The &amp;beta;-Free Layer Formed near the Surface of Vacuum-Sintered WC&amp;ndash;&amp;beta;&amp;ndash;Co Alloys Containing Nitrogen

Suzuki, Hisashi; Hayashi, Kôji; Taniguchi, Yuta

doi:10.2320/matertrans1960.22.758

Cited by 80 publications

(21 citation statements)

References 6 publications

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“…Gradient structure is created in all alloys with TiN, fine-TiC 0.5 N 0.5, and ultrafine-TiC 0.5 N 0.5 doped, showing that it is not related with nitrogen intruduction methods. The result is in accordance with the research of Suzuki et al [2], who suggested that gradient zone could be obtained by sintering cemented carbides with either TiN or TiCN under denitriding conditions. It is noted that no gradient layer exits in the S1 alloy with no nitrogen (Fig.…”

Section: Microstructures Of Surfacessupporting

confidence: 94%

“…Suzuki et al [2] pointed out that a cubic phase depleted gradient zone could be formed by sintering nitrogen-containing cemented carbides in a denitriding atmosphere. Schwarzkopf et al [3] as well as Gustafson and Öst-lund [4] believed that gradient zone formation was controlled by diffusion in the liquid binder and the thermodynamic properties of the system.…”

Section: Introductionmentioning

confidence: 99%

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Effect of nitrogen introduction methods on the microstructure and properties of gradient cemented carbides

Yang

Xiong

Sun

et al. 2011

Int J Miner Metall Mater

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Gradient cemented carbides with the surface depleted in cubic phases were prepared following normal powder metallurgical procedures. Gradient zone formation and the influence of nitrogen introduction methods on the microstructure and performance of the alloys were investigated. The results show that the simple one-step vacuum sintering technique is doable for producing gradient cemented carbides. Gradient structure formation is attributed to the gradient in nitrogen activity during sintering, but is independent from nitrogen introduced methods. A uniform carbon distribution is found throughout the materials. Moreover, the transverse rupture strength of the cemented carbides can be increased by a gradient layer. Different nitrogen carriers give the alloys distinguishing microstructure and mechanical properties, and a gradient alloy with ultrafine-TiC 0.5 N 0.5 is found optimal.

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Section: Microstructures Of Surfacessupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effect of nitrogen introduction methods on the microstructure and properties of gradient cemented carbides

Yang

Xiong

Sun

et al. 2011

Int J Miner Metall Mater

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“…These local defects, attributed to the existence of cracks, to incomplete bonding between particles, and to interconnected porosity create direct paths through which the corrosive medium can gain access to the substrate material. Nitridation is an alternative method for controlling the chemical composition and microstructure at the surface of the hardmetal in order to improve its wear resistance [24][25][26][27][28][29][30][31][32][33][34][35]. By nitriding Ti-containing hardmetals a Ti(C,N) binder-free surface can be formed.…”

Section: Introductionmentioning

confidence: 99%

Influence of binder metal and surface treatment on the corrosion resistance of (W,Ti)C-based hardmetals

Barbatti

Sket

García³

et al. 2006

Surface and Coatings Technology

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The effect of a nitridation surface treatment on the microstructure and corrosion resistance of Co and Ni-binder (W,Ti)C-based hardmetals with additions of (Ta,Nb)C was investigated. Nitridation treatment produces a surface layer with a higher hard phase (Ti,Ta,Nb,W)(C,N) content. The near-surface layer thickness and microstructure are affected by the choice of binder (Co respectively Ni). The corrosion resistance of the hardmetals was characterized using linear sweep voltammetry. The microstructure of the hardmetals was determined before and after corrosive attack by optical microscopy and SEM. The results of the corrosion tests and microstructure analyses are interpreted in terms of the correlation between the hardmetal morphology and porosity and ion transport through the interface binder-electrolyte. The nitridation treatment of the hardmetals strongly increases the resistance to aggressive corrosion media for hardmetals both with Co and Ni-binder phase and thus may positively influence the hardmetal lifetime in cutting applications in chemically aggressive environments.

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“…The formation of a de-nitrided zone on the surface of hardmetals is well know and was first described by Japanese authors [3], too. Following this, a more detailed investigation of the formation mechanism was described [4,5], which recently was also modelled by thermodynamic and diffusion software [6].…”

Section: Introductionmentioning

confidence: 99%

Diffusional control of the near-surface microstructure in functional gradient hardmetals

Lengauer¹

2005

Mat.-wiss. u. Werkstofftech.

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The efforts of the last several years of a research cooperation on diffusional near-surface microstructure modification of hardmetals are summarised. This modification was performed with a reactive gas supplied within the sintering cycle so that functional gradient hardmetals, FGHMs, were obtained, which show a graded distribution of phases. They were optimised for increased wear resistance in metal cutting operations. The thermochemical and diffusional basics of the preparation of two principally different FGHMs, one with an increased surface hardness and a decreased toughness (with 'regular gradient') and one with a decreased surface hardness but an increased toughness ('inverse gradient') are described in detail. Some of the developed grades were successfully tested and scaled up into industrial production. The FGHMs were found to outperform conventional hardmetals in certain machining tests (continuous turning as well as milling).Keywords: hardmetals, cemented carbides, diffusion, gradient, cuttingIn dieser Arbeit werden die Ergebnisse einer mehrjährigen Forschungszusammenarbeit dargestellt, die sich zur Aufgabe machte, das Randzonengefüge von Hartmetallen zu modifizieren. Diese Randzonenmodifizierung wurde durch Steuerung der Sinteratmosphäre bewerkstelligt, wodurch sog. Funktionsgradienten-Hartmetalle (FGHM) erzeugt wurden, die sich durch eine stetige Ä nderung des Gefüges mit der Tiefe auszeichnen. Diese Materialien wurden hinsichtlich Verschleißbeständigkeit in Zerspanungsanwendungen optimiert. Die thermochemischen und diffusionskinetischen Grundlagen der Herstellung von zwei unterschiedlichen Randzonentypen dieser FGHM -ein Typ mit einer erhöhten Härte der Randzone und einer verminderten Zähigkeit ("regulärer" Gradient) sowie ein Typ mit einer verminderten Härte und erhöhten Zähigkeit ("inverser" Gradient) -werden im Detail beschrieben. Einige der entwickelten Sorten wurden erfolgreich getestet und in den Produktionsmaßstab übertragen. Manche FGHM schneiden in kontinuierlichen Dreh-sowie in Frästests besser ab als kommerzielle Hartmetalle.

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The β-Free Layer Formed near the Surface of Vacuum-Sintered WC–β–Co Alloys Containing Nitrogen

Cited by 80 publications

References 6 publications

Effect of nitrogen introduction methods on the microstructure and properties of gradient cemented carbides

Effect of nitrogen introduction methods on the microstructure and properties of gradient cemented carbides

Influence of binder metal and surface treatment on the corrosion resistance of (W,Ti)C-based hardmetals

Diffusional control of the near-surface microstructure in functional gradient hardmetals

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