JP2022512933A - Binder redistribution within cemented carbide inserts for mining - Google Patents

Abstract

A method of redistributing the bonded phase of a mining cemented carbide insert containing one or more hard phase components and binders, a) preparing an untreated cemented carbide insert for mining, and b). A step of applying at least one binder puller selected from metal oxides or metal carbonates to the surface of untreated cemented carbide inserts for mining and c) firing untreated cemented carbide inserts for mining. A method and a hardness gradient comprising a sintering step, wherein the metal oxide or metal carbonate is applied to only at least one local region of the surface of the untreated cemented carbide insert for mining. Carbide with and its use. [Selection diagram] FIG. 10

Description

The present disclosure relates to a method of redistributing a binder within a mining cemented carbide insert, a mining cemented carbide insert having a hardness gradient and its use.

Cemented carbide has a unique combination of high modulus of elasticity, high hardness, high compressive strength, high wear resistance and abrasion resistance, as well as a good level of toughness. Therefore, cemented carbide is commonly used in products such as mining tools. In general, the hardness and toughness of cemented carbide can be changed by varying the binder content and the particle size of the hard phase. Higher binder content usually increases the toughness of cemented carbide, but reduces its hardness and wear resistance. Finer hard phase particle size results in higher hardness cemented carbide with higher wear resistance, whereas coarser grain size hard phase is less rigid but more impact resistant. Have.

In order to maximize the efficiency of cemented carbide inserts for mining, a combination of these properties is desired and there is a different demand for materials in different parts of the product. For example, in inserts for rock drilling and mineral cutting, it is desirable to have a tougher interior that minimizes the risk of failure and a stiffer exterior that optimizes wear resistance.

WO2010 / 056191 discloses a method of forming a cemented carbide body containing a hard phase and a bonded phase, wherein at least one portion of the intermediate surface zone has a lower average binder content than the interior of the body. There is.

However, there is still a need for methods that can create even larger hardness gradients, adjust the gradient for specific applications, and even apply to asymmetric cemented carbide inserts for mining. .. There is also a need for a method that can redistribute the bound phase, starting with a standard carbide powder that is stoichiometrically balanced with respect to carbon content.

Thereby, the present disclosure is thus a method of redistributing the bound phase into a mining cemented carbide insert containing one or more hard phase components and a binder.
a) The process of preparing untreated cemented carbide inserts for mining,
b) A step of applying at least one binder puller selected from metal oxides or metal carbonates to the surface of untreated cemented carbide inserts for mining.
c) The process of sintering untreated cemented carbide inserts for mining,
Provided is a method comprising, wherein a metal oxide or a metal carbonate is applied only to at least one local region on the surface of an untreated cemented carbide insert for mining.

The method makes it possible to redistribute the binder in a tuned and best manner to obtain optimum functionality for mining cemented carbide inserts. For example, a particular hardness profile can be created for different applications.

Further, the present disclosure is a cemented carbide insert for mining containing one or more hard phase components and binders, from a first portion of the surface to a second portion of the surface of the cemented carbide insert for mining. By the presence of a hardness gradient, the first portion of the surface is substantially opposed to the second portion of the surface.
-The first part of the surface is 30HV3 more flexible to 80HV3 harder than the second part of the surface.
-The first part of the surface is 5 to 120 HV3 harder than the bulk,
-Regarding a cemented carbide insert for mining, characterized in that the second portion of the surface is 20HV3 to 70HV3 harder than the bulk.

FIG. 3 is a schematic representation of an insert showing a binder puller and a binder pusher symmetrically applied to opposite sides. FIG. 3 is a schematic representation of an insert showing a binder puller and a binder pusher asymmetrically applied to opposite sides. 3 is an HV3 constant hardness plot for Sample A disclosed in Example 1. 3 is an HV3 constant hardness plot for Sample B disclosed in Example 1. 3 is an HV3 constant hardness plot for Sample C disclosed in Example 1. 3 is an HV3 constant hardness plot for Sample D disclosed in Example 1. 3 is an HV3 constant hardness plot for Sample E disclosed in Example 1. 8 is an HV3 constant hardness plot for Sample F disclosed in Example 1. 6 is an HV3 constant hardness plot for Sample G disclosed in Example 1. 8 is an HV3 constant hardness plot for Sample H disclosed in Example 1. 8 is an HV3 constant hardness plot for Sample I disclosed in Example 1. 6 is an HV3 constant hardness plot for Sample J disclosed in Example 1. 6 is an HV3 constant hardness plot for Sample K disclosed in Example 1. FIG. 3 is a schematic representation of an insert showing where the binder puller was applied in Example 1. HV3 centerline hardness profile for Samples A, B and C disclosed in Example 1. HV3 centerline hardness profile for Samples D, E and F disclosed in Example 1. HV3 centerline hardness profile for Samples G, H and I disclosed in Example 1. HV3 centerline hardness profile for samples J and K disclosed in Example 1. HV5 constant hardness plot for Example 2 where the binder puller and the binder pusher were asymmetrically applied. It is a schematic of the setting for a pendulum hammer test. The cobalt concentration profile discussed in Example 5 for Samples D and G. The chromium concentration profile discussed in Example 5 for Samples D and G. Example 5 Cr / Co concentration profile discussed in Example 5 for Samples D and G. 9 is the cobalt concentration profile discussed in Example 5 for Sample K. 9 is the chromium concentration profile discussed in Example 5 for Sample K. It is a plot showing the change of the insert diameter as a function of the drilling depth with respect to the samples C, F and I measured during the field test.

