A polycrystalline superhard material blank convenient for grinding and a preparation method thereof

Abstract

A polycrystalline superhard material blank convenient for grinding and a preparation method thereof, comprising a polycrystalline superhard material blank formed by high temperature and high pressure. The polycrystalline superhard material blank includes a polycrystalline superhard material product body, a machining allowance grinding layer and an easy-to-grind grinding layer. It is characterized in that: the polycrystalline superhard material product body is a finished product that meets the specification requirements after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer is the same as that of the polycrystalline superhard material product body, and is a fine-grained polycrystalline superhard material with exactly the same particle size; the easy-to-grind grinding layer is the grinding layer on the pressure-receiving surface, and there are two types: a coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material and an easy-to-grind grinding layer of different quality from the polycrystalline superhard material. The raw material of the easy-to-grind grinding layer is a coarse-grained polycrystalline superhard material product body homogeneous fine powder, the particle size of which is coarser than that of the polycrystalline superhard material product body, and the porosity is larger than that of the polycrystalline superhard material product body. The larger the porosity, the worse the wear resistance, the easier it is to grind, the processing cost is reduced, and the processing efficiency is improved; the gas absorption effect of the metal powder can also reduce the content of impurity gases in the product body to achieve the above effects.

Description

Technical Field

[0001] The present invention relates to the technical field of processing and preparation of polycrystalline superhard materials, and more specifically, to a polycrystalline superhard material blank that is easy to grind and a preparation method thereof. Background Art

[0002] Superhard materials refer to materials with extremely high hardness, which can be divided into natural and artificial types. Artificial superhard materials mainly refer to diamond and cubic boron nitride. Diamond is the hardest substance known in the world. It not only has characteristics such as high hardness, wear resistance, and good thermal stability, but also becomes an irreplaceable new material in the industrial application field with its excellent compressive strength, heat dissipation rate, sound transmission rate, current impedance, corrosion resistance, light transmission, low thermal expansion rate and other physical properties. Cubic boron nitride has a hardness second only to diamond. It not only has many excellent properties of diamond, but also has 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 industry of ferrous metals and their alloy materials. At the same time, with its excellent thermal, electrical, optical and acoustic properties, it has been applied in a series of high-tech fields and has become a functional material with development prospects. The hardness of these two superhard materials is much higher than that of other materials. Therefore, superhard materials are generally suitable for making tools for processing other materials, especially in processing hard materials, with incomparable advantages and an irreplaceable important position.

[0003] In the process of preparing superhard materials into various tools such as cutting tools and abrasives, in a high-temperature and high-pressure environment, due to the synthesis mechanism, some impurity gases are generated during the sintering process of superhard material micropowder particles. As the binder migrates in the superhard material micropowder, the impurity gases are squeezed into the voids on the surface part of the superhard material, seriously affecting the performance of the product, and resulting in defects such as virtual pits, underburning, cracks, etc. on the product surface, affecting the yield of the product. When normally producing polycrystalline superhard material products, it is necessary to add 0.5 - 1 mm to the material in the assembly link before synthesis, and then the synthesized blank goes through a grinding process to remove the redundant and defective grinding layer, and then a product with stable quality is obtained. Also, because polycrystalline superhard materials are all designed towards high wear resistance, the finer the particle size, the better the wear resistance. However, in the grinding link, it takes a long time, the efficiency is very low, and the cost is also relatively high, seriously affecting the production and manufacturing efficiency of the product. Summary of the Invention

[0004] The purpose of the present invention is to provide a polycrystalline superhard material blank that is easy to grind and a preparation method thereof, and an easy-to-grind grinding layer is provided on the surface of the polycrystalline superhard material blank to solve the problems of 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 time, low efficiency, and high cost in the grinding link, as well as the problem of product quality stability mentioned in the above background art.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A polycrystalline superhard material blank convenient for grinding and its preparation method, including a polycrystalline superhard material blank formed by high temperature and high pressure. The polycrystalline superhard material blank includes a polycrystalline superhard material product body, a machining allowance grinding layer and an easy-to-grind grinding layer. It is characterized in that: the polycrystalline superhard material product body is a finished product that meets the specification requirements after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer is the same as that of the polycrystalline superhard material product body and is fine-grained polycrystalline superhard material with exactly the same particle size; the easy-to-grind grinding layer is the grinding layer on the pressure-receiving surface, and there are two types, namely, a coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material and an easy-to-grind grinding layer of different quality from the polycrystalline superhard material.

