CN117921007B - Polycrystalline cubic boron nitride composite sheet and preparation method thereof - Google Patents

Abstract

The present invention discloses a method for preparing a polycrystalline cubic boron nitride composite sheet, comprising: mixing cubic boron nitride, a binder, metal powder, and a sulfide to obtain a mixed material; heat treating the mixed material under an inert gas or vacuum atmosphere to obtain a treated mixed material; sintering the treated mixed material with a cemented carbide substrate to obtain the polycrystalline cubic boron nitride composite sheet. When the polycrystalline cubic boron nitride composite sheet is used for cutting, the sulfide will be adsorbed on the surface of the polycrystalline cubic boron nitride to form a protective layer, avoiding direct contact between the polycrystalline cubic boron nitride layer and the cut material, thereby extending the cutting life of the polycrystalline cubic boron nitride composite sheet; at the same time, the hexagonal structure of the sulfide will also produce a lubricating effect during the cutting process, reducing the force between the polycrystalline cubic boron nitride layer and the cut material, further extending the service life of the polycrystalline cubic boron nitride composite sheet.

Description

A polycrystalline cubic boron nitride composite sheet and preparation method thereof

Technical Field

The invention relates to the field of superhard material cutting tools, and in particular to a polycrystalline cubic boron nitride composite sheet and a preparation method thereof.

Background Art

Cubic boron nitride (CBN) has high hardness, excellent chemical stability and high temperature resistance. Since polycrystalline cubic boron nitride (PCBN) has good chemical inertness to ferrous metals, PCBN tools are widely used in the processing of ferrous metals.

Usually, the CBN content of low-concentration PCBN is generally less than 75%, and it is mainly used for processing hardened steel. The CBN content of high-concentration PCBN is generally not less than 80%, and it is mainly used for processing cast iron. There are three types of cast iron processed by PCBN, gray cast iron, vermicular cast iron and ductile cast iron. The structures of these three types of cast iron usually contain ferrite, and some of the ferrite is free ferrite; although CBN has good chemical inertness to iron, the temperature at the position of the cutter head is above 800℃ in the cutting state. At this time, the free ferrite will corrode the CBN particles, causing corrosion pits and microcracks at the cutting position of the cutter head, and then the chipping phenomenon will occur, which seriously affects the service life of the PCBN tool.

Therefore, the prior art still needs to be improved and developed.

Summary of the invention

In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a polycrystalline cubic boron nitride composite sheet and a preparation method thereof, aiming to solve the problem of the short life of the existing cubic boron nitride in cutting cast iron.

The technical solution of the present invention is as follows:

A first aspect of the present invention provides a method for preparing a polycrystalline cubic boron nitride composite sheet, comprising:

Mixing cubic boron nitride, a binder, metal powder and sulfide to obtain a mixed material;

heat-treating the mixed material under an inert gas or vacuum atmosphere to obtain a treated mixed material;

The treated mixed material and the hard alloy matrix are sintered to obtain the polycrystalline cubic boron nitride composite sheet.

Optionally, the volume ratio of the cubic boron nitride, the binder, the metal powder and the sulfide is 80-98:1.8-15:0.1-15:0.1-15; preferably, the volume ratio of the cubic boron nitride is 85-90.

Optionally, the sulfide is one or more of manganese sulfide, tungsten sulfide, titanium sulfide, cuprous sulfide, cobalt sulfide, cadmium sulfide, zirconium sulfide, gallium sulfide, ytterbium sulfide, tantalum sulfide, chromium sulfide, molybdenum sulfide, and zinc sulfide.

Optionally, the particle size of the cubic boron nitride is 0.1-50 microns; preferably, the particle size of the cubic boron nitride is 0.5-10 microns; more preferably, the particle size of the cubic boron nitride is 1-5 microns.

Optionally, the binder is one or both of aluminum and titanium.

Optionally, the metal powder is one or more of cobalt, nickel, manganese, tungsten, niobium and tantalum.

Optionally, the heat treatment is performed at a temperature of 500-1000° C., for a time of 1-6 hours, and in a vacuum or inert gas atmosphere.

