Composite materials

Abstract

1. A composite material comprising a cemented carbide matrix having diamond entities embedded therein and homogeneously distributed throughout, the cemented carbide components being composed of metal carbides and a binder phase, the metal carbides having a grain size of 0.6-8 microns, the material comprising 5-65 vol% diamond entities, wherein at least 20% of the diamond entities contain pores and / or cracks filled with the cemented carbide components.

Description

[Technical Field]

[0001] The present invention relates to composite materials containing diamond entities in a cemented carbide matrix for use as inserts or wear parts in mining or rock cutting applications, and methods for making the same. [Background technology]

[0002] PCD (polycrystalline diamond) is known for its high wear resistance, making it a popular choice for industrial applications. However, in mining applications requiring strength, such as inserts for impact and rotary cutting (excluding oil and gas) or mechanical cutting, PCD performs poorly due to its brittle nature, limiting the insert's lifespan. Cemented carbide combines high modulus, hardness, high compressive strength, high wear resistance, and excellent toughness. As such, cemented carbide is commonly used in mining and cutting inserts. Cemented carbide contains a hard ceramic (carbide) phase and a binder phase.

[0003] It is desirable to combine the high wear resistance of PCD with the toughness of cemented carbide. To this end, composite materials comprising diamond in a cemented carbide matrix have been developed, such as those disclosed in US 7647992 A and WO 2009128034 A. However, known composite materials comprising diamond and cemented carbide do not have a very balanced relationship between wear resistance and toughness, making them prone to breakage and unreliable when used, for example, in mining inserts.

[0004] Conventional PCD inserts used in striking cutting offer the best performance and have layers with different concentrations of diamond in the domed area of ​​the insert, but the problem with this is that the manufacturing procedure is quite complicated and the material is very expensive. The problem to be solved is how to provide a new material that can offer high performance without excessive manufacturing costs.

[0005] definition By "hardmetal" herein is meant a material consisting of at least 50 wt. % tungsten carbide, possibly other hard constituents common in the art of manufacturing hardmetals, and a metallic binder phase preferably selected from one or more of Fe, Co and Ni.

[0006] As used herein, "HPHT" refers to a "high pressure, high temperature" process involving pressures above the diamond stability field (>50 kBar) and temperatures of at least about 1000°C.

[0007] As used herein, "SCCG" means sintered cemented carbide granules, the cemented carbide of each granule being at least 90% dense, preferably fully dense.

[0008] By "diamond entity" herein is meant either a single diamond particle or two or more diamond particles joined together, i.e., a diamond cluster, i.e., where there is a diamond-to-diamond contact point.

[0009] As used herein, "uniformly distributed throughout" means that the diamond entities are distributed evenly throughout the composite material, and there is no discernible pattern in the distribution of the diamond entities. Examples of discernible patterns include a gradient in either the size, volume, or number of diamond entities, or a satellite structure in which the material contains multiple smaller diamond entities surrounding a larger diamond entity. Summary of the Invention

[0010] According to a first aspect of the present invention there is provided a composite comprising a cemented carbide matrix having diamond entities embedded therein and homogeneously distributed throughout, the cemented carbide components being made up of metal carbides and a binder phase, the metal carbides having a grain size of 0.6-8 microns, the material comprising 5-65 vol% diamond entities, wherein at least 20% of the diamond entities contain pores and / or cracks filled with the cemented carbide components.

[0011] The vol% of diamond was analyzed by processing the SEM images using Image J software. The vol% was considered to correspond to the area%. First, the scale (pixels / μm) of the SEM image was calibrated by measuring the scale bar of the SEM image using the linear measurement function in Image J. Next, the data obtained from this measurement and the dimensions of the scale bar of the SEM image were processed using the "Set Scale" function to complete the calibration. A region of interest (ROI) in the SEM image was typically evaluated in the same frame as the analysis of the average diameter of the diamond entities. A binary image was created for the ROI using a threshold function. The threshold was set so that cemented carbide was white, diamond entities without cemented carbide components were black, and diamond entities containing CC components also contained white areas or spots. The same threshold was used for all images. Next, the "Particle Analysis" command was used, setting the size from 0 to infinity and the circularity from 0.00 to 1.00. From this, the area% of cemented carbide was calculated, and the area% of the diamond bodies was calculated by subtracting the area% of cemented carbide from 100%. A magnification was used that would fit between 50 and 250 diamond entities within the frame. It is not possible to specify a specific magnification, as the appropriate use will vary depending on the size of the diamond entities.

[0012] A diamond entity was determined to be filled with cemented carbide material if cracks / pores filled with cemented carbide material were visible in the SEM image within the entity. The diamond entities inspected by SEM, as described above, corresponded to particles in the image returned with the overlay mask from the diamond entity diameter assessment. The number of diamond entities containing pores and / or cracks filled with cemented carbide material was then divided by the total number of particles found in the overlay mask image. A magnification ratio was used that included 50–250 diamond entities within the frame. It is not possible to specify a specific magnification, as appropriate use varies depending on the size of the diamond entity. If the magnification is too low, it becomes difficult to determine where grain boundaries are located and whether they are filled; if the magnification is too high, there are insufficient diamond entities / grains to obtain adequate statistical information.

[0013] Advantageously, this provides a composite material with improved toughness while maintaining high wear resistance, thus providing a more reliable material that is less prone to chipping or breaking. Furthermore, the properties of both the diamond components and the surrounding cemented carbide matrix can be customized to suit the application in which the material will be used. The toughness of the composite material is further enhanced by the presence of a binder within the pores and / or cracks of the diamond entities. Wear resistance is maintained through the reduction in diamond crystal size and the formation of new inter-diamond bonds. This material, with layers of varying diamond concentrations in the domed region of the insert, offers the same performance as the highest-performing prior art PCD inserts currently used for impact cutting, but at a lower cost due to a lower diamond content and a simpler manufacturing process.

[0014] According to another aspect of the invention there is provided an insert for mining or rock cutting or wear part applications comprising a material as set out above or below.

[0015] Advantageously, the use of the material of the present invention in inserts for mining, rock cutting, or wear part applications increases the life of the insert due to the increased wear resistance and toughness of the material.

