Low-binder, high-density cemented carbide for neutron shielding applications

Abstract

A low-binder high-density cemented carbide composition for neutron shielding is provided, comprising a ceramic hard phase consisting of tungsten carbide (WC), stoichiometric tungsten dicarbide (W2C), or a combination thereof, and a low-weight iron (Fe)-chromium (Cr)-based metal binder phase of about 0.02 wt% to about 2.75 wt% based on the total weight of the cemented carbide composition. The Cr weight of the Fe-Cr-based metal binder phase can be present at about 5 wt% to about 16 wt% based on the total weight of the Fe-Cr-based metal binder phase. A related method of manufacturing a sintered low-binder high-density cemented carbide for neutron shielding is further presented.

Description

[Technical Field]

[0001] This disclosure relates to low-binder, high-density cemented carbide compositions and related methods for manufacturing low-binder, high-density cemented carbide for neutron shielding. [Background technology]

[0002] Regardless of the type of reactor being designed, a fundamental consideration is how to protect the reactor components from the amount of neutron flux and gamma rays produced by the reactor during nuclear fission and fusion reactions. Regarding radiation shielding, efficient biological shielding is required overall, including for other parts of the reactor such as the electronic system. A prerequisite is that the shielding material must be designed to provide protection from a variety of high-energy radioactive radiation species, including, for example, short-range alpha particles, beta particles, gamma rays, and neutrons. These conditions impose strict limitations on the types of materials that can be used during the reactor design phase. It is also crucial that the material forming the shielding is resistant to activation and not converted into other harmful radioactive isotopes upon irradiation. This means, for example, that materials containing large amounts of nickel (Ni) and cobalt (Co) cannot be used for this purpose because their radioactive half-lives are very long, posing a risk of activation upon irradiation.

[0003] Small modular fusion reactors and magnetic confinement reactors are emerging as common options for next-generation nuclear power plants. Essentially, small modular nuclear power plants have the potential advantage of being safer and more efficient than the large nuclear power plants currently in use. The drawback is that, in the case of magnetic confinement fusion reactors, they rely on copper and / or high-temperature superconductors (HTS) cooled to cryogenic temperatures to generate the magnetic field. Therefore, the space between the plasma chamber and the cryogenic conductor (copper / HTS) is quite limited. In both cases, these types of reactors present a challenge in considering the selection of radiation shielding materials due to the limited space inherent in their shape. As a result, the shielding material needs to be applied in logically thin layers while maintaining neutron shielding capability.

[0004] Therefore, the challenge lies in finding alternative shielding materials that do not require excessively thick layers to achieve a satisfactory shielding effect. Furthermore, the material must not form harmful byproducts when exposed to the fusion process. Thus, it is essential that the material does not contain any accompanying elements that would transform into harmful radionuclides that would hinder the decommissioning and refueling phases of the reactor at the end of the operating cycle. Moreover, an important aspect is that the material used for this application can be manufactured using conventional techniques without involving multiple cumbersome procedures.

[0005] In this regard, the most attractive material would be a high-density material that also possesses the ability to exhibit high corrosion and oxidation resistance. Therefore, it is crucial that neutron shielding materials for nuclear applications are high-density in order to capture and effectively suppress the neutron flux generated in the reactor. Separately, they must be made of elements with short radioactive half-lives to avoid complex decommissioning procedures when the reactor reaches the end of its life and to avoid the creation of complex facilities for storing irradiated materials. Finally, as mentioned above, since they are continuously exposed to the cooling medium during reactor operation, corrosion and oxidation resistance are essential.

[0006] Notably, the properties of cemented carbide depend primarily on the content of the metallic bonding phase and the grain size of tungsten carbide (WC). Therefore, a typical WC-cobalt (Co) or WC-nickel (Ni) cemented carbide contains approximately 2% to a maximum of approximately 30% by weight of Co or Ni, based on the total weight of the cemented carbide, and the grain size of WC can typically range from submicron to several microns. While bonding phases such as Co or Ni are advantageous in promoting robust fracture toughness and improved strength, they also undesirably reduce the corrosion resistance, wear resistance, and hardness of the cemented carbide. Thus, increasing fracture toughness and strength at the expense of reduced corrosion resistance, wear resistance, and hardness remains a significant trade-off. Furthermore, due to differences in thermal expansion coefficients compared to WC, cobalt, for example, also induces undesirable thermal stress, thus logically limiting its application at high temperatures and other harsh conditions. Therefore, in the ongoing search for solutions to mitigate the aforementioned problems, low-binder cemented carbides have naturally attracted considerable research attention and effort. The evidence from the studies conducted continues to grow, suggesting that low-binder cemented carbides, due to their lower metallic binder content, exhibit superior physical properties such as robust wear resistance, improved corrosion resistance, and increased hardness. As a result, over the years, there has been growing interest in limiting the addition of excessively high concentrations of metallic binders during the cemented carbide manufacturing process, ultimately improving corrosion resistance.

[0007] International Publication No. 2018 / 206174, which is incorporated herein by reference in its entirety, relates to a cemented carbide containing an iron-chromium (Fe-Cr) based metal binder used in the manufacture of cutting tools, wear parts, seal rings, bushings, automotive parts, molds, or tools for handling radioactive substances. However, in this case, the cemented carbide disclosed in International Publication No. 2018 / 206174 has a metal binder content exceeding 3% by weight, and thus is not optimized for handling radioactive substances. As a result, the final density of the substance is reduced, thereby essentially precluding the possibility and capacity of neutron shielding. Furthermore, the use of stoichiometric tungsten carbide such as W2C to increase the material density is not disclosed in International Publication No. 2018 / 206174.

[0008] Therefore, considering the above, there is a need for a cemented carbide composition with low binder and high density that exhibits improved corrosion resistance and has a radioactive half-life short enough to be acceptable for neutron shielding in a nuclear reactor. SUMMARY OF THE INVENTION

[0009] According to a first aspect, there is provided a cemented carbide composition for low binder high density neutron shielding in a nuclear reactor, comprising a ceramic hard phase and an iron (Fe)-chromium (Cr) based metal binder phase. The weight of Cr can be from about 5% to about 16% by weight based on the total weight of the Fe-Cr based metal binder phase.

[0010] Optionally, the weight of chromium is from about 10.5% to about 16% by weight based on the total weight of the Fe-Cr based metal binder phase.

[0011] Optionally, the weight of chromium is from about 10.5% to about 10.7% by weight based on the total weight of the Fe-Cr based metal binder phase.

[0012] Optionally, the cemented carbide composition can contain from about 0.02% to about 2.75% by weight of the Fe-Cr based metal binder phase based on the total weight of the cemented carbide composition.

[0013] Optionally, the cemented carbide composition may contain about 2.75% by weight of an Fe-Cr-based metal binder phase, based on the total weight of the cemented carbide composition.

[0014] Optionally, the hard ceramic phase may include tungsten carbide (WC), quasi-stoichiometric ditungsten carbide (W2C), or a combination thereof.

[0015] Optionally, the hard ceramic phase may include WC.

[0016] Optionally, the hard phase of the ceramic contains quasi-stoichiometric W2C.

[0017] Optionally, the hard ceramic phase includes a 1:1 ratio combination of WC and quasi-stoichiometric W2C.

[0018] Optionally, the cemented carbide composition may contain, based on the total weight of the cemented carbide composition, approximately 97.25% to approximately 99.98% by weight of the ceramic hard phase.

[0019] Optionally, the cemented carbide composition is approximately 15.25 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density of .

[0020] A cemented carbide composition with improved corrosion resistance can be obtained through optional selection.

[0021] Optionally, the Fe-Cr-based metal binder phase is prepared by blending FeCr powder with Cr3C2 powder.

[0022] Optionally, the cemented carbide composition has a Vickers hardness of HV30 ranging from about 2227HV30 to about 2700HV30 and a Palmqvist fracture toughness (KIc) ranging from about 5 MPa√m to about 7.6 MPa√m.

[0023] A method is also provided for producing a sintered low-binder high-density cemented carbide for neutron shielding in a nuclear reactor, comprising blending a powder mixture in a grinding liquid with an organic binder to form a slurry blend, the mixture comprising an iron (Fe)-chromium (Cr)-based metal binder phase containing about 5% to about 16% by weight of chromium based on the total weight of the powder forming the hard component of the ceramic hard phase and the Fe-Cr-based metal binder phase. Next, the formed slurry blend is dried to form a powder blend. Finally, the formed powder blend is sintered to obtain a sintered low-binder high-density cemented carbide for neutron shielding.

[0024] Selectively, the weight of chromium ranges from approximately 10.5% to 16% by weight, based on the total weight of the Fe-Cr metal binder phase.

