Polycrystalline superhard material blank convenient to grind and preparation method thereof

Abstract

The invention relates to a convenient-to-grind polycrystalline superhard material green body and a preparation method thereof, the convenient-to-grind polycrystalline superhard material green body comprises a polycrystalline superhard material green body formed at high temperature and high pressure, and the polycrystalline superhard material green body comprises a polycrystalline superhard material product body, a working allowance grinding layer and an easy-to-grind grinding layer, the polycrystalline superhard material product is characterized in that the polycrystalline superhard material product body is a finished product which is obtained by grinding a polycrystalline superhard material blank and meets specification requirements; the machining allowance grinding layer is made of a fine-particle polycrystalline superhard material which is homogeneous to a polycrystalline superhard material product body and is completely identical in particle size; and the grindable grinding layer is a grinding layer of a pressed surface, and is a grindable grinding layer of coarse particles homogeneous to a polycrystalline superhard material and a grindable grinding layer of non-homogeneous to the polycrystalline superhard material. The raw material of the grindable grinding layer is coarse particle polycrystalline superhard material product body homogeneous micro powder, the particle size of the grindable grinding layer is larger than that of a polycrystalline superhard material product body, the porosity of the grindable grinding layer is larger than that of the polycrystalline superhard material product body, the larger the porosity is, the poorer the abrasion resistance is, grinding is easy, the machining cost is reduced, and the machining efficiency is improved. The gas suction effect of the metal powder can also reduce the content of impurity gas in the product body, and the effect is achieved.

Description

[0001] This application is a divisional application of application number CN202011483628.3, application date 2020.12.16, patent title: A polycrystalline superhard material preform that is easy to grind and its preparation method. Technical Field

[0002] This invention relates to the field of polycrystalline superhard material processing and preparation technology, and more specifically, to a material that is easy to grind. Polycrystalline superhard material preforms and their preparation methods. Background Technology

[0003] Superhard materials refer to materials with exceptionally high hardness, and can be divided into natural and artificial types. Artificial superhard materials mainly refer to diamond and cubic boron nitride. Diamond is the hardest known substance in the world. It not only possesses high hardness, wear resistance, and good thermal stability, but also boasts excellent compressive strength, heat dissipation rate, sound transmission rate, current impedance, corrosion resistance, light transmission, and low thermal expansion coefficient, making it an irreplaceable new material in industrial applications. Cubic boron nitride is second only to diamond in hardness. It not only possesses many of diamond's excellent properties but also exhibits higher thermal stability and chemical inertness to ferrous metals and their alloys. As an engineering material, cubic boron nitride has been widely used in the processing of ferrous metals and their alloys. Furthermore, its excellent thermal, electrical, optical, and acoustic properties have led to its application in a range of high-tech fields, making it a promising functional material. Both of these superhard materials have hardness far exceeding that of other materials. Therefore, superhard materials are generally suitable for manufacturing tools for processing other materials, especially in the processing of hard materials, where they possess unparalleled advantages and occupy an irreplaceable and important position.

[0004] During the fabrication of superhard materials into various tools such as cutting tools and grinding wheels, under high temperature and high pressure, due to the synthesis mechanism, some impurity gases are generated in the superhard material microparticles during sintering. As the binder migrates in the superhard material microparticles, these impurity gases are squeezed into the voids on the surface of the superhard material, seriously affecting the product's performance and causing defects such as pits, under-burning, and cracks on the product surface, thus affecting the product yield. In the normal production of polycrystalline superhard material products, it is necessary to raise the material by 0.5-1mm in the assembly stage before synthesis. Then, the synthesized blank undergoes a grinding process to remove the excess and defective grinding layer, resulting in a product with stable quality. Since polycrystalline superhard materials are designed for high wear resistance, the finer the particle size, the better the wear resistance. However, the grinding process is time-consuming, inefficient, and costly, seriously affecting the product's production and manufacturing efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a polycrystalline superhard material blank that is easy to grind and its preparation method. An easy-grinding layer is provided on the surface of the polycrystalline superhard material blank to solve the problems mentioned in the background art, such as the influence of impurity gases on the wear resistance, thermal stability, and yield of the product during the sintering process of superhard materials, the long grinding time, low efficiency, high cost, and the problem of product quality stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a polycrystalline superhard material blank that is easy to grind and its preparation method, comprising a polycrystalline superhard material blank formed under high temperature and high pressure, the polycrystalline superhard material blank comprising a polycrystalline superhard material product body, a machining allowance grinding layer, and an easy-grinding grinding layer, characterized in that: the polycrystalline superhard material product body is a finished product that meets the specifications after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer is a fine-particle polycrystalline superhard material homogeneous with the polycrystalline superhard material product body and having the same particle size; the easy-grinding grinding layer is a grinding layer on the pressure surface, and is of two types: an easy-grinding grinding layer of coarse particles homogeneous with polycrystalline superhard material and an easy-grinding grinding layer of non-homogeneous polycrystalline superhard material.

