阅读说明：本技术 一种表面渗氮或渗硼处理的硬质合金基体聚晶立方氮化硼复合片及其制备方法 (Hard alloy matrix polycrystalline cubic boron nitride composite sheet with surface nitriding or boronizing treatment and preparation method thereof ) 是由 秦家千 李拥军 王福龙 于 2020-06-04 设计创作，主要内容包括：本发明提供一种表面渗氮或者渗硼处理的碳化钨硬质合金替代传统硬质合金作为基体制备一种聚晶立方氮化硼复合片。表面渗氮或者渗硼时钴在硬质合金表面同硼会形成钨-碳-钴-氮或者钨-碳-钴-硼系化合物层,从表层到硬质合金的硬度成梯度变化,逐渐变小。以表面渗氮或者渗硼的硬质合金作为聚晶立方氮化硼基体时,表层碳化物的硬度接近立方氮化硼层硬度,因此界面应力较小,改善聚晶立方氮化硼复合片脱层问题。同时,表面渗氮或者渗硼层在聚晶立方氮化硼复合片高温高压烧结过程中,能有效阻挡硬质合金中粘结相钴向立方氮化硼层扩散,降低立方氮化硼层金属含量,使得表面渗氮硬质合金基体聚晶立方氮化硼复合片提高复合片热稳定性、降低分层几率。(The invention provides a polycrystalline cubic boron nitride composite sheet prepared by taking tungsten carbide hard alloy subjected to surface nitriding or boronizing treatment as a matrix instead of traditional hard alloy. When the surface is nitrided or boronized, cobalt and boron form a tungsten-carbon-cobalt-nitrogen or tungsten-carbon-cobalt-boron compound layer on the surface of the hard alloy, and the hardness of the hard alloy from the surface layer is changed in a gradient manner and gradually becomes smaller. When the hard alloy with nitrided or boronized surface is used as the polycrystalline cubic boron nitride matrix, the hardness of the surface carbide is close to that of the cubic boron nitride layer, so that the interface stress is small, and the delamination problem of the polycrystalline cubic boron nitride composite sheet is improved. Meanwhile, the surface nitriding or boronizing layer can effectively prevent the binder phase cobalt in the hard alloy from diffusing to the cubic boron nitride layer in the high-temperature and high-pressure sintering process of the polycrystalline cubic boron nitride composite sheet, so that the metal content of the cubic boron nitride layer is reduced, the thermal stability of the composite sheet is improved, and the layering probability of the composite sheet is reduced.)

1. A preparation method of a hard alloy matrix polycrystalline cubic boron nitride composite sheet subjected to surface nitriding or boronizing treatment is characterized by comprising the following steps: the hard alloy with the surface subjected to nitriding or boronizing treatment is used for replacing the traditional tungsten carbide alloy matrix, and the hard alloy and cubic boron nitride of a binder system form a sintered body, and the polycrystalline cubic boron nitride composite sheet is prepared under the conditions of high temperature and high pressure.

2. The method for preparing the surface-nitrided or boronized hard alloy matrix polycrystalline cubic boron nitride compact according to claim 1, characterized in that: the hard alloy matrix subjected to surface nitriding or boriding treatment is suitable for ceramic, metal and metal ceramic binder systems.

3. The method for preparing the surface-nitrided or boronized hard alloy matrix polycrystalline cubic boron nitride compact according to claim 2, characterized in that: the surface nitriding layer or the boronizing layer of the hard alloy is 0.005-0.1 mm.

4. The method for preparing the surface-nitrided or boronized hard alloy matrix polycrystalline cubic boron nitride compact according to claim 3, characterized in that: the high-temperature high-pressure sintering condition is 2-8 GPa, and the temperature is 1100-1800 ℃.

5. A surface nitriding treatment hard alloy matrix polycrystalline cubic boron nitride composite sheet comprises a hard alloy matrix and a polycrystalline cubic boron nitride layer, and is characterized in that: and nitriding the surface of the hard alloy matrix to form a nitriding layer, and sintering the nitriding layer and the polycrystalline cubic boron nitride layer into a whole at high temperature and high pressure.