[0025] Optionally, the weight of chromium is approximately 10.5% to 10.7% by weight, based on the total weight of the Fe-Cr metal binder phase.

[0026] Optionally, the cemented carbide may contain an Fe-Cr-based metallic binder phase in an amount ranging from about 0.02% to about 2.75% by weight, based on the total weight of the cemented carbide.

[0027] Optionally, the cemented carbide contains approximately 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide.

[0028] Optionally, the hard ceramic phase may include tungsten carbide (WC), quasi-stoichiometric ditungsten carbide (W2C), or a combination thereof.

[0029] Optionally, the hard ceramic phase may include WC.

[0030] Optionally, the hard phase of the ceramic contains quasi-stoichiometric W2C.

[0031] Optionally, the hard ceramic phase includes a 1:1 ratio combination of WC and quasi-stoichiometric W2C.

[0032] Optionally, the cemented carbide may contain a ceramic hard phase of approximately 97.25% to 99.98% by weight, based on the total weight of the cemented carbide.

[0033] Optionally, cemented carbide has a viscosity of approximately 15.25 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density of .

[0034] Optionally, cemented carbide alloys with improved corrosion resistance can be obtained.

[0035] Optionally, the Fe-Cr-based metal binder phase is prepared by blending FeCr powder with Cr3C2 powder.

[0036] Optionally, cemented carbide alloys have a Vickers hardness of HV30 ranging from approximately 2227HV30 to approximately 2700HV30 and a Palmqvist fracture toughness (KIc) ranging from approximately 5 MPa√m to approximately 7.6 MPa√m.

[0037] Optionally, drying the slurry blend may include vacuum drying, air drying, freeze-drying, or spray drying.

[0038] Optionally, sintering includes hot pressing (HP), hot isostatic pressing (HIP), or plasma discharge sintering (SPS).

[0039] Other systems, methods, features, and advantages will be apparent to those skilled in the art upon consideration of the following figures and detailed description. All such additional systems, methods, features, and advantages are included in this description, are within the scope of the disclosure, and are intended to be protected by the following claims. Nothing in this section should be construed as limiting those claims. Further embodiments and advantages will be discussed below in conjunction with embodiments of the disclosure. Both the above general description of the disclosure and the following detailed description are examples and illustrative and are intended to provide further explanation of the requested disclosure.

[0040] The accompanying drawings, included to provide a further understanding of the subject matter and incorporated herein, and constituting a part thereof, illustrate implementations of the subject matter and, together with the descriptions, help to illustrate the principles of this disclosure. [Brief explanation of the drawing]

[0041] [Figure 1] This flowchart illustrates the individual process steps for manufacturing a low-binder, high-density cemented carbide for neutron shielding according to an exemplary embodiment of the subject. [Modes for carrying out the invention]

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the subject matter described herein pertains.

[0043] Where a range of values ​​is provided, such as a concentration range, a percentage range, or a ratio range, unless otherwise clearly indicated in the context, each intermediate value between the upper and lower limits of that range and other specified or intermediate values ​​within that range should be understood to be included in the subject matter to the extent of one-tenth of the lower limit. The upper and lower limits of these smaller ranges may be included independently within the smaller range, and such embodiments are also included in the subject matter, subject to any explicitly excluded limitations within the specified range. If a specified range includes one or both of the limit values, the range excluding one or both of those limit values ​​is also included in the subject matter.

[0044] The following definitions indicate the parameters of the subject matter described.

[0045] As used in this disclosure, the term “low-binder, high-density cemented carbide” generally refers to a composite material comprising (I) a ceramic hard phase (generally composed of tungsten carbide (WC), quasi-stoichiometric ditungsten carbide (W2C), or a mixture thereof), and (II) an Fe-Cr-based metallic binder matrix (i.e., forming an Fe-Cr-based metallic binder phase), where the Fe-Cr-based metallic binder is typically used in an amount ranging from about 0.02% to about 2.75% by weight based on the total weight of the cemented carbide. As used in this disclosure, the term “quasi-stoichiometric” refers to a value considerably higher than 1. The ceramic hard phase powder and the Fe-Cr-based metallic binder phase powder can be processed into a variety of microstructures that achieve a variety of mechanical and physical properties. Furthermore, additional components can be added to the composition to help control and further improve the properties achieved by the cemented carbide composition. By controlling various parameters, including particle size, Fe-Cr content, dotation (e.g., alloy carbides), and carbon content, cemented carbide manufacturers can favorably adjust and direct its performance to specific, unique applications. Cemented carbides are ideally designed to provide both the optimal physical properties of ceramics, such as high-temperature resistance and high hardness, and the optimal physical properties of metals, such as the ability to undergo plastic deformation and provide good fracture toughness. The naturally ductile, soft Fe-Cr metallic binder plays a role in counteracting the characteristic brittle behavior of the ceramic hard phase, thereby enhancing and strengthening the associated fracture toughness and durability. The ceramic hard phase of cemented carbides generally consists of refractory carbides of metals, most typically tungsten, but is not limited to this; instead, it may be titanium, tantalum, chromium, vanadium, zirconium, or any combination thereof. The ceramic hard phase may be present in cemented carbide powder in any possible combination of the above metals, in weights that are not inconsistent or unsuitable for the purposes of this subject.In this specification, for a cemented carbide to be considered a cemented carbide in this disclosure, it generally has a ceramic hard phase consisting of at least about 97.25% to about 99.98% by weight, based on the total weight of the cemented carbide.

[0046] Where used herein, “weight %” means a given weight percentage based on (I) the total weight of the cemented carbide composition for low-binder high-density neutron shielding in a reactor, (II) the total weight of the low-binder high-density cemented carbide for neutron shielding in a reactor, or (III) the total weight of the Fe-Cr-based metal binder phase. Where “weight %” is referred to in this disclosure or claims, it will also be explicitly stated whether it refers to a given weight percentage of (I), (II), or (III) in each particular scenario.

[0047] As used herein, the term "D50" refers to a particle size where 50% of the sample particles by volume are smaller than the stated D50 value, and 50% of the sample particles by volume are larger than the stated D50 value. Similarly, the term "D90" refers to a particle size where 90% of the sample particles by volume are smaller than the stated D90 value, and 10% of the sample particles by volume are larger than the stated D90 value. The term "D10" refers to a particle size where 10% of the sample particles by volume are smaller than the stated D10 value, and 90% of the sample particles by volume are larger than the stated D10 value. The width of the particle size distribution can be calculated by determining the span defined by the formula (D90-D10) / D50. The span indicates how far apart the 10th percentile and 90th percentile points are, normalized with respect to the midpoint.

[0048] Where used in the disclosure herein, the term “about” is intended to mean plus or minus 5% of the numerical values ​​used in the claims and disclosure herein. Thus, “about” can be used to provide flexibility to the endpoints of a numerical range, and a given value may be “above” or “below” that given value. Therefore, for example, a value of 50% would be, for example, 47.5%~52.25%, 47.5%~52.5%, 47.75%~50%, 50%~52.5%, 48%~48.5%, 48%~48.75%, 48%~49%, 48%~49.5%, 48%~49.75%, 48%~50%, 48%~50.25%, 48%~50.5%, 48%~50.75%, 48%~51%, 48%~51.5%, 48%~51.75%, 48%~52%, 48%~52.25%, 48%~5 2.5%, 48.25%~48.5%, 48.25%~48.75%, 48.25%~49%, 48.25%~49.5%, 48.25%~49.75%, 48.25%~50%, 48.25%~50.25%, 48.25%~50.5%, 48.25%~50.75%, 48.25%~51%, 48.25%~51.25%, 48.25%~51.5%, 48.25%~51.75%, 48.25%~52%, 48.25%~52.25%, 48.25%~52.5 %, 48.5%~48.75%, 48.5%~49%, 48.5%~49.5%, 48.5%~49.75%, 48.5%~50%, 48.5%~50.25%, 48.5%~50.5%, 48.5%~50.75%, 48.5%~51%, 48.5%~51.25%, 48.5%~51.5%, 48.5%~51.75%, 48.5%~52%, 48.5%~52.25%, 48.5%~52.5%, 49%~49.25%, 49%~49.5%, 49%~49.7 5%, 49%~50%, 49%~50.25%, 49%~50.5%, 49%~50.75%, 49%~51%, 49%~51.25%, 49%~51.5%, 49%~51.75%, 49%~52%, 49%~52.25%, 49%~52.5%, 49.5%~49.75%, 49.5%~50%, 49.5%~50.25%, 49.5%~50.5%, 49.5%~50.75%, 49.5%~51%, 49.5%~51.5%, 49.5%~51.75%, 49.5%~52%, 49.5%~52.25%, 49.5%~52.5%, 49.75%~50%, 49.75%~50.25%, 49.75%~50.5%, 49.75%~50.75%, 49.75%~51%, 49.75%~51.25%, 49.75%~51.5%, 49.75%~51.75%, 49.75%~52%, 4 It may be intended to encompass ranges such as 9.75%~52.25%, 49.75%~52.5%, 50%~50.25%, 50%~50.5%, 50%~50.75%, 50%~51%, 50%~51.25%, 50%~51.5%, 50%~52%, 50%~52.25%, and 50%~52.5%.

