Assembly structure and preparation method of polycrystalline superhard material

Abstract

The invention relates to the field of superhard material manufacturing, in particular to a polycrystalline superhard material assembly structure and a preparation method.The polycrystalline superhard material assembly structure comprises a metal cup, n cylindrical cavities used for containing mixed materials are formed in the metal cup, n is larger than 2, metal cylinders used for sealing the mixed materials are arranged in the cavities, the outer side of the metal cup is sleeved with a salt pipe, and the salt pipe is connected with the metal cup. Salt sheets are arranged at the upper end and the lower end in the salt pipe, a magnesium oxide pipe sleeves the outer side of the salt pipe, magnesium oxide sheets are arranged at the upper end and the lower end in the magnesium oxide pipe, a heating carbon pipe sleeves the outer end of the magnesium oxide pipe, and heating carbon sheets are arranged at the two ends of the heating carbon pipe; the assembly structure is simple, the process efficiency is high, and the miniature polycrystalline material composite sheet meeting the requirements can be prepared.

Description

Technical Field

[0001] The invention relates to the field of superhard material manufacturing, and in particular to an assembly structure and a preparation method of a polycrystalline superhard material. Background Art

[0002] With the promotion of superhard material application fields, the demand for small-sized polycrystalline diamond / cubic boron nitride in the micro-drilling field is increasing. The current manufacturing process of products with diameters of 1mm, 2mm, 4mm and other specifications is difficult to synthesize directly. Generally, large-diameter polycrystalline or composite sheets are processed by laser or wire cutting. The use of laser processing will cause thermal damage to the material, resulting in reduced strength of the cut material, making it difficult to meet performance requirements. In particular, for products with a diameter of less than 4mm and a height of more than 6mm with a cemented carbide substrate, alloy adhesion occurs after laser cutting, and the cut particles cannot be separated; using wire cutting to cut small-diameter products has higher requirements for the conductivity of polycrystalline / composite sheets. Coarse-grained diamond polycrystalline is currently difficult to process using wire cutting, such as Figure 4 As shown, the traditional process is a metal cup (single hole) filled with powder that is sintered into a large piece of polycrystalline superhard material that is difficult to cut. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to propose an assembly structure and a preparation method of a polycrystalline superhard material. The present invention utilizes a simple assembly structure and high process efficiency to prepare a micro-polycrystalline material composite sheet that meets the requirements.

[0004] The objective of the present invention is achieved through the following measures: an assembly structure of polycrystalline superhard material, comprising a metal cup, wherein n cylindrical cavities for accommodating a mixture are arranged inside the metal cup, where n>2, and a metal cylinder for sealing the mixture is arranged in the cavity, a salt tube is sleeved on the outside of the metal cup, and salt sheets are arranged at the upper and lower ends of the salt tube, a magnesium oxide tube is sleeved on the outside of the salt tube, and magnesium oxide sheets are arranged at the upper and lower ends of the magnesium oxide tube, and a heating carbon tube is sleeved on the outer end of the magnesium oxide tube, and heating carbon sheets are arranged at both ends of the heating carbon tube.

[0005] In the above-mentioned assembly structure of polycrystalline superhard materials, the material of the metal cup is one or a combination of niobium, tantalum, molybdenum and zirconium.

[0006] In the above-mentioned assembly structure of polycrystalline superhard materials, the sum of the heights of the metal cup and the two salt sheets is equal to the height of the salt tube.

[0007] In the above-mentioned assembly structure of polycrystalline superhard material, the sum of the heights of the salt tube and the two magnesium oxide sheets is equal to the height of the magnesium oxide tube.

[0008] In the above-mentioned assembly structure of polycrystalline superhard material, a cemented carbide cylinder in contact with the mixed material is arranged in the cavity, and the metal cylinder is arranged on the cemented carbide cylinder.

[0009] In the above-mentioned assembly structure of polycrystalline superhard materials, the outer diameter of the cemented carbide cylinder matches the inner diameter of the cavity.

[0010] In the above-mentioned assembly structure of polycrystalline superhard materials, the outer diameter of the metal cylinder matches the inner diameter of the cavity.