6. The surface-nitrided hard-metal matrix polycrystalline cubic boron nitride compact of claim 5, wherein: the surface nitriding layer of the hard alloy is a W-C-Co-N compound.

7. The surface-nitrided hard-metal matrix polycrystalline cubic boron nitride compact of claim 6, wherein: the surface nitriding layer of the hard alloy is a W-C-Co-N compound with the thickness of 0.005-0.1 mm.

8. The utility model provides a hard alloy base member glomerocryst cubic boron nitride composite sheet of surface boriding treatment, includes hard alloy base member and glomerocryst cubic boron nitride layer, its characterized in that: and carrying out boronizing treatment on the surface of the hard alloy matrix to form a boronizing layer, and sintering the boronizing layer and the polycrystalline cubic boron nitride layer into a whole at high temperature and high pressure.

9. The surface boriding treated cemented carbide substrate polycrystalline cubic boron nitride compact of claim 8, wherein: the surface boronizing layer of the hard alloy is a W-C-Co-B compound.

10. The surface boriding treated cemented carbide substrate polycrystalline cubic boron nitride compact of claim 8, wherein: the surface boronizing layer of the hard alloy is a W-C-Co-B compound with the thickness of 0.005-0.1 mm.

Technical Field

The invention relates to the technical field of preparation of polycrystalline cubic boron nitride composite sheets for cutting tools, in particular to a polycrystalline cubic boron nitride composite sheet with a surface nitriding or boronizing hard alloy matrix.

Background

The cubic boron nitride has better thermal stability than that of the artificial diamond, can still keep high enough mechanical property and hardness at high temperature, and has good red hardness; the cubic boron nitride has stable structure, high oxidation resistance and good chemical stability, and compared with diamond, the cubic boron nitride does not react with iron group elements at the temperature of 1100-1300 ℃, so the cubic boron nitride is particularly suitable for processing ferrous metal materials. The polycrystalline cubic boron nitride is prepared by sintering cubic boron nitride single crystal with optional addition of binder or under ultrahigh pressure and high temperature without addition of any binder. Polycrystalline cubic boron nitride has most of the properties of cubic boron nitride, and overcomes the defect of directional crystal face cleavage of cubic boron nitride single crystals.

Polycrystalline cubic boron nitride is mainly used for manufacturing cutter materials. The polycrystalline cubic boron nitride cutter blank mainly comprises three types, wherein one type is an integral pure polycrystalline cubic boron nitride sintered sheet; the second type is a composite sheet which is formed by taking polycrystalline cubic boron nitride as a polycrystalline layer and hard alloy as a substrate through high-temperature and high-pressure co-sintering; and thirdly, sintering to prepare polycrystalline cubic boron nitride blade blanks, and then welding the polycrystalline cubic boron nitride blade blanks to the hard alloy to prepare the polycrystalline cubic boron nitride blade. Because the hard alloy has good toughness, the hard alloy is usually used as a matrix and is combined with polycrystalline cubic boron nitride to prepare the composite sheet. However, the hard alloy substrate and the polycrystalline layer have large chemical composition difference and different thermal expansion coefficients, and the composite sheet is easy to crack and delaminate, so that the use is greatly limited. In order to solve the problems, the chinese patent CN102505090B utilizes a similar compatibility principle, adds hard alloy micro powder having the same chemical composition as the hard alloy matrix into polycrystalline layer synthesis raw material micro powder contacting with the hard alloy matrix, and changes the content of the hard alloy micro powder along the direction away from the matrix by a chemical gradient method, and the content of the hard alloy micro powder is continuously reduced along the direction away from the matrix. During ultrahigh pressure and high temperature sintering, the temperature in the synthesis cavity has gradient property, the internal temperature is high, the external temperature is low, and correspondingly, the cobalt element in the hard alloy matrix diffuses to a high temperature region, so that the compatibility and the bonding strength of the polycrystalline layer and the hard alloy matrix are enhanced. However, the major problems with the use of alloy matrices still remain, such as: 1) the metal of the alloy layer can penetrate into the CBN layer in a large quantity, so that the thermal stability of the composite sheet is reduced; 2) the interface bonding force is still the bonding of a metal permeable layer, and the layering rate is high; 3) the difference between the thermal expansion coefficients of the matrix and the CBN layer is large, and the crack resistance and the collapse resistance of the product are poor; 4) the polycrystalline cubic boron nitride composite sheet with the alloy matrix has poor heat resistance, and the vacuum welding temperature is limited to be increased in the later-stage cutter manufacturing process.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a polycrystalline cubic boron nitride composite sheet with surface nitriding or boronizing hard alloy as a matrix instead of the traditional hard alloy.