[0007] The thickness of the machining allowance grinding layer is 0.05-0.1mm, and the thickness of the easy-grinding grinding layer is 0.3-0.35mm.

[0008] The easily grindable abrasive layer is composed of coarse, homogeneous particles of the polycrystalline superhard material, with particle size larger than that of the polycrystalline superhard material product body.

[0009] The non-homogeneous, easily grindable abrasive layer of the polycrystalline superhard material has a particle size greater than or equal to that of the polycrystalline superhard material product body.

[0010] The non-homogeneous, easily grindable layer of the polycrystalline superhard material is a high-purity metal powder with good air absorption and a high melting point, such as titanium, tantalum, zirconium, and molybdenum.

[0011] The polycrystalline superhard material product body is a hexahedron. The six outer surfaces of the hexahedron are provided with a machining allowance grinding layer, and the outermost layer is provided with an easy-grinding grinding layer. The material of the polycrystalline superhard material product body is fine-particle polycrystalline cubic boron nitride micro powder. The fine-particle polycrystalline cubic boron nitride micro powder has a particle size of 2μm, accounting for 85-90%, and the remainder is metal binder Co and Ni. The coarse-particle polycrystalline cubic boron nitride micro powder has a particle size of 4μm, accounting for 70-75%, and the remainder is metal binder Sn.

[0012] The polycrystalline superhard material product body is a columnar body. The upper and lower end planes of the columnar body are provided with a grinding layer for machining allowance, and the outermost layer is provided with an easy-grinding layer. The material of the polycrystalline superhard material product body is fine-particle polycrystalline diamond powder. The particle size ratio of the fine-particle polycrystalline diamond powder is: 4-8μm accounts for 10%, 16-21μm accounts for 50%, 21-30μm accounts for 20%, and 30-40μm accounts for 20%.

[0013] The polycrystalline superhard material product body is columnar, comprising: a polycrystalline diamond composite layer and a cemented carbide matrix. The upper surface of the polycrystalline diamond composite layer is provided with a machining allowance grinding layer, and the outermost layer is provided with an easy-grinding grinding layer. The diamond composite layer is composed of fine-particle polycrystalline diamond powder, and the particle size distribution of the fine-particle polycrystalline diamond powder is: 10% for 4-8μm, 50% for 16-21μm, 20% for 21-30μm, and 20% for 30-40μm.

[0014] The preparation method of the polycrystalline superhard material blank is as follows: fine-particle polycrystalline cubic boron nitride micro powder is pressed into polycrystalline cubic boron nitride block material using a six-sided press, and then sheet-shaped easy-grinding layers that are attached to the six sides of the hexahedron are pressed out separately. Finally, the polycrystalline cubic boron nitride block material and the sheet-shaped easy-grinding layers are sintered at a high temperature and high pressure of 1200-1600℃ and 5-7GPa using a six-sided press to form a polycrystalline cubic boron nitride blank.

[0015] The preparation method of the polycrystalline superhard material blank is as follows: put the easily grindable abrasive layer material, fine polycrystalline diamond powder, and cemented carbide matrix into a metal bottom cup in sequence, then cover it with a metal cap cup, and sinter it into a polycrystalline cubic diamond blank at a high temperature and high pressure of 1350-1600℃ and 5.5-10GPa.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The raw material for the easy-grinding layer is coarse-grained polycrystalline superhard material homogeneous micro powder. Its particle size is coarser than that of the polycrystalline superhard material, and its porosity is larger than that of the polycrystalline superhard material. The larger the porosity, the worse the wear resistance, making it easier to grind, reducing processing costs and improving processing efficiency. The gas absorption effect of the metal powder can also reduce the content of impurity gases in the product body, achieving the above effects.