According to one aspect, the present disclosure is a method of redistributing the bonded phase of a WC hard phase, optionally one or more additional hard phase components and binders of a cemented carbide insert for mining.
a) The process of preparing untreated cemented carbide inserts for mining,
b) A step of applying at least one binder puller selected from metal oxides or metal carbonates to the surface of untreated cemented carbide inserts for mining.
c) The process of sintering untreated cemented carbide inserts for mining,
The present invention relates to a method comprising, wherein a metal oxide or metal carbonate is applied only to at least one local region on the surface of an untreated cemented carbide insert for mining.

One or more additional hard phase components can be selected from TaC, TiC, TiN, TiCN, NbC, CrC. The bound phase can be selected from Co, Ni, Fe or a mixture thereof, preferably Co and / or Ni, most preferably Co. Carbide inserts for mining have a suitable binder content of about 4 to about 30% by weight, preferably about 5 to about 15% by weight. Carbide inserts for mining may also optionally contain a crystallizing compound in an amount of ≤20% by weight of the binder content. The crystallizing compound is appropriately selected from the group of carbides or nitrides of carbide, mixed carbide, vanadium, chromium, tantalum and niobium. The rest of the mining carbide inserts are made up of one or more hard phase components.

In one embodiment of the method, the mining cemented carbide insert contains a hard phase containing at least 80% by weight WC, preferably at least 90% by weight WC.

In the present disclosure, the term "green" is produced by grinding the hard phase component and binder together and then pressurizing the crushed powder to form a small cemented carbide insert for mining. Refers to cemented carbide inserts for mining that have not yet been sintered. The term "binder puller", when applied to the surface of a cemented carbide insert for mining, moves the binder towards the surface during the sintering process, i.e., "binder puller" was applied. A substance that attracts a binder toward the surface. Binder pullers locally consume carbon, thereby acting by allowing the binder to flow from regions with normal carbon levels to regions depleted of carbon levels.

The inventors apply a binder puller, selected from metal oxides or metal carbonates, to at least one local region of the surface of an untreated cemented carbide insert for mining to burn its carbon. It was found that during the sinter, it is locally consumed in this region to form a carbon potential. This facilitates the transfer of the bound phase from regions with normal or higher levels of carbon to regions depleted of carbon levels. Therefore, this forms a binder-rich region on the local region of the surface of the mining cemented carbide insert. The surface of the untreated cemented carbide insert for mining coated with the binder puller is referred to as the "oxide / carbonate doped" surface. It is well known that the binder-rich region and the binder-depleted region are subject to tensile and compressive stresses after sintering, respectively. Introducing tensile stress is usually not preferable. However, the inventors have found that after treatments such as centrifugal rolling, high levels of compressive stress can be introduced to a depth of at least less than 1 mm below the rolled surface and can react to the existing tensile stress. .. Therefore, the advantage of applying the binder puller is obtained without the harmful effects of introducing tensile stress.

"At least one local region on the surface of an untreated cemented carbide insert for mining" is any location on the surface, eg, depending on where the requirements for increasing the binder content are. It may be a tip, a bottom or a side surface. The binder puller is applied to one or more local areas of the surface of the mining cemented carbide insert, depending on whether the desired action is to create a local increase in toughness or wear resistance. can do. Each "local region" may be 0.5-85%, preferably 3-75% of the total surface area of the mining cemented carbide insert.

The sintering temperature is appropriately about 1000 ° C. to about 1700 ° C., preferably about 1200 ° C. to about 1600 ° C., and most preferably about 1300 ° C. to about 1550 ° C. The sintering time is appropriately about 15 minutes to about 5 hours, preferably about 30 minutes to about 2 hours.

In one embodiment of the method, the binder puller, which is a metal oxide or metal carbonate, is Cr _{2O 3} , MnO, MnO ₂ , MoO ₂ , Fe oxide, NiO, NbO ₂ , V ₂ O ₃ , MnCO. ₃ , FeCO ₃ , CoCO ₃ , NiCO ₃ , CuCO ₃ or Ag ₂ CO ₃ are selected. Alternatively, a metal can be applied to the surface of the untreated cemented carbide insert for mining, in which case the oxide is formed by heating during the sintering process. The choice of metal oxide or metal carbonate affects the properties of the cemented carbide after sintering, such as deformation hardening, heat resistance and / or corrosion resistance, making the selection most suitable for the required application. Can be done. Metal carbonates are selected when the equivalent metal oxide is toxic and the metal carbonate is not toxic. In this method, there is a high degree of freedom in the choice of the part to which the binder puller is applied. For example, in the binder puller, whether or not the metal in the oxide or carbonate improves the wear resistance of the cemented carbide. Depending on the situation, it can be applied into the wear zone of the carbide tool or at a remote location.

In one embodiment of the method, the binder puller is Cr ₂ O ₃ . The use of Cr ₂ O ₃ as a binder puller has the advantage that a surface layer rich in chromium alloy is formed, which surface enhances the response to rolling treatment. Therefore, higher compressive stresses are introduced and the wear properties of the mining cemented carbide inserts are improved. Cr ₃ O ₂ contributes to particle refinement and therefore a reduced particle size is measured on the sides of the insert coated with Cr ₃ O ₂ .