Optionally, the mixing of cubic boron nitride, a binder, metal powder and sulfide specifically includes:

Mixing cubic boron nitride, a binder and metal powder, and drying to obtain a premixed material;

The premixed material is placed in a metal cup, compacted, heat treated under an inert gas or vacuum atmosphere, crushed, and sulfide is added and mixed to obtain the mixed material.

Optionally, the sintering of the treated mixed material and the cemented carbide substrate specifically includes:

The treated mixed material and the hard alloy substrate are placed in a metal cup and synthesized under the conditions of a temperature of 1200-1600° C. and a pressure of 5-8 GPa.

A second aspect of the present invention provides a polycrystalline cubic boron nitride composite sheet, wherein the polycrystalline cubic boron nitride composite sheet is prepared by the above-mentioned preparation method.

Beneficial effects: The method for preparing a polycrystalline cubic boron nitride composite sheet described in the present invention uniformly adds sulfide to the material used to prepare polycrystalline cubic boron nitride to obtain a polycrystalline cubic boron nitride composite sheet containing sulfide. The prepared polycrystalline cubic boron nitride composite sheet is used for cutting processing. During the processing, the sulfide will be adsorbed on the surface of the polycrystalline cubic boron nitride to form a protective layer to avoid direct contact between the polycrystalline cubic boron nitride layer and the cut material, thereby reducing the corrosion of the cut material to the polycrystalline cubic boron nitride layer under the high temperature environment generated by cutting, and extending the cutting life of the polycrystalline cubic boron nitride layer; at the same time, the sulfide is usually a hexagonal structure, which will also produce a lubricating effect during the cutting process, reducing the force between the polycrystalline cubic boron nitride layer and the cut material, and further extending the life of the polycrystalline cubic boron nitride layer.

DETAILED DESCRIPTION

The present invention provides a polycrystalline cubic boron nitride composite sheet and a preparation method thereof. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the characteristics, operations or features described in the specification can be combined in any appropriate manner to form various implementation methods. At the same time, the steps or actions in the method description can also be replaced or adjusted in order in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification are only for the purpose of clearly describing a certain embodiment and do not mean that they are necessary sequences, unless otherwise specified that a certain sequence must be followed. The instruments and reagents used are all commercially available products.

The present invention provides a method for preparing a polycrystalline cubic boron nitride composite sheet, comprising:

Mixing cubic boron nitride, a binder, metal powder and sulfide to obtain a mixed material;

heat-treating the mixed material under an inert gas or vacuum atmosphere to obtain a treated mixed material;

The treated mixed material and the hard alloy matrix are sintered to obtain the polycrystalline cubic boron nitride composite sheet.

In one embodiment, the mixing of cubic boron nitride, a binder, metal powder, and sulfide specifically includes:

Mixing cubic boron nitride, a binder and metal powder, and drying to obtain a premixed material;

The premixed material is placed in a metal cup, compacted, heat treated under an inert gas or vacuum atmosphere, crushed, and sulfide is added and mixed to obtain the mixed material.

In one embodiment, the sintering of the treated mixed material with a cemented carbide substrate specifically includes:

The treated mixed material and the hard alloy substrate are placed in a metal cup and synthesized under the conditions of a temperature of 1200-1600° C. and a pressure of 5-8 GPa.

In the present invention, a high temperature and high pressure sintering treatment method is used, which can effectively inhibit the hexagonal transformation of the cubic boron nitride single crystal and maintain the good mechanical properties of the cubic boron nitride. The present invention has no special limitation on the specific operation mode of the high temperature and high pressure conditions, and a high temperature and high pressure sintering treatment method well known to those skilled in the art can be used.

In some embodiments, in the preparation method of the polycrystalline cubic boron nitride composite sheet, 80-98 parts of cubic boron nitride, 1.8-15 parts of binder, 0.1-15 parts of metal powder, and 0.1-15 parts of sulfide are added, measured by volume; the cubic boron nitride is preferably 85-90 parts.