[0049] As used herein, the term “sintering” refers to a process of heating under controlled pressure to minimize the surface area of ​​a particle system, which is associated with the formation of bonds between adjacent smaller particles or granules and the subsequent contraction of the aggregated particles or granules. Compression and the formation of a dense solid mass are achieved by heating the particles under controlled pressure.

[0050] As used in the disclosure herein, the term “particle” refers to one or more discrete objects.

[0051] When used throughout this disclosure, the term “generally” means “typically,” “almost,” or “in the vicinity or within the range of.”

[0052] As used in the disclosure herein, the term “substantially” means the entire or near-entire scope or extent of an operation, feature, characteristic, state, structure, item, or result.

[0053] As used herein, “spherical” refers to a particle having a substantially “round” shape.

[0054] As used herein, "Palmqvist fracture toughness" means (K IcThe term refers to the ability of a material with pre-existing cracks to prevent further fracture when it absorbs energy.

[0055] As used herein, the term "HV30 Vickers hardness" (i.e., under a load of 30 kgf) is a measure of the resistance of a specimen to local plastic deformation, obtained by pressing the specimen with a Vickers tip at 30 kgf.

[0056] As used herein, ISO standard 28079-2009 specifies a method for measuring the fracture toughness and hardness of hard metals, cermets, and cemented carbides at room temperature using the indentation method. ISO standard 28079-2009 applies to the measurement of fracture toughness and hardness calculated using the diagonal lengths of indentations and cracks originating from the corners of Vickers hardness indentations, and is intended for use on metallic carbides and carbonitrides (e.g., hard metals, cermets, or cemented carbides). While the test procedure proposed in ISO standard 28079-2009 is intended for use at room temperature, it can be extended to high or low temperatures by agreement. The test procedure proposed in ISO standard 28079-2009 is also intended for use in normal laboratory air environments. Typically, it is not intended for use in corrosive environments such as strong acids or seawater. ISO standard 28079-2009 is directly comparable to ASTM standard B771, as described, for example, in “Comprehensive Hard Materials book”, 2014, Elsevier Ltd., page 312, which is incorporated herein in its entirety by reference. Therefore, fracture toughness and hardness measured using ISO standard 28079-2009 can be assumed to be the same as values ​​measured using ASTM standard B771.

[0057] As used herein, the term “corrosion” refers to the process of converting a metal into another chemical form, such as an oxide, hydroxide, carbonate, or sulfide. This is the phenomenon of gradual destruction of a material (i.e., usually a metal) through chemical and / or electrochemical reactions with the environment. In its most common usage, this refers to the electrochemical oxidation of a metal in reaction with an oxidizing agent such as oxygen or sulfates. Rust, i.e., the formation of iron oxides, is a well-known example of the electrochemical corrosion process. This type of damage typically produces one or more oxides or salts of the original metal. Corrosion can also occur in non-metallic materials, such as ceramics or polymers.

[0058] As used herein, “Physical Vapor Deposition (PVD)” refers to a variety of vacuum deposition methods that can be used to manufacture thin films and coatings. PVD is characterized by a process in which the deposited material transitions from a condensed phase to a vapor phase and then back to a thin film condensed phase. The most common PVD processes are sputtering and evaporation.

[0059] As used herein, “chemical vapor deposition (CVD)” refers to a method of producing a desired deposit by exposing a substrate to one or more volatile precursors, which react and / or decompose on the substrate surface. Often, volatile byproducts are also produced, which are removed by a gas flow through the reaction chamber.

[0060] Where used herein, the term “theoretical density” is defined as the maximum density of a material or element that can be obtained assuming the absence of voids or contaminants within the material. The formula for calculating theoretical density is as follows: ρ=(n*A) / (V*N), where: ρ is density (g / cm³) 3 ) and n is the number of atoms per unit cell, A is the atomic weight (g / mol), V is the volume per unit cell (cm³). 3 / lattice) and N is Avogadro's number (6.023 * 10 23 It is ( / moles).

[0061] Low-binding, high-density cemented carbide alloy composition for neutron shielding This disclosure is based on the premise of providing high-density cemented carbide compositions having a low metallic binder weight, typically ranging from about 0.02% by weight to a maximum of about 2.75% by weight, based on the total weight of the cemented carbide composition. Cemented carbide compositions for low-binder, high-density neutron shielding in nuclear reactors consist of a ceramic hard phase and an iron (Fe)-chromium (Cr)-based metallic binder phase. The binder phase is uniquely composed of elements that exhibit acceptablely good short radioactive half-lives (e.g., about 44 days for Fe and about 27 days for Cr), in contrast to cobalt (Co) and nickel (Ni), which have conventionally been used as metallic binders in cemented carbide compositions. Furthermore, the addition of Cr to the cemented carbide composition establishes improved corrosion resistance. Thus, the beneficial effects obtained are at least diverse. Environmentally safe cemented carbide compositions are effectively manufactured for neutron shielding in nuclear reactors, exhibiting low binder and high density, improved corrosion resistance, and short radioactive half-lives of the components constituting the cemented carbide composition. However, the embodiments disclosed herein are not strictly limited to neutron shielding in nuclear reactors. Importantly, they may find more compelling utility and could be naturally implemented in connection with other systems that may routinely require effective neutron shielding and suppression capabilities. These may include, for example, security scanners, industrial inspection systems, nuclear waste generated from, for example, defense, research and development (R&D) activities, utilities, or medical applications, and other nuclear energy-related applications that emit undesirable neutrons (e.g., nuclear waste recycling, neutron radiation (N-ray) imaging devices using neutron imaging methods to remove neutrons scattered by building elements, such as neutron generators used in, for example, oil well logging and security inspection systems).

[0062] The ceramic hard phase of the cemented carbide compositions for neutron shielding described herein most typically consists of tungsten carbide (WC), quasi-stoichiometric ditungsten carbide (W2C), or a combination thereof. In some examples, the ceramic hard phase of the cemented carbide composition may instead consist of a carbide of at least one metal selected from, for example, Group 4, Group 5, or Group 6 of the periodic table, or any combination thereof. In certain special embodiments, the ceramic hard phase may instead consist of at least one of the carbides of tungsten, titanium, tantalum, vanadium, zirconium, chromium, or any combination thereof. The ceramic hard phases incorporating the aforementioned metal carbides can be incorporated in any combination that is not inconsistent with or incompatible with the subject matter of the present invention.

[0063] The ceramic hard phase can typically be present in a weight of approximately 97.25% to approximately 99.98% based on the total weight of the cemented carbide composition. In some examples, the ceramic hard phase is present in a weight of approximately 97.50% to approximately 99.98% based on the total weight of the cemented carbide composition. In other examples, the ceramic hard phase is present in a weight of approximately 97.75% to approximately 99.98% based on the total weight of the cemented carbide composition. In yet another example, the ceramic hard phase is present in a weight of approximately 98.00% to approximately 99.98% based on the total weight of the cemented carbide composition. In yet another example, the ceramic hard phase is present in a weight of approximately 98.25% to approximately 99.98% based on the total weight of the cemented carbide composition. In yet another example, the ceramic hard phase is present in a weight of approximately 98.50% to approximately 99.98% based on the total weight of the cemented carbide composition. In yet another embodiment, the ceramic hard phase is present in an amount of about 98.75% to about 99.98% by weight, based on the total weight of the cemented carbide composition. In yet another embodiment, the ceramic hard phase is present in an amount of about 99.00% to about 99.98% by weight, based on the total weight of the cemented carbide composition. In yet another embodiment, the ceramic hard phase is present in an amount of about 99.25% to about 99.98% by weight, based on the total weight of the cemented carbide composition. In yet another embodiment, the ceramic hard phase is present in an amount of about 99.50% to about 99.98% by weight, based on the total weight of the cemented carbide composition. In yet another embodiment, the ceramic hard phase is present in an amount of about 99.75% to about 99.98% by weight, based on the total weight of the cemented carbide composition.