[0016] According to another aspect of the present invention there is provided a method for producing a material as hereinbefore or hereinafter described, comprising the steps of: a) providing friable diamond particles; b) providing sintered granules of cemented carbide; c) blending the friable diamond particles with sintered cemented carbide granules to form a homogenous powder blend; d) placing the powder mixture into a preformed refractory metal cup; e) providing a refractory metal lid, pre-sintered or sintered cemented carbide base over the powder mixture to close the cup; f) precompacting the powder in a refractory metal cup; g) surrounding the cup with a pressure medium; h) inserting the cup surrounded by the pressure medium into a high pressure, high temperature vessel; i) sintering the container at high pressure and high temperature in a high pressure and high temperature press to form a composite material; There are methods including:

[0017] Advantageously, this results in a more homogeneous mixture, resulting in uniform properties throughout the material, improved powder density, and reduced and more controllable shrinkage during the HPHT sintering cycle, which means greater control over the final shape of the manufactured product. Furthermore, this means that the properties of the hardmetal can be controlled by preparing the granules before sintering rather than during HPHT sintering, ultimately resulting in greater control over the material's properties. Furthermore, the risk of diamond entities melting and breaking, resulting in satellite formation and non-uniform properties, is reduced. The composition of the hardmetal granules and the sintering temperature determine the final WC-Co structure in terms of particle size, binder content, and properties of the hardmetal matrix. [Brief explanation of the drawings]

[0018] [Figure 1a] SEM image of composite F at 140x magnification. [Figure 1b] SEM image of composite F at 450x magnification. [Figure 2] Insert Schematic [Figure 3] SEM image of benchmark material R at 500x magnification. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1a and 1b are SEM images at 140x and 450x magnification, respectively, showing a composite material 2 comprising a cemented carbide matrix having embedded diamond entities 6 homogeneously distributed throughout, where the cemented carbide constituents include metal carbides, e.g., tungsten carbide, and a binder phase, the metal carbide grain size being 0.6-8 microns, the material containing 5-65 vol% diamond bodies, and at least 20% of the diamond entities containing pores and / or cracks 8 filled with the cemented carbide constituents. The diamond entities may have regular or irregular shapes. FIG. 1a clearly shows the homogeneous distribution of the diamond entities in the cemented carbide matrix. FIG. 1b clearly shows the presence of cracks and pores in the diamond entities filled with the cemented carbide constituents.

[0020] In one embodiment, the material comprises 35-95 vol% cemented carbide, preferably 40-90 vol% cemented carbide, more preferably 45-85 vol% cemented carbide, even more preferably 50-80 vol% cemented carbide, and most preferably 45-75 vol% cemented carbide.

[0021] Preferably, the average grain size of the tungsten carbide is 0.6-8 μm, more preferably 0.7-6 μm, even more preferably 0.8-5 μm, and most preferably 0.9-4 μm. The average WC grain size is evaluated from at least one, and preferably two or more, different micrographs for each material using one of the Jeffries methods described below. When multiple micrographs are used, an average value (for each material) is calculated from the average grain size values ​​obtained from the individual micrographs. The procedure for evaluating the average grain size using the modified Jeffries method is as follows: A rectangular frame of appropriate size was selected in the SEM micrograph to contain at least 150 WC grains. The grains within the frame and those intersecting the frame were manually counted, and the average grain size was calculated using Equation (1-3): TIFF2026500213000002.tif50170 formula, d = WC particle size (μm) L1, L2 = Frame side length (mm) M=Magnification L scale mm = Measured length of the scale bar on the micrograph (mm) L scale micro = Actual length of scale bar relative to magnification (μm) n1 = number of particles in the frame n2 = number of particles crossing the frame boundary wt%Co = known cobalt content (wt%).

[0022] Equation (2) is used to estimate the WC fraction based on the known Co content of the material. Equation (3) then calculates the average WC grain size from the ratio of the total WC area in the frame to the number of grains it contains. Equation (3) also includes a correction factor to account for the fact that in a random 2D cross section, not all grains are sectioned at their maximum diameter.

[0023] Optionally, or if the binder is not Co, the WC grain size can also be determined using EBSD on cross sections of ion-polished sintered samples. This is a more accurate, but more time-consuming method, and also provides information about the grain size distribution. When comparing Jefferies and EBSD grain sizes, the area d50 values ​​from EBSD agree well with the Jefferies values. "D50" is the equivalent diameter Dn where the sum of the areas of the grains smaller than Dn is equal to 50% of the total grain area.

[0024] The setup and method for EBSD analysis of WC grain size are as follows. TIFF2026500213000003.tif36170

[0025] Post-processing was performed using AztecCrystal 2.2 software. For WC auto-cleaning, pseudo-symmetric rotation with removal of axis 0001 and addition of a 30° angle (allowed deviation angle of 5°) was used.

[0026] WC-WC boundaries were defined as those with an azimuthal angle greater than 3 degrees and a closed boundary. Boundary grains were excluded. The smallest grains were defined as those with an area of ​​13 pixels.

[0027] Preferably, the binder phase of the cemented carbide, and therefore also one of the components filling the pores and / or cracks of the diamond entity, is selected from cobalt, nickel, iron or mixtures thereof, more preferably cobalt. The binder phase may contain added Cr, V, Ti to control grain growth during sintering of the granules and during HPHT.

[0028] In one embodiment, the distribution of diamond entities in the cemented carbide matrix is ​​normal. In other words, there is a unimodal distribution of diamond entities. In another embodiment, there may be a multimodal distribution of diamond entities.

[0029] The diamond entities are homogeneously dispersed three-dimensionally throughout the cemented carbide matrix in terms of the distance between adjacent diamond entities throughout the material. The volume of diamond entities throughout the material is homogeneously distributed, which means that the diamond entities are evenly distributed throughout the composite material and no distinguishable pattern is seen in the distribution of the diamond entities. Examples of distinguishable patterns include any gradient in the size, volume, or number of diamond entities, or a satellite structure where a plurality of smaller diamond entities surround a larger diamond entity being included in the material. This can be analyzed by comparing SEM or LOM images from regions near the body of the material and near the surface of the polished, lapped, ion-polished material. The images are analyzed in Fiji (ImageJ) according to the above description, and the area % of the diamond phase obtained is considered to correspond to the vol% of the diamond phase. The difference between the volume of diamond entities in the region near the surface and the volume of diamond entities in the region of the material body (i.e., ((highest value - lowest value) / highest value)*100) is less than 15%, preferably less than 10%. The "region near the surface" is defined as 1 / 10 of the distance from the surface (i.e., the cutting edge), and the "region of the material body" is defined as 1 / 10 of the distance from the substrate if the substrate is present, or 1 / 10 of the distance from the bottom of the insert if the substrate is not present.

