High-Binder-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] The present disclosure relates to a low-binder high-density cemented carbide composition and related methods for manufacturing a low-binder high-density cemented carbide for neutron shielding.

Background Art

[0002] When designing any type of nuclear reactor, it is fundamental to consider how to protect the components of the nuclear reactor from the neutron flux and gamma rays generated by the nuclear reactor during nuclear fission and fusion reactions. Regarding radiation shielding, efficient biological shielding is generally required, including other parts of the nuclear reactor such as electronic systems. The prerequisite is that the shielding material needs to be adjusted to provide protection from various 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 at the design stage of the nuclear reactor. It is also important that the material forming the shield itself is resistant to activation and is not converted into other harmful radioactive isotopes during irradiation. This means that materials containing a large amount of, for example, nickel (Ni) and cobalt (Co) cannot be used for this purpose because they have a very long radioactive half-life until they are removed from the environment and thus pose a risk of activation during irradiation.

[0003] As general options for next-generation nuclear power plants, small modular fusion reactors and magnetic confinement reactors have emerged. In essence, 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 extremely low temperatures to generate magnetic fields. Therefore, the space between the plasma chamber and the low-temperature conductors (copper / HTS) is quite limited. In both cases, due to their shape, these types of reactors have quite limited space, which poses a challenge in considering the selection of materials for radiation shielding. As a result, the shielding material needs to be applied in a logically thin layer while maintaining neutron shielding ability.

[0004] Therefore, the challenge is to find alternative shielding materials that do not need to be applied in layers of excessive thickness to achieve a satisfactory shielding effect. Furthermore, the material should not form harmful by-products when exposed to the fusion process. Therefore, it is essential that the material does not contain accompanying elements that would change into harmful radionuclides that would hinder the decommissioning measures and fuel replenishment stages of the reactor at the end of the operating cycle. Additionally, an important aspect is that the material used for this application can be manufactured using conventional techniques without involving multiple cumbersome procedures.

[0005] The most attractive materials in this regard would be high-density materials that further possess the ability to exhibit high corrosion resistance and oxidation resistance. Therefore, it is extremely important for neutron shielding materials for nuclear applications to be of high density in order to capture and effectively suppress the neutron flux generated in the reactor. Separately from this, it is necessary to be made of elements with short radioactive half-lives so as to avoid taking complex decommissioning measures when the life of the reactor ends and creating complex facilities for storing irradiated materials. Finally, as mentioned above, since it is continuously exposed to the cooling medium during the operation of the reactor, it is essential to have corrosion resistance and oxidation resistance.

[0006] It should be noted that the properties of cemented carbides mainly depend on the content of the metal bonding phase and the particle size of tungsten carbide (WC). Therefore, in typical WC-cobalt (Co) or WC-nickel (Ni) cemented carbides, about 2 wt% to a maximum of about 30 wt% of Co or Ni is contained based on the total weight of the cemented carbide, and the particle size of WC can typically range from the submicron level to several microns. Bonding phases such as Co or Ni are advantageous for promoting tough fracture toughness and improved strength. However, at the same time, the metal bonding phase undesirably reduces the corrosion resistance, wear resistance, and hardness of the cemented carbide. Therefore, enhancing fracture toughness and strength at the expense of a reduction in corrosion resistance, wear resistance, and hardness remains an important trade-off. A further point to note is that due to the difference in the coefficient of thermal expansion compared to WC, for example, cobalt also causes undesirable thermal stress, and thus, its application under high-temperature and other harsh conditions is logically limited. Therefore, in the continuous search for solutions to at least mitigate the aforementioned problems, low-binder cemented carbides have naturally come to be the focus of research attention and effort. The evidence obtained from the conducted research has been increasing, and in this regard, low-binder cemented carbides are suggested to exhibit excellent physical properties, such as robust wear resistance, improved corrosion resistance, and improved hardness, due to the low content of the metal binder. As a result, over the years, there has been a growing interest in restricting the addition of an overly high concentration of the metal binder during the manufacturing stage of cemented carbides and 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, sealing 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 contains about 2.75 wt% of an Fe-Cr-based metal binder phase, based on the total weight of the cemented carbide composition.

[0014] Optionally, the ceramic hard phase contains tungsten carbide (WC), stoichiometric tungsten dicarbide (W2C), or a combination thereof.

[0015] Optionally, the ceramic hard phase contains WC.

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

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

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

[0019] Optionally, the cemented carbide composition is from about 15.25 g / cm 3 to about 17 g / cm 3 and has a theoretical density.

[0020] Optionally, a cemented carbide composition with improved corrosion resistance is obtained.

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

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

[0023] A method for manufacturing a sintered low-binder high-density cemented carbide for neutron shielding in a nuclear reactor is also provided, which includes blending a powder mixture in a grinding liquid, the powder mixture including a powder forming a hard component of a ceramic hard phase and an iron (Fe)-chromium (Cr)-based metal binder phase containing about 5 wt% to about 16 wt% chromium based on the total weight of the Fe-Cr-based metal binder phase, with an organic binder to form a slurry blend. 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] Optionally, the weight of chromium is from about 10.5 wt% to about 16 wt% based on the total weight of the Fe-Cr-based metal binder phase.

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

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

[0027] Optionally, the cemented carbide contains about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide.

[0028] Optionally, the ceramic hard phase includes tungsten carbide (WC), stoichiometric tungsten dicarbide (W2C), or a combination thereof.

[0029] Optionally, the ceramic hard phase contains WC.

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

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

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

[0033] Optionally, the cemented carbide has a theoretical density of from about 15.25 g / cm 3 to about 17 g / cm 3 .

[0034] Optionally, a cemented carbide with improved corrosion resistance is obtained.

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

[0036] Optionally, the cemented carbide has an HV30 Vickers hardness in the range of from about 2227 HV30 to about 2700 HV30 and a Palmqvist fracture toughness (KIc) in the range of from about 5 MPa√m to about 7.6 MPa√m.

[0037] Optionally, drying the slurry blend includes vacuum drying, air drying, freeze drying, or spray drying by spraying.

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

[0039] Other systems, methods, features, and advantages will be apparent or will become apparent to those of ordinary skill in the art upon examination of the following figures and detailed description. Such additional systems, methods, features, and advantages are all included within this description, are within the scope of the present disclosure, and are intended to be protected by the following claims. Nothing in this section is to be construed as limiting those claims. Further aspects and advantages are discussed below in conjunction with embodiments of the present disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the claimed disclosure.

[0040] 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.

Brief Description of the Drawings

[0041]

Figure 1

Modes for Carrying Out the Invention

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter described herein belongs.