[0006] The thickness of the machining allowance grinding layer is 0.05 - 0.1 mm, and the thickness of the easy-to-grind grinding layer is 0.3 - 0.35 mm.

[0007] The coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material has a particle size larger than that of the polycrystalline superhard material product body.

[0008] The easy-to-grind grinding layer of different quality from the polycrystalline superhard material has a particle size greater than or equal to that of the polycrystalline superhard material product body.

[0009] The easy-to-grind grinding layer of different quality from the polycrystalline superhard material is high-purity metal powder with good gas absorption property and high melting point, such as titanium, tantalum, zirconium, molybdenum.

[0010] The polycrystalline superhard material product body is a hexahedron. The machining allowance grinding layer is provided on the outer surfaces of the six planes of the hexahedron, and the outermost layer is provided with an easy-to-grind grinding layer. The material of the polycrystalline superhard material product body is fine-grained polycrystalline cubic boron nitride micropowder. The particle size of the fine-grained polycrystalline cubic boron nitride micropowder is 2 μm, accounting for 85 - 90%, and the rest is metal binder Co, Ni; the particle size of the coarse-grained polycrystalline cubic boron nitride micropowder is 4 μm, accounting for 70 - 75%, and the rest is metal binder Sn.

[0011] The polycrystalline superhard material product body is a columnar body. The machining allowance grinding layer is provided on the upper and lower end planes of the columnar body, and the outermost layer is provided with an easy-to-grind grinding layer. The material of the polycrystalline superhard material product body is fine-grained polycrystalline diamond micropowder. The particle size ratio of the fine-grained polycrystalline diamond micropowder is: 4 - 8 μm accounts for 10%, 16 - 21 μm accounts for 50%, 21 - 30 μm accounts for 20%, and 30 - 40 μm accounts for 20%.

[0012] The polycrystalline superhard material product body is a columnar body, and the polycrystalline superhard material product body includes: a polycrystalline diamond composite layer and a cemented carbide substrate. A machining allowance grinding layer is provided on the upper surface of the polycrystalline diamond composite layer, and an easy-to-grind grinding layer is provided on the outermost layer. The diamond composite layer is fine-grained polycrystalline diamond micropowder, and the particle size ratio of the fine-grained polycrystalline diamond micropowder is: 10% for 4 - 8μm, 50% for 16 - 21μm, 20% for 21 - 30μm, and 20% for 30 - 40μm.

[0013] The preparation method of the polycrystalline superhard material blank is: use a six-sided top press to press fine-grained polycrystalline cubic boron nitride micropowder into a polycrystalline cubic boron nitride block material, then press out sheet-shaped easy-to-grind grinding layers that fit the six faces of the hexahedron respectively, and finally use a six-sided top press to sinter the polycrystalline cubic boron nitride block material and the sheet-shaped easy-to-grind grinding layer at a high temperature and high pressure of 1200 - 1600°C and 5 - 7GPa to form a polycrystalline cubic boron nitride blank.