[0017] 2. The larger the porosity, the more impurity gases can be contained. Impurity gases generated during the synthesis of polycrystalline superhard materials can flow out more smoothly from the surface of the grinding layer, which helps to improve the hardness, wear resistance, and thermal stability of the product and ensure product quality.

[0018] 3. This design is simple to operate, safe, and convenient to use. The synthesized products have low processing costs, high yield, and stable performance. Attached Figure Description

[0019] 1. Figure 1 This is a cross-sectional view of a polycrystalline cubic boron nitride preform.

[0020] 2. Figure 2 This is a cross-sectional view of the polycrystalline diamond preform.

[0021] 3. Figure 3 This is a cross-sectional view of the polycrystalline diamond preform.

[0022] 4. Among them: 1. Easy-grinding layer; 2. Machining allowance grinding layer; 3. Polycrystalline superhard material product body; 4. Hard alloy matrix; 5. Polycrystalline diamond composite layer. Detailed Implementation

[0023] A polycrystalline superhard material blank that is easy to grind and its preparation method are disclosed. The method includes a polycrystalline superhard material blank formed under high temperature and high pressure. The polycrystalline superhard material blank includes a polycrystalline superhard material product body 3, a machining allowance grinding layer 2, and an easy-grinding grinding layer 1. The polycrystalline superhard material product body 3 is a finished product that meets the specifications after grinding the polycrystalline superhard material blank. The machining allowance grinding layer 2 is made of fine-particle polycrystalline superhard material homogeneous with the polycrystalline superhard material product body and has the same particle size. The easy-grinding grinding layer 1 is a grinding layer on the pressure surface. It is of two types: an easy-grinding grinding layer of coarse particles homogeneous with polycrystalline superhard material and an easy-grinding grinding layer of non-homogeneous polycrystalline superhard material. Homogeneity means that it is made up of the same units or that the characteristics of each part are the same.

[0024] The thickness of the machining allowance grinding layer 2 is 0.05-0.1mm, and the thickness of the easy-grinding grinding layer 1 is 0.3-0.35mm.

[0025] The easily grindable abrasive layer of homogeneous coarse particles of the polycrystalline superhard material has a particle size larger than that of the polycrystalline superhard material product body 3.

[0026] The non-homogeneous, easily grindable abrasive layer of the polycrystalline superhard material has a particle size greater than or equal to that of the polycrystalline superhard material product body 3.

[0027] The non-homogeneous, easily grindable layer of the polycrystalline superhard material is a high-purity metal powder with good air absorption and a high melting point, such as titanium, tantalum, zirconium, and molybdenum.

[0028] The polycrystalline superhard material product body 3 is a hexahedron, with a machining allowance grinding layer 2 on each of the six planes of the hexahedron, and an easy-grinding grinding layer 1 on the outermost layer. The material of the polycrystalline superhard material product body 3 is fine-particle polycrystalline cubic boron nitride micro powder. The fine-particle polycrystalline cubic boron nitride micro powder has a particle size of 2μm, accounting for 85-90%, and the remainder is metal binder Co and Ni. The coarse-particle polycrystalline cubic boron nitride micro powder has a particle size of 4μm, accounting for 70-75%, and the remainder is metal binder Sn.

[0029] The polycrystalline superhard material product body 3 is a columnar body. The outer surfaces of the upper and lower end planes of the columnar body are provided with a machining allowance grinding layer 2, and the outermost layer is provided with an easy-to-grind grinding layer 1. The material of the polycrystalline superhard material product body 3 is fine-particle polycrystalline diamond powder. The particle size ratio of the fine-particle polycrystalline diamond powder is: 10% for 4-8μm, 50% for 16-21μm, 20% for 21-30μm, and 20% for 30-40μm; the particle size ratio of the coarse-particle polycrystalline diamond powder is: 20% for 4-8μm, 50% for 40-60μm, and 30% for 60-80μm.

[0030] The polycrystalline superhard material product body 3 is a columnar body, comprising: a polycrystalline diamond composite layer 5 and a cemented carbide matrix 4. The upper surface of the polycrystalline diamond composite layer 5 is provided with a machining allowance grinding layer 2, and the outermost layer is provided with an easy-grinding grinding layer 1. The diamond composite layer is composed of fine-particle polycrystalline diamond micro powder. The particle size distribution of the fine-particle polycrystalline diamond micro powder is: 10% for 4-8μm, 50% for 16-21μm, 20% for 21-30μm, and 20% for 30-40μm. The particle size distribution of the coarse-particle polycrystalline diamond micro powder is: 20% for 4-8μm, 50% for 40-60μm, and 30% for 60-80μm.