[0043] When ranges of values, such as concentration ranges, percentage ranges, or ratio ranges, are provided, each intervening value between the upper and lower limits of the range and other specified values or intervening values within the defined range is to be understood as being included in the subject matter described, to the tenth of the unit of the lower limit value, unless the context clearly dictates otherwise. The upper and lower limits of these smaller ranges may be independently included in the smaller ranges, and such embodiments are also included within the subject matter described, subject to any explicitly excluded limitations within the defined range. When one or both of the limiting values are included in the defined range, ranges excluding either or both of those included limiting values are also included in the subject matter described.

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

[0045] As used in the disclosure of this specification, the term "low binder high density cemented carbide" generally refers to a composite material composed of (I) a ceramic hard phase (generally composed of tungsten carbide (WC), stoichiometric tungsten dicarbide (W2C), or a mixture thereof), which is embedded, fixed, and joined (i.e., forms an Fe-Cr based metal binder phase) by an Fe-Cr based metal binder matrix, where the Fe-Cr based metal binder is typically used in a weight of about 0.02 wt% to about 2.75 wt% based on the total weight of the cemented carbide. As used in the disclosure of this specification, the term "stoichiometric" refers to being considerably higher than 1. The ceramic hard phase powder and the Fe-Cr based metal binder phase powder can be processed into various microstructures to achieve various mechanical and physical properties. Furthermore, additional components can be added to the composition to assist in controlling and further improving the properties achieved by the cemented carbide composition. By controlling various parameters including particle size, Fe-Cr content, addition (e.g., alloy carbide), and carbon content, cemented carbide manufacturers can advantageously adjust and direct its performance to suit specific unique applications. Cemented carbides are ideally designed to provide both the physical optimum properties of ceramics such as high temperature resistance and high hardness, and the physical optimum properties of metals such as the ability to undergo plastic deformation and provide good fracture toughness. The naturally ductile and soft Fe-Cr metal binder counteracts the characteristic brittle behavior of the ceramic hard phase, thereby playing a role in enhancing and strengthening the related fracture toughness and durability. The ceramic hard phase of the cemented carbide is generally composed of refractory carbides of metals, most typically tungsten, but not limited thereto, and instead may be titanium, tantalum, chromium, vanadium, zirconium, or any combination thereof. The ceramic hard phase can be present in the cemented carbide powder in any possible combination with the above metals, in a weight that does not conflict with and is not incompatible with the objectives of the subject matter.In this specification, in order to be regarded as a cemented carbide in the present disclosure, the cemented carbide generally has a ceramic hard phase composed of at least about 97.25 wt% to about 99.98 wt% based on the total weight of the cemented carbide.

[0046] As used in the disclosure of this specification, "wt%" refers to a given weight percentage based on (I) the total weight of the cemented carbide composition for low-binder high-density neutron shielding in a nuclear reactor, (II) the total weight of the low-binder high-density cemented carbide for neutron shielding in a nuclear reactor, or (III) the total weight of the Fe-Cr-based metal binder phase. When "wt%" is mentioned in the present disclosure or claims, it will also be explicitly mentioned whether it refers to the given weight percentage of (I), (II), or (III) in each specific scenario.

[0047] As used in the disclosure of this specification, the term "D50" refers to a particle size such that 50% of the volume of the sample particles is smaller than the described D50 value and 50% of the volume of the sample particles is larger than the described D50 value. Similarly, the term "D90" refers to a particle size such that 90% of the volume of the sample particles is smaller than the described D90 value and 10% of the volume of the sample particles is larger than the described D90 value. The term "D10" refers to a particle size such that 10% of the volume of the sample particles is smaller than the described D10 value and 90% of the volume of the sample particles is larger than the described 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 10% point and the 90% point are, normalized with respect to the midpoint.

[0048] As used in the disclosure of this specification, the term "about" is intended to mean plus or minus 5% of the numerical values used in the claims and the disclosure in this specification. Accordingly, "about" can be used to provide flexibility at the endpoints of a numerical range, and a given value may be "above" or "below" that given value. Thus, for example, a value of 50% can 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% - 52.5%, 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% - 49.75%, 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.Ranges such as 5% to 52%, 49.5% to 52.25%, 49.5% to 52.5%, 49.75% to 50%, 49.75% to 50.25%, 49.75% to 50.5%, 49.75% to 50.75%, 49.75% to 51%, 49.75% to 51.25%, 49.75% to 51.5%, 49.75% to 51.75%, 49.75% to 52%, 49.75% to 52.25%, 49.75% to 52.5%, 50% to 50.25%, 50% to 50.5%, 50% to 50.75%, 50% to 51%, 50% to 51.25%, 50% to 51.5%, 50% to 52%, 50% to 52.25%, 50% to 52.5% etc. may be intended to be included, which can be defined within the ranges.

[0049] As used in the disclosure of this specification, the term "sintering" refers to the process of heating under controlled pressure to minimize the surface area of a particle system, related to the formation of bonds between adjacent small particles or granules and the subsequent shrinkage of the aggregated particles or granules. Compression and the formation of a high-density solid mass are carried out by heating the particles under controlled pressure.

[0050] As used in the disclosure of this specification, the term "particle" refers to one or more discrete bodies.

[0051] As used throughout this disclosure, the term "generally / approximately" has the meaning of "typically" or "substantially" or "near or within the range of".

[0052] As used in the disclosure of this specification, the term "substantially" refers to the complete or almost complete range or degree of an operation, characteristic, property, state, structure, item, or result.

[0053] As used in this specification, "spherical" refers to particles having a substantially "round" shape.

[0054] As used in this specification, "Palmqvist fracture toughness", that is, (K IcThe term "()" refers to the ability to prevent further progression of the fracture of a pre-cracked material when it absorbs energy.

[0055] As used herein, the term "HV30 Vickers hardness" (i.e., applying a load of 30 kgf) is a measure of the resistance of a sample to local plastic deformation and is obtained by pressing a Vickers indenter into the sample using a 30 kgf load.

[0056] As used herein, ISO standard 28079-2009 defines a method for measuring the fracture toughness and hardness of hard metals, cermets, and cemented carbides at room temperature by the indentation method. ISO standard 28079-2009 is applicable to the measurement of fracture toughness and hardness calculated using the length of the diagonal of the indentation and crack generated from the corner of a Vickers hardness indentation and is intended for use with metal-bonded carbides and carbonitrides (e.g., hard metals, cermets, or cemented carbides, etc.). The test procedures proposed in ISO standard 28079-2009 are assumed for use at room temperature but can be extended to higher or lower temperatures by agreement. The test procedures proposed in ISO standard 28079-2009 are also intended for use in a normal laboratory air environment. Typically, use in a corrosive environment such as strong acid or seawater is not intended. 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 by reference in its entirety. Therefore, it can be assumed that the fracture toughness and hardness measured using ISO standard 28079-2009 are the same as the values measured using ASTM standard B771.