[0014] The preparation method of the polycrystalline superhard material blank is: sequentially place easy-to-grind grinding layer materials, fine-grained polycrystalline diamond micropowder, and a cemented carbide substrate in a metal bottom cup, then cover it with a metal cap cup, and sinter it at a high temperature and high pressure of 1350 - 1600°C and 5.5 - 10GPa to form a polycrystalline cubic diamond blank.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. The raw material of the easy-to-grind grinding layer is coarse-grained polycrystalline superhard material product body homogeneous micropowder, whose particle size is coarser than that of the polycrystalline superhard material product body, and the porosity is larger than that of the polycrystalline superhard material product body. The larger the porosity, the worse the wear resistance, and it is easy to grind, reducing the processing cost and improving the 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 accommodated, and the impurity gases generated during the synthesis of the polycrystalline superhard material 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, ensuring the product quality.

[0018] 3. This design is simple in operation, good in safety, convenient to use, the synthesized product has a low processing cost, a high finished product rate, and stable performance. Description of the Drawings

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

[0020] 2. Figure 2 It is a cross-sectional view of a polycrystalline diamond blank 1.

[0021] 3. Figure 3It is a sectional view of the polycrystalline diamond blank 2.

[0022] 4. Among them: 1. Easy-to-grind grinding layer; 2. Machining allowance grinding layer; 3. Polycrystalline superhard material product body; 4. Cemented carbide substrate; 5. Polycrystalline diamond composite layer. Specific implementation manner

[0023] A polycrystalline superhard material blank convenient for grinding and its preparation method, including a polycrystalline superhard material blank formed by 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-to-grind grinding layer 1; the polycrystalline superhard material product body 3 is a finished product that meets the specification requirements after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer 2 is the same as that of the polycrystalline superhard material product body, and is a fine-grained polycrystalline superhard material with exactly the same particle size; the easy-to-grind grinding layer 1 is the grinding layer on the pressure-receiving surface, and there are two types of easy-to-grind grinding layers, namely, a coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material and an easy-to-grind grinding layer of different quality from the polycrystalline superhard material. The same quality means that it is composed of the same units piled up, or the characteristics of each part are the same.

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

[0025] The coarse-grained easy-to-grind grinding layer of the same quality as the polycrystalline superhard material has a particle size larger than that of the polycrystalline superhard material product body 3.

[0026] The easy-to-grind grinding layer of different quality from the polycrystalline superhard material has a particle size greater than or equal to that of the polycrystalline superhard material product body 3.

[0027] The easy-to-grind grinding layer of different quality from the polycrystalline superhard material is a high-purity metal powder with good gas absorption property and high melting point, such as titanium, tantalum, zirconium, molybdenum.

[0028] The polycrystalline superhard material product body 3 is a hexahedron. The machining allowance grinding layer 2 is provided on six planes of the hexahedron, and the easy-to-grind grinding layer 1 is provided on the outermost layer. The material of the polycrystalline superhard material product body 3 is fine-grained polycrystalline cubic boron nitride micropowder. The particle size in the fine-grained polycrystalline cubic boron nitride micropowder is 2 μm, accounting for 85 - 90%, and the rest is metal binder Co, Ni; the particle size in the coarse-grained polycrystalline cubic boron nitride micropowder is 4 μm, accounting for 70 - 75%, and the rest 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 easily grindable grinding layer 1. The material of the polycrystalline superhard material product body 3 is fine-grained polycrystalline diamond micropowder. The particle size proportion of the fine-grained polycrystalline diamond micropowder is as follows: 4 - 8μm accounts for 10%, 16 - 21μm accounts for 50%, 21 - 30μm accounts for 20%, 30 - 40μm accounts for 20%; the particle size proportion of the coarse-grained polycrystalline diamond micropowder is as follows: 4 - 8μm accounts for 20%, 40 - 60μm accounts for 50%, 60 - 80μm accounts for 30%.

[0030] 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 easily grindable grinding layer 1. The diamond composite layer is fine-grained polycrystalline diamond micropowder. The particle size proportion of the fine-grained polycrystalline diamond micropowder is as follows: 4 - 8μm accounts for 10%, 16 - 21μm accounts for 50%, 21 - 30μm accounts for 20%, 30 - 40μm accounts for 20%; the particle size proportion of the coarse-grained polycrystalline diamond micropowder is as follows: 4 - 8μm accounts for 20%, 40 - 60μm accounts for 50%, 60 - 80μm accounts for 30%.

