Raw material powder for preparing cemented carbide, cemented carbide and preparation method thereof

Abstract

The present invention discloses a raw material powder for preparing cemented carbide, cemented carbide and a preparation method thereof, which solve the technical problems of poor performance in the service life, short service life and high cost of cemented carbide in the prior art. The raw material powder includes a first composition and a second composition, each of which includes a first component with a mass fraction of 60-96%, a second component with a mass fraction of 2-30% and a third component with a mass fraction of 0.5-10%. The first component is tungsten carbide and / or titanium carbide; the second component is cobalt and / or nickel; the third component is any of molybdenum carbide, tantalum carbide, niobium carbide, vanadium carbide, chromium carbide, titanium nitride and tantalum nitride. The first composition and the second composition meet any of the following constraints: (1) different particle sizes; (2) different mass fractions and / or types of the first component; (3) different mass fractions and / or types of the second component; and (4) different mass fractions and / or types of the third component.

Description

Technical Field

[0001] The present invention relates to the technical field of cemented carbide, in particular to the technical field of cemented carbide with a use segment and a clamping segment, specifically to raw material powder for preparing cemented carbide, cemented carbide and a preparation method thereof. Background Art

[0002] Cemented carbide, a material with high hardness, strength, and wear resistance, is widely used in modern industrial systems. When using a cemented carbide tool, it can be divided into a front section (the cutting edge) and a rear section (the support section). In actual use, the front section, which serves as the cutting edge, requires high overall performance and excellent cutting performance, while the rear section, which serves only as support, only requires resistance to vibration and fracture.

[0003] At present, carbide round bars, as the basic material of carbide cutting tools, are usually produced with a single material. The material of the cutting edge of the working section only has high wear resistance but not high strength, resulting in poor cutting performance of the tool. In addition, the length of the rear clamping section usually accounts for more than 50% of the entire tool, which will lead to cost waste when the same high-performance material is used as the working section. In some processing fields, the working section and the clamping section are connected by welding, which reduces the raw material cost of the clamping section to a certain extent. However, this processing method makes the phase distribution at the connection between the working section and the clamping section uneven, and the bonding strength between the working section and the clamping section is low (<2000Mpa), which makes the carbide tool easily break and fail at the rear clamping section due to the lever principle. Summary of the Invention

[0004] The main purpose of the present invention is to provide raw material powder for preparing cemented carbide, cemented carbide and its preparation method, so as to solve the technical problems of poor performance, short service life and high cost of cemented carbide in the prior art.

[0005] In order to achieve the above object, according to a first aspect of the present invention, a raw material powder for preparing cemented carbide is provided, and the technical solution is as follows:

[0006] A raw material powder for preparing a cemented carbide, wherein the cemented carbide comprises a use segment and a clamping segment, and the raw material powder comprises a first composition for preparing the use segment and a second composition for preparing the clamping segment, characterized in that:

[0007] The first composition and the second composition both comprise a first component with a mass fraction of 60-96%, a second component with a mass fraction of 2-30%, and a third component with a mass fraction of 0.5-10%.

[0008] The first component is tungsten carbide and / or titanium carbide;

[0009] The second component is cobalt and / or nickel;

[0010] The third component is any one of molybdenum carbide, tantalum carbide, niobium carbide, vanadium carbide, chromium carbide, titanium nitride and tantalum nitride;

[0011] The first composition and the second composition satisfy any of the following constraints:

[0012] (1) Different particle sizes;

[0013] (2) The mass fraction and / or type of the first component are different;

[0014] (3) The mass fraction and / or type of the second component are different;

[0015] (4) The mass fraction and / or type of the third component are different.

[0016] As a further improvement of the first aspect of the present invention, the particle size of the first composition is smaller than the particle size of the second composition.

[0017] As a further improvement of the first aspect of the present invention, the particle size of the first composition is 0.3 to 0.8 μm; and the particle size of the second composition is 0.6 to 1.5 μm.

[0018] As a further improvement of the first aspect of the present invention, the first component in the first composition is tungsten carbide, and the first component in the second composition is titanium carbide.