[0057] As used in the disclosure of this specification, the term "corrosion" refers to the process of converting a metal into a chemically distinct form, such as an oxide, hydroxide, carbonate, or sulfide. This is a phenomenon in which a material (i.e., usually a metal) is gradually destroyed by chemical and / or electrochemical reactions with the environment. In the most common usage of this term, it means the electrochemical oxidation of a metal in a reaction with an oxidizing agent such as oxygen or sulfate. Rusting, i.e., the formation of iron oxide, is a well-known example of an electrochemical corrosion process. This type of damage typically produces the (one or more) oxides or (one or more) salts of the original metal. Corrosion can also occur in materials other than metals, such as ceramics or polymers.

[0058] As used in the disclosure of this specification, "physical vapor deposition (PVD)" refers to various 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 in the disclosure of this specification, "chemical vapor deposition (CVD)" refers to a method of exposing a substrate to one or more volatile precursors, which react and / or decompose on the surface of the substrate to produce a desired deposit. Often, volatile by-products are also produced, but these are removed by a gas flow through the reaction chamber.

[0060] As used in the disclosure of this specification, the term "theoretical density" is defined as the maximum density of a material or element that could be obtained assuming that there are no voids or contaminants within the material. The calculation formula for theoretical density is as follows: ρ = (n * A) / (V * N), where ρ is the density (g / cm 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 (cm 3 / lattice), N is Avogadro's number (6.023*10 23 / mol).

[0061] Low binder high density cemented carbide composition for neutron shielding This disclosure is based on the premise of providing a high-density cemented carbide composition having a low metal binder weight, typically from about 0.02 wt% to a maximum of about 2.75 wt%, based on the total weight of the cemented carbide composition. The cemented carbide composition for low-binder high-density neutron shielding in a nuclear reactor is composed of a ceramic hard phase and an iron (Fe)-chromium (Cr)-based metal binder phase. The binder phase is uniquely composed of elements that exhibit acceptably good short radioactive half-lives (e.g., about 44 days for Fe and about 27 days for Cr), as opposed to cobalt (Co) and nickel (Ni), which have been conventionally used as metal binders in cemented carbide compositions. Furthermore, adding Cr to the cemented carbide composition establishes improved corrosion resistance. Thus, the beneficial effects obtained are at least diverse. The environmentally safe cemented carbide composition is virtually manufactured for neutron shielding in a nuclear reactor, exhibits 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 a nuclear reactor. Importantly, they may further find more persuasive utility and may be naturally implemented in connection with other systems that may routinely require effective neutron shielding and suppression capabilities. This may include, for example, security scanners, industrial inspection systems, such as those generated from defense, research and development (R&D) activities, utilities, or medical applications, nuclear waste, and other nuclear energy-related applications that emit unwanted neutrons (e.g., neutron recycling of nuclear waste, neutron radiography (N-ray) imaging devices that use neutron imaging methods to remove neutrons scattered by building elements, such as neutron generators used in well logging and security inspection systems, etc.).

[0062] The ceramic hard phase of the cemented carbide composition for neutron shielding in this specification is most typically composed of tungsten carbide (WC), stoichiometric tungsten dicarbide (W2C), or a combination thereof. In some examples, the ceramic hard phase of the cemented carbide composition may instead be composed of, for example, carbides of at least one metal selected from Group 4, Group 5, or Group 6 of the periodic table, or any combination thereof. In certain specific embodiments, the ceramic hard phase may instead be composed of at least one of tungsten, titanium, tantalum, vanadium, zirconium, chromium carbides, or any combination thereof. The ceramic hard phase including the aforementioned metal carbides can incorporate them in any combination that does not conflict with and is not incompatible with the objectives of the subject matter of the present invention.

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

[0064] The ceramic hard phase may also be present in an amount of about 97.25 wt% to about 97.50 wt%, about 97.50 wt% to about 97.75 wt%, about 97.50 wt% to about 98.00 wt%, about 97.25 wt% to about 97.75 wt%, about 97.25 wt% to about 98.00 wt%, about 97.25 wt% to about 98.25 wt%, about 97.25 wt% to about 98.50 wt%, about 97.25 wt% to about 98.75 wt%, about 97.25 wt% to about 99.00 wt%, about 97.75 wt% to about 98.00 wt%, about 98.00 wt% to about 98.25 wt%, about 97.75 wt% to about 98.25 wt%, about 98.25 wt% to about 98.50 wt%, about 98.50 wt% to about 98.75 wt%, about 98.25 wt% to about 98.75 wt%, about 98.75 wt% to about 99.00 wt%, about 99.00 wt% to about 99.25 wt%, about 98.25 wt% to about 99.25 wt%, about 98.75 wt% to about 99.25 wt%, about 98.75 wt% to about 99.50 wt%, or about 98.75 wt% to about 99.75 wt% based on the total weight of the cemented carbide composition.

[0065] The cemented carbide composition can generally contain from about 0.02 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In some examples, the cemented carbide composition contains from about 0.10 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In other examples, the cemented carbide composition contains from about 0.20 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In still other examples, the cemented carbide composition contains from about 0.25 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In yet other examples, the cemented carbide composition contains from about 0.50 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In yet other examples, the cemented carbide composition contains from about 0.75 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In other embodiments, the cemented carbide composition contains from about 1.00 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In still other embodiments, the cemented carbide composition contains from about 1.25 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In still other embodiments, the cemented carbide composition contains from about 1.50 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In still other embodiments, the cemented carbide composition contains from about 1.75 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In still other embodiments, the cemented carbide composition contains from about 2.00 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In yet other embodiments, the cemented carbide composition contains from about 2.25 wt% to about 2.75 wt% of an Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition. In yet other embodiments, the cemented carbide composition contains from about 2.50 wt% to about 2.75 wt% 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 may also be present in an amount of from about 0.02 wt% to about 0.10 wt%, from about 0.10 wt% to about 0.20 wt%, from about 0.20 wt% to about 0.25 wt%, from about 0.02 wt% to about 0.20 wt%, from about 0.02 wt% to about 0.25 wt%, from about 0.02 wt% to about 0.50 wt%, from about 0.02 wt% to about 0.75 wt%, from about 0.25 wt% to about 0.50 wt%, from about 0.25 wt% to about 0.75 wt%, from about 0.50 wt% to about 0.75 wt%, from about 0.75 wt% to about 1.00 wt%, from about 1.00 wt% to about 1.25 wt%, from about 0.50 wt% to about 1.00 wt%, from about 0.50 wt% to about 1.25 wt%, from about 0.50 wt% to about 1.50 wt%, from about 0.50 wt% to about 1.75 wt%, from about 0.50 wt% to about 2.00 wt%, from about 0.50 wt% to about 2.25 wt%, from about 0.50 wt% to about 2.50 wt%, from about 1.25 wt% to about 1.50 wt%, from about 1.50 wt% to about 1.75 wt%, from about 1.75 wt% to about 2.00 wt%, from about 1.25 wt% to about 2.00 wt%, from about 1.25 wt% to about 2.25 wt%, from about 2.00 wt% to about 2.25 wt%, from about 2.25 wt% to about 2.50 wt%, or from about 2.00 wt% to about 2.50 wt% based on the total weight of the cemented carbide composition.