The invention has the technical conception that the hardness and the thermal expansion coefficient of the hard alloy and the cubic boron nitride layer are obviously different, if a gradient layer is designed, the performance of the interface is close, the interface stress is reduced, and the delamination rate is reduced. The hard alloy surface nitriding or boronizing treatment technology has reported that a layer of W-C-Co-N or W-C-Co-B compound is formed on the hard alloy surface after the surface nitriding or boronizing treatment, the hardness is gradually reduced from the surface layer to the hard alloy, and the hardness of the surface layer is close to the hardness of a cubic boron nitride layer. The surface W-C-Co-N or W-C-Co-B series compound contains no metal, so that a large amount of metal cannot permeate into the cubic boron nitride layer under the condition of high temperature and high pressure, and the hard alloy nitriding or the interface of the mixed initial material of the boronized layer W-C-Co-N or W-C-Co-B series compound and the cubic boron nitride layer can generate chemical reaction under the condition of high temperature and high pressure to form chemical bond combination.

The technical scheme of the invention is as follows:

a preparation method of a polycrystalline cubic boron nitride composite sheet of a hard alloy matrix subjected to surface nitriding or boronizing treatment is characterized in that the hard alloy subjected to surface nitriding or boronizing treatment is used for replacing a traditional tungsten carbide alloy matrix, and the hard alloy and cubic boron nitride of a binder system form a sintered body, and the polycrystalline cubic boron nitride composite sheet is prepared under the conditions of high temperature and high pressure.

The hard alloy matrix subjected to surface nitriding or boronizing treatment is suitable for ceramic, metal and metal ceramic binder systems.

The surface nitriding layer or the boronizing layer of the hard alloy is 0.005-0.1 mm.

The high-temperature high-pressure sintering condition is 2-8 GPa, and the temperature is 1100-1800 ℃.

The surface nitriding treatment of the hard alloy substrate forms a nitriding layer, and the nitriding layer and the polycrystalline cubic boron nitride layer are sintered into a whole at high temperature and high pressure.

The surface nitriding layer of the hard alloy is a W-C-Co-N compound.

The surface nitriding layer of the hard alloy is a W-C-Co-N compound with the thickness of 0.005-0.1 mm.

And carrying out boronizing treatment on the surface of the hard alloy matrix to form a boronizing layer, and sintering the boronizing layer and the polycrystalline cubic boron nitride layer into a whole at high temperature and high pressure.

The surface boronizing layer of the hard alloy is a W-C-Co-B compound.

The surface boronizing layer of the hard alloy is a W-C-Co-B compound with the thickness of 0.005-0.1 mm.

The surface of the hard alloy used by the invention can form a layer of W-C-Co-N or W-C-Co-B series compound on the surface of the hard alloy subjected to surface nitriding or boronizing, the hardness of the hard alloy is gradually reduced from the surface layer to the hard alloy, and the hardness of the surface layer is close to that of the cubic boron nitride layer. The surface W-C-Co-N or W-C-Co-B series compound contains no metal, so that a large amount of metal cannot permeate into the cubic boron nitride layer under the condition of high temperature and high pressure, and the hard alloy nitriding or the interface of the mixed initial material of the boronized layer W-C-Co-N or W-C-Co-B series compound and the cubic boron nitride layer can generate chemical reaction under the condition of high temperature and high pressure to form chemical bond combination. Therefore, surface nitriding or boronizing cemented carbides can solve the main problems of the alloy matrix:

1. compared with the traditional hard alloy matrix, the metal content in the cubic boron nitride layer is reduced, and the thermal stability is improved;

2. the interface bonding force is changed from the original metal permeable layer bonding into chemical bond bonding, so that the layering probability is reduced;

3. the hard alloy nitriding or boronizing layer W-C-Co-N or W-C-Co-B series compound and the cubic boron nitride layer have closer thermal expansion coefficients, reduce the macroscopic stress and improve the crack resistance and the collapse resistance of the product;

4. the surface nitriding or boronizing hard alloy matrix polycrystalline cubic boron nitride has higher heat resistance.