[0030] In one embodiment, the binder content of the cemented carbide matrix 4 is 2 to 20 weight percent (wt%), for example 5 to 20 wt%. Advantageously, this provides a material having a cemented carbide matrix with an optimal balance between hardness and toughness. Preferably, the binder content in the cemented carbide portion of the matrix is >1 wt%, more preferably >2 wt%, still more preferably >3 wt%, most preferably >4 wt%, and the binder content is <20 wt%, more preferably <wt%, most preferably <14 wt%. This is measured using energy dispersive spectroscopy (EDS) or wavelength dispersive spectroscopy (WDS) on the cemented carbide region of the sintered sample phase.

[0031] In one embodiment, the cemented carbide matrix further comprises one or more elements selected from Cr, Ta, Ti, Nb, Mo, Zr, or their carbides, nitrides, carbonitrides, or mixtures thereof, and V, present as elements, at a content of 100 ppm to 15 wt%, depending on the added element and purpose of the addition. The addition of one or more of these elements advantageously acts as a grain growth inhibitor, controlling grain growth within the granules. Furthermore, the melting point of the HPHT synthesis is lowered, thereby reducing fatigue of the cemented carbide die in the press, thereby saving costs and materials. When the grain growth inhibitor is chromium, an additional benefit is improved plastic deformation and corrosion resistance of the material.

[0032] In one embodiment, the cemented carbide matrix further comprises a gamma phase selected from carbides or nitrides of niobium, tantalum, titanium, or mixtures thereof. Advantageously, the presence of the gamma phase improves the wear resistance of the cemented carbide matrix. When the gamma phase is tantalum or niobium, the resistance to plastic deformation at high temperatures is increased.

[0033] In one embodiment, the D50 of the diamond entity is 10 to 500 μm, preferably 10 to 300 μm, more preferably 12 to 250 μm, even more preferably 12 to 200 μm, even more preferably 15 to 200 μm, even more preferably 20 to 200 μm, and most preferably 12 to 150 μm.

[0034] The average diameter of diamond entities was analyzed by processing SEM images in Image J software. First, the scale (pixels / μm) of the SEM image was calibrated by measuring the scale bar of the SEM image using Image J's linear measurement function. Next, the data obtained from this measurement and the dimensions of the SEM image scale bar were processed using the "Set Scale" function to complete the calibration. After that, a region of interest (ROI) was selected using the rectangle tool, and once satisfied, the "Duplicate" function was used. This image was saved and used for analysis. Next, the SEM image was converted to 8-bit image format (unless it was already in 8-bit image format). Next, a binary image was created using the automatic thresholding method "Li" to return diamonds as white and WC and / or binder (Co) as black (background). After this, the binary image was cleaned up using the "Remove Outliers" command using the default settings of "Radius" 2.0 pixels, "Threshold" 50, and "Outliers" set to Bright. To evaluate the average diameter of diamond entities, the "Particle Analysis" function was used, with size set to 0–infinity, circularity set to 0.00–1.00, overlay mask set to "Exclude Edges," and "Include Holes" set to "Display." The "Féret diameter" (i.e., the longest distance between any two points along the contour) was used as the diameter of the diamond entities, and the average was used as the average diameter of the diamond entities. The magnification was selected to include 50–250 diamonds within the frame. The ROI was selected to include 50–250 diamond entities within the frame.

[0035] Advantageously, this allows for the formation of a homogeneous blend between the diamond entities within the cemented carbide matrix. This size range increases the degree of diamond particle fragmentation during processing and densification, creating new cracks and cavities into which the cemented carbide constituents can infiltrate, further increasing the toughness of the diamond body.

[0036] In one embodiment, the diamond entity comprises a single crystal diamond. The mean diameter or D50 of the diamond single crystal is 6-100 μm, preferably 6-80 μm, more preferably 8-60 μm, even more preferably 10-80 μm, and most preferably 15-80 μm or 12-60 μm. The grain size of the diamond single crystal is analyzed using EBSD on a powdered, lapped, ion-polished sample where the diamond and CC matrix are at the same height level. To be classified as a different diamond crystal, the difference in orientation must be 10 degrees or more.

[0037] In one embodiment, the diamond entities are at least partially in the form of diamond clusters, which are defined as two or more diamond particles joined together.

[0038] According to the present invention, the pores and / or cracks 8 of the diamond entity 6 are filled by infiltration. Because the elements in the cemented carbide source are tougher than diamond, strengthening is achieved by providing the diamond with a tough material. These elements can also improve the retention of the diamond to the cemented carbide by increasing the contact area, i.e., reducing the risk of pullout. Using diamond raw material with existing defects such as cracks, cavities, etc., or diamond raw material that may develop such defects during the manufacturing process, allows the pores and / or cracks to be filled with elements from the cemented carbide matrix. A diamond entity 6 containing pores and / or cracks filled with components from the cemented carbide matrix is ​​defined as a cemented carbide element that can be observed within the diamond entity 6 using an SEM at a magnification of 1k or less.

[0039] In one embodiment, at least one element from the cemented carbide source infiltrates at least 20%, preferably at least 25%, more preferably at least 30% of the diamond entity 6 .

[0040] In one embodiment of the present invention, at least 20%, preferably at least 25%, more preferably at least 30% of the diamond entities contain pores and / or cracks filled with at least one element from the cemented carbide source.

[0041] In one embodiment, at least 25% of the diamond entities comprise a plurality of crystals having two or more different orientations, where different orientations are defined as two or more substantially adjacent diamond crystals that differ in orientation by at least 10 degrees.