[0019] As a further improvement of the first aspect of the present invention, the second component in the first composition is cobalt, and the second component in the second composition is nickel; and / or, the mass fraction of the second component in the first composition is less than the mass fraction of the second component in the second composition.

[0020] As a further improvement of the first aspect of the present invention, the mass fraction of the third component in the first composition is greater than the mass fraction of the third component in the second composition; and / or, the number of types of the third component in the first composition is greater than the number of types of the third component in the second composition.

[0021] As a further improvement of the first aspect of the present invention, the first composition and the second composition both comprise 80-92% by mass of the first component, 3-12% by mass of the second component, and 0.5-8% by mass of the third component.

[0022] As a further improvement of the first aspect of the present invention, the difference in magnetic saturation of the cemented carbide of the using segment and the clamping segment is ≤5%, and the difference in powder flow rate of the first composition and the second composition is ≤5s.

[0023] In order to achieve the above object, according to a second aspect of the present invention, a method for preparing cemented carbide is provided, and the technical solution is as follows:

[0024] The preparation method of cemented carbide comprises the following steps:

[0025] Obtaining the raw material powder described in the first aspect above;

[0026] ball milling the first composition and the second composition respectively;

[0027] placing the first composition and the second composition into a mold and pressing them into a green body;

[0028] The green body is sintered to obtain a cemented carbide having a use segment and a clamping segment.

[0029] In order to achieve the above object, according to the third aspect of the present invention, a cemented carbide is provided, and the technical solution is as follows:

[0030] The cemented carbide is prepared from the raw material powder described in the first aspect, or prepared by the preparation method described in the second aspect.

[0031] First, in the present invention, the using section and the clamping section of the cemented carbide are combined by powder metallurgy using the same series of raw material powder and a synchronous sintering process. The microstructure of the connection between the using section and the clamping section of the obtained cemented carbide is tightly combined, and the microscopic properties are more consistent. Therefore, the cemented carbide is not easy to break and fail due to the lever principle, which significantly extends the service life of the cemented carbide.

[0032] Secondly, although the use section and clamping section of the cemented carbide of the present invention use the same series of raw material powder, the present invention further regulates the particle size, mass fraction and selection of the raw material powder, which not only reduces the raw material cost of the clamping section, but also ensures the supporting effect of the clamping section and the wear resistance and strength of the use section, thereby ensuring the use effect.

[0033] It can be seen that the present invention improves the raw material powder for preparing cemented carbide and can adopt the existing powder sintering process. The technical solution is simple and easy to implement, and effectively solves the technical problems of poor performance, short service life and high cost of cemented carbide in the existing technology, and has extremely strong practicality.

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings that constitute part of this invention are intended to assist in understanding the invention. The contents provided in the drawings and their related descriptions in the present invention may be used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1This is a metallographic photograph of the cemented carbide of Example 1.

[0037] Figure 2 This is a metallographic photograph of the cemented carbide of Example 2.

[0038] Figure 3 This is a metallographic photograph of the cemented carbide of Example 3. DETAILED DESCRIPTION

[0039] The present invention is described clearly and completely below with reference to the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention with reference to the accompanying drawings, it should be noted that:

[0040] The technical solutions and technical features provided in each part of the present invention, including the following description, may be combined with each other unless there is any conflict.

[0041] In addition, the embodiments of the present invention described below are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0042] Regarding the terms and units in the present invention: The terms "include", "have" and any variations thereof in the description and claims of the present invention and the related parts are intended to cover non-exclusive inclusions.