Drawings

FIG. 1 is a schematic view of the structure of the present invention.

Detailed Description

As shown in fig. 1, the hard alloy matrix polycrystalline cubic boron nitride composite sheet subjected to surface nitriding treatment comprises a hard alloy matrix 1 and a polycrystalline cubic boron nitride layer 3, wherein a nitriding layer 2 is formed by surface nitriding treatment of the hard alloy matrix 1, and the nitriding layer 2 and the polycrystalline cubic boron nitride layer 3 are sintered into a whole at high temperature and high pressure.

The surface nitriding layer 2 of the hard alloy 1 is a W-C-Co-N compound.

The surface nitriding layer 2 of the hard alloy 1 is a W-C-Co-N compound with the thickness of 0.005-0.1 mm.

And carrying out boronizing treatment on the surface of the hard alloy matrix 1 to form a boronizing layer 2, and sintering the boronizing layer 2 and the polycrystalline cubic boron nitride layer into a whole at high temperature and high pressure.

The surface boronizing layer 2 of the hard alloy 1 is a W-C-Co-B compound.

The surface boronizing layer 2 of the hard alloy 1 is a W-C-Co-B compound with the thickness of 0.005-0.1 mm.

Example 1

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which takes hard alloy subjected to surface nitriding treatment as the matrix and takes a ceramic binder and a cubic boron nitride mixed blank as a cubic boron nitride layer.

The surface nitrided hard alloy used in this example was produced by the host edt materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface nitrided layer of 0.05 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 50 parts of cubic boron nitride having an average particle size of 2 μm and 50 parts of titanium carbide having an average particle size of 2 μm.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: using surface nitriding hard alloy to replace a traditional hard alloy sheet as a matrix, and pressing the initial material obtained in the first step onto the surface nitriding hard alloy matrix through a die;

the third step: and assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 5.5 GPa, the temperature is 1450 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 2

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which takes hard alloy subjected to surface nitriding treatment as the matrix and takes a ceramic binder and a cubic boron nitride mixed blank as a cubic boron nitride layer.

The surface nitrided hard alloy used in this example was produced by the host edt materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface nitrided layer of 0.005 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 90 parts of cubic boron nitride with the average particle size of 0.1 micron and 10 parts of metal aluminum powder with the average particle size of 1 micron.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: using surface nitriding hard alloy to replace a traditional hard alloy sheet as a matrix, and pressing the initial material obtained in the first step onto the surface nitriding hard alloy matrix through a die;

the third step: and assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 2GPa, the temperature is 1100 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 3

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which takes hard alloy subjected to surface nitriding treatment as the matrix and takes a ceramic binder and a cubic boron nitride mixed blank as a cubic boron nitride layer.

The surface nitrided hard alloy used in this example was produced by the host edt materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface nitrided layer of 0.1 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 10 parts of cubic boron nitride having an average particle size of 30 μm and 90 parts of titanium carbide having an average particle size of 30 μm.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: using surface nitriding hard alloy to replace a traditional hard alloy sheet as a matrix, and pressing the initial material obtained in the first step onto the surface nitriding hard alloy matrix through a die;

the third step: assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 8 GPa, the temperature is 1800 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 4

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which takes hard alloy subjected to surface nitriding treatment as the matrix and takes a ceramic binder and a cubic boron nitride mixed blank as a cubic boron nitride layer.