[0011] The method for preparing a polycrystalline superhard material using the above-mentioned polycrystalline superhard material assembly structure comprises the following steps:

[0012] S1: Filling the mixed powder into multiple cavities of a metal cup;

[0013] S2: Place the metal cylinder in the cavity of the metal cup to seal the cavity;

[0014] S3: The outer side of the metal cup covered with the metal cylinder is sequentially equipped with a salt tube, a magnesium oxide tube, and a heating carbon tube assembly. At the same time, salt sheets are placed at the upper and lower ends of the salt tube, and magnesium oxide sheets are placed at the upper and lower ends of the magnesium oxide tube;

[0015] S4: The assembled assembly is placed in a pyrophyllite block and sintered in a six-sided top press at a sintering temperature of 1450-1600°C for 5-10 minutes. After being taken out from the six-sided top press and cracked, a micro-polycrystalline superhard material monolith wrapped in a metal cup can be obtained;

[0016] S5: Use wire cutting to cut the whole block longitudinally to obtain micro polycrystalline superhard material.

[0017] In the above-mentioned method for preparing polycrystalline superhard materials, in step S1, the mixed powder is covered with a cemented carbide cylinder, and the metal cylinder is covered on the cemented carbide cylinder. After cutting in S5, a micro polycrystalline superhard material with a cemented carbide substrate is obtained.

[0018] A porous high-temperature metal cup is used. The high-temperature metal can be niobium, tantalum, molybdenum, zirconium and other materials. It provides shielding protection for polycrystalline sintering in the hole. The high thermal conductivity of the metal can provide a uniform temperature field. The number of holes can be 3-100, and the diameter is 0.5-15mm. That is, metal cups with different apertures can be customized according to the diameter of the required micro-polycrystalline superhard material. After cutting in step S5, the metal cup and the metal cylinder need to be disposed of, and the inside of the metal cup is the material finally prepared by the present invention.

[0019] The cemented carbide cylinder has the same aperture as the metal cup cavity and a height of 0-15 mm. The cemented carbide cylinder serves as a substrate for the polycrystalline superhard material. That is, after the frame of the metal cup and the outer frame of each cavity are longitudinally cut in step S5, the cavity is a composite sheet (i.e., a polycrystalline superhard material with a cemented carbide substrate). If, in step S1, only the mixed powder is loaded into the cavity without placing the cemented carbide cylinder, the final product is a polycrystalline superhard material without a cemented carbide substrate. At the same time, polycrystalline superhard materials of different heights can also be prepared.

[0020] The metal cylinder, whose diameter is the same as the hole diameter of the metal cup cavity, covers the mixed powder and the cemented carbide cylinder, and forms a sealed cavity with the metal cup to shield and protect the inside of the hole.

[0021] The salt tube is placed on the outside of the metal cup. Its main function is to provide a uniform pressure field. The salt is in a molten liquid state under sintering temperature conditions.

[0022] The magnesium oxide tube is on the outside of the salt pipe and serves as insulation and heat preservation.

[0023] The heated carbon tubes and carbon sheets are both heating elements that provide heat to the sintered polycrystals.

[0024] Beneficial effects of the invention: In view of the difficulty in micro-drill cutting, the invention provides a novel method for preparing micro-polycrystalline superhard materials. A porous high-temperature metal cup is used to load a mixture of diamond / cubic boron nitride powder and a binder and a cemented carbide substrate into the porous high-temperature metal cup. The metal blocks are sintered at high temperature and high pressure to form an integral metal block with the micro-polycrystalline superhard material wrapped inside. The micro-polycrystalline superhard material is then separated by wire cutting. The high thermal conductivity of the metal can be used to provide a uniform temperature field and to provide shielding protection for polycrystalline sintering, thereby ensuring the performance of the micro-polycrystalline superhard material. At the same time, the high conductivity of the metal can be used for wire cutting separation, thereby providing a new method for manufacturing micro-polycrystalline materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the assembly structure of polycrystalline superhard materials Figure 1 ;

[0026] Figure 2 A top view of the assembled structure of polycrystalline superhard materials;

[0027] Figure 3 It is a schematic diagram of a wire-cut metal cup;

[0028] Figure 4 It is a traditional metal cup structure.

[0029] In the figure: 1-carbon tube, 2-metal cylinder, 3-hard alloy cylinder, 4-magnesium oxide tube, 5-salt tube, 6-metal cup, 7-mixed powder, 8-heated carbon sheet, 9-magnesium oxide sheet, 10-salt sheet. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1: Figure 1 , Figure 2 , Figure 3 As shown, an assembly structure of a polycrystalline superhard material includes a metal cup, which is a high-temperature metal cup. The metal cup has n cylindrical cavities inside for accommodating a mixture, where n>2. The material of the high-temperature metal cup can be one or more combinations of materials such as niobium, tantalum, molybdenum, and zirconium, which provide shielding protection for polycrystalline sintering in the hole, and can provide a uniform temperature field by utilizing the high thermal conductivity of the metal. The number of holes can be 3-100, with a diameter of 0.5-15 mm, that is, metal cups with different apertures can be customized according to the diameter of the required micro-polycrystalline superhard material, and the mixture is usually a mixture of diamond / cubic boron nitride powder and a binder.