In the present invention, the volume percentage of cubic boron nitride in the polycrystalline cubic boron nitride composite sheet is 80-98%, the volume percentage of the binder is 1.8-15%, the volume percentage of the metal powder is 0.1-15%, and the volume percentage of the sulfide is 0.1-15%; the volume percentage of cubic boron nitride is preferably 85-90%. The content of cubic boron nitride has a great influence on the hardness and thermal conductivity of the polycrystalline cubic boron nitride composite sheet. The higher the content of cubic boron nitride, the higher the hardness of the prepared polycrystalline cubic boron nitride composite sheet and the better the thermal conductivity. The content of sulfide has a great influence on the wear resistance of the polycrystalline cubic boron nitride composite sheet. When the volume percentage of sulfide is lower than 0.1%, the wear resistance of the polycrystalline cubic boron nitride composite sheet is not significantly improved; when the volume percentage of sulfide is higher than 15%, it will affect the bonding between the cubic boron nitride particles, and some sulfides will produce volatiles. The larger the proportion of sulfide, the greater the vapor pressure of the material, which is dangerous to use under high temperature and high pressure.

In some embodiments, the sulfide is one or more of manganese sulfide, tungsten sulfide, titanium sulfide, cuprous sulfide, cobalt sulfide, cadmium sulfide, zirconium sulfide, gallium sulfide, ytterbium sulfide, tantalum sulfide, chromium sulfide, molybdenum sulfide, and zinc sulfide.

In the present invention, sulfide will be adsorbed on the surface of polycrystalline cubic boron nitride to form a protective layer, which prevents the polycrystalline cubic boron nitride layer from direct contact with the cut material during the cutting process, thereby reducing the corrosion of the cut material to the polycrystalline cubic boron nitride layer under the high temperature environment generated by cutting, and extending the cutting life of the polycrystalline cubic boron nitride layer. At the same time, sulfide is usually a hexagonal structure, which will also produce a lubricating effect during the cutting process, reducing the force between the polycrystalline cubic boron nitride layer and the cut material, and further extending the life of the polycrystalline cubic boron nitride layer.

In some embodiments, the particle size of the cubic boron nitride is 0.1-50 microns; preferably, the particle size of the cubic boron nitride is 0.5-10 microns; more preferably, the particle size of the cubic boron nitride is 1-5 microns.

In the present invention, the more dispersed the particle size of the cubic boron nitride is, the greater the performance fluctuation is; when the particle size of the cubic boron nitride is less than 0.5 microns, the material has many pores and large shrinkage, which will lead to poor bonding and difficulty in forming a completely dense composite material, requiring higher pressure; when the particle size of the cubic boron nitride is higher than 10 microns, the impact resistance of the polycrystalline cubic boron nitride will be reduced, and it is currently less used. Therefore, the particle size of the cubic boron nitride is preferably 0.5-10 microns, and more preferably 1-5 microns.

In some embodiments, the binder is one or both of aluminum and titanium.

In the present invention, aluminum and titanium can react with cubic boron nitride under high temperature and high pressure conditions, so that the cubic boron nitride particles are more firmly bonded, thereby improving the wear resistance of the polycrystalline cubic boron nitride composite sheet.

In some embodiments, the metal powder is one or more of cobalt, nickel, manganese, tungsten, niobium, and tantalum.

In the present invention, the metal powder has a certain promoting effect on the bonding of cubic boron nitride, and can also improve the conductivity of the polycrystalline cubic boron nitride composite sheet.

In some embodiments, the heat treatment is performed at a temperature of 500-1000° C., for a time of 1-6 h, and in a vacuum or inert gas atmosphere.

In the present invention, the specific operation of the heat treatment is not particularly limited, and conventional heat treatment operations by those skilled in the art can be used. The heat treatment is to remove adsorbed oxygen and moisture in cubic boron nitride, binder, metal powder and sulfide, ensure the purity of the powder, and avoid the reaction between impurities and sulfide, thereby ensuring the performance of the polycrystalline cubic boron nitride composite sheet.

The present invention also provides a polycrystalline cubic boron nitride composite sheet, wherein the polycrystalline cubic boron nitride composite sheet is prepared by the above-mentioned preparation method.

The technical solution of the present invention is further described below in conjunction with specific embodiments.