[0031] The preparation method of the polycrystalline superhard material blank is as follows: fine-particle polycrystalline cubic boron nitride micro powder is pressed into polycrystalline cubic boron nitride block material using a six-sided press, and then sheet-shaped easy-to-grind grinding layers 1 are pressed out to fit the six faces of the hexahedron. Finally, the polycrystalline cubic boron nitride block material and the sheet-shaped easy-to-grind grinding layers 1 are sintered into a polycrystalline cubic boron nitride blank at a high temperature and high pressure of 1200-1600℃ and 5-7GPa using a six-sided press.

[0032] The preparation method of the polycrystalline superhard material blank is as follows: put the easily grindable abrasive layer 1 material, fine polycrystalline diamond powder, and cemented carbide matrix 4 into a metal bottom cup in sequence, and then cover it with a metal cap cup. Sinter it into a polycrystalline cubic diamond blank at a high temperature and high pressure of 1350-1600℃ and 5.5-10GPa.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Specific Implementation Example 1 like Figure 1As shown, the preparation method of the polycrystalline superhard material blank is as follows: the material of the polycrystalline superhard material product body 3 is fine-particle polycrystalline cubic boron nitride micro powder, which is hexahedral in shape. The fine-particle polycrystalline cubic boron nitride micro powder is vacuum treated and formed into a polycrystalline cubic boron nitride block material under certain pressure and temperature. Then, sheet-shaped easy-grinding layers 1 are pressed out and attached to the six faces of the hexahedron. The sheet-shaped easy-grinding layers 1 are attached to the outer surfaces of the six faces of the polycrystalline cubic boron nitride block material. Then, the polycrystalline cubic boron nitride block material and the sheet-shaped easy-grinding layers are sintered together under high temperature and high pressure using a six-sided press. Specific Implementation Example 2 like Figure 2 As shown, the preparation method of the polycrystalline superhard material blank is as follows: 1. The metal cap cup and metal base cup serve as a protective layer, and the two are fitted together with a gap. The material can be zirconium, iron, niobium, tan, molybdenum, etc.; 2. During assembly, the metal base cup is placed first, followed by the easily grindable material, which is then smoothed with a T-shaped hammer. Then, a diamond wear-resistant composite layer is added and smoothed with a T-shaped hammer. The easily grindable material is then placed again, and the metal cap cup is then placed on top; 3. The assembled material, along with the metal base cup and metal cap cup, is sintered in a high-temperature and high-pressure environment to obtain the polycrystalline superhard material blank; 4. The polycrystalline superhard material blank undergoes further finishing processes such as annealing, grinding of the easily grindable layer, grinding of the machining allowance layer, flat grinding, and polishing. Specific Implementation Example 3 like Figure 3 As shown, the preparation method of the polycrystalline superhard material product body is as follows: 1. The metal cap cup and metal base cup serve as protective layers, and the two are fitted together with a gap. The materials can be zirconium, iron, niobium, tan, molybdenum, etc.; 2. During assembly, the metal base cup is placed first, followed by the easily grindable material, which is then flattened with a T-shaped hammer. Then, a diamond wear-resistant composite layer is added and flattened with a T-shaped hammer. Next, the cemented carbide substrate is placed, and then the metal cap cup is placed on top; 3. The assembled material, along with the metal base cup and metal cap cup, is sintered in a high-temperature and high-pressure environment to obtain the polycrystalline superhard material blank; 4. The polycrystalline superhard material blank undergoes further finishing processes such as annealing, grinding of the easily grindable layer, grinding of the machining allowance layer, flat grinding, and polishing.

[0037] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A polycrystalline superhard material blank for ease of grinding, comprising a high pressure high temperature formed polycrystalline superhard material blank comprising a polycrystalline superhard material product body (3), a machining allowance grinding layer (2) and an easy-to-grind grinding layer (1), characterised in that: The polycrystalline superhard material product body (3) is a finished product that meets the specifications after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer (2) is fine-particle polycrystalline superhard material that is homogeneous with the polycrystalline superhard material product body and has the same particle size; the easy-grinding grinding layer (1) is the grinding layer of the pressure surface, which is one of two types: easy-grinding grinding layer of coarse particles homogeneous with polycrystalline superhard material and easy-grinding grinding layer of non-homogeneous polycrystalline superhard material.