The metal oxide or metal carbonate is appropriately provided on the surface in an amount of about 0.1 to about 100 mg / cm ² , preferably in an amount of about 1 to about 50 mg / cm ² . The cemented carbide powder blend to be initiated has a suitable carbon balance equivalent to 0.95 <Com /% Co <1 or has excess carbon to compensate for the carbon loss due to the application of oxides or carbonates. Com is 100 * S _{, insert} / σ _{S, cobalt} [in the formula, σ _S is a weight-specific saturation magnetization measured at Tm ³ / kg, σ _{S, cobalt} = 2.01E-4Tm ³ / kg. Is]. Com is a Forester Koerzimat CS. It is measured in units of 1097.

In one embodiment of the method, the binder puller is applied to the top of the mining cemented carbide insert. In another embodiment of the method, the binder puller is applied to the sides of the mining cemented carbide insert. Therefore, the properties of cemented carbide inserts for mining can be adjusted to suit the application. The binder puller is probably selected to be applied to a location on the surface of the mining cemented carbide insert that is exposed to the highest wear.

In one embodiment, the method applies at least one binder pusher to at least one different local region of the surface of an untreated cemented carbide insert for mining between steps a) and b). Including further. In the present disclosure, the term "binder pusher", when applied to the surface of a mining carbide insert, moves the binder away from the surface during the sintering process, i.e. the binder, "binder". A "pusher" refers to a substance that is pushed away from the coated surface. Binder pullers applied to at least one local area of the surface and binder pushers applied to at least one different local area of the surface of the cemented carbide insert for mining are standard applications. Untreated cemented carbide inserts with a carbon content within the range used in, for example, within the range 0.95 <Com /% Co <1, are therefore used using standard processes. It means that it can be made to tolerate efficiency in production. Preferably, the movement is directed to the depth of the insert rather than along the surface of the insert.

In one embodiment of the method, the binder pusher is selected from metal carbides, carbon powders such as graphite, or mixtures thereof. The application of metal carbide, carbon powder or mixtures thereof creates a carbon gradient, which can move the cobalt away from the surface on which it is applied, i.e. the binder is the internal bulk of this local region. Pushed away from the surface of the carbide towards. The choice of metal carbide has the additional effect of atomizing the particles in the applied local area, whereas the selection of carbon powder has the effect of promoting the growth of particles in the applied local area. Have. The differences that occur in the produced particle growth gradients are not as significant as the effect of the binder gradient on the hardness gradient.

In one embodiment, the binder pusher is a combination of metal carbide and carbon powder. The weight ratio of the metal carbide to the carbon powder is about 0.05 to about 50, preferably about 0.1 to about 25, more preferably about 0.2 to about 15, even more preferably about 0.3 to about 12. , Most preferably about 0.5-8. The metal carbide is adequately provided on the surface in an amount of about 0.1 to about 100 mg / cm ² , preferably in an amount of about 1 to about 50 mg / cm ² . The carbon powder is adequately provided on the surface in an amount of about 0.1 to about 100 mg / cm ² , preferably in an amount of about 0.5 to about 50 mg / cm ² .

If only carbon powder, such as graphite, is selected as the binder pusher, this results in coarsening of the hard phase particles in the area to which it is applied. This makes it possible to achieve a combination of high wear resistance and improved thermal conductivity within zones on mining buttons exposed to working rocks, as well as high toughness behind these zones. It becomes.

In one embodiment of the method, the metal carbide is selected from chromium, vanadium, magnesium, iron or nickel carbide, preferably chromium carbide, such as Cr ₃ C ₂ , Cr ₂₃ C ₆ , Cr ₇ C ₃ . ..

It is advantageous to choose a metal carbide such as Cr ₃ C ₂ in combination with carbon powder. This is because this combination moves off the binder-doped surface and the addition of carbon blocks the particle miniaturization of Cr ₃ C ₂ .

During sintering, any metal carbide applied to the surface of the untreated mining cemented carbide insert should be substantially dissolved.

In one embodiment of the method, the binder puller and binder pusher are applied to different localized areas of the surface of the mining cemented carbide insert. Applying the binder puller and binder pusher to different local areas creates a binder gradient between the two surfaces. The gradient of this binder forms a hard, binder-depleted surface in the area where the binder pusher is applied, and a tough, binder-rich surface in the area where the binder puller is applied. This means that a hardness gradient has been created. Binder pullers and binder pushers combined and applied to different local areas of the surface of mining cemented carbide inserts in larger carbide bodies where previously known methods cannot produce sufficiently deep gradients. Especially useful for creating hardness gradients. Binder pullers can be applied to selected areas on the surface of untreated mining carbide inserts and binder pushers can be applied to different selected areas on the surface of untreated mining carbide inserts. Can be applied to. A binder pusher can be placed in the wear zone to reduce the binder content and thus improve the wear resistance of the region, or even if it is preferred to have higher thermal conductivity. Abrasion resistance can be improved. Topical application of the binder puller and binder pusher presents a unique possibility for creating a carbide body with the required properties.

Another advantage of using this method is that self-sharpening zones can be created if the wear rates of different areas of the surface are not uniform. The contact pressure between the worn insert and the rock increases as the tip becomes sharper as the contact area decreases. With uniform materials, wear results in a worn flat surface that often requires re-sharping with a diamond grinding tool. Grinding re-sharpening is costly and the drill bit must be removed. By having non-uniform material properties, it is possible to have zones that wear faster and zones that wear slower. When the material properties of the mining inserts are adjusted to have a wear surface with areas of different wear rates, the formation of flat surfaces due to wear is avoided and, as a result, more than when a uniform material is used. A sharp wear surface is created.