Example 1

The materials are measured by volume. 90 parts of cubic boron nitride (particle size is 5 microns), 5 parts of aluminum powder, and 4.9 parts of cobalt powder are mixed evenly by ball milling. After mixing, the materials are dried, and the dried materials are put into a metal cup and treated at 700°C in vacuum for 6 hours. Then the treated materials are poured out of the metal cup, 0.1 parts of tungsten sulfide are added, and the materials are mixed evenly by ball milling. The materials are dried, put into a metal cup, and treated at 500°C with inert gas for 2 hours. Then, they are assembled and synthesized with a cemented carbide substrate. The synthesis conditions are pressure 5 GPa and temperature 1500°C.

The sample prepared in this embodiment was processed into a tool for cutting performance test. The cut material was gray cast iron HT200. Under the condition of a cutting stroke of 12570 m, the flank wear of the tool in this embodiment was 106 μm.

Example 2

The materials are measured by volume. 85 parts of cubic boron nitride (particle size is 1 micron), 10 parts of aluminum powder, 2 parts of cobalt powder and 1 part of manganese powder are mixed evenly by ball milling. After mixing, the materials are dried, and the dried materials are put into a metal cup and treated at 800°C under inert gas for 3 hours. Then the treated materials are poured out of the metal cup, and 2 parts of chromium sulfide are added. The materials are mixed evenly by ball milling, and the materials are dried and put into a metal cup. They are vacuum treated at 500°C for 6 hours, and then assembled with a cemented carbide substrate. The synthesis conditions are pressure 7 GPa and temperature 1500°C.

The sample prepared in this embodiment was processed into a tool for cutting performance test. The cut material was gray cast iron HT200. Under the condition of a cutting stroke of 10740 m, the flank wear of the tool in this embodiment was 95 μm.

Example 3

The materials are measured by volume. 80 parts of cubic boron nitride (particle size is 6 microns), 7 parts of aluminum powder, 2 parts of cobalt powder and 2 parts of nickel powder are mixed evenly by ball milling. After mixing, the materials are dried, put into a metal cup, and vacuum treated at 800°C for 1 hour. Then the treated material is poured out of the metal cup, 9 parts of titanium sulfide are added, the materials are mixed evenly by ball milling, the materials are dried, put into a metal cup, and vacuum treated at 600°C for 4 hours. Then, they are assembled and synthesized with a cemented carbide substrate. The synthesis conditions are pressure 5 GPa and temperature 1200°C.

The sample prepared in this embodiment was processed into a tool for cutting performance test. The cut material was ductile iron QT600. Under the condition of a cutting stroke of 10050 m, the flank wear of the tool in this embodiment was 84 μm.

Comparative Example 1

The difference between this comparative example and Example 1 is that tungsten sulfide is not added, and other materials and operations are the same.

The sample prepared in this comparative example was processed into a tool for cutting performance test. The cut material was gray cast iron HT200. Under the condition of a cutting stroke of 12570 m, the flank wear of the tool in this comparative example was 145 μm.

Comparative Example 2

The difference between this comparative example and Example 2 is that chromium sulfide is not added, and other materials and operations are the same.

The sample prepared in this comparative example was processed into a tool for cutting performance test. The cut material was gray cast iron HT200. Under the condition of a cutting stroke of 10740 m, the flank wear of the tool in this comparative example was 148 μm.

Comparative Example 3

The difference between this comparative example and Example 3 is that titanium sulfide is not added, and other materials and operations are the same.

The samples prepared in this comparative example were processed into cutting tools for cutting performance testing. The cutting material was ductile iron QT600. Under the condition of a cutting stroke of 10050 m, the flank wear of the cutting tool in this comparative example was 154 μm.

The data of the above embodiments and comparative examples are analyzed: Combining the experimental results of embodiment 1 with comparative example 1, it can be seen that, under the same other conditions, the flank wear of the tool with tungsten sulfide is 73% of the flank wear of the tool without tungsten sulfide; Combining the experimental results of embodiment 2 with comparative example 2, it can be seen that, under the same other conditions, the flank wear of the tool with chromium sulfide is 64% of the flank wear of the tool without chromium sulfide; Combining the experimental results of embodiment 3 with comparative example 3, it can be seen that, under the same other conditions, the flank wear of the tool with titanium sulfide is 54% of the flank wear of the tool without titanium sulfide.