[0032] A carbide cylinder in contact with the mixture is arranged in the cavity, and the carbide cylinder acts as a substrate. A metal cylinder is arranged on the top of the carbide cylinder, and the metal cylinder plays the role of closing the cavity and protecting the mixture in the cavity. The outer diameter of the carbide cylinder matches the inner diameter of the cavity. The outer diameter of the metal cylinder matches the inner diameter of the cavity. A salt tube is arranged on the outside of the metal cup, and salt sheets are arranged at the upper and lower ends of the salt tube. The main function is to provide a uniform pressure field. The salt is a molten liquid under the sintering temperature condition. A magnesium oxide tube is arranged on the outside of the salt tube, and magnesium oxide sheets are arranged at the upper and lower ends of the magnesium oxide tube. The magnesium oxide tube is on the outside of the salt tube for insulation and heat preservation. A heating carbon tube is arranged on the outer end of the magnesium oxide tube, and heating carbon sheets are arranged at both ends of the heating carbon tube. The heating carbon tube and the carbon sheet are both heating elements, which provide heat to the sintered polycrystal. The sum of the heights of the metal cup and the two salt sheets is equal to the height of the salt tube. The sum of the heights of the salt tube and the two magnesium oxide sheets is equal to the height of the magnesium oxide tube.

[0033] The method for preparing a polycrystalline superhard material using the above-mentioned polycrystalline superhard material assembly structure comprises the following steps:

[0034] S1: The mixed powder is loaded into a plurality of cavities of a metal cup, and a cemented carbide cylinder is mounted on the mixed powder, with the cemented carbide cylinder in the cavity;

[0035] S2: Install the metal cylinder in the cavity of the metal cup and on the carbide cylinder;

[0036] S3: The outer side of the metal cup covered with the metal cylinder is sequentially equipped with a salt tube, a magnesium oxide tube, and a heating carbon tube assembly. At the same time, salt sheets are placed at the upper and lower ends of the salt tube, and magnesium oxide sheets are placed at the upper and lower ends of the magnesium oxide tube;

[0037] S4: The assembled assembly is placed in a pyrophyllite block and sintered in a six-sided top press at a sintering temperature of 1450°C for 5 minutes. After being taken out from the six-sided top press and cracked, a micro-polycrystalline superhard material monolith wrapped in a metal cup is obtained;

[0038] S5: Use wire cutting to cut the whole block longitudinally to obtain micro polycrystalline superhard material.

[0039] In this embodiment, the metal cup is customized to have 15 holes with a hole diameter of 4 mm and a metal cup diameter of 30 mm. The diamond mixed powder and the cemented carbide cylinder are loaded into the porous metal cup. Through the above preparation method, a micro polycrystalline diamond composite sheet with a diameter of 3 mm and an alloy matrix is ​​prepared.

[0040] Example 2: The assembly structure of the polycrystalline superhard material in this example is the same as that in Example 1, which will not be described here. This example only describes the differences.

[0041] The method for preparing a polycrystalline superhard material by using an assembled structure of the polycrystalline superhard material comprises the following steps:

[0042] S1: Filling the mixed powder into multiple cavities of a metal cup;

[0043] S2: Install the metal cylinder into the cavity of the metal cup and on the mixed powder;

[0044] S3: The outer side of the metal cup covered with the metal cylinder is sequentially equipped with a salt tube, a magnesium oxide tube, and a heating carbon tube assembly. At the same time, salt sheets are placed at the upper and lower ends of the salt tube, and magnesium oxide sheets are placed at the upper and lower ends of the magnesium oxide tube;

[0045] S4: The assembled assembly is placed in a pyrophyllite block and sintered in a six-sided top press at a sintering temperature of 1600°C for 10 minutes. After being taken out from the six-sided top press and cracked, a micro-polycrystalline superhard material monolith wrapped in a metal cup can be obtained;

[0046] S5: Use wire cutting to cut the whole block longitudinally to obtain micro polycrystalline superhard material.

[0047] In this embodiment, the metal cup is customized to have 6 holes with a hole diameter of 5 mm and a metal cup diameter of 22 mm. The diamond mixed powder is loaded into the porous metal cup, and micro polycrystalline diamond with a diameter of 3.5 mm is prepared by the above preparation method.

[0048] Example 3: The assembly structure of the polycrystalline superhard material in this example is the same as that in Example 1, which will not be described again here. This example only describes the differences.

