A study on WC-Ni cemented carbides: Constitution, alloy compositions and properties, including corrosion behaviour

Steinlechner, Robert; Calderon, Raquel de Oro; Koch, Thomas; Linhardt, P.; Schubert, Wolf‐Dieter

doi:10.1016/j.ijrmhm.2021.105750

Cited by 26 publications

(5 citation statements)

References 32 publications

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“…Firstly, the Co-rich HMs (Co-Ni and Co-Ni-Cr-Mo) are much less resistant than the Ni-rich ones (Ni-Co, Ni-Co-Cr-Mo) and addition of Cr + Mo (Co-Ni-Cr-Mo and Ni-Co-Cr-Mo) enhances dramatically the corrosion resistance of both grades. This quantitative outcome is coherent with the literature on the corrosion-resistance enhancement of grades with these additives[43,44,65,66,71]. The voltammetric behavior of the Cr + Mo containing Co-rich grade (Co-Ni-Cr-Mo) is similar to that of the Ni-rich (Ni-Co) one without binder additives.Focusing on the details of the CVs of Figure1a-d-in combination with the evolution of the anodic charge with ATV and number of cycles, analyzed in FigureS1in the Supplementary Material-it can be noticed that there are classes of the CV pattern group in specific potential ranges, as detailed in FiguresS2-S5in the Supplementary Material.…”

supporting

confidence: 88%

“…These corrosion products are porous electronic insulators that, on the one hand, screen part of the electrode surface and increase the interfacial ohmic drop but, on the other hand, allow the contact of the active underlying HM with the electrolyte. In this way, the corrosion process is hindered and, with specific binder compositions, brought below practically significant thresholds, but never totally impeded [42][43][44].…”

Section: Introductionmentioning

confidence: 99%

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In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Bozzini,

Tavola,

Travella

et al. 2023

Metals

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Recycling of hardmetal scrap is strategic for critical raw materials recovery. Available recycling processes are polluting and have a large carbon footprint. Attempts to exploit controlled corrosion failed in industrial practice, owing to self-limiting processes. We revisit the corrosion route, in view of gaining the fundamental knowledge enabling high-throughput recovery. We selected the worst-case approach of highly corrosion-resistant CoNiWC-based hardmetal grades and neutral aqueous electrolyte at room temperature. Systematic electrochemical measurements, UV–Vis spectroscopy and SEM microscopy disclosed that, even though there is no hope to overcome the self-limiting corrosion rate, nevertheless, by exploiting the mechanical action of anodic O2 evolution acting precisely at the interface between the residual active material and the corrosion film, the latter can be efficiently removed, periodically reactivating the hardmetal corrosion in a way that results in an ultra-high scrap destruction rate, of interest for real-life industrial processes.

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supporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Bozzini,

Tavola,

Travella

et al. 2023

Metals

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“…In recent years, the role of Cr as an additive has been progressively extending to grades with progressively higher binder content. As far as the solubility of Cr in Ni-base grades is concerned, de Oro Calderon at TU Wien also reported a value of 11 wt% in low-carbon conditions [28] and 9 wt% with a high carbon-content, yielding graphite and Cr 3 C 2 [29].…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behaviour of Cemented Carbides with Co- and Ni-Alloy Binders in the Presence of Abrasion