[0064] The ceramic hard phase is also based on the total weight of the cemented carbide composition in approximately 97.25% to approximately 97.50% by weight, approximately 97.50% to approximately 97.75% by weight, approximately 97.50% to approximately 98.00% by weight, approximately 97.25% to approximately 97.75% by weight, approximately 97.25% to approximately 98.00% by weight, approximately 97.25% to approximately 98.25% by weight, approximately 97.25% to approximately 98.50% by weight, approximately 97.25% to approximately 98.75% by weight, approximately 97.25% to approximately 99.00% by weight, approximately 97.75% to approximately 98.00% by weight, and approximately It may exist in weights ranging from 98.00% to approximately 98.25% by weight, from approximately 97.75% to approximately 98.25% by weight, from approximately 98.25% to approximately 98.50% by weight, from approximately 98.50% to approximately 98.75% by weight, from approximately 98.25% to approximately 98.75% by weight, from approximately 98.75% to approximately 99.00% by weight, from approximately 99.00% to approximately 99.25% by weight, from approximately 98.25% to approximately 99.25% by weight, from approximately 98.75% to approximately 99.25% by weight, from approximately 98.75% to approximately 99.50% by weight, or from approximately 98.75% to approximately 99.75% by weight.

[0065] A cemented carbide composition may generally contain about 0.02% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In some examples, the cemented carbide composition contains about 0.10% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In other examples, the cemented carbide composition contains about 0.20% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another example, the cemented carbide composition contains about 0.25% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another example, the cemented carbide composition contains about 0.50% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition contains about 0.75% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition contains about 1.00% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition contains about 1.25% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition contains about 1.50% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition contains about 1.75% to about 2.75% by weight of an Fe-Cr-based metallic binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition comprises about 2.00% to about 2.75% by weight of an Fe-Cr-based metal binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition comprises about 2.25% to about 2.75% by weight of an Fe-Cr-based metal binder phase, based on the total weight of the cemented carbide composition. In yet another embodiment, the cemented carbide composition comprises about 2.50% to about 2.75% by weight of an Fe-Cr-based metal binder phase, based on the total weight of the cemented carbide composition.

[0066] The Fe-Cr-based metal binder phase is also present in amounts of approximately 0.02% to 0.10% by weight, approximately 0.10% to 0.20% by weight, approximately 0.20% to 0.25% by weight, approximately 0.02% to 0.20% by weight, approximately 0.02% to 0.25% by weight, approximately 0.02% to 0.50% by weight, approximately 0.02% to 0.75% by weight, approximately 0.25% to 0.50% by weight, approximately 0.25% to 0.75% by weight, approximately 0.50% to 0.75% by weight, approximately 0.75% to 1.00% by weight, approximately 1.00% to 1.25% by weight, and approximately 0.50% to 1.00% by weight. It may exist in weights of approximately 0.50% to 1.25% by weight, approximately 0.50% to 1.50% by weight, approximately 0.50% to 1.75% by weight, approximately 0.50% to 2.00% by weight, approximately 0.50% to 2.25% by weight, approximately 0.50% to 2.50% by weight, approximately 1.25% to 1.50% by weight, approximately 1.50% to 1.75% by weight, approximately 1.75% to 2.00% by weight, approximately 1.25% to 2.00% by weight, approximately 1.25% to 2.25% by weight, approximately 2.00% to 2.25% by weight, approximately 2.25% to 2.50% by weight, or approximately 2.00% to 2.50% by weight.

[0067] In certain specific embodiments, the cemented carbide composition may contain a metal binder phase based on an Fe-Cr-based metal binder phase at a concentration of about 2.75% by weight, based on the total weight of the cemented carbide composition.

[0068] The Cr weight of the metal binder phase can typically range from about 5% to about 16% by weight, based on the total weight of the Fe-Cr metal binder phase. In some examples, the Cr weight of the metal binder phase is about 8% to about 16% by weight, based on the total weight of the Fe-Cr metal binder phase. In other examples, the Cr weight of the metal binder phase is about 10% to about 16% by weight, based on the total weight of the Fe-Cr metal binder phase. In yet another example, the Cr weight of the metal binder phase is about 12% to about 16% by weight, based on the total weight of the Fe-Cr metal binder phase. In yet another example, the Cr weight of the metal binder phase is about 14% to about 16% by weight, based on the total weight of the Fe-Cr metal binder phase.

[0069] The Cr weight of the metal binder phase may be approximately 5% to 6% by weight, approximately 5% to 7% by weight, approximately 5% to 8% by weight, approximately 5% to 9% by weight, approximately 5% to 10% by weight, approximately 8% to 9% by weight, approximately 8% to 10% by weight, approximately 8% to 11% by weight, approximately 8% to 12% by weight, approximately 8% to 13% by weight, approximately 10% to 12% by weight, approximately 10% to 13% by weight, approximately 10% to 14% by weight, approximately 10% to 15% by weight, approximately 12% to 13% by weight, approximately 12% to 14% by weight, or approximately 12% to 15% by weight.

[0070] In certain specific embodiments, the Cr weight of the metal binder phase is approximately 10.5% to 16% by weight, based on the total weight of the Fe-Cr metal binder phase.

[0071] In certain other specific embodiments, the Cr weight of the metal binder phase is approximately 10.5% to 10.7% by weight, based on the total weight of the Fe-Cr metal binder phase.

[0072] Grain growth inhibitors commonly known to those skilled in the art, such as vanadium carbide (VC), chromium carbide (Cr3C2), tantalum carbide (TaC), titanium carbide (TiC), and zirconium carbide (ZrC), which suppress grain growth of WC and quasi-stoichiometric W2C during processing, can be present in any combination and weight in the neutron shielding cemented carbide composition, provided that they do not contradict the objectives of the present invention and are not incompatible.

[0073] The grain growth inhibitor is used in amounts of approximately 0.15% to 2.00% by weight, approximately 0.25% to 2.00% by weight, approximately 0.50% to 2.00% by weight, approximately 0.15% to 0.50% by weight, approximately 0.75% to 2.00% by weight, approximately 1.00% to 2.00% by weight, approximately 1.25% to 2.00% by weight, approximately 0.50% to 1.25% by weight, and approximately 0.50% to 1.00% by weight. It may exist in weights of 0.50% by weight, approximately 0.50% to approximately 1.75% by weight, approximately 0.75% to approximately 1.25% by weight, approximately 1.00% to approximately 1.25% by weight, approximately 1.00% to approximately 1.50% by weight, approximately 1.25% to approximately 1.50% by weight, approximately 1.25% to approximately 1.75% by weight, approximately 1.25% to approximately 2.00% by weight, approximately 1.50% to approximately 2.00% by weight, or approximately 1.75% to approximately 2.00% by weight.

[0074] The ceramic hard phase powder and Fe-Cr metal binder phase powder described herein may have any average particle size that is not inconsistent with the purposes of this disclosure. Generally, the ceramic hard phase powder and Fe-Cr metal binder phase powder can exhibit an average particle size of, for example, about 0.5 μm to about 30 μm. In some examples, the ceramic hard phase powder and Fe-Cr metal binder phase powder have an average particle size in the range of about 1 μm to about 5 μm. In other examples, the ceramic hard phase powder and Fe-Cr metal binder phase powder have an average particle size in the range of about 1 μm to about 10 μm. In yet another example, the ceramic hard phase powder and Fe-Cr metal binder phase powder have an average particle size in the range of about 1 μm to about 15 μm. In yet another example, the ceramic hard phase powder and Fe-Cr metal binder phase powder have an average particle size in the range of about 1 μm to about 20 μm. In further examples, the ceramic hard phase powder and the Fe-Cr-based metal binder phase powder have an average particle size ranging from approximately 1 μm to approximately 25 μm. In yet another example, the ceramic hard phase powder and the Fe-Cr-based metal binder phase powder have an average particle size ranging from approximately 1 μm to approximately 30 μm.

[0075] The ceramic hard phase powder and the Fe-Cr-based metal binder phase powder may also have average particle sizes ranging from approximately 5 μm to approximately 10 μm, approximately 10 μm to approximately 15 μm, approximately 5 μm to approximately 15 μm, approximately 15 μm to approximately 20 μm, approximately 5 μm to approximately 20 μm, approximately 20 μm to approximately 25 μm, approximately 5 μm to approximately 25 μm, approximately 25 μm to approximately 30 μm, or approximately 5 μm to approximately 30 μm.

