TECHNICAL FIELD

The present invention relates to a niobium carbide-containing product. The niobium carbide-containing product may for example be used for improving the wear resistance of objects such as, for example, tools.

BACKGROUND

Wear resistant materials may improve the performance, productivity and life cycle of products in many fields and/or industries, e.g. the metal, aerospace, mining and construction industries. Due to increasing demands of materials and product properties such as wear and/or hardness, there is a need for an even more intensified research and

development in this area. Cemented carbide is a hard material which is frequently used in many industrial applications, e.g., in cutting tools for machining, whereby tungsten carbide (WC), titanium carbide (TiC) or tantalum carbide (TaC) are commonly used as the aggregate. In the field of hard materials, it will be appreciated that the structure of a cemented carbide bonded together by a metallic binder is dominated by the composition of WC and cobalt (Co). Despite having several desirable properties, it should be noted that this composition also suffers from drawbacks. For example, carcinogenic effects of cobalt alloys or compounds in human populations have arisen in hard-metal industries and at cobalt production.

Furthermore, in 2011, the National Toxology Program of the US Department of Health and Human Services published that cobalt tungsten carbide is anticipated to cause cancer. To provide an alternative to WCCo, research and investigations have been performed to study the effect of adding one or more metals in the form of metal carbide into steels, high-performance alloys and casts.

SUMMARY

In view of the above discussion, a concern of the present invention is to provide a metal carbide-containing product that may alleviate or even eliminate drawbacks associated with for example tungsten carbide-containing products.

To address at least one of this concern and other concerns, a niobium carbide- containing product in accordance with the independent claim is provided. Preferred embodiments are defined by the dependent claims.

According to an aspect of the present invention, a niobium carbide-containing product is provided. The niobium carbide-containing product comprises a plurality of niobium carbide-containing particles. All, or substantially all, of the niobium carbide-containing particles have an irregular shape or a spherical shape. The shape of the carbide-containing particles may be varying in the niobium carbide-containing product from irregularly shaped to spherically shaped. Some of the carbide-containing particles may have an irregular shape, and some (e.g., the remainder of the carbide-containing particles) of the carbide-containing particles may have a spherical shape. No or very few of the carbide-containing particles may have cubic shape. All, or substantially all, of the niobium carbide-containing particles are monocrystalline. An average particle size of the plurality of niobium carbide-containing particles is within a range from 30 pm to 400 pm (i.e. 30 micrometre to 400 micrometre), or from about 30 pm to about 400 pm.

The niobium carbide-containing product may include substantially only the niobium carbide-containing particles. For example, the niobium carbide-containing product may consist of the niobium carbide-containing particles and any possible impurity or impurities which may have been introduced during the process of manufacturing the niobium carbide-containing product. Any impurities in the niobium carbide-containing product may however only be present in negligible, or trace, amounts. In the niobium carbide-containing product, each of the niobium carbide-containing particles may consist of niobium carbide and any possible impurity. Thus, in the niobium carbide-containing product, each of the niobium carbide-containing particles may include only niobium carbide and possibly any impurity which may have been introduced during the process of manufacturing the niobium carbide- containing product.

The niobium carbide-containing product comprises relatively large monocrystalline particles containing (e.g., being constituted of) niobium carbide. The size of the niobium carbide-containing particles of the niobium carbide-containing product is such so as to make the niobium carbide-containing product particularly useful in a range of applications including thermal spraying, cladding and infiltration, for example.

In, e.g., thermal spraying applications, cladding applications and infiltration applications (e.g., melt infiltration applications) for improving wear resistance of objects such as, for example, tools, tungsten carbide-containing products are often used. It has been found by the inventors that the niobium carbide-containing product may provide for a number of advantages as compared to other metal carbide-containing products, and in particular as compared to tungsten carbide-containing products, in applications for improving wear resistance such as mentioned above, by means of the relatively large, more spherical, and monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product.

For example, by means of the relatively large monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product, the niobium carbide-containing product may have a relatively low density, e.g., a lower density than tungsten carbide-containing products. The niobium carbide-containing product may have a density within a range from (about) 7.5 g/cm ³ to (about) 7.9 g/cm ³ , such as, for example, from 7.69 g/cm ³ to 7.82 g/cm ³ .

