured a multi-modal distribution of WC particles ranging from 0.2 to 20 µm with a mean free path (MFP) between particles of 8.5 ± 0.7 µm. In comparison, coatings with agglomerated WC had WC size range of 0.3 to 1.3 µm and a MFP of 31 ± 4 µm. The sliding wear behavior of coatings was studied with a sliding speed of 3 mm/s under normal loads of 5 and 12 N. Coatings with cast WC were found to be more wear resistant than coatings with agglomerated WC. The multi-modal size distribution of cast WC with significantly lower MFP minimized adhesive wear and helped to develop a higher coverage of protective mechanically mixed layers (MMLs) that typically formed near WC particles. For coatings with cast WC, subsurface microstructure and chemical analysis suggested higher oxidation for MMLs with lower depths of deformation zones extended beneath MMLs compared to coatings with agglomerated powder. The two main factors for improved wear resistance of cast WC coatings compared to agglomerated WC coatings were the stability of the MMLs, and the wider size distribution and lower MFP, which offered better load supporting properties.

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“…Ultra‐coarse grained WC‐Co cemented carbides (WC grain size >6 μm) possess high hardness and shock resistance, moderate fracture toughness and good wear resistance over various temperatures, which thus have been widely used in the particular field of extremely high wear applications like mining and drilling . Traditionally, the ultra‐coarse grained WC‐Co cemented carbides were prepared by sintering the ball milled WC and Co powder mixture compacts . However, the big WC particles were always crushed into fine ones by milling balls.…”

Section: Introductionmentioning

confidence: 99%

“…Aside from the precursor selection, the defluidization resulting from the adhesion of particles is another issue of FBCVD because the deposition operation will be terminated with the arrival of defluidization . Particularly, the deposition of Co worsened the fluidization process due to its possible sintering at high temperature . Therefore, interacting with the deposition of Co, what are the minimum size of fluidized WC powders and its corresponding fluidization time (defined as the total time from the beginning of fluidization of powders to the occurrence of defluidization) is another key issue in making the core‐shell powders by FBCVD.…”

Section: Introductionmentioning

confidence: 99%

A novel core‐shell structured ultra‐coarse WC‐Co composite powders prepared by fluidized bed chemical vapor deposition

Zhang

Xin

et al. 2018

J Am Ceram Soc

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The ultra‐coarse WC‐Co composite powders with a core‐shell structure were effectively prepared by fluidized bed chemical vapor deposition (FBCVD) using CoCl2 precursor. An excellent interfacial bonding was formed between WC and the deposited Co. Defluidization was the major barrier to depositing high‐Co‐content composite powders, which was caused by the adhesion of the deposited Co particles. Decreasing the deposition temperature reduced the cohesion force of the deposited Co particles, which was thus beneficial to preventing the defluidization. Increasing the WC particle size and the gas velocity increased the collision force and benefited the fluidization. The final Co contents were largely dependent on the deposition and fluidization behaviors. For the conditions tested, the optimal deposition temperature was 800°C while the minimum WC particle size suitable for FBCVD was 25 μm.

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Influences of the preparation methods of WC–Co powders on the sintering and microstructure of coarse grained WC–8Co hardmetals

Cited by 33 publications

References 25 publications

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Effect of WC morphology on dry sliding wear behavior of cold-sprayed Ni-WC composite coatings

A novel core‐shell structured ultra‐coarse WC‐Co composite powders prepared by fluidized bed chemical vapor deposition

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