2. A polycrystalline super hard material body convenient for grinding according to claim 1, characterised in that: The thickness of the machining allowance grinding layer (2) is 0.05-0.1 mm, and the thickness of the easy-grinding grinding layer (1) is 0.3-0.35 mm.

3. The polycrystalline superhard material preform for easy grinding as described in claim 1, characterized in that: The easily grindable abrasive layer (1) of the polycrystalline superhard material is composed of coarse particles with a particle size larger than that of the polycrystalline superhard material product body (3).

4. The polycrystalline superhard material preform for easy grinding as described in claim 1, characterized in that: The non-homogeneous grinding layer (1) of the polycrystalline superhard material has a particle size greater than or equal to that of the polycrystalline superhard material product body (3).

5. The polycrystalline superhard material preform for easy grinding as described in claim 4, characterized in that: The non-homogeneous, easily grindable abrasive layer (1) of the polycrystalline superhard material is a high-purity metal powder with good air absorption and high melting point, such as titanium, tantalum, zirconium, and molybdenum.

6. The polycrystalline superhard material preform for easy grinding as described in claim 1, characterized in that: The polycrystalline superhard material product body (3) is a hexahedron. The six outer surfaces of the hexahedron are provided with a machining allowance grinding layer (2), and the outermost layer is provided with an easy-grinding grinding layer (1). The material of the polycrystalline superhard material product body (3) is fine-particle polycrystalline cubic boron nitride micro powder. The particle size of the fine-particle polycrystalline cubic boron nitride micro powder is 2μm, accounting for 85-90%, and the remainder is metal binder Co and Ni. The particle size of the coarse-particle polycrystalline cubic boron nitride micro powder is 4μm, accounting for 70-75%, and the remainder is metal binder Sn.

7. The polycrystalline superhard material preform for easy grinding as described in claim 1, characterized in that: The polycrystalline superhard material product body (3) is a columnar body. The upper and lower end planes of the columnar body are provided with a machining allowance grinding layer (2), and the outermost layer is provided with an easy-to-grind grinding layer (1). The material of the polycrystalline superhard material product body (3) is fine-particle polycrystalline diamond powder. The particle size ratio of the fine-particle polycrystalline diamond powder is: 4-8μm accounts for 10%, 16-21μm accounts for 50%, 21-30μm accounts for 20%, and 30-40μm accounts for 20%.

8. The polycrystalline superhard material preform for easy grinding as described in claim 1, characterized in that: The polycrystalline superhard material product body (3) is a columnar body. The polycrystalline superhard material product body (3) includes: a polycrystalline diamond composite layer (5) and a cemented carbide substrate (4). The upper surface of the polycrystalline diamond composite layer (5) is provided with a machining allowance grinding layer (2), and the outermost layer is provided with an easy-grinding grinding layer (1).

9. The method for preparing a polycrystalline superhard material preform that is easy to grind, as described in claim 6, is characterized in that: The preparation method of the polycrystalline superhard material blank is as follows: fine-particle polycrystalline cubic boron nitride micro powder is pressed into polycrystalline cubic boron nitride block material using a six-sided press, and then sheet-shaped easy-to-grind grinding layers (1) that are attached to the six sides of the hexahedron are pressed out respectively. Finally, the polycrystalline cubic boron nitride block material and sheet-shaped easy-to-grind grinding layers (1) are sintered into polycrystalline cubic boron nitride blank at a high temperature and high pressure of 1200-1600℃ and 5-7GPa using a six-sided press.

10. The method for preparing a polycrystalline superhard material preform that is easy to grind, as described in claim 8, is characterized in that: The preparation method of the polycrystalline superhard material blank is as follows: put the easily grindable grinding layer (1) material, fine polycrystalline diamond micro powder and hard alloy matrix (4) into the metal bottom cup in sequence, and then cover it with a metal cap cup. Sinter it into a polycrystalline cubic diamond blank at a high temperature and high pressure of 1350-1600℃ and 5.5-10GPa.

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