FIELD OF THE DISCLOSURE

[0001] The present application relates to a cemented carbide with a binder phase having nanometric carbide precipitates therein. The present application further relates to a method of fabricating a cemented carbide having nanometric carbide precipitates therein.

BACKGROUND

[0002] Cemented carbides, also known as “hardmetals,” are commonly used powder metallurgy products that have wide industrial applicability. For instance, cemented carbides have been used in industries where hardness, wear resistance, and fracture toughness are desired, such as in the manufacture of tools, wire drawing, drill bits for drilling metals and rocks in the mining industry, nozzles, knives, chipless forming, etc. Cemented carbides generally include a binder that is made of a relatively soft and ductile material, such as Co, Ni, Fe, etc., and a relatively hard carbide material, such as WC, TiC, TaC, NbC, etc. When the relatively soft and ductile material and the relatively hard carbide material are combined and processed (e.g. by pressing and sintering), the relatively hard carbide material becomes “cemented” in the relatively soft material thereby producing a cemented carbide.

[0003] Cemented carbides can achieve a wide variety of properties (e.g., hardness, wear resistance, fracture toughness, traverse rupture strength, compressive strength, modulus of elasticity, thermal expansion coefficient, etc.). In mining applications, cemented carbides are desired to have intermediate values of hardness (i.e., around 1500 HV30, and good levels of fracture toughness (i.e., around 11.5 Kic (MN/m ^3/2 )) to resist wear and impact loading. Even higher values of hardness are desired, while still maintaining the good levels of fracture toughness. However, in general, as the hardness of a cemented carbide increases, the fracture toughness decreases. Thus, cemented carbides that achieve higher values of hardness without sacrificing good levels of fracture toughness remain desired.

[0004] Others have attempted to achieve produce cemented carbides with higher values of hardness and good levels of fracture toughness, but have only achieved marginal success. For example, WO 2017/055332 discloses a cemented carbide material with a binder phase that includes nanoparticles having a material according to the formula CoxWyCz, where x is a value in the range from 1 to 7, y is a value in the range from 1 to 10, and z is a value in the range from 0 to 4. WO 2017/055332 purports to provide a cemented carbide material having improved fracture toughness without a significant reduction in hardness and wear resistance. However, WO 2017/055332 indicates that the nanoparticles in its binder phase correspond to the eta- (C03W3C or Co6W6C) or theta-phases (C02W4C). The eta-phase is known to be very brittle, which is expected to negatively influence the overall performance of the disclosed cemented carbide material. Moreover, the presence of the eta-phase implies the presence of a third phase in the cemented carbide material of WO 2017/055332 that was not recognized or disclosed therein. Thus, further improvements are still needed over the marginal successes shown in WO 2017/055332.

[0005] In addition, as disclosed in detail in the present application, a method of fabricating a cemented carbide to achieve such excellent hardness and fracture toughness involves utilizing differing carbide particle sizes as starting materials. Others have also attempted to fabricate cemented carbides by using differing carbide particle sizes. For example, EP 1 022 350 discloses a method of making a cemented carbide body with a bimodal grain size distribution. In the disclosed method of EP 1 022 35, the grains of the group of smaller grains are pre-coated with a grain growth inhibitor with or without a binder metal. EP 1 022 350 indicates that it is essential that there is no change in grain size or grain size distribution as a result of the mixing procedure or as a result of the grain growth in the sintering step. As a result, the disclosed method obtains a structure with an extremely low grain growth, thereby reducing porosity. EP 1 022 35, however, does not consider or characterize the influence of such a method on hardness and fracture toughness, nor does EP 1 022 35 disclose the preparation of nanoparticles to achieve such hardness and fracture toughness.

[0006] In an effort to improve upon and solve the problems of known cemented carbides, the inventors have discovered the cemented carbides and methods of the present application. In doing so, the cemented carbides and methods of the present application improve the hardness property of these materials by increasing the hardness of the binder phase while retaining, at the same time, good levels of fracture toughness. In addition, the good levels of fracture toughness are achieved even while maintaining approximately the same amount of binder content, thereby avoiding the unnecessary addition of relatively expensive binder materials, such as Co. Thus, the cemented carbides and methods of the present application improve upon and solve the problems of known cemented carbides and methods of production.

SUMMARY

[0007] In view of the above-mentioned exemplary problems with conventional and known cemented carbide compositions and methods, the present application provides new and improved cemented carbides and methods.

[0008] A first embodiment of the present application includes a cemented carbide including a carbide phase and a binder phase, where the cemented carbide has a microstructure including nanometric carbide precipitates in the binder phase.

[0009] In one embodiment, the cemented carbide includes the carbide phase that includes a carbide selected from the group consisting of WC, Cr3C2, VC, NbC, TaC, TiC, ZrC, M02C, HfC, and mixtures thereof.

[0010] In one embodiment, the binder phase includes a binder selected from the group consisting of Co, Ni, Fe, and mixtures thereof.