In one embodiment of the method, the binder puller and binder pusher are applied to substantially opposite local regions of the surface of the mining cemented carbide insert.

In one embodiment, the method of applying the binder puller and binder pusher is selected from pressurization, dipping, painting, spraying (air brushing), stamping or 3D printing. Dipping can be done with or without masking. Binder pullers and binder pushers can be applied to the surface of untreated cemented carbide inserts for mining in the form of liquid dispersions or slurries. In such cases, the liquid phase is preferably water, alcohol or polymer, eg polyethylene glycol. The concentration of the slurry is appropriately 5 to 50% by weight, for example, 15 to 40% by weight of the powder in the liquid phase. This range is advantageous so that the full action of the binder puller or pusher is recognized. If the powder content is too high, there may be problems due to clogging and ramping in the liquid dispersion or slurry. Alternatively, the binder puller and binder pusher can be introduced as a solid material, for example, by adding the powder to the pressurized mold at the appropriate location. The powder can be mixed with a hard phase powder, such as a WC-based powder. Binder pullers and binder pushers can also be applied to mining cemented carbide inserts in any other suitable manner. The composition and concentration of the slurry and the method by which it is applied affect the control of the redistribution of the binder and thus allow the control of the hardness profile of the cemented carbide inserts for mining.

In one embodiment of the method, the binder puller is applied rotationally symmetrically to the first portion (10) of the surface and the binder pusher is applied to the second portion (20) of the surface, as shown in FIG. ) Is applied.

In one embodiment of the method, the binder puller is applied asymmetrically to the first portion (10) of the surface and the binder pusher is applied to the second portion (20) of the surface as shown in FIG. ) Is applied.

Flexibility is present in the area where the binder puller and binder pusher are applied, which allows for the location of the "wear zone", i.e., the location on the surface with the most enhanced wear properties. Will be. For example, the wear zone may be either the top or the sides of the insert, depending on where the interaction between the mining cemented carbide insert and the excavated rock is highest. This will vary depending on the application in which it is used and the location of the mining carbide insert on the rock drill bit.

Cemented carbide inserts for mining are placed under high compressive loads. As a result, surface cracking caused by small cracks grows to critical size through repeated intermittent high loads, which is a common cause of insert failure. It is known that the presence of compressive stress can prevent crack growth and material wear, so introducing compressive stress to the surface of the insert can reduce this problem. Known methods of introducing compressive stresses into the surface of mining cemented carbide inserts include shot peening, vibration rolling and centrifugal rolling. All of these methods increase the life of the mining cemented carbide inserts based on the mechanical impact or deformation of the outer surface of the body.

In one embodiment of the method, after sintering, the cemented carbide insert for mining is treated by a rolling process. Cemented carbide inserts for mining are provided for post-treatment surface hardening that introduces high levels of compressive stress into the inserts. For mining inserts, this is usually a rolling process and may be centrifugal or vibration. However, other post-treatment surface hardening methods, such as shot peening, can also be used. After rolling, the increase in magnetic coercive force (kA / m) is usually measured.

The "standard" rolling process is typically performed using a vibrating tumbler, such as the ReniCirillo RC 650, which rolls an approximately 30 kg insert at 50 Hz for approximately 40 minutes. An alternative typical "standard" rolling process would be a centrifugal tumbler, such as the ERBA-120, which has a closed lid at the top and a rotating disk at the bottom. While the disc (Φ600 mm) is rotating, cooling water containing an antioxidant is continuously delivered at 5 liters per minute. Tungsten carbide medium can also be added to increase the load on the tumbler. Due to the rotation, the insert collides with other inserts or with any medium added. Collisions and sliding remove sharp edges and cause strain hardening. For "standard" rolling, rolling motions using centrifugal tumblers are typically run from 120 RPM for at least 20 minutes.

In one embodiment of the method, the rolling process is a "high energy rolling" (HET) method. High energy rolling processes can be used to introduce higher levels of compressive stress into the mining cemented carbide inserts. Many possible differences that can be used to introduce HET, including the type of tumbler, the capacity of the medium to be added (if any), the processing time and process settings, eg RPM for centrifugal tumblers, etc. There is a process setting. Therefore, the most suitable method for defining HET is "setting up any process that introduces a certain degree of deformation hardening in a uniform mining cemented carbide insert of WC-CO with a mass of about 20 g". From that point. In the present disclosure, HET is defined as a rolling process that introduces a change in hardness as measured using HV3 after at least the following rolling (ΔHV 3%):
ΔHV3% = 9.72-0.00543 * HV3 _bulk (Equation 1)
ΔHV3% = 100 * (HV3 _0.3mm -HV3 _bulk ) / HV3 _bulk (Equation 2)
[In the formula, HV3 _bulk is the average of at least 30 indentation points measured at the innermost (center) of the mining cemented carbide insert, and HV3 _{0.3 mm} is the rolled surface of the mining cemented carbide insert. It is the average of at least 30 indentation points 0.3 mm below.] This is based on measurements made for mining cemented carbide inserts with uniform properties. The "uniform property" means that the difference in hardness from the surface zone to the bulk zone after sintering is 1% or less. The rolling parameters used to achieve the deformation hardening described in equations (1) and (2) for uniform cemented carbide inserts for mining apply to cemented carbide bodies with gradient properties.