[0043] The specific embodiment of the raw material powder for preparing cemented carbide of the present invention is as follows: the cemented carbide includes a use section and a clamping section, the raw material powder includes a first composition for preparing the use section and a second composition for preparing the clamping section, the first composition and the second composition both include a first component with a mass fraction of 60-96%, a second component with a mass fraction of 2-30% and a third component with a mass fraction of 0.5-10%; wherein the first component is tungsten carbide (WC) and / or titanium carbide (TiC); the second component is cobalt (Co) and / or nickel (Ni); the third component is any of molybdenum carbide (Mo2C), tantalum carbide (TaC), niobium carbide (NbC), vanadium carbide (VC), chromium carbide (Cr3C2), titanium nitride (TiN) and tantalum nitride (TaN); the first composition and the second composition meet any of the following constraints: (1) different particle sizes; (2) different mass fractions and / or types of the first component; (3) different mass fractions and / or types of the second component; (4) different mass fractions and / or types of the third component.

[0044] Regarding constraint (1), it is preferred that the particle size of the first composition be smaller than the particle size of the second composition. Thus, by using a smaller particle size for the first composition, it is possible to form a user segment with higher cutting performance, while the relatively larger particle size of the second composition can reduce raw material costs. Further preferably, the particle size of the first composition is 0.3 to 0.8 μm, and the particle size of the second composition is 0.6 to 1.5 μm. This makes it easier to obtain, less expensive, and reduces the difference in the connection between the user segment and the clamping segment, resulting in a user segment with higher wear resistance and strength.

[0045] Regarding constraint (2), it is preferred that the first component in the first composition be tungsten carbide and the first component in the second composition be titanium carbide. It has been demonstrated that, when the contents and types of the second and third components are the same, the cemented carbide prepared from tungsten carbide has superior wear resistance and hardness to that prepared from titanium carbide.

[0046] Regarding constraint (3), it is preferred that the second component in the first composition is cobalt and the second component in the second composition is nickel; and / or the mass fraction of the second component in the first composition is less than the mass fraction of the second component in the second composition.

[0047] For example, if the mass fraction of the second component in the first composition is equal to the mass fraction of the second component in the second composition, the second component in the first composition is cobalt, and the second component in the second composition is nickel; if the mass fraction of the second component in the first composition is less than the mass fraction of the second component in the second composition, the second component in both the first composition and the second composition is cobalt; if the mass fraction of the second component in the first composition is less than the mass fraction of the second component in the second composition, the second component in the first composition is cobalt, and the second component in the second composition is nickel.

[0048] Regarding constraint (4), it is preferred that the mass fraction of the third component in the first composition is greater than the mass fraction of the third component in the second composition; and / or the number of types of the third component in the first composition is greater than the number of types of the third component in the second composition.

[0049] For example, the number of types of the third component in the first composition is equal to the number of types of the third component in the second composition, and the mass fraction of the third component in the first composition is greater than the mass fraction of the third component in the second composition; the number of types of the third component in the first composition is greater than the number of types of the third component in the second composition, and the mass fraction of the third component in the first composition is equal to the mass fraction of the third component in the second composition; the number of types of the third component in the first composition is greater than the number of types of the third component in the second composition, and the mass fraction of the third component in the first composition is greater than the mass fraction of the third component in the second composition.

[0050] In order to reduce the difference in the connection between the use section and the clamping section, and the first component has the highest proportion and the greatest impact on the performance of the cemented carbide, it is preferred to make the mass fraction of the first component in the first composition equal to the mass fraction of the first component in the second composition. This can simplify the process of regulating the mass fraction and selection of the second and third components while ensuring the service life.

[0051] In order to minimize the difference between the connection between the use section and the clamping section, it is preferred that the first composition and the second composition satisfy any one or any two of the above constraints.

[0052] Preferably, the first composition and the second composition each comprise 80-92% by mass of the first component, 3-12% by mass of the second component, and 0.5-8% by mass of the third component.

[0053] Preferably, the difference in magnetic saturation of the cemented carbide in the working section and the clamping section is ≤5%, and the difference in powder flow rate between the first and second compositions is ≤5s. This further reduces inconsistencies at the junction of the working and clamping sections caused by differences in particle size, mass fraction, and selection.