Further, by means of the relatively large monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product, the niobium carbide-containing product may have a relatively low solubility in other metals, e.g., in melts, particularly iron-based melts. For example, the niobium carbide-containing product may have a lower solubility in other metals, e.g., in melts, than tungsten carbide-containing products. In case the niobium carbide-containing product would comprise other elements than the niobium carbide-containing particles, these other elements may dissolve or melt when the niobium carbide-containing product is put into a melt, whereas the niobium carbide- containing particles may remain substantially undissolved or not melted. The niobium carbide-containing product may be at least partly integrated with a melt (e.g., an iron-based melt), or, in other words, penetrated by the surrounding melt. The niobium carbide-containing product may by means of capillary action absorb (or suck) the surrounding melt into the niobium carbide-containing product. This may resemble that of a sugar cube dipped into a liquid such as coffee when the liquid penetrates into the sugar cube by way of capillary forces.

Further, by means of the relatively large monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product, the niobium carbide-containing product may have a coefficient of thermal expansion (e.g., linear or volumetric) that is relatively close (e.g., substantially corresponds) to a coefficient of thermal expansion (e.g., linear or volumetric) of iron and other metals or metallic materials. In particular, the niobium carbide-containing product may have a coefficient of thermal expansion (e.g., linear or volumetric) that is closer (e.g., substantially corresponds) to a coefficient of thermal expansion (e.g., linear or volumetric) of iron and other metals or metallic materials as compared to other metal carbide-containing products, particularly as compared to tungsten carbide-containing products. Thereby, any object or tool that has been reinforced by means of using the niobium carbide-containing product, so as to produce a reinforced object or tool, may exhibit a relatively high uniformity in thermal expansion with respect to different parts or portions of the reinforced object or tool.

Further, by means of the relatively large monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product, the niobium carbide-containing product may have a relatively low friction coefficient, e.g., a lower friction coefficient than tungsten carbide-containing products.

Further, by means of the relatively large monocrystalline particles comprising or being constituted of niobium carbide in the niobium carbide-containing product, the niobium carbide-containing product may have a relatively high hardness, generally within a range 1500-2200HV0.5 (using the unit of hardness given by the Vickers test known as the Vickers Pyramid Number (HV)) or about 1500-2200HV0.5.

As mentioned in the foregoing, the niobium carbide-containing product may include substantially only the niobium carbide-containing particles. Thereby, the niobium carbide-containing product may provide for a more environmentally friendly (e.g., less toxic) product as compared to other metal carbide-containing products. For example, the niobium carbide-containing product is (much) more environmentally friendly and (much) less toxic than tungsten carbide-containing products.

At least some (e.g., all) of the plurality of niobium carbide-containing particles may be aggregated together to form of an aggregate, e.g., by means of one or more binders. Thereby, the niobium carbide-containing product may at least in part be in the form of an aggregate, or compound. The one or more binders may for example comprise at least one material selected from a group comprising bentonite, starch, Portland cement, dextrin, sodium silicate, lime and/or gelatin. Thereby, the niobium carbide containing product may be provided as a solid or semi-solid lump of material. Alternatively, or in addition, at least some (e.g., all) of the plurality of niobium carbide-containing particles may be in the form of a granular material, or powder.

The niobium carbide-containing product may be placed in desired positions in a melt and/or mould for producing reinforced objects or tools. The niobium carbide may thereby be concentrated in areas of the object or tool where there is a particular need for an increased wear resistance of the object or tool. Thus, it may not be necessary to provide an even distribution of the niobium carbide into the melt, and instead a customized object or tool may be provided which may exhibit wear resistance properties at particular desired areas or parts of the object or tool.

Using the niobium carbide-containing product to produce reinforced objects or tools may done in different ways. For example, the niobium carbide-containing product may be arranged in a mould for forming an object or tool. An iron-based melt may be introduced into the mould such that the niobium carbide-containing product and the iron-based melt at least partly integrate to form a reinforced object or tool, which subsequently can be extracted from the mould. According to another example, an iron-based object or tool may be provided, and at least a part of the niobium carbide-containing product may be melted on at least one surface of the object or tool for reinforcing the object or tool. According to another example, at least some of the plurality of niobium carbide-containing particles of the niobium carbide- containing product may be in the form of granular material or powder, which may be encapsulated in a (cored) wire, e.g. by a milling or rolling process. The wire may for example be made of steel. The diameter of the wire may for example be in the range from 9 mm to 6 mm, e.g., 9 mm, 13 mm or 16 mm, and the thickness of the wire may for example be in a range from 0.3 mm to 0.5 mm. The metal wire may be fed into an (iron-based) melt provided in a mould such that the powder in the wire at least partly integrates with the melt to form a reinforced object or tool. The reinforced object or tool may thereafter be extracted from the mould.