[0011] In one embodiment, the carbide phase includes WC and the binder phase includes Co. [0012] In one embodiment, the nanometric carbide precipitates are nanometric WC precipitates.

[0013] In one embodiment, the cemented carbide has a hardness of 1450 HV30- 1550 HV30. In some embodiments, the cemented carbide has a hardness of 1250 HV30- 1350 HV30. In other embodiments, the cemented carbide has a hardness of up to 2000 HV30, or up to 2100 HV30.

[0014] In one embodiment, the cemented carbide has a fracture toughness of 8 MN/m ^3/2 -15 MN/m ^3/2 . In some embodiments, the cemented carbide achieves a fracture toughness of 9 MN/m ^3/2 -15 MN/m ^3/2 . In other embodiments, the cemented carbide achieves a fracture toughness of 10 MN/m ^3/2 -15 MN/m ^3/2 . In yet other embodiments, the cemented carbide achieves a fracture toughness of 11 MN/m ^3/2 -15 MN/m ^3/2 . In still other embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -15 MN/m ^3/2 . In further other embodiments, the cemented carbide achieves a fracture toughness of 13 MN/m ^3/2 -15 MN/m ^3/2 . In even other embodiments, the cemented carbide achieves a fracture toughness of 14 MN/m ^3/2 MN/m ^3/2 . In certain embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -12.5 MN/m ^3/2 . In certain particular embodiments, the cemented carbide achieves a fracture toughness of 8 MN/m ^3/2 -10 MN/m ^3/2 (i.e. for the hardest carbide above).

[0015] In one embodiment, the nanometric WC precipitates have a size of less than 250 nm. In other embodiments, the nanometric WC precipitates have a size of less than 200 nm. In yet other embodiments, the nanometric WC precipitates have a grain size of 0.001 nm-250 nm, 0.1 nm-10 nm, 10 nm-20 nm, 20 nm-50 nm, 50 nm-75 nm, 50n m-100nm, 50 nm-150nm, 50 nm-200 nm, 50 nm-225 nm, or from 50 nm-250 nm determined by visual measurement by electron microscopy.

[0016] A second embodiment of the present application includes tool including the disclosed cemented carbides.

[0017] A third embodiment of the present application includes a method of fabricating a cemented carbide including a) mixing a binder with a first WC powder to obtain a hardened binder phase slurry, where the first WC powder has a particle size of less than 0.5 pm determined by dynamic digital image analysis (DIA), static laser light scattering (SLS), or by visual measurement by electron microscopy; b) mixing the hardened binder phase slurry with a second WC powder to obtain a cemented carbide composition, where the second WC powder has a particle size of 2pm to 10pm determined by dynamic digital image analysis (DIA), static laser light scattering (SLS), or by visual measurement by electron microscopy; c) preparing a green part from the cemented carbide composition; and d) sintering the green part to obtain the cemented carbide.

[0018] In one embodiment, in the method of fabricating a cemented carbide, the first WC powder is doped with a dopant.

[0019] In one embodiment, in the method of fabricating a cemented carbide, the dopant is present in an amount of about 0.6wt.% relative to the first WC powder.

[0020] In one embodiment, in the method of fabricating a cemented carbide, the binder is selected from the group consisting of Co, Cr, VC, and mixtures thereof.

[0021] In one embodiment, in the method of fabricating a cemented carbide, a weight ratio of the first WC powder to the binder is greater than 0.5.

[0022] In one embodiment, in the method of fabricating a cemented carbide, a weight ratio of the first WC powder to the binder is greater than 1.5.

[0023] In one embodiment, in the method of fabricating a cemented carbide, the cemented carbide has a hardness of 1450 HV30-1550 HV30, 1250 HV30-1350 HV30, up to 2000 HV30, or up to 2100 HV30, and the cemented carbide has a fracture toughness of 8 MN/m ^3/2 -15 MN/m ^3/2 , 9 MN/m ^3/2 -15 MN/m ^3/2 , 10 MN/m ^3/2 -15 MN/m ^3/2 , 11 MN/m ^3/2 -15 MN/m ^3/2 , 12 MN/m ^3/2 -15 MN/m ^3/2 , 13 MN/m ^3/2 -15 MN/m ^3/2 , 14 MN/m ^3/2 -15 MN/m ^3/2 , 12 MN/m ^3/2 -12.5 Mn/m ^3/2 , or 8 MN/m ^3/2 MN/m ^3/2 (i.e. for the hardest carbide above).

[0024] In one embodiment, in the method of fabricating a cemented carbide, the nanometric WC precipitates have a grain size of less than 250 nm, less than 200 nm or from 0.001 nm-250 nm, 0.1 nm-10 nm, 10 nm-20 nm, 20 nm-50 nm, 50 nm-75 nm, 50 nm-100 nm, 50 nm-150 nm, 50 nm-200 nm, 50 nm-225 nm, or from 50 nm-250 nm determined by visual measurement by electron microscopy.