[0042] 2 illustrates an insert 10 for mining or rock cutting or wear part applications that includes a material described above or below. The insert typically includes a base portion 12, a working tip portion 14, and a core 16. However, it should be understood that the insert may have different shapes. The insert 10 may be formed symmetrically or asymmetrically, for example. In one embodiment, the insert 10 includes a dome-shaped working tip portion 14 that includes a composite material 2 described above or below, and a base portion 12 that includes a cemented carbide.

[0043] The cemented carbide composition of the base portion 12 (also known as the substrate) includes cemented carbide having a composition within the ranges set forth above and below.

[0044] In one embodiment, the cemented carbide base contains 4-15 wt% Co.

[0045] In one embodiment, the cemented carbide base contains Cr.

[0046] In one embodiment, the cemented carbide base has a room temperature Vickers hardness of 900 to 1650 HV20.

[0047] In one embodiment, the cemented carbide base has a K1C > 10 mPa / m as measured by the Palmqvist method from a 30 kg Vickers indentation using the Shetty equation. 1 / 2 It has a fracture toughness exceeding .

[0048] Preferably, for impact applications such as top hammer or DTH (down-the-hole) cutting, the binder concentration is 4-12 wt%, more preferably -10 wt%, and most preferably 5-8 wt%. Preferably, the average particle size of the hard metal is 0.7-5 μm, more preferably 1-4 μm, and the room temperature hardness is 1200-1650 HV20.

[0049] Preferably, for rotary applications, the binder concentration is 8 to 20 wt%, more preferably 8 to 15 wt%, and most preferably 10 to 15 wt%. Preferably, the average particle size of the hard metal is 2 to 10 μm, more preferably 2 to 8 μm, and most preferably 2 to 6 μm, and the room temperature hardness is 1000 to 1300 HV20.

[0050] Preferably, for mechanical rock cutting, the binder concentration is 6-15 wt%, more preferably 6-12 wt%. Preferably, the average particle size of the hard metal is 6-18 μm, more preferably 6-15 μm, and the room temperature hardness is 800-1100 HV20.

[0051] Preferably, for wear part applications, such as support inserts for drill bits, the binder concentration is 3-10 wt%, more preferably 3-8 wt%, most preferably 3-7 wt%. Preferably, the hard metal has an average particle size of 0.6-4 μm, more preferably 0.6-3 μm, and a room temperature hardness of 1300-2000 HV20.

[0052] Preferably, the diameter of the base portion 12 is 5 to 40 mm, more preferably 7 to 30 mm, and most preferably 7 to 24 mm.

[0053] Preferably, the thickness of the tip portion 14, measured along the longitudinal direction, is between 0.1 and 15 mm, more preferably 0.2 and 10 mm, even more preferably 0.5 and 5 mm, and most preferably 0.8 and 4 mm.

[0054] Preferably, the volume of the tip portion 14 is 2 to 50 vol % of the total volume of the insertion portion 10, more preferably 5 to 40 vol %, and most preferably 8 to 30 vol %.

[0055] Alternatively, the insert 10 can be freestanding without the cemented carbide base.

[0056] The present application further relates to a method for producing the above or below mentioned material, comprising the steps of: a) providing friable diamond particles; b) providing sintered granules of cemented carbide; c) blending diamond particles with sintered cemented carbide granules to form a homogenous powder blend; d) placing the powder mixture into a preformed refractory metal cup; e) providing a refractory metal lid or a pre-sintered or sintered cemented carbide base over the powder mixture to close the cup; f) precompacting the powder in a refractory metal cup; g) surrounding the cup with a pressure medium; h) inserting the cup surrounded by the pressure medium into a high pressure, high temperature vessel; i) sintering the container at high pressure and high temperature in a high pressure and high temperature press to form a composite material; There are methods including:

[0057] As used herein, "friable" means that the diamond particles have one or more of the following characteristics: rough surfaces; cavities; pores; cracks; polycrystalline structures; inclusions; crystallographic defects; and / or elongated, irregular, sharp, or angular shapes. Friable diamond particles have the property of breaking up into small pieces (fragments) when under pressure.

[0058] An example of a diamond raw material with more friable properties is an abrasive grain designed for resin or vitrified bond system grinding wheels. Another example of a diamond raw material with more friable properties is polycrystalline diamond powder, such as those designed for lapping and polishing, in which many small crystals are bonded together to form larger polycrystalline diamond particles.

[0059] In the field of PCD sintering, it is recommended to use diamond raw material, which is diamond with less crystal defects and therefore has strong strength.However, in the present invention, surprisingly, it is found that it is appropriate to use diamond raw material with more friable properties, which is counterintuitive, because friable diamond crystals are typically not very strong.However, this composite material has unexpectedly improved toughness and wear resistance.

[0060] The friable diamond granules can be produced by, for example, but not limited to, freeze-spray drying or spray drying, and the density of diamond (3.52 g / cm 3), which has a relative density of about 15-40% compared to that of conventional diamond raw materials. An example of a diamond raw material with more friable properties is abrasive grains designed for resin or vitrified bond system grinding wheels. The friable properties of such grits can be attributed to their more elongated and irregular shape, rougher surfaces, multi- / polycrystalline structures within such particles, and inclusions. Another example of a diamond raw material with more friable properties is polycrystalline diamond powder, such as those designed for lapping and polishing, in which many small crystals are bonded together to form large polycrystalline diamond particles. In the field of PCD sintering, it is recommended to use diamond raw materials with fewer crystal defects and therefore tougher diamonds. However, in the present invention, it was surprisingly found that it is appropriate to use diamond raw materials with more friable properties, which is counterintuitive, since friable diamond crystals are typically not very tough.

[0061] In one embodiment, the D50 or average diameter of the cemented carbide granules ranges from 5 to 60 microns.

[0062] Sintered cemented carbide granules can be produced in a variety of ways. Spray-dried granules are prepared by conventional methods, i.e., a powder of the desired composition and WC particle size is mixed with an organic binder, usually PEG, and a liquid, usually a water / ethanol blend, to form a slurry. The slurry is spray-dried to form granules.