By changing process parameters in the process for producing the niobium carbide-containing product, the niobium carbide-containing particles in the niobium carbide- containing product can be made to vary between irregularly shaped particles and spherically shaped particles. For example, substantially all of the niobium carbide-containing particles may have a spherical shape. In the context of the present application, by substantially all of the niobium carbide-containing particles having a spherical shape, it is meant that at least 90%, or for example 95% or more, of the niobium carbide-containing particles have a spherical shape. In the context of the present application, by a niobium carbide-containing particle having a spherical shape, it is not necessarily meant that the niobium carbide- containing particle has a shape of a perfect sphere (although it may have), and it is to be understood that the niobium carbide-containing particle may have a semispherical shape, i.e. a shape that is similar to a shape of a perfect sphere. No or few niobium carbide-containing particles may have a cubic shape (e.g., < 1% of the niobium carbide-containing particles may have a cubic shape)

As mentioned above, at least some (e.g., all) of the plurality of niobium carbide-containing particles may be aggregated together to form of an aggregate, such that the niobium carbide-containing product at least in part may be in the form of an aggregate, e.g., as a solid or semi-solid lump of material. It may be verified that all or substantially all of the niobium carbide-containing particles have a spherical shape for example by analyzing the microstructure of a face (e.g., a surface) of a sample taken from the niobium carbide- containing product, e.g., in the form of an aggregate, by means of light optical microscopy (LOM) and/or another or other types of appropriate image capturing systems (e.g., a scanning electron microscope (SEM)) and using appropriate image analysis method or means as known in the art.

By substantially all of the niobium carbide-containing particles being monocrystalline, it is meant that at least 90%, or for example 95% or more, of the niobium carbide-containing particles are monocrystalline. It may be verified that all or substantially all of the niobium carbide-containing particles are monocrystalline for example by analysis of a sample taken from the niobium carbide-containing product, e.g., in the form of an aggregate, by means of X-ray crystallography, electron diffraction and/or another or other types of method or means for studying crystal structure of solids as known in the art.

In the context of the present application, by a niobium carbide-containing particle being monocrystalline, it is meant that the niobium carbide-containing particle comprises or is constituted by a solid material that has the same crystal structure throughout the material or at least has the same crystal structure in the greater part of the material. Each or any of all or substantially all of the niobium carbide-containing particles may for example exhibit a cubic (e.g., a cubic NaCl, or a cubic diamond) type of crystal structure.

The niobium carbide-containing particles may be referred to as niobium carbide-containing grains. An average particle size of the plurality of niobium carbide- containing particles may hence be referred to as an average grain size of the plurality of niobium carbide-containing grains.

By an average particle size of the plurality of niobium carbide-containing particles it may be meant an average diameter of the plurality of niobium carbide-containing particles, or an average of a dimensional quantity of the plurality of niobium carbide- containing particles that approximates the diameter of the plurality of niobium carbide- containing particles (in view of that the niobium carbide-containing particles may not have shapes of a sphere or a perfect sphere (although they may have), and may have semispherical shapes, i.e. shapes that are similar to a shape of a perfect sphere).

As mentioned in the foregoing, the niobium carbide-containing particles may be referred to as niobium carbide-containing grains. An average particle size of the plurality of niobium carbide-containing particles may be referred to as an average grain size of the plurality of niobium carbide-containing grains.

As mentioned in the foregoing, an average particle size of the plurality of niobium carbide-containing particles is within a range from 30 pm to 400 pm, or from about 30 pm to about 400 pm. The average particle size of the plurality of niobium carbide- containing particles may for example be determined by means of one or more image analysis method or means as known in the art applied to one or more images representing the microstructure of the niobium carbide-containing product. The image(s) may be produced for example by means of LOM, SEM and/or another or other types of appropriate image capturing systems applied to, e.g., a face (e.g., a surface) of a sample taken from the niobium carbide-containing product, e.g., in the form of an aggregate. Using such image analysis method or means for determining the average particle size of the plurality of niobium carbide- containing particles, the average may for example be an average per surface unit of the face of the sample. The average particle size of the plurality of niobium carbide-containing particles may in alternative or in addition be determined for example by means of laser light scattering, e.g., laser diffraction, measurements carried out on (a sample of) the niobium carbide- containing product e.g. in which niobium carbide-containing particles are in the form a granular material, or powder. For example by using techniques such as laser light scattering measurements, the average particle size may be determined as a volume equivalent sphere diameter.