[0025] In one embodiment, in the method of fabricating a cemented carbide, the method further includes adding a grain growth inhibitor in a weight of about 5 wt.% of the binder weight in either step a) or step b).

[0026] Other systems, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, features and advantages be included within this description, be within the scope of the present disclosure, and be protected by the following claims. Nothing in this section should be taken as a limitation on those claims. Further aspects and advantages are discussed below in conjunction with the embodiments of the disclosure. It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are examples and explanatory and are intended to provide further explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are included to provide a further understanding of the subject matter and are incorporated in and constitute a part of this specification, illustrate implementations of the subject matter and together with the description serve to explain the principles of the disclosure.

[0028] FIG. 1 shows a Scanning Electron Microscope (SEM) image of a cemented carbide having a microstructure including nanometric carbide precipitates in the binder phase. DETAILED DESCRIPTION

[0029] Unless defined otherwise all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently described subject matter pertains.

[0030] Where a range of values is provided, for example, concentration ranges, percentage ranges, or ratio ranges, it is understood that each intervening value, to the tenth of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the described subject matter. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and such embodiments are also encompassed within the described subject matter, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the described subject matter.

[0031] The following definitions set forth the parameters of the described subject matter.

[0032] As used herein this disclosure, the term "D50" refers to a particle size corresponding to 50% of the volume of the sampled particles being smaller than and 50% of the volume of the sampled particles being greater than the recited D50 value. Similarly, the term "D90" refers to a particle size corresponding to 90% of the volume of the sampled particles being smaller than and 10% of the volume of the sampled particles being greater than the recited D90 value. The term "D10" refers to a particle size corresponding to 10% of the volume of the sampled particles being smaller than and 90% of the volume of the sampled particles being greater than the recited D10 value. A width of the particle size distribution can be calculated by determining the span, which is defined by the equation (D90-D10)/D50. The span gives an indication of how far the 10 percent and the 90 percent points are apart normalized with the midpoint. [0033] To determine mean particle sizes from a given particle size distribution, a skilled artisan would be readily familiar with the ISO 4499-2:2008 standard. The ISO 4499-2:2008 standard provides guidelines for the measurement of hardmetal grain size by metallographic techniques using optical or electron microscopy. It is intended for sintered WC/Co hardmetals containing primarily WC as the hard phase. It is also intended for measuring the grain size and distribution by a linear-intercept technique.

[0034] To further supplement the ISO 4499-2:2008 standard, a skilled artisan would equally know about the ASTM B390-92 (2006) standard. This standard is used for visual comparison and classification of the apparent grain size and distribution of cemented tungsten carbides that typically contain cobalt as a metallic binder in the binder phase.

[0035] Cemented carbide grades can be classified according to the WC grain size. Different types of grades have been defined as nano, ultrafine, submicron, fine, medium, medium coarse, coarse and extra coarse. As used herein this disclosure, the term (I) “nano grade” is defined as a material with a grain size of less than about 0.2 pm; (II) “ultrafine grade” is defined as a material with a grain size between about 0.2 pm and about 0.5 pm; (III) “submicron grade” is defined as a material with a grain size between about 0.5 pm and about 0.9 pm; (IV) “fine grade” is defined as a material with a grain size between about 1.0 pm and about 1.3 pm; (V) “medium grade" is defined as a material with a grain size between about 1.4 pm and about 2.0 pm; (VI) “medium coarse grade” is defined as a material with a grain size between about 2.1 pm and about 3.4 pm; (VII) “coarse grade" is defined as a material with a grain size between about 3.5 pm and about 5.0 pm; and (VIII) “extra coarse grade” is defined as a material with a grain size greater than about 5.0 pm.

[0036] As used herein this disclosure, “wt.%” refers to a given weight percent of the total weight of a cemented carbide, unless specifically indicated otherwise.

[0037] As used herein this disclosure, the terms “about” and “approximately” are used interchangeably. It is meant to mean plus or minus 1% of the numerical value of the number with which it is being used. Thus, “about” and “approximately” are used to provide flexibility to a numerical range endpoint by providing that a given value may be “above" or “below" the given value. As such, for example a value of 50% is intended to encompass a range defined by 49.5%-50.5%.

[0038] As used herein this disclosure, the term “predominantly” is meant to encompass at least 95% of a given entity.

[0039] As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result.

[0040] Wherever used throughout the disclosure, the term “generally” has the meaning of “approximately”, “typically” or “closely” or “within the vicinity or range of.

[0041] As used herein this disclosure, the term “Palmqvist fracture toughness” i.e. Kic, refers to the ability of a material with pre-cracks to resist further fracture propagation upon absorbing energy.

[0042] As used herein this disclosure, the term “HV30 Vickers hardness” (i.e. applying a 30 kgf load) is a measure of the resistance to localized plastic deformation, which is obtained by indenting the sample with a Vickers tip at 30 kgf.