[0054] The specific embodiment of the method for preparing cemented carbide of the present invention comprises the steps of:

[0055] Step 100, obtaining the raw material powders mentioned above, and obtaining corresponding first and second compositions according to the required constraints;

[0056] Step 200, ball-milling the first composition and the second composition respectively; to facilitate subsequent pressing, preferably a small amount (2% of the total amount of the first composition or the second composition) of paraffin wax or PEG is added to the first composition and the second composition, and spray drying is performed after the ball milling is completed; the preferred ball milling process is wet milling with alcohol, and the specific wet milling time is controlled according to the desired particle size.

[0057] Step 300: Place the first composition and the second composition into a mold and press them into a green body. The preferred pressing process is: using a double-cavity hopper for molding and pressing at a pressing pressure of 10 to 40T.

[0058] Step 400, sintering the green body to obtain a cemented carbide having a use section and a clamping section; the preferred sintering process is: first stage: heating the furnace to a temperature of 320-360°C at a rate of 1-3°C / min and keeping it warm for 2-6 hours; second stage: heating the product again at a rate of 1-3°C / min until a liquid phase appears; third stage: introducing high-purity argon gas at a pressure of 1.5KPa into the furnace, then heating the product to a final sintering temperature of 1400-1450°C at a rate of 1-3°C / min and keeping it warm for 10-30 minutes; fourth stage: introducing high-purity argon gas at a pressure of 5Mpa into the furnace, keeping it warm for 30-60 minutes, and naturally cooling to obtain the cemented carbide.

[0059] The specific embodiment of the cemented carbide of the present invention is: prepared from the above-mentioned raw material powder, or prepared by the above-mentioned preparation method. The cemented carbide is preferably, but not limited to, cylindrical or rectangular. The diameter of the cylindrical cemented carbide is 2 to 25 mm, the length is 20 to 200 mm, the length of the rectangular cemented carbide is 20 to 200 mm, the width is 2 to 20 mm, and the height is 1 to 10 mm. The length of the use section preferably accounts for 10 to 50%. The cemented carbide is further processed to obtain the required cemented carbide tools, such as standard series drills, standard end mills, standard reamers, standard taps, alloy ball teeth, PCD tool bars, anti-vibration tool bars, etc.

[0060] The beneficial effects of the present invention are described below through specific examples.

[0061] Examples 1-11 use the same preparation process to prepare cemented carbide. The total length of the cemented carbide and the lengths of the use section and the clamping section are the same. The corresponding raw material powder ratios and the performance data of the cemented carbide are shown in Tables 1 and 2.

[0062] In each of Examples 1-7, the raw material powder ratios for the working section and the clamping section are identical, with only the particle sizes of the first and second compositions differing. The only difference between Examples 1-3 is the particle size of the raw material powders in the working section and the clamping section. The difference between Examples 4-7 and Example 1 is the different ratios of the first, second, and third components. The difference between the control example and Example 4 is the particle size difference between the first and second compositions. The difference between the working section and the clamping section of Example 8 is the first component. The difference between the working section and the clamping section of Example 9 is the second component. The difference between the working section and the clamping section of Example 10 is the lower mass fraction of the second component and the higher mass fraction of the third component. The difference between the working section and the clamping section of Example 11 is the type of additive. It has been verified that the difference in the magnetic saturation of the cemented carbide between the working section and the clamping section of Examples 1-11 and the control example is ≤5%, and the difference in the powder flow rate between the first and second compositions is ≤5s.

[0063] Table 1

[0064]

[0065] Table 2

[0066]

[0067] It has been verified that the cemented carbides of Examples 1-11 all have good hardness and strength, indicating that when the raw material powder of the present invention is selected according to a certain ratio and specific constraints, cemented carbides with excellent performance can be obtained.

[0068] Figure 1-3 The metallographic photographs are respectively of the cemented carbides of Examples 1-3, which show that the phase distribution at the connection between the use section and the clamping section of the obtained cemented carbides is relatively uniform.

[0069] The carbide round bars from Examples 1-11 were further processed into standard 6mm x 75mm end mills, and their service life was tested. Testing was conducted on 7075 aluminum alloy for 7 hours and on 316L stainless steel for 4 hours. The results showed minimal wear, smooth, burr-free workpiece surfaces, and no breakage or chipping, demonstrating the tool's service life met its standard requirements.