[0063] The sintering temperature of the cemented carbide granules is used to control both the WC particle size and density and is preferably 1250-1550°C, more preferably 1270-1500°C, and most preferably 1300-1500°C. Depending on the sintering temperature, the sintered cemented carbide granules are preferably fully dense or have a density of at least 90%, depending on the granule composition and sintering temperature. Sintering can be carried out in a vacuum, or in a N2 / Ar atmosphere, or in a carbonizing atmosphere which can be provided at least in part by one or more carbon-containing gases such as CO2, CO, CH4, etc.

[0064] The sintering process usually begins with a debinding step to remove the organic binder, which is usually carried out at temperatures between 300 and 600°C.

[0065] In one embodiment, the ultra-hard granules are substantially fully dense.

[0066] The use of fully or nearly fully dense cemented carbide granules below a certain D50 or D90 helps control homogeneity when mixing lighter material, diamond, with heavier material, SCCG. The cemented carbide granule size also defines the shortest distance to the next diamond entity.

[0067] In one embodiment, the WC grain size within the sintered cemented carbide granules is 0.6-8 μm. Advantageously, this grain size range provides a means to balance and optimize hardness and toughness for mining applications. Grain size is measured by image analysis of SEM images from secondary electron images or backscattered electron images using the Jefferies method, which gives the average grain size, or by analysis of EBSD images of ion-polished surfaces using the area D50 value.

[0068] Preferably, the average WC particle size in the sintered cemented carbide granules is 0.6 to 8 microns, more preferably 0.7 to 5 microns, even more preferably 0.8 to 3 microns, and most preferably 0.8 to 4 microns.

[0069] The binder phase content (preferably Co) in the SCCG before HPHT treatment is 6-20 wt%, more preferably 7-15 wt%, and most preferably 8-13 wt%. In the composite after HPHT treatment, the binder content in the cemented carbide part ranges from about 2 wt% to about 18 wt%, depending on the amount of diamond and the degree of binder penetration. The binder phase content of the cemented carbide part of the composite after HPHT can be analyzed by EDS (energy dispersive spectroscopy) or, more preferably, WDS (wavelength dispersive spectroscopy) on a sufficiently large ion-polished area where only cemented carbide is present.

[0070] In one embodiment, the D50 size of the SCCG is 5 to 60 microns. Advantageously, this range provides good flowability and high powder density, with the mass of each SCCG approximately equal to the mass of the diamond particles. The D50 size of the cemented carbide granules is preferably 5 to 40 microns, more preferably 5 to 30 microns. Particle size distribution was measured over the entire size range from 0.1 μm to 8750 μm using a laser diffraction method in full compliance with ISO 13320, using a Sympatec GmbH Helos BR instrument and a Rodos M / Vibri dry sampling unit. The powder was analyzed using a combined R3 (0.9 to 175 μm) and R5 (4.5 to 875 μm) measurement range. For each measurement range, samples were analyzed in triplicate using 0.5 g of powder. The results from the two measurement ranges were then combined in Windows 5.7.2.2 software to cover the 0.9 to 875 μm range.

[0071] In one embodiment, the D90 size of the SCCG is <80 μm, preferably <70 μm, even more preferably <60 μm, most preferably <50 μm. Advantageously, this reduces the distance to the next diamond entity and is also important for the granule mass, which is crucial for the homogeneity of the final material and should be as close as possible to the mass of diamond in the feed material to reduce the risk of segregation during mixing and filling into the cup.

[0072] In one embodiment, the (D90-D10) range of the cemented carbide granules is <50 μm, preferably <40 μm, more preferably <30 μm. Advantageously, a narrow distribution of the sintered cemented carbide granules provides a more homogeneous distribution of the diamond entities within the cemented carbide matrix, making it easier to control the distance between the diamond entities within the composite, and therefore more uniform material properties.

[0073] D10, D50, and D90 are calculated using Windox software. D10, D50, or D90 are defined as the size values ​​corresponding to the cumulative size distribution at 10%, 50%, or 90%, respectively, and represent the particle size below which 10%, 50%, or 90% of the sample lie. Alternative notations are x10, x50, and x90, as used in Windox software.

[0074] In one embodiment, the powder density of the SCCG powder is >35%, preferably >40%, more preferably >45% of that of a fully dense sintered body of such granules. Powder density (or apparent density) is measured using a Hall flow meter by filling a known volume (Hall density cup) with a funnel placed over where the powder is added.

[0075] In one embodiment, the tap density of the SCCG powder is preferably >40%, more preferably >50%, and most preferably >55% of the fully sintered body. Tap density is achieved by filling a known volume (Hall density cup or similar) with powder granules and tapping or "knocking" them to pack more tightly. Advantageously, high granule density locks the diamond particles into place after filling the refractory metal cup. Additionally, low shrinkage during HPHT helps control shape and size, and helps avoid sudden pressure drops (so-called blowouts) during HPHT that can lead to catastrophic failure of the cemented carbide dies in the HPHT cell.

[0076] In one embodiment, prior to the HPHT step, graphite or other sp2 The presence of carbon advantageously allows the HPHT process to be carried out above the stability field of diamond in the presence of a catalytic metal (Co), which lowers the melting point of the binder and facilitates the infiltration of diamond particles, resulting in their conversion to diamond.

[0077] In one embodiment, after HPHT, the interior of the cemented carbide granules comprises primarily fcc-Co, and the binder layer around the remaining granules comprises primarily hcp-Co.

[0078] In step c), mixing can be achieved by vibration, turbo blending, or shaking, such as with a commercial paint shaker.

[0079] In step d), the refractory metal cup is preferably made from titanium, but may also be made from niobium, tantalum, or other suitable refractory metal. The cup is shaped according to the needs of the product being formed.

[0080] In step e), either a refractory metal lid or a preformed base of pre-sintered or sintered cemented carbide is inserted into the refractory metal cup over the powder mixture to close the cup. The choice of cemented carbide base in terms of particle size and composition depends on the intended application. "Pre-sintered" in this context means that the cemented carbide base is not sintered to full density before being placed in the cup; full density is achieved in a subsequent HPHT step.