[0067] In certain particular embodiments, the cemented carbide composition may include a metal binder phase based on about 2.75 wt% of the Fe-Cr based metal binder phase based on the total weight of the cemented carbide composition.

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

[0069] The Cr weight of the metal binder phase can be present at from about 5 wt% to about 6 wt%, from about 5 wt% to about 7 wt%, from about 5 wt% to about 8 wt%, from about 5 wt% to about 9 wt%, from about 5 wt% to about 10 wt%, from about 8 wt% to about 9 wt%, from about 8 wt% to about 10 wt%, from about 8 wt% to about 11 wt%, from about 8 wt% to about 12 wt%, from about 8 wt% to about 13 wt%, from about 10 wt% to about 12 wt%, from about 10 wt% to about 13 wt%, from about 10 wt% to about 14 wt%, from about 10 wt% to about 15 wt%, from about 12 wt% to about 13 wt%, from about 12 wt% to about 14 wt%, or from about 12 wt% to about 15 wt% based on the total weight of the Fe-Cr based metal binder phase.

[0070] In a certain particular embodiment, the Cr weight of the metal binder phase is from about 10.5 wt% to about 16 wt% based on the total weight of the Fe-Cr based metal binder phase.

[0071] In certain other particular embodiments, the Cr weight of the metal binder phase is from about 10.5 wt% to about 10.7 wt% based on the total weight of the Fe-Cr based metal binder phase.

[0072] Grain growth inhibitors generally 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 the grain growth of WC and stoichiometric W2C during processing, are not inconsistent with the objectives of the present invention and can be present in the cemented carbide composition for neutron shielding in any combination and in any weight, provided they are not incompatible.

[0073] The grain growth inhibitor can be present in an amount by weight of from about 0.15 wt% to about 2.00 wt%, from about 0.25 wt% to about 2.00 wt%, from about 0.50 wt% to about 2.00 wt%, from about 0.15 wt% to about 0.50 wt%, from about 0.75 wt% to about 2.00 wt%, from about 1.00 wt% to about 2.00 wt%, from about 1.25 wt% to about 2.00 wt%, from about 0.50 wt% to about 1.25 wt%, from about 0.50 wt% to about 1.50 wt%, from about 0.50 wt% to about 1.75 wt%, from about 0.75 wt% to about 1.25 wt%, from about 1.00 wt% to about 1.25 wt%, from about 1.00 wt% to about 1.50 wt%, from about 1.25 wt% to about 1.50 wt%, from about 1.25 wt% to about 1.75 wt%, from about 1.25 wt% to about 2.00 wt%, from about 1.50 wt% to about 2.00 wt%, or from about 1.75 wt% to about 2.00 wt% based on the total weight of the cemented carbide composition.

[0074] The ceramic hard phase powder and the Fe-Cr-based metal binder phase powder described in the disclosure herein may have any average particle size that is not inconsistent with the objectives of the present disclosure. The ceramic hard phase powder and the Fe-Cr-based metal binder phase powder can generally exhibit an average particle size in the range of, for example, about 0.5 μm to about 30 μm. In some examples, the ceramic hard phase powder and the Fe-Cr-based 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 the Fe-Cr-based metal binder phase powder have an average particle size in the range of about 1 μm to about 10 μm. In still other examples, the ceramic hard phase powder and the Fe-Cr-based metal binder phase powder have an average particle size in the range of about 1 μm to about 15 μm. In yet other examples, the ceramic hard phase powder and the Fe-Cr-based 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 in the range of about 1 μm to about 25 μm. In still other examples, the ceramic hard phase powder and the Fe-Cr-based metal binder phase powder have an average particle size in the range of about 1 μm to about 30 μm.

[0075] The ceramic hard phase powder and the Fe-Cr-based metal binder phase powder may also have an average particle size in the range of about 5 μm to about 10 μm, about 10 μm to about 15 μm, about 5 μm to about 15 μm, about 15 μm to about 20 μm, about 5 μm to about 20 μm, about 20 μm to about 25 μm, about 5 μm to about 25 μm, about 25 μm to about 30 μm, or about 5 μm to about 30 μm.

[0076] To determine the particle size, one of ordinary skill in the art can typically use any of dynamic digital image analysis (DIA), static laser light scattering (SLS) also known as laser diffraction, or visual measurement by electron microscopy (techniques known as image analysis and light obscuration). Each method covers a characteristic size range for which measurements are possible. These ranges overlap in part. However, the results of measuring the same sample can all be different depending on the particular method used. One of ordinary skill in the art wishing to determine the particle size or particle size distribution will readily know how each of the aforementioned methods is generally carried out and practiced. Accordingly, for the reader to gain further understanding of each procedure and methodology, reference is made, 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 hereby incorporated by reference in their entirety.

[0077] The cemented carbide composition for neutron shielding described in this specification can typically exhibit Vickers hardness values in the range of about 2227 HV30 to about 2700 HV30. In some examples, the Vickers hardness value is in the range of about 2250 HV30 to about 2700 HV30. In other examples, the Vickers hardness value is in the range of about 2275 HV30 to about 2700 HV30. In still other examples, the Vickers hardness value is in the range of about 2300 HV30 to about 2700 HV30. In yet other examples, the Vickers hardness value is in the range of about 2325 HV30 to about 2700 HV30. In still yet other examples, the Vickers hardness value is in the range of about 2350 HV30 to about 2700 HV30. In other embodiments, the Vickers hardness value is in the range of about 2375 HV30 to about 2700 HV30. In still other embodiments, the Vickers hardness value is in the range of about 2400 HV30 to about 2700 HV30. In still other embodiments, the Vickers hardness value is in the range of about 2425 HV30 to about 2700 HV30. In still other embodiments, the Vickers hardness value is in the range of about 2450 HV30 to about 2700 HV30. In still other embodiments, the Vickers hardness value is in the range of about 2475 HV30 to about 2700 HV30. In yet other embodiments, the Vickers hardness value is in the range of about 2500 HV30 to about 2700 HV30.