In alternative, or in addition, the average particle size of the plurality of niobium carbide-containing particles may for example be determined by way of sieve analysis (e.g., by means of a so called test sieve). For example, at least some of the plurality of niobium carbide-containing particles may be in the form of granular material. The average particle size of the plurality of niobium carbide-containing particles may for example be determined by way of passing the granular material through one or more test sieves having selected nominal aperture size(s), such that only particles having an average particle size within a selected range may pass through the apertures of the test sieve(s).

According to one or more embodiments of the present invention, an average particle size of the plurality of niobium carbide-containing particles may be within a range from 30 pm to 100 pm, or from 30 pm to 60 pm. It has been found by the inventors that with an average particle size of the plurality of niobium carbide-containing particles being within a range from 30 pm to 100 pm, the niobium carbide-containing product may be particularly advantageous for use in powder welding applications and/or in thermal spraying applications (e.g., high-velocity oxygen fuel spraying applications and/or flame spraying applications). It has further been found by the inventors that with an average particle size of the plurality of niobium carbide-containing particles being within a range from 30 pm to 60 pm, the niobium carbide-containing product may become even more advantageous for use in thermal spraying applications, such as, for example, high-velocity oxygen fuel spraying applications and/or flame spraying applications.

According to one or more embodiments of the present invention, an average particle size of the plurality of niobium carbide-containing particles may be within a range from 60 pm to 400 pm, or from 60 pm to 100 pm. It has been found by the inventors that with an average particle size of the plurality of niobium carbide-containing particles being within a range from 60 pm to 400 pm, the niobium carbide-containing product may be particularly advantageous for use in thermal spraying applications such as, for example, flame spraying applications, cladding applications (e.g., laser cladding applications) and/or plasma- transferred arc welding applications. It has further been found by the inventors that with an average particle size of the plurality of niobium carbide-containing particles being within a range from 60 pm to 100 pm, the niobium carbide-containing product may become even more advantageous for use in cladding applications such as, for example, laser cladding

applications.

According to one or more embodiments of the present invention, an average particle size of the plurality of niobium carbide-containing particles is within a range from 50 pm to 400 pm, or 100 pm to 400 pm. It has been found by the inventors that with an average particle size of the plurality of niobium carbide-containing particles being within a range from 50 pm to 400 pm, the niobium carbide-containing product may be particularly advantageous for use in cladding applications (e.g., laser cladding applications), plasma transferred arc welding applications and/or in infiltration applications.

Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings.

Figure 1 illustrates particle size distribution of niobium carbide-containing particles of the niobium-carbide product in accordance with an embodiment of the present invention.

Figures 2 and 3 are images of a surface of a sample taken from the niobium carbide-containing product in the form of an aggregate, in accordance with an embodiment of the present invention.

Figures 4 to 6 are images of the niobium carbide-containing product in the form of a granular material, in accordance with an embodiment of the present invention.

Figures 7 to 11 are images of the niobium carbide-containing product in accordance with embodiments of the present invention, illustrating how by changing process parameters in the process for producing the niobium carbide-containing product, the niobium carbide-containing particles in the niobium carbide-containing product can be made to vary between (more) irregularly shaped particles and (more) spherically shaped particles.

DETAILED DESCRIPTION

The present invention will now be described hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art.

Figure 1 illustrates particle size distribution of niobium carbide-containing particles of the niobium-carbide product in accordance with an embodiment of the present invention. The particle size distribution illustrated in Figure 1 have been determined by means of laser light diffraction measurements carried out on dispersed particulate sample of the niobium carbide-containing product in accordance with an embodiment of the present invention, using the particle sizing instrument Mastersizer 2000 manufactured by Malvern Instruments Limited, Grovewood Road, Malvern, Worcestershire, UK. Using this particle sizing instrument, a laser beam is made to pass through the dispersed particulate sample, and the angular variation in intensity of the scattered light is measured, thereby obtaining a scattering pattern. Based on the measured variation in intensity of the scattered light, the size of the particles that gave rise to the scattering pattern is determined using Mie theory of light scattering, with the particle size being determined as a volume equivalent sphere diameter.

The graph denoted by A in Figure 1 represents the volume fraction (percentage) of the dispersed particulate sample (on the left-most vertical axis denoted by “volume (%)”) as a function of the determined particle size (on the horizontal axis). Thus, the graph denoted by A in Figure 1 indicates the volume fractions (percentage) of the dispersed particulate sample in which the particles have a certain particle size.