[0070] The “magnetic saturation” means the percentage of magnetic cobalt in the material, expressed as %Co; the test is performed using the national standard “GB / T23369-2009 Standard Test Method for Determination of Magnetic Saturation (MS) of Cemented Carbide”.

[0071] The flow rate is the time required for 50g of cemented carbide powder to flow through a standard funnel with an aperture, expressed in seconds (s). The test was conducted using the national standard "GBT 1482-1984 Metal Powder Flowability - Standard Funnel Method (Hall Rheometer)".

[0072] The “hardness” mentioned above refers to the ability of a metal material to resist other harder objects from pressing into the surface, and is tested using the national standard “GB / T3849.1-2015 Cemented Carbide Rockwell Hardness Test (Scale A) Part 1”.

[0073] The “strength” mentioned above refers to the ability of a material to resist bending without breaking, and is tested using the national standard “GB / T 3851-2015 Method for Determination of Transverse Fracture Strength of Cemented Carbide”.

[0074] The above describes the relevant contents of the present invention. Based on this description, a person skilled in the art will be able to implement the present invention. Based on the above contents of the present invention, all other embodiments obtained by a person skilled in the art without making any creative efforts should fall within the scope of protection of the present invention.

Claims

1. A raw material powder for preparing a cemented carbide, wherein the cemented carbide comprises a use segment and a clamping segment, wherein the raw material powder comprises a first composition for preparing the use segment and a second composition for preparing the clamping segment, characterized in that: The first composition and the second composition both comprise a first component with a mass fraction of 60-96%, a second component with a mass fraction of 2-30%, and a third component with a mass fraction of 0.5-10%. The first component is tungsten carbide and / or titanium carbide; The second component is cobalt and / or nickel; The third component is any one of molybdenum carbide, tantalum carbide, niobium carbide, vanadium carbide, chromium carbide, titanium nitride and tantalum nitride; The first composition and the second composition satisfy the following constraints: (1) Different particle sizes; (2) The selection of the first component is different; (3) The mass fraction and type of the second component are different; (4) The mass fraction and type of the third component are different; The difference in magnetic saturation of the cemented carbide between the using segment and the clamping segment is ≤5%, and the difference in powder flow rate between the first composition and the second composition is ≤5s.

2. The raw material powder for preparing cemented carbide according to claim 1, characterized in that: The particle size of the first composition is less than the particle size of the second composition.

3. The raw material powder for preparing cemented carbide according to claim 2, characterized in that: The particle size of the first composition is 0.3 to 0.8 μm; the particle size of the second composition is 0.6 to 1.5 μm.

4. The raw material powder for preparing cemented carbide according to claim 1, characterized in that: The first component in the first composition is tungsten carbide, and the first component in the second composition is titanium carbide.

5. The raw material powder for preparing cemented carbide according to claim 1, characterized in that: The second component in the first composition is cobalt, and the second component in the second composition is nickel; the mass fraction of the second component in the first composition is less than the mass fraction of the second component in the second composition.

6. The raw material powder for preparing cemented carbide according to claim 1, characterized in that: The mass fraction of the third component in the first composition is greater than the mass fraction of the third component in the second composition; the number of types of the third component in the first composition is greater than the number of types of the third component in the second composition.

7. The raw material powder for preparing cemented carbide according to claim 1, characterized in that: The first composition and the second composition both include 80-92% by mass of a first component, 3-12% by mass of a second component, and 0.5-8% by mass of a third component.

8. A method for preparing a cemented carbide, comprising the steps of: Obtaining the raw material powder according to any one of claims 1 to 7; ball milling the first composition and the second composition respectively; placing the first composition and the second composition into a mold and pressing them into a green body; The green body is sintered to obtain a cemented carbide having a use segment and a clamping segment.

9. Cemented carbide, characterized by: The invention is prepared from the raw material powder according to any one of claims 1 to 7, or prepared by the preparation method according to claim 8.

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