[0031] The preparation method of the polycrystalline superhard material blank is as follows: Use a cubic press to press the fine-grained polycrystalline cubic boron nitride micropowder into a polycrystalline cubic boron nitride bulk material, then press out the sheet-shaped easily grindable grinding layer 1 that fits the six faces of the hexahedron respectively, and finally use a cubic press to sinter the polycrystalline cubic boron nitride bulk material and the sheet-shaped easily grindable grinding layer 1 at a high temperature and high pressure of 1200 - 1600°C and 5 - 7 GPa to form a polycrystalline cubic boron nitride blank.

[0032] The preparation method of the polycrystalline superhard material blank is as follows: Put the easily grindable grinding layer 1 material, fine-grained polycrystalline diamond micropowder, and the cemented carbide substrate 4 into the metal bottom cup in sequence, then cover it with a metal cap cup, and sinter it at a high temperature and high pressure of 1350 - 1600°C and 5.5 - 10 GPa to form a polycrystalline cubic diamond blank.

[0033] The following further illustrates the present invention in conjunction with the drawings and specific embodiments. Specific Embodiment 1

[0035] As Figure 1As shown in the figure, the preparation method of the polycrystalline superhard material blank is as follows: The material of the polycrystalline superhard material product body 3 is fine-grained polycrystalline cubic boron nitride micropowder, and its shape is hexahedron. The fine-grained polycrystalline cubic boron nitride micropowder is vacuum-treated and forms a polycrystalline cubic boron nitride massive material under the action of a certain pressure and temperature. Then, sheet-shaped easy-to-grind abrasive layers 1 that fit the six faces of the hexahedron are extruded respectively; the sheet-shaped easy-to-grind abrasive layers 1 are attached to the outer surfaces of the six faces of the polycrystalline cubic boron nitride massive material, and then the polycrystalline cubic boron nitride massive material and the sheet-shaped easy-to-grind abrasive layers are sintered into one body at high temperature and high pressure by a six-side press. Specific Embodiment 2

[0037] As Figure 2 shown in the figure, the preparation method of the polycrystalline superhard material blank is as follows: 1. The metal cap cup and the metal bottom cup exist as a protective layer, and the two are sleeved together with a clearance fit. The materials can be zirconium, iron, niobium, tantalum, molybdenum, etc.; 2. During assembly, first place the metal bottom cup, then place the easy-to-grind abrasive layer material, level it with a T-shaped hammer, then add a diamond wear-resistant composite layer, level it with a T-shaped hammer, then place the easy-to-grind abrasive layer material again, and then cover it with 1 - metal cap cup; 3. Place the assembled material together with the metal bottom cup and the metal cap cup in a high-temperature and high-pressure environment for sintering to obtain a polycrystalline superhard material blank; 4. The polycrystalline superhard material blank is further finely processed through processes such as annealing, grinding of the easy-to-grind abrasive layer, grinding of the machining allowance layer, surface grinding, and polishing. Specific Embodiment 3

[0039] As Figure 3 shown in the figure, the preparation method of the polycrystalline superhard material product body is as follows: 1. The metal cap cup and the metal bottom cup exist as a protective layer, and the two are sleeved together with a clearance fit. The materials can be zirconium, iron, niobium, tantalum, molybdenum, etc.; 2. During assembly, first place the metal bottom cup, then place the easy-to-grind abrasive layer material, level it with a T-shaped hammer, then add a diamond wear-resistant composite layer, level it with a T-shaped hammer, then place the cemented carbide matrix, and then cover it with 1 - metal cap cup; 3. Place the assembled material together with the metal bottom cup and the metal cap cup in a high-temperature and high-pressure environment for sintering to obtain a polycrystalline superhard material blank; 4. The polycrystalline superhard material blank is further finely processed through processes such as annealing, grinding of the easy-to-grind abrasive layer, grinding of the machining allowance layer, surface grinding, and polishing.