The surface nitrided hard alloy used in this example was produced by the host edt materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface nitrided layer of 0.02 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 50 parts of cubic boron nitride with the average particle size of 2 microns, 10 parts of metal aluminum powder with the average particle size of 2 microns and 40 parts of titanium carbide with the average particle size of 2 microns.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface nitrided hard alloy matrix, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: using surface nitriding hard alloy to replace a traditional hard alloy sheet as a matrix, and pressing the initial material obtained in the first step onto the surface nitriding hard alloy matrix through a die;

the third step: assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 5 GPa, the temperature is 1400 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 5

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface boronized hard alloy matrix, which takes a hard alloy subjected to surface boronizing treatment as the matrix and a mixed blank of a ceramic binder and cubic boron nitride as a cubic boron nitride layer.

The surface boriding cemented carbide used in this example was produced by dorend materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface boriding layer of 0.1 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 50 parts of cubic boron nitride having an average particle size of 2 μm and 50 parts of titanium carbide having an average particle size of 2 μm.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a boronized surface cemented carbide substrate, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: pressing the initial material obtained in the first step onto the surface boronized hard alloy substrate through a die by using the surface boronized hard alloy to replace a traditional hard alloy sheet as the substrate;

the third step: and assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 5.5 GPa, the temperature is 1450 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 6

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface boronized hard alloy matrix, which takes a hard alloy subjected to surface boronizing treatment as the matrix and a mixed blank of a ceramic binder and cubic boron nitride as a cubic boron nitride layer.

The surface boriding cemented carbide used in this example was produced by the host edt materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface boriding layer of 0.01 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 90 parts of cubic boron nitride with the average particle size of 0.1 micron and 10 parts of metal aluminum powder with the average particle size of 1 micron.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a boronized surface cemented carbide substrate, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: pressing the initial material obtained in the first step onto the surface boronized hard alloy substrate through a die by using the surface boronized hard alloy to replace a traditional hard alloy sheet as the substrate;

the third step: and assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 2GPa, the temperature is 1100 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 7

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface boronized hard alloy matrix, which takes a hard alloy subjected to surface boronizing treatment as the matrix and a mixed blank of a ceramic binder and cubic boron nitride as a cubic boron nitride layer.

The surface boriding cemented carbide used in this example was produced by dorend materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface boriding layer of 1 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 10 parts of cubic boron nitride having an average particle size of 30 μm and 90 parts of titanium carbide having an average particle size of 30 μm.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a boronized surface cemented carbide substrate, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: pressing the initial material obtained in the first step onto the surface boronized hard alloy substrate through a die by using the surface boronized hard alloy to replace a traditional hard alloy sheet as the substrate;

the third step: assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 8 GPa, the temperature is 1800 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.

Example 8

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a surface boronized hard alloy matrix, which takes a hard alloy subjected to surface boronizing treatment as the matrix and a mixed blank of a ceramic binder and cubic boron nitride as a cubic boron nitride layer.

The surface boriding cemented carbide used in this example was produced by dorend materials ltd, and had a thickness of 4 mm, a diameter of 58 mm, and a surface boriding layer of 0.2 mm.

In the embodiment, the cubic boron nitride layer is composed of the following components in parts by mass: 50 parts of cubic boron nitride with the average particle size of 2 microns, 10 parts of metal aluminum powder with the average particle size of 2 microns and 40 parts of titanium carbide with the average particle size of 2 microns.

The embodiment provides a preparation method of a polycrystalline cubic boron nitride composite sheet with a boronized surface cemented carbide substrate, which comprises the following steps:

the first step is as follows: respectively and uniformly mixing the cubic boron nitride with different contents and titanium carbide to obtain a series of initial materials with different cubic boron nitride contents;

the second step is that: pressing the initial material obtained in the first step onto the surface boronized hard alloy substrate through a die by using the surface boronized hard alloy to replace a traditional hard alloy sheet as the substrate;

the third step: assembling the blocks pressed in the second step into a high-temperature high-pressure synthesis block, and sintering at high temperature and high pressure, wherein the pressure is 5 GPa, the temperature is 1400 ℃, and the temperature is kept for 20 minutes to obtain the novel polycrystalline cubic boron nitride composite sheet.