[0081] In step f), a preformed substrate of refractory metal or sintered hard metal is inserted into the refractory metal cup on top of the powder mixture and the cup is closed. The addition of the hard metal substrate advantageously forms a base portion of the cemented carbide, allowing the cutting tip shape to be designed or tailored to the application, for example, by allowing a blend of a larger amount of cemented carbide granules with diamond on one side or part of the tip. The choice of cemented carbide base portion in terms of grain size and binder content depends on the target application. The tip shape can be either symmetrical or asymmetrical.

[0082] In step g), the pressure medium can be, for example, hBN or NaCl mixtures that melt during the high-temperature, high-pressure stage above the diamond stability field.

[0083] For step h), high pressure vessels include, but are not limited to, for example, cubes or cylinders of natural or synthetically reconstituted pyrophyllite.

[0084] A typical HPHT cycle in step i) involves a rapid ramp to 1225°C at a maximum pressure of 52 kBar over 50-65 seconds, followed by a gradual ramp down to the sintering hold temperature at 52 kBar over 200-300 seconds. A typical soak temperature is 1350-1425°C for 100-200 seconds, followed by a rapid ramp down to 52 kBar for 200-400 seconds; power is immediately removed, and a natural cooling ramp via the cooling water jacket is allowed to dissipate heat for 40 seconds, after which the applied pressure is gradually released. Temperature is controlled by a W-Re thermocouple within the cube. A full cycle takes approximately 15-25 minutes. Sintering temperatures are typically 1300-1500°C, preferably 1320-1450°C, and most preferably 1350-1420°C. The sintering pressure is typically between 50 kBar and 60 kBar, preferably between 50 kBar and 55 kBar, and most preferably 52 kBar.

[0085] The pressure and contact with the cemented carbide granules causes significant disruption of the diamond and metal binder, allowing the cemented carbide to dissolve and infiltrate, filling cavities in the diamond entities or anchoring diamond crystals or allowing the formation of new diamond entities.

[0086] After HPHT processing, the outer diameter of the part is cleaned up using centerless grinding, and if necessary, the cup on the dome is removed by grinding or blasting with SiC grit. If the part is a mining insert, it is ground to the exact dimensions required. If necessary, the insert can be shot blasted and / or tumbled (such as high-energy tumbling). The insert can then be shrink-fit and brazed into the cavity of the drill bit.

[0087] Example Example 1 - Sample Overview The inventive specimens were fabricated by mixing diamond and sintered cemented carbide granules (SCCG) in the desired composition for 2.5 minutes using a Caulk VARI-MIX II vibratory unit. The amount of powder mixture to fill the Ti cup was calculated based on the volume of the Ti cup and the desired height of the cutting layer. The comparative specimens were fabricated using only SCCG powder. A cylindrical cemented carbide base was fabricated using conventional methods, and then the desired dome shape of the tip was formed on it.

[0088] Table 2 provides an overview of the powder mixtures and substrates used in the samples. TIFF2026500213000004.tif239170

[0089] Sample C is a comparative sample that uses soft, freeze-spray-dried diamond-containing granules in the powder mixture, with a D100 diamond granule size of 500 μm, a bimodal diamond particle size distribution with maxima at 6 μm and 25 μm, and a powder density of 1.11 g / cm 3 The relative density of diamond in the diamond-containing granules compared to pure diamond is 32%. The soft diamond granules also contained 10 wt% PEG binder, which was removed in a hydrogen and nitrogen gas mixture up to 500 °C before the HPHT step.

[0090] Table 3 shows the properties of the cemented carbide granules in the mixed powder. TIFF2026500213000005.tif124170

[0091] Sintered cemented carbide granules SCCG-3, SCCG-4, SCCG-5, and SCCG-6 were produced using soft spray-dried cemented carbide granules with a relative density of approximately 25%, an average granule diameter of approximately 80-100 microns, and a maximum size of 250 microns. The spray-dried granules were placed on yttrium oxide-coated graphite trays. Each tray, 278 mm in diameter, was loaded with 1.5 kg of spray-dried granules. Sintering consisted of a debinding step to remove PEG from the spray-dried granules and a solid-state sintering step at 1275 °C for 60 min under a partial pressure of 250 mbar. The partial pressure consisted of equal flows of argon and carbon monoxide. After sintering, the granules were deagglomerated in a small ball mill for 20 min using approximately 2 kg of cylindrical cemented carbide grinding bodies. Deagglomeration was performed under dry conditions; no liquid was added to the ball mill.

[0092] The deagglomerated powders SCCG-3 and SCCG-6 were used as received after the deagglomeration step, while the deagglomerated powders SCCG-4 and SCCG-5 were finally fractionally sieved at 63 μm, and the fraction <63 μm was used. The samples using SCCG-3 and SCCG-6 were used as comparative samples because the D50 size of the cemented carbide granules was too large.

[0093] The SCCG and diamond powder were then blended in a Caulk VARI-MIX II vibratory unit for 2.5 minutes. The powder mixture was then poured into a titanium refractory metal cup with a wall thickness of 127 μm. A sintered cemented carbide base was then placed on top of the powder mixture to close the cup and house the assembly. The powder mixture in the refractory metal cup was pre-compacted by pressing a cemented carbide body onto the powder mixture. The housed assembly was surrounded by a pressure medium made of hexagonal boron nitride (hBN), a carbon foil heater, and a cylinder made of a mixture of carbon lamp black and sodium chloride. These internal components were housed within a reconstituted pyrophyllite pressure medium vessel, which was then inserted into a high-pressure, high-temperature cubic press and sintered at high pressure and high temperature to form a dome-shaped insert. HPHT sintering was performed at a pressure of 52 kbar. Details of the sintering temperatures used are listed in Table 3.

[0094] The samples were then HPHT sintered to form dome-shaped inserts. Table 4 shows the characteristics of the HPHT sintering conditions used and the post-sintering yields. After HPHT sintering, the inserts were polished and / or blasted with SiC to clean the domes. Table 4 also reports the wear uniformity of the domes after SiC blasting. TIFF2026500213000006.tif135170

[0095] Table 4 shows that the comparative samples suffered either or both failure due to delamination after HPHT sintering or non-homogeneous wear during SiC blasting / cleaning of the dome, whereas the inventive samples were free of failure after HPHT sintering and did not exhibit homogeneous wear during SiC blasting / cleaning of the dome. Homogeneous wear during SiC blasting of the dome indicates homogeneous material properties, improving insert performance and providing inserts that are less susceptible to cracking.