[0078] The values of HV30 Vickers hardness are from about 2227 HV30 to about 2250 HV30, from about 2250 HV30 to about 2275 HV30, from about 2275 HV30 to about 2300 HV30, from about 2227 HV30 to about 2300 HV30, from about 2300 HV30 to about 2325 HV30, from about 2325 HV30 to about 2350 HV30, from about 2350 HV30 to about 2375 HV30, from about 2375 HV30 to about 2400 HV30, from about 2400 HV30 to about 2425 HV30, from about 2400 HV30 to about 2450 HV30, from about 2400 HV30 to about 2475 HV30, from about 2400 HV30 to about 2500 HV30, from about 2227 HV30 to about 2325 HV30, from about 2227 HV30 to about 2350 HV30, from about 2227 HV30 to about 2375 HV30, from about 2227 HV30 to about 2400 HV30, from about 2227 HV30 to about 2425 HV30, from about 2227 HV30 to about 2450 HV30, from about 2227 HV30 to about 2475 HV30, from about 2227 HV30 to about 2500 HV30, from about 2250 HV30 to about 2325 HV30, from about 2250 HV30 to about 2350 HV30, from about 2250 HV30 to about 2375 HV30, from about 2250 HV30 to about 2400 HV30, from about 2250 HV30 to about 2425 HV30, from about 2250 HV30 to about 2450 HV30, from about 2250 HV30 to about 2475 HV30, from about 2250 HV30 to about 2500 HV30, from about 2275 HV30 to about 2325 HV30, from about 2275 HV30 to about 2350 HV30, from about 2275 HV30 to about 2375 HV30, from about 2275 HV30 to about 2400 HV30, from about 2275 HV30 to about 2425 HV30, from about 2275 HV30 to about 2450 HV30, from about 2275 HV30 to about 2475 HV30, from about 2275 HV30 to about 2500 HV30, from about 2300 HV30 to about 2350 HV30, from about 2300 HV30 to about 2375 HV30, from about 2300 HV30 to about 2400 HV30, from about 2300 HV30 to about 2425 HV30, from about 2300 HV30 to about 2450 HV30, from about 2300 HV30 to about 2475 HV30, from about 2300 HV30 to about 2500 HV30, from about 2325 HV30 to about 2375 HV30, from about 2325 HV30 to about 2400 HV30, from about 2325 HV30 to about 2425 HV30,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 manufacturing 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., in a ball mill, attritor mill, or planetary mill at 25 °C, 298.15 K, and a pressure of 101.325 kPa) to form a powder blend. In some embodiments, instead of using a ball, attritor mill, or planetary mill as a physical mixing device, ultrasonic mixing may be a suitable option for the mixing method. Thus, in this case, ultrasonic mixing uses sound energy to effectively process, for example, powders, pastes, liquids, and combinations thereof, with epoch-making speed, quality, and reproducibility. Powders of almost any size, material properties, or morphology are quickly and thoroughly mixed, for example, using an acoustic mixer. Acoustic processing is often orders of magnitude faster than conventional techniques. In this specification, an acoustic mixer can employ, for example, a motion of 60 Hz, where each particle randomly collides with adjacent particles, changes its path, and then collides with other particles that behave similarly disorderly and then collides again. The main purpose of the grinding operation is to promote a good distribution of the Fe-Cr-based metal binder phase powder and favorable wettability between the 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, is essential to deaggregate crystals formed by tungsten carbide (WC) crystals, or ditungsten carbide (W2C) crystals, or combinations thereof. An acceptable Fe-Cr-based metal binder phase powder distribution and good wettability between the powder components are fundamental parameters for obtaining a cemented carbide of excellent 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 quite poor, as a result, undesirable pores and cracks may occur in the final sintered body, which has an adverse effect on the produced cemented carbide for neutron shielding. In some cases, the ceramic hard phase powder and the Fe-Cr-based metal binder powder may be crushed or ground by other means before the grinding operation.

[0082] As will be apparent to those skilled in the art, the grinding is carried out by first adding a grinding liquid to the powder to form a ground powder slurry composition. The grinding liquid can be water, alcohol such as, but not limited to, ethanol, methanol, isopropanol, butanol, cyclohexanol, etc., organic solvents such as acetone or toluene, etc., alcohol mixtures, mixtures of alcohol and solvents, or similar components. The properties of the ground powder slurry composition are determined, inter alia, by the amount of grinding liquid added. Since a considerable amount of energy is required for drying the ground powder slurry composition, it is necessary to minimize the amount of grinding liquid used in order to reduce costs. However, in order to realize a ground powder slurry composition that can be easily pumped and prevent clogging of the system, 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, pH adjusters, etc. can also be added to the slurry. Prior to grinding, non-limiting examples of (one or more) organic binders such as, for example, 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 from, for example, 15% by volume and 25% by volume of the total volume of the formed slurry (i.e., the total volume % constituted by each of the aforementioned components). This is basically done to promote the formation of a ceramic hard phase and an Fe-Cr-based metal binder phase powder blend during the grinding operation.

[0083] The ground powder slurry composition can then be spray-dried, freeze-dried, or vacuum-dried and granulated to provide a free-flowing powder aggregate typically showing a spherical shape. As used in the disclosure herein, the term "free-flowing" refers to a loosely packed cemented carbide powder where there is pore space between each free-flowing particle of the cemented carbide powder and there is no physical limitation or barrier that inhibits the free-flowing ability of the particles of the cemented carbide powder.

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

[0085] The dried cemented carbide powder may be subjected to a pre-sintering temperature increase treatment to completely remove the (one or more) organic binders, which is also called depegging or dewaxing of the (one or more) organic binders. Suitable temperatures for the complete removal of the (one or more) organic binders include those starting from 200°C and ending at 450°C, starting from 200°C and ending at 500°C, starting from 200°C and ending at 550°C, starting from 200°C and ending at 600°C, starting from 250°C and ending at 450°C, starting from 250°C and ending at 500°C, starting from 250°C and ending at 550°C, starting from 250°C and ending at 600°C, starting from 300°C and ending at 450°C, starting from 300°C and ending at 500°C, starting from 300°C and ending at 550°C, or starting from 300°C and ending at 600°C. This can typically be carried out by applying a hydrogen (H2) flow rate in a reactive H2 atmosphere from about 1000 liters / hour to about 10000 liters / hour, from about 3000 liters / hour to about 10000 liters / hour, from about 6000 liters / hour to about 10000 liters / hour, or from about 9000 liters / hour to about 10000 liters / hour. The temperature can usually be steadily increased, for example, at a rate of about 0.70°C / minute. In some examples, after removing the (one or more) organic binders, the temperature can be continuously increased at a rate of about 2°C / minute and shifted to about 10°C / minute when a certain temperature range is reached, or, for example, increased at a rate of about 2°C / minute and changed to about 5°C / minute when a specific temperature range is reached again. The aforementioned temperature ranges for depegging or dewaxing (i.e., debinding of the organic binder) can generally be reached after heating in a sintering furnace for about 60 minutes to about 90 minutes, or about 60 minutes to about 7 hours. Therefore, generally, a specific selected heating pattern is determined, and over a specific time, the desired complete dewaxing phase transition of the cemented carbide powder is brought about and carried out in such a way as to be imparted. Generally, the pre-sintering cycle for dewaxing the (one or more) organic binders can be carried out in a reactive (H2) atmosphere, a vacuum, or a non-reactive inert atmosphere such as nitrogen (N2) or argon (Ar).