HET rolling is an insert that operates or rolls at about 150 RPM if the rolling motion is performed without the medium or with a medium of a size larger than the rolling insert. It can usually be carried out using the ERBA 120 with a disc size of about 600 mm, which operates at about 200 RPM when smaller size media are used. A medium that operates at about 200 RPM or is smaller in size than the rolling insert if the rolling operation is performed without the medium or with a medium larger than the rolling insert. Can usually be performed using a Rosler tumbler with a disc size of about 350 mm, which operates at about 280 RPM when used. Normally, the parts are rolled for at least 40-60 minutes. HET is rich in binder because the compressive stress introduced from HET reacts with the tensile stress formed by the higher coefficient of thermal expansion of the binder-rich zone adjacent to the binder-depleted zone. Allows the use of included surface zones.

Another aspect of the present invention is a cemented carbide insert for mining, which comprises one or more hard phase components and binders, from a first portion to a second surface of the cemented carbide insert for mining. After sintering, the hardness gradient is present up to the part and the first part of the surface is substantially opposed to the second part of the surface.
-The first part of the surface is 30HV3 more flexible to 80HV3 harder than the second part of the surface.
-The first part of the surface is 5 to 120 HV3 harder than the bulk,
-The second part of the surface is 20HV3 to 70HV3 harder than the bulk,
Regarding cemented carbide inserts for mining.

Hardness measurements are taken after sintering and before any post-sintering treatment, eg rolling.

In one embodiment, the hardness gradient is
-The first part of the surface is 2% more flexible to + 6% harder than the second part of the surface.
-The first part of the surface is +0.5 to + 10% harder than the bulk,
-Suppose that the second part of the surface is + 0.3% to 6% harder than the bulk.

The first portion of the surface is the surface to which the binder puller is applied to form an oxide / carbonate doped surface. The second portion of the surface is the surface facing the portion coated with the binder puller (the side facing the oxide / carbonate doped surface). In some cases, the second portion of the surface may be coated with a binder pusher to form a carbide-doped surface.

This is also shown in Table 1 below:

The term "bulk" as used herein means the cemented carbide in the innermost part (center) of a rock drill insert, the zone with the lowest hardness for the present disclosure.

Vickers hardness mapping is used to measure the hardness of cemented carbide inserts. The cemented carbide is cut along the vertical axis and polished using standard procedures. The Vickers indentation with a 3 kg load is then symmetrically distributed over the polished area. The diamonds in FIGS. 3-13 and 16 indicate the location of the HV3 indentation. Hardness measurements are performed using a programmable hardness tester, KB30S, manufactured by KB Pruftechnik GmbH, calibrated for the HV3 test block published by Euro Products Calibration Laboratory, UK. Hardness is measured according to ISO EN6507.

HV3 measurement was performed by the following method:
-Scan the edges of the sample.
-Program a hardness tester to generate indentations at a specified distance from the edge of the sample.
-Make indentations with a 3 kg load at all programmed coordinates.
-The computer moves the stage to each coordinate with the indentation, activates the auto-adjustment light, autofocus, and automatically measures the size of each indentation.
-The user inspects all photographs of indentations for focus and other substances that disturb the result.

Make 10-40 indentations and perform HV3 measurements on the oxide / carbonate-doped surface and the side facing the oxide / carbonate-doped surface at a distance of 0.3-0.8 mm below the surface. Then, the average HV3 measurement value was calculated. HV3 measurements on the bulk are made over a region of about 1.5-2 mm ² at the lowest hardness location near the center of the polished area and averaged from about 15-20 indentations.

In one embodiment, the maximum concentration (% binder-max) is less than 20% higher than the minimum concentration (% binder-min) in the mining cemented carbide insert.

In one embodiment,% binder-min (eg, minimum Co concentration /% Co-min) is a percentage of the total height of the sintered cemented carbide inserts for mining, 1-50% from the first portion of the surface. , Preferably at a depth of 5-40%. % Binder-min is typically at a depth of 0.5-10 mm, preferably 0.8-7 mm from the first portion of the surface.

In one embodiment, there are two peaks in the binder concentration. One is near the surface and one is in the bulk of the mining cemented carbide insert. The first maximum binder concentration (% binder-max1) (eg% Co-max1) is present in the first portion of the surface (eg, oxide / carbonate doped surface) and the second maximum bond. Agent concentration (% binder-max2) (eg% Co-max2) is a percentage of the total height of the cemented carbide insert for mining, 15 from the first portion of the surface (eg, oxide / carbonate doped surface). It is present at a depth of ~ 75%, preferably 20 ~ 65%. In one embodiment,% binder-max1 ≥% binder-max2. In an alternative embodiment,% binder-max1 ≤% binder-max2. % Binder-max2 is usually 2-15 mm, preferably 4-2 mm from the first portion of the surface. The difference in height between% binder-min and% binder-max2 is usually 1.5-12 mm, preferably 2.5-10 mm.

In one embodiment, the first maximum chromium concentration (% Cr-max1) is present in the first portion of the surface (eg, oxide / carbonate doped surface). In one embodiment, the second maximum chromium concentration (% Cr-max2) is further present in the second portion of the surface (eg, the surface facing the oxide / carbonate doped surface) and% Cr-max1. >% Cr-max2. The minimum chromium concentration (% Cr-min) is located between% Cr-max1 and% Cr-max2 in the bulk of the cemented carbide insert for mining. % Cr-min is preferably a percentage of the total height of the sintered cemented carbide inserts for mining, at a depth of 40-99%, more preferably 50-98% from the first portion of the surface. .. "On the surface" is defined as up to 0.3 mm from the surface.