[0076] To determine particle size, those skilled in the art can typically use one of the following methods: dynamic digital image analysis (DIA), static laser scattering (SLS), also known as laser diffraction, or visual measurement using an electron microscope (a technique known as image analysis and light shielding). Each method covers a measurable characteristic size range. These ranges partially overlap. However, the results of measuring the same sample may all differ depending on the specific method used. Those skilled in the art who wish to determine particle size or particle size distribution will readily know how each of the aforementioned methods is generally carried out and practiced. Therefore, for further understanding of each procedure and methodology, readers should refer, for example, to (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; Vol.7(3):69, which are incorporated herein in their entirety by reference.

[0077] The cemented carbide compositions for neutron shielding described herein can typically exhibit HV30 Vickers hardness values ​​ranging from about 2227 HV30 to about 2700 HV30. In some examples, the HV30 Vickers hardness values ​​range from about 2250 HV30 to about 2700 HV30. In other examples, the HV30 Vickers hardness values ​​range from about 2275 HV30 to about 2700 HV30. In yet another example, the HV30 Vickers hardness values ​​range from about 2300 HV30 to about 2700 HV30. In yet another example, the HV30 Vickers hardness values ​​range from about 2325 HV30 to about 2700 HV30. In yet another example, the HV30 Vickers hardness values ​​range from about 2350 HV30 to about 2700 HV30. In other embodiments, the HV30 Vickers hardness value is in the range of about 2375 HV30 to about 2700 HV30. In yet another embodiment, the HV30 Vickers hardness value is in the range of about 2400 HV30 to about 2700 HV30. In yet another embodiment, the HV30 Vickers hardness value is in the range of about 2425 HV30 to about 2700 HV30. In yet another embodiment, the HV30 Vickers hardness value is in the range of about 2450 HV30 to about 2700 HV30. In yet another embodiment, the HV30 Vickers hardness value is in the range of about 2475 HV30 to about 2700 HV30. In yet another embodiment, the HV30 Vickers hardness value is in the range of about 2500 HV30 to about 2700 HV30.

[0078] The Vickers hardness values ​​for HV30 range from approximately 2227HV30 to 2250HV30, 2250HV30 to 2275HV30, 2275HV30 to 2300HV30, 2227HV30 to 2300HV30, 2300HV30 to 2325HV30, 2325HV30 to 2350HV30, 2350HV30 to 2375HV30, 2375HV30 to 2400HV30, 2400HV30 to 2425HV30, 2400HV30 to 2450HV30, and 2400HV30 to 2475HV30. , approximately 2400HV30 to approximately 2500HV30, approximately 2227HV30 to approximately 2325HV30, approximately 2227HV30 to approximately 2350HV30, approximately 2227HV30 to approximately 2375HV30, approximately 2227HV30 to approximately 2400HV30, approximately 2227HV30 to approximately 2425HV30, approximately 2227HV30 to approximately 2450HV30, approximately 2227HV30 to approximately 2475HV30, approximately 2227HV30 to approximately 2500HV30, approximately 2250HV30 to approximately 2325HV30, approximately 2250HV30 to approximately 2350HV30, approximately 2250HV30 to approximately 2 375HV30, approximately 2250HV30 to approximately 2400HV30, approximately 2250HV30 to approximately 2425HV30, approximately 2250HV30 to approximately 2450HV30, approximately 2250HV30 to approximately 2475HV30, approximately 2250HV30 to approximately 2500HV30, approximately 2275HV30 to approximately 2325HV30, approximately 2275HV30 to approximately 2350HV30, approximately 2275HV30 to approximately 2375HV30, approximately 2275HV30 to approximately 2400HV30, approximately 2275HV30 to approximately 2425HV30, approximately 2275HV30 to approximately 2450HV30, approximately 2275H From V30 to approximately 2475HV30, from approximately 2275HV30 to approximately 2500HV30, from approximately 2300HV30 to approximately 2350HV30, from approximately 2300HV30 to approximately 2375HV30, from approximately 2300HV30 to approximately 2400HV30, from approximately 2300HV30 to approximately 2425HV30, from approximately 2300HV30 to approximately 2450HV30, from approximately 2300HV30 to approximately 2475HV30, from approximately 2300HV30 to approximately 2500HV30, from approximately 2325HV30 to approximately 2375HV30, from approximately 2325HV30 to approximately 2400HV30, from approximately 2325HV30 to approximately 2425HV30,It may also be in the range of from about 2325 HV30 to about 2450 HV30, from about 2325 HV30 to about 2475 HV30, from about 2325 HV30 to about 2500 HV30, from about 2350 HV30 to about 2400 HV30, from about 2350 HV30 to about 2425 HV30, from about 2350 HV30 to about 2450 HV30, from about 2350 HV30 to about 2475 HV30, or from about 2350 HV30 to about 2500 HV30, from about 2375 HV30 to about 2425 HV30, from about 2375 HV30 to about 2450 HV30, from about 2375 HV30 to about 2475 HV30, or from about 2375 HV30 to about 2500 HV30.

[0079] The cemented carbide composition for neutron shielding described in this specification substantially has a Palmqvist fracture toughness (K Ic ) value in the range of from about 5 MPa√m to about 7.6 MPa√m. In some examples, the Palmqvist fracture toughness (K Ic ) value is in the range of from about 6 MPa√m to about 7.6 MPa√m. In other examples, the Palmqvist fracture toughness (K Ic ) value is in the range of from about 7 MPa√m to about 7.6 MPa√m.

[0080] The Palmqvist fracture toughness (K Ic ) value may also be in the range of from about 5 MPa√m to about 6 MPa√m, from about 5 MPa√m to about 7 MPa√m, or from about 6 MPa√m to about 7 MPa√m.

[0081] Method for producing sintered low-binder, high-density cemented carbide for neutron shielding. A cemented carbide composition of a desired particle size can be produced by subjecting a ceramic hard phase powder and an Fe-Cr-based metal binder phase powder to a grinding operation for several hours (e.g., 8, 16, 32, 64 hours) under ambient conditions (i.e., a ball mill, attritor mill, or planetary mill at 25°C, 298.15K, and a pressure of 101.325kPa) to form a powder blend. In some embodiments, instead of using a ball, attritor mill, or planetary mill as the physical mixing apparatus, ultrasonic mixing may be a suitable choice of mixing method. In this case, ultrasonic mixing uses sound energy to effectively process, for example, powders, pastes, liquids, and combinations thereof with groundbreaking speed, quality, and repeatability. Powders of almost any size, material properties, or form can be mixed quickly and thoroughly using, for example, an acoustic mixer. Acoustic processing is often orders of magnitude faster than conventional techniques. In this specification, the acoustic mixer may employ, for example, motion at 60 Hz, so that each particle randomly collides with adjacent particles, altering its path, and similarly collides with other particles behaving in a disordered manner, and then collides again. The main purpose of the grinding operation is to promote a good distribution of Fe-Cr-based metal binder phase powder and favorable wettability between powder components. Subjecting the powder to a grinding operation is essential to enhance the physical integrity of the ground ceramic hard phase powder and Fe-Cr-based metal binder phase powder, and in some cases, essential for deaggregating crystals formed by tungsten carbide (WC) crystals, ditungsten carbide (W2C) crystals, or combinations thereof. An acceptable Fe-Cr-based metal binder phase powder distribution and good wettability between powder components are fundamental parameters for obtaining cemented carbide of good physical quality for neutron shielding. On the other hand, if the quality of the Fe-Cr-based metal binder phase powder distribution and wettability is considerably poor, it can result in undesirable pores and cracks in the final sintered body, which adversely affects the cemented carbide for neutron shielding produced. In some cases, the ceramic hard phase powder and the Fe-Cr-based metal binder powder may be crushed or otherwise pulverized before the grinding operation.

[0082] As will be apparent to those skilled in the art, grinding is carried out by first adding a grinding liquid to the powder to form a ground powder slurry composition. The grinding liquid may be water, alcohol, for example, ethanol, methanol, isopropanol, butanol, cyclohexanol, etc., organic solvent, for example, acetone or toluene, alcohol mixtures, alcohol-solvent mixtures, or similar components. The properties of the ground powder slurry composition are determined, in particular, by the amount of grinding liquid added. Since a considerable amount of energy is required to dry the ground powder slurry composition, the amount of grinding liquid used should be kept to a minimum in order to reduce costs. However, in order to achieve a ground powder slurry composition that can be easily pumped and to prevent system clogging, it is necessary to add a sufficient amount of grinding liquid. Furthermore, other compounds well known to those skilled in the art, such as dispersants and pH adjusters, can also be added to the slurry. Before grinding, non-limiting examples of organic binders (one or more), such as polyethylene glycol (PEG), paraffin, polyvinyl alcohol (PVA), long-chain fatty acids, waxes, or any combination thereof, or similar components, can be added to the ground powder slurry composition in amounts of, for example, 15% and 25% by volume (i.e., the total volume composed of each of the aforementioned components) of the total volume of the formed slurry. This is done primarily to facilitate the formation of the ceramic hard phase and the Fe-Cr-based metal binder phase powder blend during the grinding operation.