[0086] Next, the cemented carbide powder undergoes a densification process and ultimately forms a high-density cemented carbide for neutron shielding. As used in the disclosure of this specification, the term "densification process" means any process that (i) compresses (i.e., presses) the cemented carbide powder and (ii) densifies (i.e., increases the density and sinters the material by heating). In some examples, the densification process can be performed by hot pressing (HP) the cemented carbide powder. HP is a relatively slow process, and compression is typically performed uniaxially. Heating is performed simultaneously by an element incorporated into the press. In other examples, the densification process can be carried out by hot isostatic pressing (HIP). HIP is also a relatively slow process, and compression is performed isotropically, i.e., the pressure is applied in three directions or three axes. Heating is performed simultaneously by an element incorporated into the press. Thus, HIP subjects the cemented carbide powder to both high temperature and isostatic gas pressure, for example, within a high-pressure vessel. The pressurized gas used can be, 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 vessel 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), and typically about 15,000 psi (about 100 MPa) is the most commonly used pressure. In still other examples, the densification process can be carried out by spark plasma sintering (SPS). The main feature of SPS is that a pulsed direct current (DC) or alternating current (AC) passes through the sintering mold. In contrast to HP and HIP, where heat is supplied by an external heating element, the heat is generated internally. This results in faster heating and cooling rates (e.g., up to 1000 K / min). Thus, the sintering process is generally fast and typically completed within a few minutes. Due to the speed of this process, it is ensured that there is a possibility of densifying nano-sized or nanostructured cemented carbide powder while avoiding coarsening associated with standard densification techniques.In SPS, the compression is typically uniaxial, but with respect to the stress state, an isotropic stress state may be reached due to the effect imparted by the rigid sintering mold that houses and encapsulates the cemented carbide powder. As described above, heat is supplied by subjecting the sintering mold to an electric current field, and the electric current field passes through the sintering mold containing the cemented carbide powder. SPS can be used as a tool for forming functionally gradient 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 carbides compared to conventional densification methods. In yet other examples, the same methodology as the aforementioned technique can be similarly employed in the densification process of cemented carbide powder, which will be apparent to those skilled in the art.

[0087] The temperature applied to the aforementioned sintering densification process can mainly range from 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 carried out on the cemented carbide powder or as an additional process on the sintered cemented carbide. In this case, the cemented carbide material is compressed and typically vacuum sintered in a non-reactive inert atmosphere, such as argon (Ar) or nitrogen (N2). Next, the sintered cemented carbide may undergo an additional HIP treatment step. This additional HIP step serves the purpose of removing pores that may be present in the sintered cemented carbide powder. During vacuum sintering, the temperature applied can range, for example, from 1300 °C to 1500 °C, from 1300 °C to 1600 °C, from 1300 °C to 1700 °C, from 1300 °C to 1800 °C, from 1300 °C to 1900 °C, from 1300 °C to 2000 °C, from 1400 °C to 1500 °C, from 1400 °C to 1600 °C, from 1400 °C to 1700 °C, from 1400 °C to 1800 °C, from 1400 °C to 1900 °C, from 1400 °C to 2000 °C, from 1500 °C to 1600 °C, from 1500 °C to 1700 °C, from 1500 °C to 1800 °C, from 1500 °C to 1900 °C, or from 1500 °C to 2000 °C.

[0089] Referring to FIG. 1, this figure shows a flow diagram representing the individual process steps for manufacturing a low-binder high-density cemented carbide for neutron shielding according to an exemplary embodiment of the present subject matter. FIG. 1 shows that in step 100, the process begins by blending a powder mixture in a grinding liquid containing a powder forming a hard component of a ceramic hard phase and an iron (Fe)-chromium (Cr) based metal binder phase containing about 5 wt% to about 16 wt% 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] -

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

[0083] -

[0084] to obtain a powder blend. In step 105, a pre-sintering temperature increase procedure is performed, whereby any remaining organic binder is completely removed and dewaxing and degassing of the formed powder blend are performed as disclosed in paragraph

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

[0086] -

[0088] (this may include hot press (HP), hot isostatic pressing (HIP), or spark plasma sintering (SPS)), and finally a sintered high-density cemented carbide for use in neutron shielding is formed. However, it should be understood that sintering generally includes a process defined by dewaxing, solid-state sintering, liquid-phase sintering, and cooling of the sintered material to its final ambient conditions after the sintering operation is completely completed. One skilled in the art would know that the aforementioned steps of the densification process described in paragraphs

[0085] -

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

[0090] The cemented carbide composition for neutron shielding described herein may typically have a theoretical density in the range of from about 15.25 g / cm 3 to about 17 g / cm 3 In some examples, the cemented carbide composition is about 15.50 g / cm3 has a theoretical density in the range of from about 17 g / cm 3 to about 17 g / cm. In other examples, the cemented carbide composition has a theoretical density in the range of from about 15.75 g / cm 3 to about 17 g / cm 3 to about 17 g / cm. In yet other examples, the cemented carbide composition has a theoretical density in the range of from about 16 g / cm 3 to about 17 g / cm 3 to about 17 g / cm. In still other examples, the cemented carbide composition has a theoretical density in the range of from about 16.25 g / cm 3 to about 17 g / cm 3 to about 17 g / cm. In still other examples, the cemented carbide composition has a theoretical density in the range of from about 16.50 g / cm 3 to about 17 g / cm 3 to about 17 g / cm. In still other examples, the cemented carbide composition has a theoretical density in the range of from about 16.75 g / cm 3 to about 17 g / cm 3 to about 17 g / cm.

[0091] The cemented carbide composition also has a theoretical density in the range of from about 15.25 g / cm 3 to about 15.50 g / cm 3 to about 15.50 g / cm 3 to about 15.75 g / cm 3 to about 15.75 g / cm 3 to about 16 g / cm 3 to about 15.25 g / cm 3 to about 15.75 g / cm 3 to about 15.25 g / cm 3 to about 16 g / cm 3 to about 15.25 g / cm 3 to about 16.25 g / cm 3 to about 16 g / cm 3 to about 16.25 g / cm 3 to about 16 g / cm 3 to about 16.50 g / cm 3 to about 16 g / cm 3 to about 16.75 g / cm 3 to about 16.25 g / cm 3 to about 16.50 g / cm 3 to about 16.25 g / cm 3 to about 16.75 g / cm 3, or about 16.50 g / cm 3 to about 16.75 g / cm 3 and may also have a theoretical density in the range of.