[0043] As used herein this disclosure, the ISO 28079-2009 standard specifies a method for measuring the fracture toughness and hardness of hardmetals, cermets and cemented carbides at room temperature by an indentation method. The ISO 28079-2009 standard applies to a measurement of fracture toughness and hardness calculated by using the diagonal lengths of indentations andcracks emanating from the comers of a Vickers hardness indentation, and it is intended for use with metal-bonded carbides and carbonitrides (e.g. hardmetals, cermets or cemented carbides). The test procedures proposed in the ISO 28079-2009 standard are intended for use at ambient temperatures but can be extended to higher or lower temperatures by agreement. The test procedures proposed in the ISO 28079:2009 standard are also intended for use in a normal laboratory-air environment. They are typically not intended for use in corrosive environments, such as strong acids or seawater. The ISO 28079-2009 standard is directly comparable to the standard ASTM B771 as disclosed for example in “Comprehensive Hard Materials book”, 2014, Elsevier Ltd. Page 312, which is incorporated herein by reference in its entirety. Thus, it can be assumed that the measured fracture toughness and hardness using the ISO 28079-2009 standard will be the same as the measured values employing the ASTM B771 standard.

[0044] The cemented carbides and methods of the present application are now described by reference to the embodiments. The description provided herein is not intended to limit the scope of the claims, but to exemplify the variety encompassed by the present application. The embodiments are described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.

Cemented Carbide

[0045] The cemented carbide includes at least a carbide phase and a binder phase, and the cemented carbide has a microstructure including nanometric carbide precipitates in the binder phase. The carbide phase is the majority phase of the cemented carbide. The carbide phase generally represents between 65 wt.% and 97 wt.% of the cemented carbide. In some embodiments, the carbide phase represents between 70 wt.% to 97 wt.% of the cemented carbide. In other embodiments, the carbide phase represents between 75 wt.% to 97 wt.% of the cemented carbide. In yet other embodiments, the carbide phase represents between 80 wt.% to 97 wt.% of the cemented carbide. In still other embodiments, the carbide phase represents between 85 wt.% to 97 wt.% of the cemented carbide. In certain particular embodiments, the carbide phase represents between 70 wt.% to 75 wt.%, 70 wt.% to 80 wt.%, 70 wt.% to 85 wt.%, 75 wt.% to 80 wt.%, 75 wt.% to 85 wt.%, 75 wt.% to 90 wt.%, 80 wt.% to 85 wt.%, 80 wt.% to 90 wt.%, or 92 wt.% to 97 wt.% of the cemented carbide.

[0046] The binder phase is the minority phase of the cemented carbide. The binder phase generally represents between 3 wt.% to 25 wt.% of the cemented carbide. In some embodiments, the binder phase represents between 7 wt.% to 25 wt.% of the cemented carbide. In other embodiments, the binder phase represents between 10 wt.% to 25 wt.% of the cemented carbide. In yet other embodiments, the binder phase represents between 12 wt.% to 25 wt.% of the cemented carbide. In still other embodiments, the binder phase represents between 15 wt.% to 25 wt.% of the cemented carbide. In further other embodiments, the binder phase represents between 17 wt.% to 25 wt.% of the cemented carbide. In certain embodiments, the binder phase represents between 20 wt.% to 25 wt.% of the cemented carbide. In certain particular embodiments, the binder phase represents between 3 wt.% to 7 wt.%, 5 wt.% to 7 wt.%, 7 wt.% to 10 wt.%, 10 wt.% to 15 wt.%, 15 wt.% to 20 wt.%, or between 22 wt.% to 25 wt.% of the cemented carbide.

[0047] The carbide phase of the cemented carbide includes a carbide. For instance, the carbide can be WC, Cr3C2, VC, NbC, TaC, TiC, ZrC, M02C, HfC, and mixtures thereof. In certain embodiments, the carbide is WC. In other embodiments, the carbide is WC and at least one other carbide. As discussed in detail with respect to the method of fabrication below, the carbide phase can be prepared by using a combination of ultrafine carbide powders with coarse to ultra-coarse carbide powders. Such particle sizes respectively have a Fisher Number FSSS of 0.4 pm-0.5 pm, or a Fisher Number FSSS of 0.45 pm-0.5 pm with a BET around 3 m ² /g for the ultrafin powders, and a Fisher Number FSSS of 4 pm, or from 1 pm to 10 pm for the ultra-coarse carbide powders. In certain embodiments, the carbide phase can be prepared by using a combination of carbide powders. The first WC powder can be ultrafine WC powder typically having a first particle size of < 0.5 pm and a second particle size of 2 pm to 10 pm. In other embodiments, the carbide phase can be prepared by using a combination of carbide powders having a first particle size of < 0.5 pm and a second particle size of 3 pm to 10 pm. In yet other embodiments, the carbide phase can be prepared by using a combination of carbide powders having a first particle size of < 0.5 pm and a second particle size of 4 pm to 10 pm. In still other embodiments, the carbide phase can be prepared by using a combination of carbide powders having a first particle size of < 0.5 pm and a second particle size of 5 pm to 10 pm. In certain particular embodiments, the first particle size can be 0.2 pm. In certain other particular embodiments, the second particle size can be 10 pm.