It can be seen from the analysis of the above experimental data that the polycrystalline cubic boron nitride composite sheet provided by the present invention has excellent wear resistance and can extend the life of the polycrystalline cubic boron nitride composite sheet in cutting cast iron.

In summary, the present invention discloses a method for preparing a polycrystalline cubic boron nitride composite sheet, comprising: mixing cubic boron nitride, a binder and metal powder, and drying to obtain a premixed material; loading the premixed material into a metal cup, compacting, heat-treating the premixed material under an inert gas or vacuum atmosphere, crushing, adding a sulfide and mixing to obtain the mixed material; heat-treating the mixed material under an inert gas or vacuum atmosphere to obtain a treated mixed material; loading the treated mixed material and a cemented carbide substrate into a metal cup, and sintering the premixed material under high temperature and high pressure conditions to obtain the polycrystalline cubic boron nitride composite sheet.

Compared with the prior art, the polycrystalline cubic boron nitride composite sheet prepared by the preparation method of the present invention can form a protective layer on the surface of the polycrystalline cubic boron nitride by adsorbing sulfides when used in cutting processing, thereby avoiding direct contact between the polycrystalline cubic boron nitride layer and the cut material, thereby reducing the corrosion of the cut material to the polycrystalline cubic boron nitride layer under the high temperature environment generated by cutting, and extending the cutting life of the polycrystalline cubic boron nitride layer; at the same time, the sulfide is usually a hexagonal structure, which can also produce a lubricating effect during the cutting process, reducing the force between the polycrystalline cubic boron nitride layer and the cut material, and further extending the life of the polycrystalline cubic boron nitride layer.

It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims (7)

1. A method for preparing a polycrystalline cubic boron nitride composite sheet, comprising: Mixing cubic boron nitride, a binder, metal powder and sulfide to obtain a mixed material; heat-treating the mixed material under an inert gas or vacuum atmosphere to obtain a treated mixed material; Sintering the treated mixed material and a cemented carbide substrate to obtain the polycrystalline cubic boron nitride composite sheet; The volume ratio of the cubic boron nitride, the binder, the metal powder and the sulfide is 80-98:1.8-15:0.1-15:0.1-15; The binder is one or both of aluminum and titanium; The metal powder is one or more of cobalt, nickel, manganese, tungsten, niobium and tantalum. 2. The preparation method according to claim 1, characterized in that the sulfide is one or more of manganese sulfide, tungsten sulfide, titanium sulfide, cuprous sulfide, cobalt sulfide, cadmium sulfide, zirconium sulfide, gallium sulfide, ytterbium sulfide, tantalum sulfide, chromium sulfide, molybdenum sulfide, and zinc sulfide. 3. The preparation method according to claim 1, characterized in that the particle size of the cubic boron nitride is 0.1-50 microns. 4. The preparation method according to claim 1 is characterized in that the temperature of the heat treatment is 500-1000°C, the time is 1-6h, and the atmosphere is vacuum or inert gas. 5. The preparation method according to claim 1, characterized in that the mixing of cubic boron nitride, a binder, metal powder and sulfide specifically comprises: Mixing cubic boron nitride, a binder and metal powder, and drying to obtain a premixed material; The premixed material is placed in a metal cup, compacted, heat treated under an inert gas or vacuum atmosphere, crushed, and sulfide is added and mixed to obtain the mixed material. 6. The preparation method according to claim 1, characterized in that the sintering of the treated mixed material and the cemented carbide substrate specifically comprises: The treated mixed material and the hard alloy substrate are placed in a metal cup and synthesized under the conditions of a temperature of 1200-1600° C. and a pressure of 5-8 GPa. 7. A polycrystalline cubic boron nitride composite sheet, characterized in that the polycrystalline cubic boron nitride composite sheet is prepared by the preparation method according to any one of claims 1 to 6.