[0049] The method for preparing a polycrystalline superhard material by using an assembled structure of the polycrystalline superhard material comprises the following steps:

[0050] S1: The mixed powder is loaded into a plurality of cavities of a metal cup, and a cemented carbide cylinder is mounted on the mixed powder, with the cemented carbide cylinder in the cavity;

[0051] S2: Install the metal cylinder in the cavity of the metal cup and on the carbide cylinder;

[0052] S3: The outer side of the metal cup covered with the metal cylinder is sequentially equipped with a salt tube, a magnesium oxide tube, and a heating carbon tube assembly. At the same time, salt sheets are placed at the upper and lower ends of the salt tube, and magnesium oxide sheets are placed at the upper and lower ends of the magnesium oxide tube;

[0053] S4: The assembled assembly is placed in a pyrophyllite block and sintered in a six-sided top press at a sintering temperature of 1500°C for 8 minutes. After being taken out from the six-sided top press and cracked, a micro-polycrystalline superhard material monolith wrapped in a metal cup can be obtained;

[0054] S5: Use wire cutting to cut the whole block longitudinally to obtain micro polycrystalline superhard material.

[0055] In this embodiment, the metal cup is customized to have 8 holes with a hole diameter of 6 mm and a metal cup diameter of 28 mm. The CBN mixed powder and the cemented carbide cylinder are loaded into the porous metal cup. Through the above preparation method, a micro polycrystalline cubic boron nitride composite sheet with a diameter of 5 mm and an alloy matrix is ​​prepared.

[0056] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An assembly structure of polycrystalline superhard materials, characterized in that: It comprises a metal cup, wherein n cylindrical cavities for accommodating a mixture are arranged inside the metal cup, where n>2, a metal cylinder for sealing the mixture is arranged inside the cavity, a salt tube is sleeved on the outside of the metal cup, salt sheets are arranged at the upper and lower ends of the salt tube, a magnesium oxide tube is sleeved on the outside of the salt tube, magnesium oxide sheets are arranged at the upper and lower ends of the magnesium oxide tube, a heating carbon tube is sleeved on the outer end of the magnesium oxide tube, and heating carbon sheets are arranged at both ends of the heating carbon tube.

2. The assembly structure of polycrystalline superhard material according to claim 1, characterized in that: The metal cup is made of one or more combinations of niobium, tantalum, molybdenum and zirconium.

3. The assembly structure of polycrystalline superhard materials according to claim 1, characterized in that: The sum of the heights of the metal cup and the two salt sheets is equal to the height of the salt pipe.

4. The assembly structure of polycrystalline superhard materials according to claim 1, characterized in that: The sum of the heights of the salt tube and the two magnesium oxide sheets is equal to the height of the magnesium oxide tube.

5. The assembly structure of polycrystalline superhard material according to claim 1, characterized in that: A hard alloy cylinder in contact with the mixed material is arranged in the cavity, and the metal cylinder is arranged on the hard alloy cylinder.

6. The assembly structure of polycrystalline superhard material according to claim 5, characterized in that: The outer diameter of the cemented carbide cylinder matches the inner diameter of the cavity.

7. The assembly structure of polycrystalline superhard materials according to claim 6, characterized in that: The outer diameter of the metal cylinder matches the inner diameter of the cavity.

8. A method for preparing a polycrystalline superhard material using the assembled structure of the polycrystalline superhard material according to any one of claims 1 to 7, characterized in that: The steps include: S1: Filling the mixed powder into multiple cavities of a metal cup; S2: Place the metal cylinder in the cavity of the metal cup to seal the cavity; S3: The outer side of the metal cup covered with the metal cylinder is sequentially equipped with a salt tube, a magnesium oxide tube, and a heating carbon tube assembly. At the same time, salt sheets are placed at the upper and lower ends of the salt tube, and magnesium oxide sheets are placed at the upper and lower ends of the magnesium oxide tube; S4: The assembled assembly is placed in a pyrophyllite block and sintered in a six-sided top press at a sintering temperature of 1450-1600°C for 5-10 minutes. After being taken out from the six-sided top press and cracked, a micro-polycrystalline superhard material monolith wrapped in a metal cup can be obtained; S5: Use wire cutting to cut the whole block longitudinally to obtain micro polycrystalline superhard material.

9. The method for preparing a polycrystalline superhard material according to claim 8, characterized in that: In the step S1, the mixed powder is covered with a cemented carbide cylinder, and the metal cylinder is covered on the cemented carbide cylinder. After cutting in S5, a micro-polycrystalline superhard material with a cemented carbide substrate is obtained.

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