[0048] For determining a particle size, one having ordinary skill in the art may typically employ either dynamic digital image analysis (DIA), static laser light scattering (SLS) also known as laser diffraction, or by visual measurement by electron microscopy, a technique known as image analysis and light obscuration. Each method covers a characteristic size range within which measurement is possible. These ranges partly overlap. However, the results for measuring the same sample may vary all depending on the particular method that is used. A skilled artisan who wants to determine particle sizes or particle size distributions would readily know how each mentioned method is commonly performed and practiced. Thus, the reader is directed to for example, (i) “Comparison of Methods. Dynamic Digital Image Analysis, Laser Diffraction, Sieve Analysis", Retsch Technology and (ii) the scientific publication by Kelly et al., “Graphical comparison of image analysis and laser diffraction particle size analysis data obtained from the measurements of nonspherical particle systems”, AAPS PharmSciTech. 2006 Aug 18; VoL7(3):69, to further gain insight into each procedure and methodology, all of which documents, are incorporated herein by reference in their entirety.

[0049] The carbide can also be doped with a dopant. In certain embodiments, the dopant can be at least one transition metal of the groups 4, 5, and 7 of the periodic table. In other embodiments, the dopant can be Cr. The dopant can influence the properties of the carbide such that the grain size of the carbide is controlled. For example, doping ultrafine WC (i.e., > 0.5 pm) with Cr (about 0.6 wt.% of the WC) can help avoid grain growth of the WC ultrafine particles during subsequent sintering. [0050] The binder phase, also known as a “matrix phase,” includes a binder. The binder can be a metallic binder material, such as Co, Ni, Fe, and mixtures thereof. In certain embodiments, the binder material is Co. In other embodiments, the binder material is Co and at least one other binder material.

[0051] The cemented carbide can also include a grain growth inhibitor. In certain embodiments, the grain growth inhibitor is Cr3C2, VC, TaC, TiC, M02C, and mixtures thereof. In other embodiments, the grain growth inhibitor is Cr3C2 with a grain size of the carbide phase ranging from 0.5 pm to 3 pm, from 1 pm to 3 pm, from 1.5 pm to 3 pm, from 2 pm to 3 pm, or ranging from 2.5 pm to 3 pm determined by dynamic digital image analysis (DIA), static laser light scattering (SLS), or by visual measurement by electron microscopy.

[0052] The cemented carbide have a microstructure that contains nanometric carbide precipitates therein. The nanometric carbide precipitates are generally present in the binder phase of the cemented carbide. That is, as shown in FIG. 1, the nanometric carbide precipitates can be present in the binder phase of the cemented carbide after the cemented carbide has been sintered. The nanometric carbide precipitates help increase the hardness of the binder phase, thereby enhancing the hardness of the sintered cemented carbide. However, the nanometric carbide precipitates do not decrease the fracture toughness of the sintered cemented carbide. Thus, the presence of the nanometric carbide precipitates in the binder phase increases the hardness of the binder phase while retaining, at the same time, the good levels of fracture toughness.

[0053] The term “nanometric” generally indicates that the carbide precipitates have a particle size measured in terms of nanometers. For instance, the nanometric carbide precipitates can typically have a grain size of less than 200 pm, less than 150 pm, less than 100 pm, less than 50 pm, less than 25 pm, or a grain size of 100 nm.

[0054] In certain embodiments, nanometric tungsten carbide precipitates are produced during sintering. The nanometric WC precipitates have a grain size of generally less than 250 nm, less than 200 nm or from 0.001 nm-250 nm, 0.1 nm-10 nm, 10 nm-20 nm, 20 nm-50 nm, 50 nm-75 nm, 50 nm-100 nm, 50 nm-150 nm, 50 nm-200 nm, 50 nm- 225 nm, or from 50 nm-250 nm determined by visual measurement by electron microscopy.

[0055] In one embodiment, the cemented carbide has a hardness of 1450 HV30- 1550 HV30. In other embodiments, the cemented carbide has a hardness of 1250 HV30- 1350 HV30. In yet other embodiments, the cemented carbide has a hardness of up to 2000 HV30, or up to 2100 HV30. The hardness is an HV30 Vickers hardness with test load of 30 kgf measured according to ISO 6507-1.

[0056] The cemented carbide typically achieves a fracture toughness of 8 MN/m ^3/2 to 15 MN/m ^3/2 . In some embodiments, the cemented carbide achieves a fracture toughness of 9 MN/m ^3/2 -15 MN/m ^3/2 . In other embodiments, the cemented carbide achieves a fracture toughness of 10 MN/m ^3/2 -15 MN/m ^3/2 . In yet other embodiments, the cemented carbide achieves a fracture toughness of 11 MN/m ^3/2 -15 MN/m ^3/2 . In still other embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -15 MN/m ^3/2 . In further other embodiments, the cemented carbide achieves a fracture toughness of 13 MN/m ^3/2 -15 MN/m ^3/2 . In even other embodiments, the cemented carbide achieves a fracture toughness of 14 MN/m ^3/2 -15 MN/m ^3/2 . In certain embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -12.5 MN/m ^3/2 . In certain particular embodiments, the cemented carbide achieves a fracture toughness of 8 MN/m ^3/2 MN/m ^3/2 . The toughness is the fracture toughness measured according to ISO 28079:2009 i.e., the Palmqvist method.