[0083] The pulverized powder slurry composition can then be spray-dried, freeze-dried, or vacuum-dried and granulated to provide typically spherical free-flowing powder aggregates. As used herein, the term “free-flowing” refers to loosely packed cemented carbide powder in which there are pore spaces between each free-flowing particle of cemented carbide powder and there are no physical limitations or barriers that restrict the free-flowing ability of the particles of cemented carbide powder.

[0084] In spray drying, the ceramic hard phase powder and the Fe-Cr metallic bond mixed with an organic liquid can be atomized through a suitable nozzle in a drying tower, and the small individual droplets are instantly dried by the horizontal inflow of a high-temperature gas stream into the drying tower, forming spherical powder aggregates with free flow, for example, in a nitrogen, argon, or air stream. As used herein, "atomization" refers to the process by which a bulk liquid supply is converted into individual droplets, thereby significantly increasing the surface area of ​​the supply liquid and thus significantly increasing the achievable evaporation rate of a given solvent (i.e., grinding liquid). The spraying stage is designed to create optimal conditions for evaporating a given solvent from the grinding powder slurry composition. Nozzles and rotary sprayers are used to form the spray. The drying tower may be equipped with only one nozzle, or it may be equipped with multiple nozzles to form spherical ceramic hard phase powder and Fe-Cr metallic bond phase powder blend aggregates with free flow.

[0085] The dried cemented carbide powder may be subjected to a pre-sintering temperature rise treatment to completely remove (one or more) organic binders, which is also called depegging or dewaxing of (one or more) organic binders. Suitable temperatures for complete removal of (one or more) organic binders include starting at 200°C and ending at 450°C, starting at 200°C and ending at 500°C, starting at 200°C and ending at 550°C, starting at 200°C and ending at 600°C, starting at 250°C and ending at 450°C, starting at 300°C and ending at 500°C, starting at 300°C and ending at 550°C, or starting at 300°C and ending at 600°C. This can typically be carried out in a reactive H2 atmosphere by applying hydrogen (H2) flow rates of approximately 1,000 liters / hour to approximately 10,000 liters / hour, approximately 3,000 liters / hour to approximately 10,000 liters / hour, approximately 6,000 liters / hour to approximately 10,000 liters / hour, or approximately 9,000 liters / hour to approximately 10,000 liters / hour. The temperature can usually be increased at a constant rate, for example, approximately 0.70°C / min. In some examples, after removing (one or more) organic binders, the temperature can be increased continuously at a rate of approximately 2°C / min and shifted to approximately 10°C / min when a certain temperature range is reached, or, for example, increased at a rate of approximately 2°C / min and changed to approximately 5°C / min when another certain temperature range is reached. The aforementioned temperature range for depegging or dewaxing (i.e., debonding of organic binders) can generally be achieved after heating in a sintering furnace for about 60 to 90 minutes, or about 60 minutes to 7 hours. Thus, generally, a specific type of heating pattern is selected and carried out in such a manner that the desired complete dewaxing phase transition of the cemented carbide powder is brought about and imparted over a specific period of time. Generally, the pre-sintering cycle for dewaxing of (one or more) organic binders can be carried out in a reactive (H2) atmosphere, vacuum, or a non-reactive inert atmosphere such as nitrogen (N2) or argon (Ar).

[0086] Next, the cemented carbide powder undergoes a compaction process to ultimately form a high-density cemented carbide for neutron shielding. As used herein, the term “compactment process” means any process that (i) compresses (i.e., presses) and (ii) compacts (i.e., densifies and sinters the material by heating) the cemented carbide powder. In some examples, the compaction process can be carried out by hot pressing (HP) of the cemented carbide powder. HP is a relatively slow process, and compression is usually performed uniaxially. Heating is performed simultaneously by elements incorporated into the press. In other examples, the compaction process can be carried out by hot isostatic forming (HIP). HIP is also a relatively slow process, and compression is performed isotropically, i.e., pressure is applied in three directions or three axes. Heating is performed simultaneously by elements incorporated into the press. Thus, HIP subjects the cemented carbide powder to both high temperature and isobaric gas pressure, for example, in a high-pressure vessel. The pressurizing gas used is, for example, argon. Most typically, an inert gas such as argon is used so that the material undergoing HIP does not undergo a chemical reaction. The chamber is heated and the pressure inside the container increases. The pressure is applied to the cemented carbide powder from all three directions. The inert argon gas can typically be applied from about 7,350 psi (about 50.7 MPa) to about 45,000 psi (about 310 MPa), with about 15,000 psi (about 100 MPa) being the most commonly used pressure. In yet another example, the consolidation process can be carried out by discharge plasma sintering (SPS). The main feature of SPS is that a pulsed direct current (DC) or alternating current (AC) passes through the sintering mold. Heat is generated internally, in contrast to HP and HIP which are supplied by external heating elements. This results in faster heating and cooling rates (e.g., up to 1000 K / min). Therefore, the sintering process is generally fast, typically completed within a few minutes. The speed of this process ensures the possibility of densifying nano-sized or nanostructured cemented carbide powders while avoiding the coarsening associated with standard densification techniques.In SPS, compression is typically uniaxial, but with respect to the stress state, it can reach an isotropic stress state due to the effect imparted by the rigid sintered mold that contains and encases the cemented carbide powder. As described above, heat is supplied by exposing the sintered mold to an electric field, and the electric field passes through the sintered mold containing the cemented carbide powder. SPS can be used as a tool for forming functionally graded soft magnetic cemented carbide powder and is useful for accelerating the development of magnetic materials. Notably, SPS improves the oxidation resistance and wear resistance of sintered cemented carbide compared to conventional compaction methods. Furthermore, in other examples, a methodology similar to the art described above can also be applied to the compaction process of cemented carbide powder, which will be apparent to those skilled in the art.

[0087] The temperatures applied to the aforementioned sintering and compaction process can mainly be in the range of starting at 1300°C and ending at 1500°C, starting at 1300°C and ending at 1600°C, starting at 1300°C and ending at 1700°C, starting at 1300°C and ending at 1800°C, starting at 1400°C and ending at 1500°C, starting at 1400°C and ending at 1600°C, starting at 1400°C and ending at 1700°C, starting at 1400°C and ending at 1800°C, starting at 1500°C and ending at 1600°C, starting at 1500°C and ending at 1700°C, or starting at 1500°C and ending at 1800°C.

[0088] In the case of HIP, HIP can be performed on cemented carbide powder or as an additional step on sintered cemented carbide. In this case, the cemented carbide material is compressed and vacuum sintered, typically in a non-reactive, inert atmosphere, such as argon (Ar) or nitrogen (N2). The sintered cemented carbide may then undergo an additional HIP treatment step. This additional HIP step serves to remove any pores that may be present in the sintered cemented carbide powder. During vacuum sintering, the applied temperatures are, for example, 1300°C to 1500°C, 1300°C to 1600°C, 1300°C to 1700°C, 1300°C to 1800°C, 1300°C to 1900°C, 1300°C to 2000°C, 1400°C to 1500°C, 1400°C to 1600°C, and 1400°C. The temperature range can be as follows: starting from 1700°C and ending at 1700°C, starting from 1400°C and ending at 1800°C, starting from 1400°C and ending at 1900°C, starting from 1400°C and ending at 2000°C, starting from 1500°C and ending at 1600°C, starting from 1500°C and ending at 1700°C, starting from 1500°C and ending at 1800°C, starting from 1500°C and ending at 1900°C, or ending at 2000°C.

[0089] Referring to Figure 1, this figure shows a flow chart representing the individual process steps for manufacturing a low-binder, high-density cemented carbide for neutron shielding according to exemplary embodiments of the subject matter. Figure 1 shows that in step 100, the process is initiated by blending a powder mixture in a grinding liquid, which includes a powder forming the hard component of the ceramic hard phase and an iron (Fe)-chromium (Cr)-based metal binder phase containing about 5% to about 16% by weight of chromium based on the total weight of the Fe-Cr-based metal binder phase, with an organic binder to form a slurry blend as described in paragraphs

[0081] to

[0082] . Next, in step 102, the formed slurry blend is dried by one of the described methodologies as described in paragraphs

[0083] to

[0084] to obtain a powder blend. In step 105, a pre-sintering temperature rise procedure is performed, which completely removes any residual organic binder and dewaxes and depeges the formed powder blend as disclosed in paragraph

[0085] . This process finally ends in step 110, where the dewaxed powder blend is sintered by performing one of the compaction methodologies described in paragraphs

[0086] to

[0088] (this may include hot pressing (HP), hot isostatic forming (HIP), or discharge plasma sintering (SPS)) to finally form a sintered high-density cemented carbide that will be used for neutron shielding. However, it should be understood that sintering generally involves a process defined by depegging, solid sintering, liquid phase sintering, and the final cooling of the sintered material to ambient conditions after the sintering operation is completely finished. Those skilled in the art will know that the aforementioned steps of the compaction process described in paragraphs

[0085] to

[0088] can all be performed at once in the same compaction apparatus. Alternatively, those skilled in the art will know that they can also be performed sequentially in different compaction apparatuses.