The chemical concentration in the cemented carbide insert for mining is measured along the center line of the cross section of the cemented carbide insert for mining using a wavelength dispersive spectroscope (WDS).

Another aspect of the disclosure relates to the use of cemented carbide inserts for mining described earlier or later herein for rock drilling or oil and gas drilling.

The following examples are exemplary and non-limiting examples.

Example 1
Binder puller only application Table 2 outlines the analyzed samples:

For Samples A-I in Table 2, cemented carbide inserts were produced using a powder blend with a composition of 94% by weight WC and 6% by weight Co. The WC powder particle size measured as FSSS was 5-7 μm before pulverization. Under wet conditions in a ball mill, WC and Co powders are ground using ethanol with 2 wt% polyethylene glycol (PEG8000) as an organic binder (pressurizer) and a cemented carbide grind. did. After pulverization, the slurry is spray-dried in an _N2 atmosphere and then uniaxially compressed to a size of about 12 mm outer diameter (OD) and about 17-20 mm high (Sample B = 18.7 mm high; Sample C = height 17.4 mm; sample D = height 18.7 mm; samples E and F = height 17.4 mm; samples G, H and I = height 20.2 mm), weight approximately 14-17 g, respectively. A mining insert with a spherical dome (“cutting edge”) at the top. The insert was ground over the negative part, but the dome and bottom part were left in the sintered state.

Samples A, B and C were not slurry coated. Samples D, E and F are comparative examples in which only the binder pusher is applied to the top, i.e., the dome-shaped surface of the cemented carbide insert for mining, in the form of a "carbon-doped slurry" using dipping techniques. be. The carbon-doped slurry consists of 25% by weight Cr _{3C 2} and 5% by weight graphite dispersed in water and is applied to the cemented carbide insert so that approximately 60% of the total length of the insert is exposed to the carbide-doped slurry. did. Samples F, G and H are embodiments of the invention coated with only the binder puller, the sample being an "oxide-doped slurry" containing 30% by weight Cr _{3O 2 and} 70% by weight PEG300. Was applied to the dome-shaped surface of the cemented carbide insert at an amount of 0.25 to 0.28 mg / mm ² by exposing about 60% of the total length of the insert to the oxide slurry. All samples were sintered using Sinter-HIP at an Ar-pressure of 55 bar at 1410 ° C. for 1 hour. For these examples, the slurry was applied symmetrically, i.e., to the dome-shaped surface for equal distances extending downward from each of the sides of the insert.

Samples B, E and H were rolled using a "standard roll" using an ERBA-120 centrifugal tumbler at 120 RPM for 30 minutes. Samples C, F and I were tumbled using "High Energy Rolling (HET)" and using the ERBA-120 centrifugal tumbler 170RPM or for 40 minutes.

Samples J and K are embodiments of the invention in which the cemented carbide insert has a higher binder content. Cemented carbide inserts were produced using a powder blend with a composition of 89% by weight WC and 11% by weight Co. The WC powder particle size measured as FSSS was 8-12 μm before pulverization. Under wet conditions in a ball mill, WC and Co powders are ground using ethanol with 2 wt% polyethylene glycol (PEG8000) as an organic binder (pressurizer) and a cemented carbide grind. did. After grinding, the slurry is spray dried in an _N2 atmosphere and then uniaxially compressed to a size of about 17 mm outer diameter (OD) and about 22 mm height, about 31 g weight, each top conical. A mining insert with a tip (“cut edge”). The insert was ground over the columnar portion, but the tip and bottom portions of the cone were left in the sintered state.

Samples J and K are embodiments of the invention coated with only the binder slurry, where the sample is "oxidized" containing 30% by weight Cr _{3O 2 and} 70% by weight PEG 300 using dipping techniques. Approximately 75% of the total length of the insert is exposed to the oxide-doped slurry in an amount of 0.25 to 0.35 mg / mm ² over the tip of the cone and the portion of the columnar area. Was treated by applying to. Samples were sintered using Sinter-HIP at an AR-pressure of 55 bar at 1410 ° C. for 1 hour. For these examples, the slurry was applied symmetrically, i.e., to the dome-shaped surface for equal distances extending downward from each of the sides of the insert.

Sample K uses a 50 kg medium in the form of a 7 mm diameter carbide ball at 250 RPM for 60 minutes in a Rosler model FKS 04.1 E-SA centrifugal tumbler using "High Energy Rolling (HET)". And rolled.

3 to 13 show HV3 constant hardness maps for Samples A to I, respectively, and FIGS. 15 to 18 show centerline plots for Samples A to K from Table 2. The hardness profile of the cemented carbide insert is as shown in Table 1. As shown in FIG. 14, the binder puller was applied to the tip (30) of the mining cemented carbide insert.

It can be seen that the hardness profile of the present invention is very different from the prior art, showing that there is a more flexible core zone in the bulk and higher hardness is present at both the top and bottom of the mining cemented carbide insert. ..