Tools

[0057] The present application concerns a tool including the disclosed cemented carbides. For example, the tool can be, but is not limited to, a mining button. In certain particular embodiments, the tool is used as a wear part, e.g., wire drawing die, other metal forming applications, drilling tools, mining buttons or rotary tools. Method of Fabrication

[0058] In addition to the above discussed cemented carbide compositions and tool, the present application concerns a method of fabricating a cemented carbide. The cemented carbides produced by the disclosed methods generally have the abovediscussed properties. Thus, the discussion above is incorporated herein by reference.

[0059] The method of fabricating a cemented carbide includes step a). In step a), a binder is mixed with a first WC powder to obtain a hardened binder phase slurry. The binder can be a metallic binder material, such as Co, Ni, Fe, and mixtures thereof. In certain embodiments, the binder material is Co. In other embodiments, the binder material is Co and at least one other binder material. The binder can be a powder having a submicronic grain size with a Fisher Number FSSS of typically ranging from 0.7-1.1, from 0.8-1.1, from 0.9-1.1, or from 1.0-1.1 in step a). The weight ratio of the first WC powder to the binder should be high enough to avoid the full dissolution of the ultrafine WC during the sintering. The weight ratio can be >0.5, >1.0, or >1.5. For example, a weight ratio of 1.5 would be the result of a mixture of 9 grams of WC for 6 grams of Co.

[0060] The first WC powder can be ultrafine WC powder typically having a first particle size of < 0.5 pm. In some embodiments, the first WC powder has a first particle size of < 0.4 pm. In other embodiments, the first WC powder has a first particle size of < 0.3 pm. In yet other embodiments, the first WC powder has a first particle size of < 0.2 pm. In still other embodiments, the first WC powder has a first particle size of < 0.1 pm determined by dynamic digital image analysis (DIA), static laser light scattering (SLS), or by visual measurement by electron microscopy. The first WC powder contains WC, but can be partially substituted with other carbides, such as Cr3C2, VC, NbC, TaC, TiC, ZrC, M02C, HfC, and mixtures thereof. For example, 0.6 wt.% of Cr3C2.

[0061] The first WC powder can be doped with a dopant. In certain embodiments, the dopant can be at least one transition metal of the groups 4, 5, and 7 of the periodic table. In other embodiments, the dopant can be Cr. The dopant can influence the properties of the carbide such that the grain size of the carbide is controlled. The amount of dopant can generally be between 0.2 wt.% and 1 wt.% relative to the weight of the first WC powder. In some embodiments, the amount of dopant may be between 0.4 wt.% and 1 wt.% relative to the weight of the first WC powder. In other embodiments, the amount of dopant may be between 0.6 wt.% and 1 wt.% relative to the weight of the first WC powder. In still other embodiments, the amount of dopant may be between 0.8 wt.% and 1 wt.% relative to the weight of the first WC powder. In certain particular embodiments, the amount of dopant may be 0.5 wt.% relative to the weight of the first WC powder

[0062] In addition to the binder powder and first WC powder, the mixture can include a liquid for producing the hardened binder phase slurry. The liquid can be water, alcohol, organic solvent, etc. For example, ethanol, acetone and/or water. The mixture can further include an organic binder, e.g., PEG or a wax, including, e.g. parrafin wax. The mixing time depends on the amounts utilized. In one embodiment, the mixture of the binder powder and the first WC powder is mixed for 6 hours for 15 grams of the binder powder and first WC powder. In other embodiments, the mixing time can be 18 hours for 750 grams of powder. The mixing in step a) can occur at room temperature and ambient pressure, for example, 25°C at 1 atm.

[0063] The method of fabricating a cemented carbide includes step b). In step b), the hardened binder phase slurry obtained in step a) is mixed with a second WC powder to obtain a cemented carbide composition. The “cemented carbide composition" refers to the composition that will subsequently be processed into a cemented composition in steps c) and d). That is, in step b), the cemented carbide composition can be considered a precursor to the final cemented carbide.

[0064] The second WC powder used in step b) is coarse to extra coarse WC powder. In some embodiments, the second WC powder has a second particle size of 2 pm to 10 pm. In other embodiments, the second WC powder has a second particle size of 3 pm to 10 pm. In yet other embodiments, the second WC powder has a second particle size of 4 pm to 10 pm. In still other embodiments, the second WC powder has a second particle size of 5 pm to 10 pm. In certain particular embodiments, the second WC powder has a second particle size that can be up to 8.5 pm, or up to 10 pm determined by dynamic digital image analysis (DIA), static laser light scattering (SLS), or by visual measurement by electron microscopy. The second WC powder contains WC, but can be partially substituted with other carbides, such as Cr3C2, VC, NbC, TaC, TiC, ZrC, M02C, HfC, and mixtures thereof. For example, 0.5wt.% amounts of partial substitution.