[0090] The cemented carbide compositions for neutron shielding described herein are typically about 15.25 g / cm³. 3 Approximately 17g / cm³ 3 It can have a theoretical density in the range of [this range]. In some examples, cemented carbide compositions have a density of approximately 15.50 g / cm³.3 Approximately 17g / cm³ 3 It has a theoretical density in the range of [value missing]. In other examples, cemented carbide compositions have a density of approximately 15.75 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density in the range of [value]. In yet another example, cemented carbide compositions have a density of approximately 16 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density in the range of [value missing]. In another example, the cemented carbide composition has a density of approximately 16.25 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density in the range of [value missing]. In another example, the cemented carbide composition has a density of approximately 16.50 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density in the range of [value missing]. In another example, the cemented carbide composition has a density of approximately 16.75 g / cm³. 3 Approximately 17g / cm³ 3 It has a theoretical density within the range of [this range].

[0091] The cemented carbide composition also contains approximately 15.25 g / cm³. 3 Approximately 15.50 g / cm³ 3 , about 15.50g / cm 3 Approximately 15.75 g / cm³ 3 , about 15.75g / cm 3 Approximately 16g / cm³ 3 , about 15.25g / cm 3 Approximately 15.75 g / cm³ 3 , about 15.25g / cm 3 Approximately 16g / cm³ 3 , about 15.25g / cm 3 Approximately 16.25 g / cm³ 3 , about 16g / cm 3 Approximately 16.25 g / cm³ 3 , about 16g / cm 3 Approximately 16.50 g / cm³ 3 , about 16g / cm 3 Approximately 16.75 g / cm³ 3 , about 16.25g / cm 3 Approximately 16.50 g / cm³ 3 , about 16.25g / cm 3 Approximately 16.75 g / cm³ 3, or approximately 16.50 g / cm³ 3 Approximately 16.75 g / cm³ 3 It may also have a theoretical density within that range.

[0092] Table 1 below shows the theoretical densities of certain special embodiments of cemented carbide compositions A to E of this application, compared to comparative sample F. Table 1 shows that when the metallic binder phase has a weight about 9% higher than 2.75% by weight based on the total weight of the cemented carbide composition (i.e., 3% by weight for comparative sample H compared to 2.75% by weight for sample G of this application), the theoretical density is 15.21 g / cm³. 3 From 15.17 g / cm³ 3 This indicates a decrease in the neutron shielding potential of comparative sample H, thus negatively impacting it. In other words, this means that low-density cemented carbide samples need to have a greater thickness to achieve the same neutron shielding effect and capability compared to high-density cemented carbide samples. TIFF0007887505000001.tif61170 [Examples]

[0093] The following embodiments are provided to those skilled in the art to provide a complete disclosure and explanation of the methods for preparing and using the subject matter described herein, and are not intended to limit the scope of what the inventors consider to be a disclosure, nor are they intended to indicate that the following experiments represent all or only experiments performed. While efforts have been made to ensure accuracy with respect to the numerical values ​​used, it should be considered that some experimental errors and deviations are inevitable.

[0094] Example 1 A high-density cemented carbide composition containing a ceramic hard phase and a low-weight iron (FE)-chromium (CR)-based metal binder phase exhibits superior corrosion resistance compared to comparative samples. TIFF0007887505000002.tif110170

[0095] Table 2 shows that as the weight of the metal binder phase used approaches 3% by weight based on the total weight of the cemented carbide composition (i.e., comparative samples E-F), comparative samples E and F, respectively, exhibit (I) low continuity and (II) poor continuity of the passive layer Cr3O2 on the metal binder surface. Therefore, in this case, comparative samples E and F may have reduced corrosion resistance because the positive effect on the continuity of the passive layer Cr3O2 imparted to the metal binder surface decreases. Comparative sample D demonstrates good continuity of the passive layer (Cr3O2) on the metal binder surface despite the metal binder phase being 3% by weight, which is thought to be due to the Cr content being approximately 10.7% by weight based on the total weight of the Fe-Cr-based metal binder phase.

[0096] Example 2 A high-density cemented carbide composition containing a ceramic hard phase and a low-weight iron (Fe)-chromium (Cr)-based metal binder phase exhibits robust hardness and fracture toughness. TIFF0007887505000003.tif90170

[0097] Table 3 shows the compositions of samples W2C_Fe, WC_Fe1, WC_Fe2, WC_Fe3, WC_Fe4, WC_Fe5, and WC_Fe6, each containing an Fe-Cr-based metal binder in the range of 0.02% to 2.75% by weight, WC in the range of 97.25% to 99.98% by weight, and W2C in the range of 99.98% by weight.

[0098] HV30 Vickers hardness and Palmqvist fracture toughness (K lc The measurements of ) were taken for cemented carbide in accordance with ISO 28079:2009, as described in paragraph

[0056] of the disclosure herein. Three indentations were performed for each material at 30 kgf using equipment from Vickers Limited. The length of the cracks originating from the diagonals of the indentations and the corners of the indentations were measured using an optical microscope at 500x magnification.

[0099] As shown in Table 3, the HV30 Vickers hardness values ​​obtained for samples W2C_Fe, WC_Fe1, WC_Fe2, WC_Fe3, WC_Fe4, WC_Fe5, and WC_Fe6 range from 2227HV30 to 2700HV30. On the other hand, the obtained Palmqvist fracture toughness (K Ic The values ​​range from 5 MPa√m to 7.6 MPa√m.

[0100] While this disclosure is described in relation to its embodiments, those skilled in the art will understand that additions, deletions, modifications, and substitutions not specifically described can be made without departing from the spirit and scope of this disclosure as defined in the appended claims.

[0101] With regard to the use of substantially any plural and / or singular terms herein, those skilled in the art can substitute plurals for singulars and / or singulars for plurals as appropriate to the context and / or use. For clarity, various singular / plural substitutions are not explicitly shown herein.

[0102] The subjects described herein may be contained within other different components, or may represent different components connected to other different components. The architectures described herein are merely illustrative, and it should be understood that many other architectures can be implemented to achieve the same function. Conceptually, any arrangement of components to achieve the same function is effectively “associated” in such a way that the desired function is achieved. Therefore, any two components combined herein to achieve a particular function, regardless of architecture or intermediate components, can be considered “associated” with each other in such a way that the desired function is achieved. Similarly, any two such associated components can be considered “operably connected” or “operably coupled” with each other to achieve the desired function, and any two components that can be associated in such a way can be considered “operably coupled” with each other to achieve the desired function. Specific examples of operably coupled components include, but are not limited to, physically matable and / or physically interacting components, as well as / or wirelessly interactable and / or wirelessly interacting components, as well as / or logically interacting and / or logically interactable components.

[0103] In some cases, one or more components may be referred to herein as “configured to,” “configured by,” “configurable to,” “operable to,” “adaptable,” “able to,” or “alignable to.” Those skilled in the art will recognize that, unless otherwise specified in the context, such terms (e.g., “configured to”) can generally encompass components in an active state and / or in an inactive state and / or a standby state.

[0104] While specific aspects of the subject matter of the present invention described herein are shown and explained, it will be apparent to those skilled in the art that changes and modifications can be made based on the teachings herein without departing from the subject matter described herein and its broader aspects. Accordingly, the appended claims shall encompass within their scope all such changes and modifications that fall within the true spirit and scope of the subject matter described herein. Those skilled in the art will generally understand that the terms used herein, and in particular in the appended claims (e.g., in the body of the appended claims), are generally intended to be “open” terms (for example, the term “includes” should be interpreted as “includes, but not limited to,” the term “has” should be interpreted as “has at least,” and the term “includes” should be interpreted as “includes, but not limited to,” etc.).