The graph denoted by B in Figure 1 represents the accumulated volume fraction (percentage) of the dispersed particulate sample (on the right-most vertical axis, which has the unit of percent) as a function of the determined particle size (on the horizontal axis). Thus, the graph denoted by B in Figure 1 indicates the total volume fractions

(percentage) of the dispersed particulate sample in which the particles have a particle size up to but not exceeding a certain particle size.

As illustrated in Figure 1, niobium carbide-containing particles of the niobium- carbide product in accordance with the illustrated embodiment of the present invention exhibit particle sizes up to 400 pm.

As mentioned in the foregoing, at least some (e.g., all) of the plurality of niobium carbide-containing particles of the niobium carbide-containing product may be aggregated together to form of an aggregate, such that the niobium carbide-containing product at least in part may be in the form of an aggregate, e.g., as a solid or semi-solid lump of material. Figures 2 and 3 are images of the microstructure of a surface of a sample taken from the niobium carbide-containing product in the form of such an aggregate, in accordance with an embodiment of the present invention. The images in Figure 2 and 3 have been obtained by means of light optical microscopy (LOM), and show cross-sections of niobium carbide- containing particles in the niobium carbide-containing product being in the form of the aggregate. Included in the images in Figures 2 and 3 are indications of length representing 50 pm in the respective images. As can be deduced by means of the indications of length in Figures 2 and 3, the particle size of the niobium carbide-containing particle depicted in Figure 2 is about 100 pm, and the particle sizes of the niobium carbide-containing particle depicted in Figure 3 are within a range from about 30 pm to about 100 pm. Included in the images in Figures 2 and 3 are also results of Vickers hardness tests carried out at the depicted surfaces, which results are 1758±69.9HV0.05 and 2118±69.7HV0.2 for Figures 2 and 3, respectively.

Figures 4 to 6 are images of the niobium carbide-containing product in the form of a granular material, in accordance with an embodiment of the present invention. The images in Figures 4 to 6 have been obtained by means of a scanning electron microscope (SEM), and show niobium carbide-containing particles of the niobium carbide-containing product in the form of a granular material at different magnifications. At the bottom right in each of Figures 4 to 6 are indications of length representing 100 pm, 20 pm, and 10 pm in Figures 4 to 6, respectively. As indicated by the indications of length in Figures 4 to 6, respectively, an average particle size of the niobium carbide-containing particles depicted in Figures 4 to 6 is within a range from about 30 pm to about 100 pm.

Based on the images in Figures 2 and 3 obtained by LOM and/or the images in Figures 4 to 6 obtained by SEM, or similar images obtained by means of another or other types of appropriate image capturing systems, an average particle size of the plurality of niobium carbide-containing particles of the niobium carbide-containing product may be determined for example using appropriate image analysis method or means as known in the art. The average may for example be an average per surface unit of the face of the sample depicted in Figures 2 and 3 or an average per unit area of the depicted granular material in Figures 4 to 6.

The niobium carbide-containing product according to embodiments of the present invention, such as any of the niobium carbide-containing products depicted in Figures 2 to 6, may be made by means of a process comprising (or constituted by) heat treatment of niobium-containing material placed in a metal matrix at an elevated temperature (e.g., above room temperature or ambient temperature) and in an oxygen controlled atmosphere. The process may for example be carried out in a carburization furnace, a pit furnace, or a sealed atmosphere furnace. The oxygen controlled atmosphere may be an atmosphere which is controlled or controllable such that the amount of oxygen is negligible or substantially zero.

For example, the niobium-containing material may comprise niobium carbide, e.g., in the form of a powder, which may be placed in, e.g., an iron matrix and be heated so as to be held at a temperature between (about) 1600 °C to (about) 3000 °C during a selected period of time in an oxygen controlled atmosphere. According to another example, the niobium-containing material may comprise niobium oxide and (e.g., NbiOs) carbon (e.g., a mixture thereof), e.g., in the form of powders, which may be placed in, e.g., an iron matrix and be heated so as to be held at a temperature between (about) 1600 °C to (about) 3000 °C during a selected period of time in an oxygen controlled atmosphere. The carbon may for example be provided by way of a carbon-containing powder, which for example may comprise (possibly a mixture of) sub-bituminous coal, bituminous coal, lignite, anthracite, graphite, coke, petroleum coke, bio-carbon such as charcoal, soot, carbon black, and/or activated carbon. The maximum temperature at which the niobium-containing material placed in an iron matrix is held may be selected so as to not exceed the evaporation temperature of the material of the metal matrix. Possibly, grain-growth facilitating material such as, for example, iron may be used in the process for making the niobium carbide-containing product. Possibly, one or more products which may facilitate attaining a spherical niobium carbide- containing particles may be used in the process for making the niobium carbide-containing product, for example a boron-containing power such as, for example, a ferroboron powder. The average particle size of the plurality of niobium carbide-containing particles of the resulting niobium carbide-containing product is dependent on the length of the period of time during which the niobium-containing material placed in an iron matrix is held at an elevated temperature, and further on the value of the elevated temperature. For example, the niobium-containing material placed in an iron matrix may be heated so as to be held at a temperature between (about) 1800 °C to (about) 2600 °C during a period of time between (about) 1 hour to (about) 12 hours in an oxygen controlled atmosphere.