[0096] Tables 5 and 6 show the properties of commercially available samples that are considered to be state of the art and serve as "benchmarks" for the properties of inserts manufactured in accordance with the present invention. These samples have a high diamond content and therefore are much more expensive to manufacture than the samples of the present invention. These samples were manufactured using three layers of diamond within the dome, each layer having a different concentration of diamond. TIFF2026500213000007.tif44170TIFF2026500213000008.tif57170Table 7 shows the properties of the inserts after HPHT sintering. TIFF2026500213000009.tif66170

[0097] Table 7 (evaluated with Image J version 1.54d) shows that Benchmark Comparison R has a much lower percentage of diamond entities containing pores and / or defects and / or cracks filled with the cemented carbide constituents, and is therefore outside the scope of the claims. Figures 1a and 1b show SEM images of the structure of Sample F taken at magnifications of x140 and x450, respectively, which show a high percentage of diamond entities containing pores and / or defects and / or cracks filled with the cemented carbide constituents. Comparing this to the SEM image of Sample R, Figure 3, shows a much lower percentage of diamond entities containing pores and / or defects and / or cracks filled with the cemented carbide constituents.

[0098] Further comparative samples are given in Table 8. The samples shown in this table were produced by conventional sintering in vacuum at a temperature of 1410°C, with an argon pressure of 60 bar applied at the maximum temperature. TIFF2026500213000010.tif79170

[0099] Table 9 shows examples of hardness and fracture toughness of sintered SCCG and cemented carbide. TIFF2026500213000011.tif70170

[0100] Table 9 shows that all SCCGs had K1C > 10 mPa / m, indicating that the hardness and toughness of sintered SCCGs and cemented carbide can be controlled by their composition. It was not possible to measure the hardness and toughness of diamond composites because high hardness would break the measuring equipment.

[0101] Example 4 - Homogeneity The samples were polished, lapped, and ion-polished until the cemented carbide matrix and diamond entities were flush. SEM images were then taken approximately 100 microns from the top of the dome (surface) and approximately 100 microns above the substrate. Images were analyzed using the ImageJ program in Fiji. The image scale was set in the program prior to image analysis. The region of interest was set to the carbide matrix, and the diamond entities were considered the background. A threshold was set so that diamond entities without CC components were black and diamond entities with CC components also contained white areas or spots. The same threshold was used for all images. The images were then converted to binary images, and the "grain size" was measured to determine the area of ​​the "particles" (CC matrix). The area percentage of the diamond entities was calculated as 100% minus the area percentage of the CC matrix. The area percentage is considered to correspond to the vol% of the phase. Table 10 shows that homogeneous samples were achieved only when SCCG and diamond were mixed at high powder density and low D50 and D90. The results are shown in Table 10. TIFF2026500213000012.tif49170

[0102] The results in Table 10 show that the distribution of diamond entities in the inventive sample is homogeneous, while the distribution of diamond entities in the comparative sample is non-homogeneous.

[0103] Example 5 - Lathe wear test The specimens were subjected to an abrasion test, in which the tip of the specimen was abraded against the counter surface of a rotating granite log during a turning operation. The test parameters used were as follows: a 100 N load was applied to each insert, the granite log rpm was approximately 190, the log diameter ranged from 130 to 150 mm, and the horizontal feed rate was 0.339 mm / rev. To ensure that differences in rock composition did not significantly affect the results, as much of the log length as possible (up to 300 mm) was used in each test. If large fragments were removed from the log, these sections were avoided, resulting in some tests being less than 300 mm long. The sliding distance varied depending on the diameter and length of the usable rock section, but was generally between 330 and 460 mm. For the three specimens of each grade tested, the mass loss versus sliding distance showed an approximately linear relationship. The specimens were cooled under a continuous stream of water. Each specimen was carefully washed and weighed before and after testing. The mass loss of one sample per material was evaluated, and the sample volume loss for each tested material was calculated from the measured mass loss and sample density, and the results are shown in Table 11. TIFF2026500213000013.tif82170

[0104] Table 11: Wear test results Table 11 shows that the inventive samples, despite their lower diamond content and resulting lower cost, exhibit lower wear rates than the comparative samples and similar wear rates to the benchmark examples. Furthermore, the lower diamond content and separate diamond entities significantly reduce the mismatch between the CTE (coefficient of thermal expansion) of the diamond-containing layer in the present invention and the cemented carbide base. Therefore, the need for a layer structure with a lower diamond composition toward the carbide base is eliminated.

[0105] Example 6 - Insert Compression Test The insert compression test method involves compressing a drill bit insert between two plane-parallel, rigid counter-faces at a constant displacement rate until the insert breaks. A test fixture based on the ISO 4506:2017(E) standard "Hardmetals - Compression test" with Hyperion H6F-grade cemented carbide anvils with a hardness greater than 2000 HV was used, but the test method itself was adapted for toughness testing of rock drill inserts. The fixture was mounted on an Instron 5989 test frame.

[0106] The load axis was aligned with the axis of rotational symmetry of the insert. The counterface of the fixture met the parallelism required by ISO 4506:2017(E), i.e., a maximum deviation of 0.5 μm / mm. The specimens were subjected to a constant load at a crosshead displacement rate of 0.6 mm / min until fracture, and the load-displacement curve was recorded. The compliance of the test equipment and test fixture was subtracted from the measured load-displacement curve before test evaluation. One diamond composite insert was tested, but at least three cemented carbide inserts were tested per run. Before each test, the counterface was inspected for damage. Insert failure was defined as occurring when the measured load suddenly dropped by at least 1000 N. Subsequent inspection of the tested inserts confirmed that this coincided with the onset of a visible crack in all cases. The load at failure was measured, and the material strength was calculated. Strength, characterized by the total absorbed deformation energy until fracture, is calculated from the maximum load and insert displacement at fracture. A summary of the crush strength (IC) in Joules (J) and fracture energy (Ec) required to fracture the sample is given in Table 12 below. TIFF2026500213000014.tif26170

[0107] All samples tested were "as-sintered" 10 mm spherical dome inserts. Crush testing showed that the strength of the inventive inserts was significantly improved compared to the cemented carbide reference insert, even though the substrate of sample G was the same cemented carbide grade as used in sample W.