[0105] Furthermore, a person skilled in the art will understand that if a particular number of claims are intended to be described in an introduced claim, such intention is explicitly stated in the claim, and if such statement is absent, such intention is not present. For example, to aid understanding, the attached claims below may include the use of the introductory phrases “at least one” and “one or more” to introduce the description of a claim. However, the use of such phrases should not be interpreted as meaning that the introduction of the description of a claim with the indefinite article “a” or “an” limits any particular claim containing the introduced description to a claim containing only one such description, even if the same claim contains the introductory phrase “one or more” or “at least one” and an indefinite article such as “a” or “an” (for example, “a” and / or “an” should typically be interpreted as meaning “at least one” or “one or more”); the same applies to the use of the definite article used to introduce a quotation of a claim.

[0106] In addition, even if a specific number of claims introduced is explicitly stated, a person skilled in the art will recognize that such a statement should typically be interpreted as meaning at least the number stated (for example, the mere statement “two claims” without other modifiers typically means at least two claims, or two or more claims).

[0107] Furthermore, when a convention similar to "at least one of A, B, and C, etc." is used, such interpretation is generally intended to mean that a person skilled in the art would understand the convention (for example, "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or all of A, B, and C). Furthermore, a person skilled in the art will understand that, typically, any delimiter and / or phrase presenting two or more alternative terms in a description, claims, or drawings should be understood, unless otherwise specified in the context, as presumably intended to include one of the terms, either of the terms, or both of the terms. For example, the phrase “A or B” would typically be understood to include the possibilities of “A” or “B” or “A and B.”

[0108] Those skilled in the art will understand that, with respect to the attached claims, the operations described herein can generally be performed in any order. Furthermore, while various operation flows are presented in (one or more) sequences, it should be understood that the various operations can also be performed in orders other than those illustrated, or simultaneously. Examples of such alternative orders include, unless otherwise specified in the context, overlapping, interleaving, interrupting, rearranging, incrementing, preparing, supplementing, simultaneous, reverse, or other variant orders. Moreover, terms such as “responding,” “related,” or other past tense adjectives are not generally intended to exclude such variants unless otherwise specified in the context.

[0109] Those skilled in the art will understand that the specific exemplary processes and / or devices and / or techniques described herein are representative of more general processes and / or devices and / or techniques taught elsewhere in this specification, for example, in the claims appended herein and / or elsewhere in this application.

[0110] While various aspects and embodiments are disclosed herein, other aspects and embodiments will also be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are illustrative and not intended to limit, and the true scope and spirit are set forth by the following claims.

[0111] The exemplary embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized and other modifications made without departing from the spirit or scope of the subject matter presented herein.

[0112] Where a range of values ​​is presented, unless the context explicitly indicates otherwise, it should be understood that each intervening value, up to one-tenth of the lower limit unit, between the upper and lower limits of that range and any other stated or intervening value within that range, is included within this disclosure. Upper and lower limits that may independently be included in these smaller ranges are also included within the scope of this disclosure, subject to any limit values ​​that are expressly excluded within the specified range. If one or both limit values ​​are included in the specified range, the range that excludes both included limit values ​​is also included within this disclosure.

[0113] Those skilled in the art will recognize that the components (e.g., operations), devices, objects, and accompanying discussions described herein are used as examples to clarify concepts and that various configurations are intended. Therefore, the specific examples and accompanying descriptions used herein are intended to represent a more general class. In general, the use of specific examples is intended to represent that class, and the absence of specific components (e.g., operations), devices, and objects should not be interpreted as limiting.

[0114] In addition, for example, the (one or more) sequences and / or temporal order of the systems and methods described herein are illustrative and should not be construed as inherently restrictive. Therefore, it should be understood that process steps may be shown and described in sequence or temporal order, but are not necessarily limited to being performed in a specific sequence or order. For example, the steps of such a process or method can generally be performed in a variety of different sequences and orders, while still being within the scope of this disclosure.

[0115] Finally, the publications and / or patents discussed herein are provided solely for the purpose of disclosure prior to the filing date of the disclosure described herein. Nothing in this specification should be construed as acknowledging that the disclosure described herein does not have prior rights to such disclosure due to prior disclosures.

Claims

1. A high-density cemented carbide composition, Based on the total weight of the cemented carbide composition, the ceramic hard phase is present in an amount of 97.25% to 99.98% by weight, and An iron (Fe)-chromium (Cr)-based metal binder phase present in an amount of 0.02% to 2.75% by weight based on the total weight of the cemented carbide composition, comprising chromium present in an amount of 10.5% to 16% by weight based on the total weight of the Fe-Cr-based metal binder phase. A high-density cemented carbide composition containing the following:

2. The high-density cemented carbide composition according to claim 1, wherein the chromium is present in an amount of 10.5% to 10.7% by weight, based on the total weight of the Fe-Cr-based metal binder phase.

3. The high-density cemented carbide composition according to claim 1, wherein the Fe-Cr-based metal binder phase is present in an amount of 2.75% by weight based on the total weight of the cemented carbide composition.

4. The aforementioned hard ceramic phase is tungsten carbide (WC), ditungsten carbide (W ２ C), or a combination thereof, the high-density cemented carbide composition according to claim 1.

5. The high-density cemented carbide composition according to claim 4, wherein the ceramic hard phase contains WC.

6. The aforementioned ceramic hard phase is W ２ A high-density cemented carbide composition according to claim 4, comprising C.

7. The aforementioned hard ceramic phase consists of WC and W ２ The high-density cemented carbide composition according to claim 4, comprising a combination of C in a 1:1 mass ratio.

8. The cemented carbide composition is 15.25 g / cm³ ３ From 17 g / cm ３ The high-density cemented carbide composition according to claim 1, having the theoretical density of [a certain value].

9. The high-density cemented carbide composition according to claim 1, which yields a cemented carbide composition with improved corrosion resistance.

10. The cemented carbide composition has a Vickers hardness of 2227HV30 to 2700HV30 and a Palmqvist fracture toughness (K) of 5 MPa√m to 7.6 MPa√m. Ｉｃ The high-density cemented carbide composition according to claim 1, having the following:

11. A method for manufacturing sintered high-density cemented carbide, A powder mixture in a grinding liquid, containing an iron (Fe)-chromium (Cr)-based metal binder phase containing 10.5% to 16% by weight of chromium based on the total weight of the powder forming the ceramic hard phase and the Fe-Cr-based metal binder phase, is blended with an organic binder to form a slurry blend. The slurry blend is dried to form a powder blend, and The powder blend is sintered to form the sintered high-density cemented carbide. Includes, A method for producing a sintered high-density cemented carbide, wherein the Fe-Cr-based metal binder phase is present in an amount of 0.02% to 2.75% by weight based on the total weight of the sintered cemented carbide, and the ceramic hard phase is present in an amount of 97.25% to 99.98% by weight based on the total weight of the sintered cemented carbide.

12. A method for producing a sintered high-density cemented carbide according to claim 11, wherein the chromium is present in an amount of 10.5% to 10.7% by weight based on the total weight of the Fe-Cr-based metal binder phase.

13. A method for producing a sintered high-density cemented carbide according to claim 11, wherein the Fe-Cr-based metal binder phase is present in an amount of 2.75% by weight based on the total weight of the cemented carbide.

14. The aforementioned hard ceramic phase is tungsten carbide (WC), ditungsten carbide (W ２ A method for producing a sintered high-density cemented carbide according to claim 11, comprising C), or a combination thereof.

15. A method for producing a sintered high-density cemented carbide according to claim 14, wherein the ceramic hard phase includes WC.

16. The aforementioned ceramic hard phase is W ２ A method for producing a sintered high-density cemented carbide alloy according to claim 14, comprising C.

17. The ceramic hard phase is a combination of WC and W ２ The method for producing a sintered high-density cemented carbide according to claim 14, comprising a combination of WC and W in a mass ratio of 1:

1.

18. The aforementioned cemented carbide is 15.25 g / cm³ ３ From 17 g / cm ３ A method for producing a sintered high-density cemented carbide according to claim 11, having the theoretical density of [a specific value].

19. A method for producing a sintered high-density cemented carbide according to claim 11, which yields a cemented carbide with improved corrosion resistance.

20. The aforementioned cemented carbide has a Vickers hardness of 2227HV30 to 2700HV30 and a Palmqvist fracture toughness (K) of 5 MPa√m to 7.6 MPa√m. Ｉｃ A method for producing a sintered high-density cemented carbide according to claim 11, comprising the following:

21. A method for producing a sintered high-density cemented carbide according to claim 11, wherein drying the slurry blend includes vacuum drying, air drying, freeze-drying, or spray drying by spraying.

22. A method for producing a sintered high-density cemented carbide according to claim 11, wherein the sintering includes hot pressing (HP), hot isostatic forming (HIP), or discharge plasma sintering (SPS).

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