For the embodiment of the present invention illustrated in Figure 1 and described in the foregoing with reference to Figure 1, the niobium carbide-containing product was made by means of a process comprising heat treatment of the niobium-containing material placed in a metal matrix and held at a temperature at about 2500 °C during about 6 hours in an oxygen controlled atmosphere.

Figures 7 to 11 are images of the niobium carbide-containing product in accordance with embodiments of the present invention, illustrating how by changing process parameters in the process for producing the niobium carbide-containing product, the niobium carbide-containing particles in the niobium carbide-containing product can be made to vary between (more) irregularly shaped particles and (more) spherically shaped particles. At the bottom right in each of Figures 7 to 11 are indications of length representing 100 pm. Figures 7 to 11 have been obtained similarly to Figure 4 to 6. The niobium carbide-containing product illustrated in Figure 7 has relatively irregularly shaped niobium carbide-containing particles in the niobium carbide-containing product, and the niobium carbide-containing products illustrated in the respective ones of Figures 8 to 11 have niobium carbide-containing particles being increasingly spherically shaped in the niobium carbide-containing product. No or few niobium carbide-containing particles may have a cubic shape (e.g., < 1% of the niobium carbide-containing particles may have a cubic shape). Niobium carbide-containing products in accordance with embodiments of the present invention depicted in Figures 7 to 11 can be made in a way similar to the niobium carbide-containing products in accordance with embodiments of the present invention depicted in Figures 2 to 6 as described in the foregoing, by changing process parameters in the process for producing the niobium carbide-containing product.

In conclusion, a niobium carbide-containing product is disclosed. The niobium carbide-containing product comprises a plurality of niobium carbide-containing particles. Substantially all of the niobium carbide-containing particles have an irregular shape or a spherical shape. Substantially all of the niobium carbide-containing particles are

monocrystalline. An average particle size of the plurality of niobium carbide-containing particles is within a range from 30 pm to 400 pm. Various aspects of the present invention may be appreciated from the following enumerated example embodiments (EEEs):

EEE 1. A niobium carbide-containing product, comprising:

a plurality of niobium carbide-containing particles;

wherein substantially all of the niobium carbide-containing particles have a spherical shape;

wherein substantially all of the niobium carbide-containing particles are monocrystalline; and

wherein an average particle size of the plurality of niobium carbide-containing particles is within a range from 30 pm to 400 pm.

EEE 2. A niobium carbide-containing product according to EEE 1, wherein an average particle size of the plurality of niobium carbide-containing particles is within a range from 30 pm to 100 pm, or from 30 pm to 60 pm.

EEE 3. A niobium carbide-containing product according to EEE 1, wherein an average particle size of the plurality of niobium carbide-containing particles is within a range from 60 pm to 400 pm, or from 60 pm to 100 pm.

EEE 4. A niobium carbide-containing product according to EEE 1, wherein an average particle size of the plurality of niobium carbide-containing particles is within a range from 50 pm to 400 pm.

EEE 5. A niobium carbide-containing product according to any one of EEEs 1-4, wherein at least some of the plurality of niobium carbide-containing particles are aggregated together to form of an aggregate such that the niobium carbide-containing product is at least in part in the form of an aggregate.

EEE 6. A niobium carbide-containing product according to any one of EEEs 1-4, wherein at least some of the plurality of niobium carbide-containing particles are in the form of granular material.

EEE 7. A niobium carbide-containing product according to any one of EEEs 1-6, wherein each of the niobium carbide-containing particles consists of niobium carbide and any possible impurity. While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the appended claims, the word“comprising” does not exclude other elements or steps, and the indefinite article”a” or“an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.