Gaudenzi

Tavola

Tedeschi

et al. 2022

Metals

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More and more often, cemented carbides are employed for the production of wear resistant components and have to face highly demanding service conditions that combine different damage mechanisms. A key example is the range of tetraphasic (sea water, sand, liquid and gaseous hydrocarbons) flows encountered in the Oil and Gas extraction industry. Notwithstanding the importance of operating regimes of this type, the availability of fundamental and quantitative information on the corrosion performance of cemented carbides in the presence of abrasion is still limited. In this paper, we report a systematic study of the corrosion behaviour of cemented tungsten carbide grades with binders containing different amounts of cobalt (Co), nickel (Ni), chromium (Cr) and noble metal additions, subjected to controlled mechanical abrasion, impacting the stability and nature of pseudopassivation films. In this work, special attention is devoted to Cr, a classical of additive that inhibits the Ostwald ripening of tungsten carbide (WC) particles and notably improves the corrosion resistance of grades with ultrafine-to-fine WC grain size and low-to-medium binder content. We assessed the impact of binder composition on the anodic behaviour by means of linear-sweep voltammetry and chronopotentiometry as well as on the mechanical properties. The application of controlled abrasion conditions under electrochemical control is carried out with an in-house modified ASTM B611 apparatus, equipped with a three-electrode system, enabling the systematic investigation of the synergy of electrochemical and mechanical damaging conditions. Increased corrosion resistance in environments without and with added chloride—both in the absence and in the presence of abrasion—was observed in all the Co- and Ni-based grades to which growing quantities of Cr were added. Moreover, doping with ruthenium (Ru) further enhances corrosion resistance. Regarding corrosion in the presence of abrasion, the addition of Cr and Ru increases the ability of regenerating the pseudopassivation film. The optimized compositions of the binder have been highlighted that open up attractive opportunities of improved service behaviour and deployment in new applications.

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“…The chemical formula of the η phase in the 15 vol% W doped cermets was Ni 28 Nb 10 W 36 C 15 , as determined by quantitative WDS–EPMA of 20 points analysis of the η grains, which is closed to M 6 C. The composition and lattice parameter of the η phase is known to vary upon refractory carbide (TiC, VC, TaC, Cr 3 C 2 , or Mo 2 C) additions in WC–Co alloys 21 . There is no η phase formation in the NbC–Ni system, as a carbon deficiency results in a substoichiometric cubic NbC x phase, 10 in contrast to the hexagonal stoichiometric Mo 2 C phase in Mo 2 C–20Ni (wt%) cermets 22 or WC phase in WC–Co/Ni/Fe cermets 23–25 . The submicrometer black intragranular spherical spots were small pores or oxygen‐rich NbC x O y .…”

Section: Resultsmentioning

confidence: 99%

“…Backscattered There is no η phase formation in the NbC-Ni system, as a carbon deficiency results in a substoichiometric cubic NbC x phase, 10 in contrast to the hexagonal stoichiometric Mo 2 C phase in Mo 2 C-20Ni (wt%) cermets 22 or WC phase in WC-Co/Ni/Fe cermets. [23][24][25] The submicrometer black intragranular spherical spots were small pores or oxygen-rich NbC x O y . 26 W addition did not show a significant influence on the (Nb,W)C grain growth as shown in Figure 2b-f. An (Nb,W)C core-rim structure with a slightly darker contrast core was observed in the BSE images of all W-doped cermets.…”

Section: Microstructurementioning

confidence: 99%

Effect of carbon and tungsten content on the phase equilibria, microstructure, and mechanical properties of (Nb,W)C–Ni cermets

Huang

Zhang

2023

J Am Ceram Soc.

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With the assistance of thermodynamic simulation, the NbC–Ni based cermets with different W and C additions were designed and sintered in liquid state at 1390°C for 90 min in vacuum. By controlling the carbon and tungsten content, (Nb,W)C–Ni based cermets were prepared with varied phase constitution, microstructure, and mechanical properties. The microstructure, composition of phases, grain size, and equilibrium phases were investigated using scanning electron microscopy, electron probe microanalysis, EBSD, and X‐ray diffraction. The simulation reasonably predicted the experimentally observed phase constitutions. Depending on the additions, detailed analysis indicated that the cermets were composed of either a combination of cubic (Nb,W)C solid solution and Ni alloy binder or with an additional carbon‐deficient phase. Furthermore, mechanical analysis showed a strong dependence of its mechanical properties (Vickers hardness, indentation toughness, and flexural strength) on the phases and NbC grain size.

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A study on WC-Ni cemented carbides: Constitution, alloy compositions and properties, including corrosion behaviour

Cited by 26 publications

References 32 publications

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Corrosion Behaviour of Cemented Carbides with Co- and Ni-Alloy Binders in the Presence of Abrasion

Effect of carbon and tungsten content on the phase equilibria, microstructure, and mechanical properties of (Nb,W)C–Ni cermets

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