[0065] The mixing time in step b) depends on the amounts utilized, In one embodiment, the mixture of the hardened binder phase slurry and the second WC powder is mixed for 2 hours for 100 grams of powder in the hardened binder phase slurry and the second WC powder. Since the hardened binder phase slurry contains liquid, the method can optionally include a step of liquid removal, such that a dry mixing process can be used in step b). The dry mixing process can be, for example, accoustic milling, such as a resodyn mixer, ball milling or other milling.

[0066] In either step a) or step b), a grain growth inhibitor can be added. In certain particular embodiments, the grain growth inhibitor is Cr3C2, VC, TaC, TiC, M02C, and mixtures thereof. In other embodiments, the grain growth inhibitor is Cr3C2. In other embodiments, the grain growth inhibitor is a mixture of Cr3C2 and VC. The grain growth inhibitor can generally be added in an amount of typically ranging from 0.1 wt.% to 1 wt.%. In some embodiments, the grain growth inhibitor is added in an amount of ranging from 0.3 wt.% to 1 wt.%. In other embodiments, the grain growth inhibitor is added in an amount of ranging from 0.5 wt.% to 1 wt.%. In still other embodiments, the grain growth inhibitor is added in an amount of ranging from 0.7 wt.% to 1 wt.%. In certain embodiments, the grain growth inhibitor is added in an amount of 0.3 wt.%. In certain particular embodiments, the grain growth inhibitor is added in an amount of about 5 wt.% of the binder weight.

[0067] In step c), a green part can be formed from the cemented carbide composition obtained in step b). The green part sometimes called a “green body” can be formed with known techniques, such as uniaxial pressing, cold isostatic pressing, extrusion, green machining, and injection molding. [0068] In step d), the green part can be sintered to obtain a cemented carbide. During the sintering of the green part, nanometric tungsten carbide precipitates can be generated. The cemented carbide contains the nanometric tungsten carbide precipitates generally in an amount of 0.1 wt.% to 10 wt.%. In some embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 0.5 wt.% to 10 wt.%. In other embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 0.75 wt.% to 10 wt.%. In yet other embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 1 wt.% to 10 wt.%. In still other embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 3 wt.% to 10 wt.%. In further other embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 5 wt.% to 10 wt.%. In even other embodiments, the cemented carbide contains the nanometric tungsten carbide precipitates in an amount of 7 wt.% to 10 wt.%.

[0069] The nanometric carbide precipitates generally have a grain size of less than 200 pm, less than 150 pm, less than 100 pm, less than 50 pm, less than 25 pm, or a grain size of 100 nm determined by visual measurement by electron microscopy. As shown in FIG. 1, the nanometric carbide precipitates are present in the binder phase of the sintered cemented carbide composition. The nanometric carbide precipitates increase the hardness of the binder phase, thereby enhancing the hardness of the sintered cemented carbide. However, the nanometric carbide precipitates do not decrease the fracture toughness of the sintered cemented carbide composition. Thus, the presence of the nanometric carbide precipitates in the binder phase increases the hardness of the binder phase while retaining, at the same time, the good levels of fracture toughness.

[0070] The cemented carbides prepared by the method can achieve a hardness of 1450 HV30-1550 HV30. In some embodiments, the cemented carbide has a hardness of 1250 HV30-1350 HV30. In other embodiments, the cemented carbide has a hardness of up to 2000 HV30, or up to 2100 HV30. The hardness is an HV30 Vickers hardness with a test load of 30 kgf measured according to ISO 6507-1. [0071] The cemented carbides prepared by the method can generally achieve a fracture toughness of 8 MN/m ^3/2 -15 MN/m ³ ' ² . In some embodiments, the cemented carbide achieves a fracture toughness of 9 MN/m ^3/2 -15 MN/m ³ ' ² . In other embodiments, the cemented carbide achieves a fracture toughness of 10 MN/m ³ ' ² -! 5 MN/m ³ ' ² . In yet other embodiments, the cemented carbide achieves a fracture toughness of 11 MN/m ³ ' ² - 15 MN/m ³ ' ² . In still other embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -15 MN/m ³ ' ² . In further other embodiments, the cemented carbide achieves a fracture toughness of 13 MN/m ^3/2 -15 MN/m ³ ' ² . In even other embodiments, the cemented carbide achieves a fracture toughness of 14 MN/m ³ ' ² - 15 MN/m ³ ' ² . In certain embodiments, the cemented carbide achieves a fracture toughness of 12 MN/m ^3/2 -12.5 MN/m ³ ' ² . In certain particular embodiments, the cemented carbide achieves a fracture toughness of 8 MN/m ^3/2 MN/m ³ ' ² (for the hardest carbide above). The toughness is the fracture toughness measured according to ISO 28079-2009 i.e., the Palmqvist method.