[0092] Table 1 below shows the theoretical densities of certain specific embodiments of the cemented carbide compositions A to E of the present application compared to the comparative sample F. Table 1 shows that when the metal binder phase has a weight that is 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, while 2.75% by weight for sample G of the present application), the theoretical density is from 15.21 g / cm 3 to 15.17 g / cm 3 and shows a decrease, weakening the neutron shielding potential of comparative sample H and having an adverse effect. In other words, this means that for cemented carbide samples with a low density, in order to obtain the same neutron shielding effect and ability as compared to cemented carbide samples with a high density, it is necessary to have a greater thickness. TIFF2025521160000001.tif61170

Examples

[0093] The following examples are presented to provide those skilled in the art with a complete disclosure and description of the methods of making and using the described subject matter, and are not intended to limit the scope that the inventor regards as the disclosure, nor are they intended to indicate that the following experiments are all the experiments performed or the only experiments. Efforts have been made to ensure the accuracy of the numerical values used, but it is necessary to consider that there are some experimental errors and deviations.

[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 excellent corrosion resistance compared to comparative samples TIFF2025521160000002.tif110170

[0095] Table 2 shows that when 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), for each of Comparative Sample E and Comparative Sample F, (I) low continuity and (II) poor continuity of the passive layer Cr3O2 on the metal binder surface are shown. 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 applied 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 showing a weight of 3% by weight, which is considered 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 comprising a ceramic hard phase and a low - weight iron (Fe) - chromium (Cr) - based metal binder phase exhibits robust hardness and fracture toughness. TIFF2025521160000003.tif90170

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

[0098] The measured values of HV30 Vickers hardness and Palmqvist fracture toughness (K lc ) were measured for the cemented carbides in accordance with ISO 28079:2009 as described in paragraph

[0056] of the disclosure herein. For each material, three indentations were performed at 30 kgf using an apparatus from Vickers Limited. The diagonal of the indentation and the length of the crack generated from the angle of the indentation were measured at a magnification of 500 times using an optical microscope.

[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 are in the range of 2227 HV30 to 2700 HV30. On the other hand, the obtained Palmqvist fracture toughness (K Ic ) values are in the range of 5 MPa√m to 7.6 MPa√m.

[0100] Although this disclosure has been described in connection with its embodiments, those skilled in the art will understand that additional, deletion, modification, and substitution not specifically described can be made without departing from the spirit and scope of this disclosure as defined in the appended claims.

[0101] Regarding the use of substantially any plural and / or singular terms herein, those skilled in the art can replace from plural to singular and / or from singular to plural depending on the context and / or application. For clarity, various singular / plural substitutions are not explicitly shown herein.

[0102] The subject matter described in this specification may refer to different components contained within other different components or to different components connected to other different components. The architecture thus depicted is merely exemplary, and it should be understood that many other architectures that achieve the same functionality can actually be implemented. In a conceptual sense, any arrangement of components for achieving the same functionality is effectively "associated" so that the desired functionality is achieved. Thus, any two components combined in this specification to achieve a particular functionality can be considered to be "associated" with each other so that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated can also be considered to be "operably connected" or "operably coupled" to each other to achieve the desired functionality, and any two components that can be so associated can also be considered to be "operably coupled" to each other to achieve the desired functionality. Specific examples of operable coupling include, but are not limited to, components that can physically fit together and / or physically interact, and / or components that can wirelessly interact and / or wirelessly interact with each other, and / or components that logically interact and / or can logically interact with each other.

[0103] In some cases, one or more components may be referred to in this specification as "configured to", "configured by", "configurable to", "operable / operable to", "adapt / adaptable", "able to", "aligned / aligned with", etc. Those skilled in the art will recognize that such terms (e.g., "configured to") generally can include components in an active state, and / or components in a non-active state, and / or components in a standby state, unless otherwise specified in the context.

[0104] While specific embodiments of the subject matter of the invention described herein are shown and described, it will be apparent to those skilled in the art that, based on the teachings herein, changes and modifications can be made without departing from the subject matter described herein and its broader aspects, and accordingly, the appended claims are intended to encompass all such changes and modifications within the true spirit and scope of the subject matter described herein. Those skilled in the art will generally understand that terms used herein, particularly in the appended claims (e.g., the body of the appended claims), are generally intended to be open terms (e.g., the term "comprising" should be interpreted as "comprising but not limited to", the term "having" should be interpreted as "having at least", the term "including" should be interpreted as "including but not limited to", etc.).

[0105] Furthermore, those skilled in the art will understand that if a specific number of introductions of a claim item is intended, such intention is explicitly stated in the claim, and if there is no such statement, such intention does not exist. For example, for the sake of understanding, the following appended claims may include the use of introductory phrases "at least one" and "one or more" to introduce claim items. However, the use of such phrases should not be construed to mean that a particular claim containing an introduced claim item introduced by an indefinite article "a" or "an" is limited to a claim containing only one such introduction, even if the same claim contains both an introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should typically be interpreted as meaning "at least one" or "one or more"); the same is true for the use of definite articles used to introduce the citation of a claim.

[0106] In addition, even if a specific number of introduced claims is explicitly recited, one of ordinary skill in the art will recognize that such a recitation should typically be construed to mean at least the recited number (e.g., a mere recitation of "two recitations" without other modifiers will typically mean at least two recitations, or two or more recitations).

[0107] Furthermore, when conventions similar to "at least one of A, B, and C" are used, generally such an interpretation is intended in a sense that one of ordinary skill in the art will understand the convention (e.g., a system having "at least one of A, B, and C" would include, but not be limited to, a system 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). When conventions similar to "at least one of A, B, or C" are used, generally such an interpretation is intended in a sense that one of ordinary skill in the art will understand the convention (e.g., a system having "at least one of A, B, or C" would include, but not be limited to, a system 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). Additionally, one of ordinary skill in the art will typically understand that disjunctive words and / or phrases presenting two or more alternative terms in any of the description, claims, or drawings are to be construed, absent a particular context indicating otherwise, as encompassing one of the terms, any of the terms, or both terms. For example, the phrase "A or B" will typically be understood to encompass the possibilities of "A" or "B" or "A and B".

[0108] Regarding the appended claims, those skilled in the art will understand that the operations described therein can generally be performed in any order. Also, although various operation flows are presented in an (one or more) arrangement, it should be understood that the various operations can be performed in an order other than the illustrated order or simultaneously. Examples of such alternative orders include, unless otherwise specifically noted in the context, repetition, interleaving, interruption, rearrangement, increment, preparation, supplementation, simultaneity, reversal, or other modified orders. Furthermore, terms such as "responding", "relating", or other past participle adjectives generally do not intend to exclude such modifications unless otherwise specifically noted in the context.

[0109] Those skilled in the art will understand that the foregoing specific exemplary processes and / or devices and / or techniques represent more general processes and / or devices and / or techniques taught elsewhere in this specification, such as in the appended claims of this specification and / or elsewhere in this application.