Example 2
Binder Puller and Binder Pusher Application Cemented Carbide Inserts use the same starting materials as Samples J and K (89 wt% WC + 11 wt% Co) and the methods described in Table 2 / Example 1. Formed. A mining insert with a columnar bottom 24 mm long and 19 mm in diameter and a spherical (semi-dome) tip was formed by uniaxial pressurization. Two types of PEG slurries were made. The first "binder puller" consisted of 30% Cr ₂ O ₃ + PEG and the second "binder pusher" consisted of 25% Cr ₃ C ₂ + 5% C + PEG. The slurry was then applied to the surface of the insert by dipping the insert into the slurry. The insert was then sintered at 1410 ° C. and a pressure of 50 bar in an argon atmosphere. In this example, the two slurries were asymmetrically applied to the opposite sides. That is, as shown in FIG. 2, the binder puller was applied to the side surface of the insert (10) and the binder pusher was applied to the opposite side (20). The HV5 constant hardness map is shown in FIG. It can be seen that this method is used to produce more flexible cores and this hardness profile has been shown to provide efficient drilling behavior. The two slurries could instead be applied symmetrically, as shown in FIG. Controlling the concentration and positioning of the coatings of the two slurries enhances the ability to adjust the redistribution of the bound phase to meet the application needs.

Example 3
Insert compression test The toughness of the drill bit inserts of Samples B, C, E, F, H and I shown in Table 2 / Example 1 was characterized using the insert compression (IC) test. The IC test method comprises compressing the drill bit insert at a constant displacement rate between the hard counter surfaces of the two parallel planes until the insert fails. Based on ISO 4506: 2017 (E) standard "Hard Metal-Compression Test", a test fixture with a cemented carbide anvil with a hardness higher than 2000 HV was used, while the test method itself tested the toughness of the rock drill insert. Adapted to do. Fixture was fitted to the Instron 5899 test frame.

The load axis was the same as the axis of rotational symmetry of the insert. The counter surface of the fixture met the degree of parallelism required by the ISO 4506: 2017 (E) standard, ie, a maximum deviation of 0.5 μm / mm. The tested inserts were loaded with a constant velocity crosshead displacement equal to 0.6 mm / min, recording the load displacement curve until failure occurred. Prior to test evaluation, the integrity of the test equipment and test fixtures was subtracted from the measured load displacement curves. Three inserts were tested for each sample type. Prior to each test, the counter surface was inspected for damage. When the measured load suddenly dropped by at least 1000 N, it was defined as an insert failure. Subsequent inspection of the inserted inserted confirmed that in all cases this was consistent with the occurrence of macroscopically visible cracks. Material toughness was characterized in terms of total deformation energy absorbed by fracture. The results of the insert compression test are shown in Table 3:

According to the IC test results, the toughness of the sample treated according to the method of the present invention is higher than that of the sample known in the prior art when comparing the similarly rolled samples.

Example 4
Pendulum Hammer For a pendulum hammer test, a cemented carbide insert for mining having a dome-shaped tip with a radius of 5.0 mm and a diameter of 10.0 mm was produced, and Samples B and C were produced as in the method described in Example 1. , E, F, H and I were processed. A schematic of the pendulum hammer test settings is shown in FIG. The insert was firmly secured to the holder (30) so that only the dome area protruded. On the pendulum (40), a rigid counter surface is fixed to the pendulum hammer head (50). The counter surface used was a hard, fine-grained, hard metal grade polished plate (h = 5.00 mm, l = 19.40 mm, w = 19.40 mm) with a Vickers hardness of approximately 1900 HV30. When the pendulum is released, the counter surface hits the tip of the sample. If the sample fails, the impact energy (E) absorbed by the sample and measured in joules (J) is not recorded. For the first pendulum angle given, the impact energy is given in Equation 3 [in the equation, m is the total mass of the pendulum hammer 4.22 kg, g is the gravitational constant 9.81 m / s2, and L is the pendulum hammer. It has a length of 0.231 and m and α are angles in the radian].
E = (mtot × g × L × (1-cos (α)) (Equation 3)

To determine the energy required to break the sample, a pendulum initially released from a suitable low angle is made to collide with the sample. The angle is then gradually increased at 5 degree paces until the sample fails. Then, the insert made of the same sample is collided at an angle 3 degrees lower than the collision angle that caused the defect, the increase in the collision angle is made smaller, and the test is repeated. Record the angle at which the insert will not break and calculate the corresponding collision energy. In these tests, the counter surface is replaced every 5-10 collisions. The results are shown in Table 4 below:

The results show that there is a significant increase in impact resistance compared to the samples produced using the method of the invention when comparing the samples rolled in an equivalent manner.

Example 5
Chemical Analysis The chemical gradient of the sample was investigated by wavelength dispersive spectroscope (WDS) analytical means using the Jeol JXA-8530F microprobe. For the samples D (comparison) and G (invention) shown in Table 2 / Example 1, a line scan was performed along the center line on the cross section of the sintered material before rolling. Samples were prepared with a precision cutter, followed by mechanical grinding and polishing. The final step of sample preparation was performed by polishing with a soft cloth with a 1 μm diamond paste. A line scan was performed using an acceleration voltage of 15 kV with a step size of 100 μm and a probe diameter of 100 μm. Perform 3 line scans per sample and report the average. The cobalt concentration profile is compared in FIG. 21, the chromium concentration profile is compared in FIG. 22, and the Cr / Co concentration profile is compared in FIG. 23.

A line scan was performed along the centerline of the cross section of sample K after rolling for comparison with the cemented carbide inserts for mining, which have higher binder concentrations. It is assumed that the rolling does not affect the chemical composition or WDS analysis. Line scans for Co and Cr concentrations are shown in FIGS. 24 and 25, respectively.