EXAMPLES

[0072] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the described subject matter and are not intended to limit the scope of what the inventors regard as their disclosure nor are they intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are by weight, molecular weight is weight average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.

EXAMPLE 1

PRODUCTION OF A CEMENTED CARBIDE HAVING A MICROSTRUCTURE INCLUDING NANOMETRIC CARBIDE PRECIPITATES IN THE BINDER PHASE IN ACCORDANCE WITH A FIRST EMBODIMENT [0073] In step i), 6 grams of cobalt was mixed in a ball mill together with 1.2 kilograms of tungsten carbide (WC) balls, with 0.3 grams of Cr3C2, with 9.37 grams of nano powder of WC, with 50 milliliters of ethanol, and with 2 grams of polyethylene glycol (PEG) for 2 hours. In step ii), 84.33 grams of WC with a Fisher Number FSSS of 4.0 was added and milling was further conducted in the ball mill with the 1.2 kilograms WC balls for 6 hours. In step iii), the mixture was dried, pressed and sintered to obtain a cemented carbide having a microstructure including nanometric carbide precipitates in the binder phase as shown in FIG. 1.

EXAMPLE 2

PRODUCTION OF A CEMENTED CARBIDE HAVING A MICROSTRUCTURE INCLUDING NANOMETRIC CARBIDE PRECIPITATES IN THE BINDER PHASE IN ACCORDANCE WITH A SECOND EMBODIMENT

[0074] In step i), 308 grams of cobalt was mixed in a ball mill with 20 kilograms of tungsten carbide (WC) balls, with 15.4 grams of Cr3C2, with 1.2 liters of ethanol, and with 125 grams of polyethylene glycol (PEG) for 6 hours. In step ii), 4315 grams of WC with a Fisher Number FSSS of 4.0 was added and milling was further conducted in the ball mill with the 20 kilograms WC balls for 18 hours. In step iii), the mixture was dried, pressed and sintered to obtain a cemented carbide having a similar microstructure including nanometric carbide precipitates in the binder phase as shown in FIG. 1.

EXAMPLE 3

PRODUCTION OF A CEMENTED CARBIDE HAVING A MICROSTRUCTURE

INCLUDING NANOMETRIC CARBIDE PRECIPITATES IN THE BINDER PHASE IN

ACCORDANCE WITH A THIRD EMBODIMENT

[0075] In step i), 6.2 grams of cobalt was mixed in a ball mill with 1.2 kilograms of tungsten carbide (wc) balls, with 0.24 grams of Cr3C2, with 9.37 grams of nano powder of WC, with 50 milliliters of ethanol, and with 2 grams of polyethylene glycol (PEG) for 6 hours. In step ii), 86.30 grams of WC with a Fisher Number FSSS of 6.0 was added and milling was further conducted in the ball mill with the 1.2 kilograms WC balls for 2 hours. In step iii), the mixture was dried, pressed and sintered to obtain a cemented carbide having an equivalent microstructure including nanometric carbide precipitates in the binder phase as shown in FIG. 1.

[0076] Although the present disclosure has been described in connection with embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departure from the spirit and scope of the disclosure as defined in the appended claims.

[0077] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity.

[0078] The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable," to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wirelessly interacting components, and/or logically interacting, and/or logically interactable components. [0079] In some instances, one or more components may be referred to herein as “configured to,” “configured by," “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Those skilled in the art will recognize that such terms (e.g., “configured to") can generally encompass activestate components and/or inactive-state components and/or standby-state components, unless context requires otherwise.

[0080] While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. [0081] In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations).

[0082] Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.).

[0083] It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or“B” or “A and B.”

[0084] With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.

[0085] Those skilled in the art will appreciate that the foregoing specific exemplary processes and/or devices and/or technologies are representative of more general processes and/or devices and/or technologies taught elsewhere herein, such as in the claims filed herewith and/or elsewhere in the present application.

[0086] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

[0087] The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

[0088] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. The upper and lower limits of these smaller ranges which can independently be included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either both of those included limits are also included in the disclosure.

[0089] One skilled in the art will recognize that the herein described components (e.g., operations), devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components (e.g., operations), devices, and objects should not be taken as limiting.

[0090] Additionally, for example any sequence(s) and/or temporal order of sequence of the system and method that are described herein this disclosure are illustrative and should not be interpreted as being restrictive in nature. Accordingly, it should be understood that the process steps may be shown and described as being in a sequence or temporal order, but they are not necessarily limited to being carried out in any particular sequence or order. For example, the steps in such processes or methods generally may be carried out in various different sequences and orders, while still falling within the scope of the present disclosure.

[0091] Finally, the discussed application publications and/or patents herein are provided solely for their disclosure prior to the filing date of the described disclosure. Nothing herein should be construed as an admission that the described disclosure is not entitled to antedate such publication by virtue of prior disclosure.