[0110] Although various aspects and embodiments are disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes and are not intended to be limiting, and the true scope and spirit are indicated by the following claims.

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

[0112] Where a range of values is provided, each intervening value between the upper and lower limits of the range and any other stated value or intervening value within the stated range, to one tenth of the unit of the lower limit, is to be understood as being included within the present disclosure, unless the context clearly dictates otherwise. Upper and lower limits that can independently be included in these smaller ranges are also included within the scope of the present disclosure, subject to any limit values explicitly excluded from the stated range. Where one or both of the limit values are included in the stated range, ranges excluding both of the included limit values are also included within the present disclosure.

[0113] One of ordinary skill in the art will recognize that the components (e.g., operations), devices, articles, and attendant discussions described herein are used as examples for purposes of clarity of concepts, and that various configurations are contemplated. Accordingly, the specific examples and attendant descriptions used herein are intended to represent more general classes. Generally, the use of a particular example is intended to represent that class, and the absence of a particular component (e.g., operation), device, and article should not be construed as limiting.

[0114] In addition, for example, the (one or more) arrangements and / or temporal order of arrangements of the systems and methods described herein are exemplary and should not be construed as being inherently limiting. Accordingly, process steps may be presented and described in an arrangement or temporal order, but it should be understood that they are not necessarily limited to being performed in a particular arrangement or order. For example, such process or method steps generally may be performed in various different arrangements and orders while remaining within the scope of the present disclosure.

[0115] Finally, the published applications and / or patents discussed herein are provided for the purpose of disclosures only prior to the filing date of the described disclosure. Nothing in this specification should be construed as an admission that the described disclosure does not have the right to antedate such disclosure by virtue of prior disclosure.

Claims

1. A high-density cemented carbide composition comprising: a ceramic hard phase, and an iron (Fe)-chromium (Cr)-based metal binder phase containing about 5 wt% to about 16 wt% chromium based on the total weight of the Fe-Cr-based metal binder phase, the iron (Fe)-chromium (Cr)-based metal binder phase A high-density cemented carbide composition containing.

2. The high-density cemented carbide composition according to claim 1, wherein the weight of the chromium is about 10.5 wt% to about 16 wt% based on the total weight of the Fe-Cr-based metal binder phase.

3. The high-density cemented carbide composition according to claim 2, wherein the weight of the chromium is about 10.5 wt% to about 10.7 wt% based on the total weight of the Fe-Cr-based metal binder phase.

4. The high-density cemented carbide composition according to claim 1, wherein the cemented carbide composition contains about 0.02 wt% to about 2.75 wt% of the Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition.

5. The high-density cemented carbide composition according to claim 4, wherein the cemented carbide composition contains about 2.75 wt% of the Fe-Cr-based metal binder phase based on the total weight of the cemented carbide composition.

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

7. The high-density cemented carbide composition according to claim 6, wherein the ceramic hard phase contains WC.

8. The ceramic hard phase is stoichiometric W ２ C-containing cemented carbide composition according to claim 6.

9. The ceramic hard phase contains a combination in a 1:1 ratio of WC and stoichiometric W ２ C, and the high-density cemented carbide composition according to claim 6.

10. The high-density cemented carbide composition according to claim 1, wherein the cemented carbide composition contains about 97.25 wt% to about 99.98 wt% of the ceramic hard phase based on the total weight of the cemented carbide composition.

11. The cemented carbide composition has a theoretical density of about 15.25 g / cm ３ to about 17 g / cm ３ The high-density cemented carbide composition according to claim 1.

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

13. The Fe—Cr-based metal binder phase is produced by blending FeCr powder with Cr ３ C ２ powder, and the high-density cemented carbide composition according to claim 1.

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

15. A method for manufacturing a sintered high-density cemented carbide, comprising: blending a powder mixture in a grinding liquid containing a powder for forming a hard component of the ceramic hard phase and an iron (Fe)-chromium (Cr)-based metal binder phase containing about 5 wt% to about 16 wt% chromium based on the total weight of the Fe-Cr-based metal binder phase with an organic binder to form a slurry blend; drying the slurry blend to form a powder blend; and sintering the powder blend to form the sintered high-density cemented carbide A method for manufacturing a sintered high-density cemented carbide containing.

16. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein the weight of the chromium is from about 10.5% by weight to about 16% by weight based on the total weight of the Fe—Cr-based metal binder phase.

17. The method for manufacturing a sintered high-density cemented carbide according to claim 16, wherein the weight of the chromium is from about 10.5% by weight to about 10.7% by weight based on the total weight of the Fe—Cr-based metal binder phase.

18. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein the cemented carbide contains from about 0.02% by weight to about 2.75% by weight of an Fe—Cr metal binder phase based on the total weight of the cemented carbide.

19. The method for manufacturing a sintered high-density cemented carbide according to claim 18, wherein the cemented carbide contains about 2.75% by weight of an Fe—Cr metal binder phase based on the total weight of the cemented carbide.

20. The method for producing a sintered high-density cemented carbide according to claim 15, wherein the ceramic hard phase contains tungsten carbide (WC), stoichiometric tungsten dicarbide (W ２ C), or a combination thereof.

21. The method for manufacturing a sintered high-density cemented carbide according to claim 20, wherein the ceramic hard phase contains WC.

22. The ceramic hard phase is near-stoichiometric W ２ C-containing method for producing a sintered high-density cemented carbide according to claim 20.

23. The ceramic hard phase contains a combination of WC and stoichiometric W ２ C in a 1:1 ratio, a method for producing the sintered high-density cemented carbide according to claim 20.

24. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein the cemented carbide contains from about 97.25% by weight to about 99.98% by weight of a ceramic hard phase based on the total weight of the cemented carbide.

25. The cemented carbide has a theoretical density of about 15.25 g / cm ３ to about 17 g / cm ３ The method for manufacturing a sintered high-density cemented carbide according to claim 15, having

26. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein a cemented carbide with improved corrosion resistance is obtained.

27. The method for producing a sintered high-density cemented carbide according to claim 15, wherein the Fe—Cr-based metal binder phase is produced by blending FeCr powder with Cr ３ C ２ powder.

28. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein the cemented carbide has a Vickers hardness HV30 in the range of about 2227 HV30 to about 2700 HV30 and a Palmqvist fracture toughness (K Ｉｃ in the range of about 5 MPa√m to about 7.6 MPa√m).

29. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein drying the slurry blend includes vacuum drying, air drying, freeze drying, or spray drying by spraying.

30. The method for manufacturing a sintered high-density cemented carbide according to claim 15, wherein the sintering includes hot pressing (HP), hot isostatic pressing (HIP), or spark plasma sintering (SPS).

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