[0108] Example 7 - EBDS Each specimen was analyzed in the same way by cutting plane-parallel sections from the insert using EDM and mechanically polishing them. The specimens were then ion-polished in flat mode at 6 V for approximately 200–300 min, 2 V for 20 min, and a specimen angle of 4° until the diamond and cemented carbide were flush with each other.

[0109] Three large maps for diamond analysis and two small maps for WC analysis were performed using Aztec 6.0 software. The microscope and analytical setup are shown in Table 13. TIFF2026500213000015.tif50170

[0110] Post-processing was performed using AztecCrystal 2.2 software. For the diamond map, wild spike removal and zero solution removal were performed up to 5 neighbors, with 10 iterations per step. Furthermore, the axis

[0111] Pseudo-symmetric rotations with an angle of 60 degrees (allowed deviation angle of 5 degrees) were removed. Diamond-diamond boundaries were defined as boundaries with a misorientation angle of 10 degrees or more and a closed boundary. Boundary particles were excluded. The smallest grains were defined as those with an area size of 50 pixels. For WC automatic cleaning, pseudo-symmetric rotations and the removal of the axis

[0001] and the addition of an angle of 30 degrees (allowed deviation angle of 5 degrees) were used. WC-WC boundaries were defined as boundaries with a misorientation angle of 3 degrees or more and a closed boundary. Boundary particles were excluded. The smallest grains were defined as those with an area size of 13 pixels. TIFF2026500213000016.tif62170

[0111] Field Trial - Test 1 Bits with three 9mm inserts on the front and six 10mm inserts on the periphery were tested in tophammer applications in an underground mine in northern Sweden. Prior to installation in the drill bit body, the inserts were post-sintered using a bidirectional vibration procedure with a CorobEVOshake 500 paint shaker operating at 75% of maximum rpm (equivalent to approximately 430 rpm) for 5 minutes, along with 3 kg of 7mm cemented carbide media. The pre-cut diamond layer thickness for the X was 1.3 mm for the 9mm inserts and 2.0 mm for the 10mm inserts.

[0112] The diameter of the drill bits was measured in three directions before and after cutting and the average diameter reduction was calculated. The results, along with the wear resistance calculated as diameter wear / meter of cut, are shown in Table 15 below. No insert failure occurred during cutting and both bits had a significant amount of diamond remaining when cutting stopped. TIFF2026500213000017.tif27170

[0113] It can be seen that the sample of the present invention has improved wear resistance compared to the comparative sample of the prior art.

[0114] Field Trial - Test 2 The second test was performed using the same setup as the field test (Test 1) and the results are shown in Table 16 below. The thickness of the diamond layer before cutting on TIFF2026500213000018.tif32170Y was 1.2 mm for the 9 mm insert and 2.0 mm for the 10 mm insert.

[0115] The bit with the sample S insert reached the end of its life. The bit with the sample R insert had one of the peripheral inserts chipped, but none of the other bits tested had any chipped inserts.

[0116] As a result, it was found that the inventive sample had higher wear resistance than comparative sample S, which is a common material for cemented carbide tips used in top hammer applications. Surprisingly, despite a difference of more than 50% in diamond content, the difference in wear resistance between Y and R was only about 30%.

Claims

1. a cemented carbide matrix (4) having embedded diamond entities (6) homogeneously distributed throughout; The components of the cemented carbide include a metal carbide and a binder phase, The particle size of the metal carbide is 0.6 to 8 microns, The material is 5-65 vol% diamond. A composite material (2) comprising: A composite material (2) characterized in that at least 20% of the diamond entities (6) contain pores and / or cracks (8) filled with cemented carbide constituents.

2. The composite material (2) of claim 1, wherein the binder content of the cemented carbide matrix is ​​2 to 20 weight percent (wt%).

3. A composite material (2) according to claim 1 or 2, wherein the diamond entities (6) have an average diameter of 10 to 500 μm.

4. 4. The composite material (2) of any one of claims 1 to 3, wherein at least 25% of the diamond entities comprise a plurality of crystals having two or more different orientations, where different orientations are defined as two or more substantially adjacent diamond crystals that have a difference in orientation of at least 10 degrees.

5. An insert (10) for a mining or rock cutting or wear part, comprising a material (2) according to any one of claims 1 to 4.

6. 6. An insert (10) according to claim 5, comprising a dome-shaped tip (14) comprising the composite material (2) according to any one of claims 1 to 5, and a base (12) comprising a cemented carbide.

7. 7. The insert of claim 6, wherein the base portion (12) comprises chromium.

8. An insert according to claim 6 or 7, wherein the base part (12) contains 4-15 wt% Co and has a room temperature Vickers hardness between 900 and 1650 HV20.

9. A method for producing a material (2) according to any one of claims 1 to 4, comprising: a) providing friable diamond particles; b) providing sintered cemented carbide granules (SCCG); c) blending the diamond particles with sintered cemented carbide granules to form a homogenous powder blend; d) placing the powder mixture into a preformed refractory metal cup; e) providing a refractory metal lid or a pre-sintered or sintered cemented carbide base over the powder mixture to close the cup; f) precompacting the powder in a refractory metal cup; g) surrounding the cup with a pressure medium; h) inserting the cup surrounded by the pressure medium into a high pressure, high temperature vessel; i) sintering the container at high pressure and high temperature in a high pressure and high temperature press to form a composite material; A method comprising:

10. 10. The method of claim 9, wherein the D50 size of the SCCG is in the range of 5 to 60 microns.

11. 11. The method of claim 9 or 10, wherein the average tungsten carbide grain size in the SCCG is between 0.6 and 8 μm.

12. 12. The method according to any one of claims 9 to 11, wherein the relative powder density of the SCCG is >35% compared to the density of a fully sintered body of such granules.

13. SCCG is >10 MPa / m １／２ 13. The method of claim 9, wherein the alloy has a K1C fracture toughness of 0.1% or less.

14. 14. The method of any one of claims 9 to 13, wherein prior to the HPHT step, the SCCG has graphite on its surface.

Images