For samples produced according to the method of the invention, the highest Co concentration can be found at the tip and bulk of the cemented carbide insert, the lowest Cr concentration and the lowest Cr / Co concentration in the bulk of the cemented carbide insert. It can be seen that it is found.

Example 6
Field Test Cemented Carbide Inserts C (Comparison), F (Comparison) and I (Comparison) on the field trails of the Sandvik test mine in Tampere, Findand, where excavation of granodiorite (granite with quartzite). Tested.

Drill bits were made using 6 gauge inserts and 3 front inserts per bit. The gauge insert had a sintered diameter of 10 mm and a height of 16.6 mm. The front insert had a sintered diameter of 9 mm and a height of 13.8. All inserts had a spherical dome tip. In this test, the wear on the gauge insert was compared. This is the most important part of the bit in terms of bit life. Therefore, front inserts for all bits were made according to Example 1, Sample C using standard cemented carbide, and gauge inserts were modified to assess the effect of the composition on wear. ..

The test was carried out using a hydraulic HFX5 top hammer drill device (manufactured by Sandvik Tamrock) at an operating pressure of 210 bar, a supply pressure of 90 bar and a rotation pressure of 70 bar at 230 rpm.

A slide caliper was used to measure the diameter of the gauge insert as a function of the drilling depth measured approximately every 50 m. Two bits with a C insert, one bit with an F insert and three bits with an I insert were recovered. Larger changes in diameter are a sign of greater wear. The change in diameter as a function of drilling depth is shown in FIG. 26, and an overview of the drilled meters is shown in Table 5 below as a function of diameter loss:

The excavation meter per 1 mm of change in diameter is larger for the insert (I) of the present invention compared to the comparative inserts (C and F), and the insert (I) of the present invention is compared with the comparative insert (C). It can be clearly seen that there is a 55% increase in wear resistance and a 32% increase in wear resistance compared to the comparative insert (F).

Claims (15)

A method of redistributing the bonded phase of a cemented carbide insert for mining, which comprises a WC hard phase component, optionally one or more additional hard phase components, and a binder.
a) The process of preparing untreated cemented carbide inserts for mining,
b) A step of applying at least one binder puller selected from metal oxides or metal carbonates to the surface of a cemented carbide insert for mining.
c) The process of sintering the untreated carbide insert for mining,
A method comprising, wherein a metal oxide or metal carbonate is applied only to at least one local area on the surface of an untreated cemented carbide insert for mining. The method of claim 1, wherein the binder puller is Cr ₂ O ₃ . Between steps b) and c)
Claim 1 further comprises the step of applying at least one binder pusher selected from metal carbide, carbon powder or mixtures thereof to at least one different local region on the surface of the cemented carbide insert for mining. Or the method according to claim 2. The method of any one of claims 1 to 3, wherein the binder puller and binder pusher are applied to substantially opposite local regions of the surface of the untreated cemented carbide insert for mining. The method according to any one of claims 1 to 4, wherein the binder puller and the binder pusher are applied symmetrically. The method according to any one of claims 1 to 5, wherein the binder puller and the binder pusher are applied asymmetrically. The method according to any one of claims 1 to 6, wherein the cemented carbide insert for mining is processed by a rolling process after sintering. The rolling process is a "high energy rolling" process, after which the uniform cemented carbide insert for mining is deformed and hardened to a ΔHV3% ≧ 9.72-0.00543 * HV3 _bulk . Item 7. The method according to Item 7. A cemented carbide insert for mining that contains one or more hard phase components and binders, with a hardness gradient from the first portion of the surface to the second portion of the surface of the cemented carbide insert for mining. After sintering, the first portion of the surface is substantially opposed to the second portion of the surface.
-The first part of the surface is 30HV3 more flexible to 80HV3 harder than the second part of the surface.
-The first part of the surface is 5 to 120 HV3 harder than the bulk,
-A cemented carbide insert for mining, characterized in that the second portion of the surface is 20HV3 to 70HV3 harder than the bulk. The cemented carbide insert for mining according to claim 9, wherein the maximum binder concentration (% binder-max) is less than 20% higher than the minimum concentration (% binder-min) in the cemented carbide insert for mining. 30. The mining according to claim 9 or 10, wherein the% binder-min is a percentage of the total height of the sintered cemented carbide inserts for mining, at a depth of 1-50% from the first portion of the surface. For cemented carbide inserts. -The maximum concentration of the first binder (% binder-max1) is present in the first portion of the surface.
-The maximum second binder concentration (% binder-max2) is present at a depth of 15-75% of the first portion of the surface, as a percentage of the total height of the sintered cemented carbide inserts for mining.
The cemented carbide insert for mining according to any one of claims 9 to 11. The cemented carbide insert for mining according to any one of claims 9 to 12, wherein the first chromium maximum concentration (% Cr-max1) is present in the first portion of the surface. An additional second maximum chromium concentration (% Cr-max2) is present in the second portion of the surface.
-% Cr-max1>% Cr-max2,
-The minimum chromium concentration (% Cr-min) is located between% Cr-max1 and% Cr-max2.
The cemented carbide insert for mining according to claim 13. 22. The cemented carbide insert for mining according to claim 14, wherein% Cr-min is a percentage of the total height of the sintered cemented carbide insert for mining and is at a depth of 40 to 99% from the first portion of the surface. ..

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