[0040] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A polycrystalline superhard material blank facilitating grinding, comprising a polycrystalline superhard material blank formed by high temperature and high pressure, the 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), characterized in that: The polycrystalline superhard material product body (3) is a finished product that meets the specification requirements after grinding the polycrystalline superhard material blank; the material of the machining allowance grinding layer (2) is the same as that of the polycrystalline superhard material product body and is composed of fine-grained polycrystalline superhard materials with exactly the same particle size; the easy-to-grind grinding layer (1) is the grinding layer on the pressure-receiving surface and is one of two types: a coarse-grained easy-to-grind grinding layer made of the same polycrystalline superhard material and an easy-to-grind grinding layer made of a material different from the polycrystalline superhard material; the thickness of the machining allowance grinding layer (2) is 0.05 - 0.1 mm, and the thickness of the easy-to-grind grinding layer (1) is 0.3 - 0.35 mm; The polycrystalline superhard material product body (3) is a hexahedron. The machining allowance grinding layer (2) is provided on the outer surfaces of the six planes of the hexahedron, and the outermost layer is provided with the easy-to-grind grinding layer (1). The material of the polycrystalline superhard material product body (3) is fine-grained polycrystalline cubic boron nitride micropowder. The particle size in the fine-grained polycrystalline cubic boron nitride micropowder is 2 μm, accounting for 85 - 90%, and the rest is the metal binder Co, Ni; the particle size in the coarse-grained polycrystalline cubic boron nitride micropowder is 4 μm, accounting for 70 - 75%, and the rest is the metal binder Sn; Alternatively, 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 machining allowance grinding layer (2) is provided on the upper surface of the polycrystalline diamond composite layer (5), and the outermost layer is provided with the easy-to-grind grinding layer (1).

2. The polycrystalline superhard material blank convenient for grinding according to claim 1, wherein: For the easy-to-grind grinding layer (1) made of the same polycrystalline superhard material, the particle size of the particles is larger than that of the polycrystalline superhard material product body (3).

3. The polycrystalline superhard material compact for facilitating grinding according to claim 1, characterized in that: For the easy-to-grind grinding layer (1) made of a material different from the polycrystalline superhard material, the particle size of the particles is greater than or equal to that of the polycrystalline superhard material product body (3).

4. The polycrystalline superhard material compact for facilitating grinding according to claim 3, characterized in that: The easy-to-grind grinding layer (1) made of a material different from the polycrystalline superhard material is a high-purity metal powder with good gas absorption properties and a high melting point. The high-purity metal powder is any one of titanium, tantalum, zirconium, and molybdenum.

5. The preparation method of a polycrystalline superhard material blank convenient for grinding according to claim 1, characterized in that: The preparation method of the polycrystalline superhard material blank is as follows: use a cubic press to press the fine-grained polycrystalline cubic boron nitride micropowder into a polycrystalline cubic boron nitride bulk material, then press out the sheet-shaped easy-to-grind grinding layer (1) that fits the six faces of the hexahedron respectively, and finally use a cubic press to sinter the polycrystalline cubic boron nitride bulk material and the sheet-shaped easy-to-grind grinding layer (1) at a high temperature and high pressure of 1200 - 1600 °C and 5 - 7 GPa to form a polycrystalline cubic boron nitride blank.

6. The preparation method of a polycrystalline superhard material blank convenient for grinding according to claim 1, characterized in that: The preparation method of the polycrystalline superhard material blank is as follows: sequentially place the material of the easy-to-grind grinding layer (1), fine-grained polycrystalline diamond micropowder, and the cemented carbide substrate (4) in a metal bottom cup, then cover it with a metal cap cup, and sinter it at a high temperature and high pressure of 1350 - 1600 °C and 5.5 - 10 GPa to form a polycrystalline cubic diamond blank.

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