Catalyst for synthesizing flaky CBN, flaky CBN as well as preparation method and application of flaky CBN

Abstract

The invention provides a catalyst for synthesizing flaky CBN, flaky CBN and a preparation method and application of the flaky CBN. According to the sheet-shaped CBN synthesis catalyst, magnesium nitride and lithium hydride are taken as main components of the catalyst, calcium boride and titanium nitride are taken as catalyst additives, and the CBN synthesis catalyst with relatively small catalyst viscosity is designed. Hexagonal boron nitride is used as an initial raw material, under the action of the catalyst, irregular flaky orange CBN is synthesized at high temperature and high pressure, and the CBN has the characteristics of low strength, high sharpness and the like, and has the characteristic of high self-sharpening when being used as an abrasive material. The invention further provides application of the flaky CBN serving as a grinding material in grinding high-speed steel, surface hardening steel, hard alloy, alloy steel, nickel-based high-temperature alloy or cobalt-based high-temperature alloy, and therefore the grinding efficiency can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of superhard materials, and in particular to a catalyst for synthesizing flaky CBN, flaky CBN, and a preparation method and application thereof. Background Art

[0002] Cubic boron nitride (CBN) abrasives are second only to diamond in hardness, offering high hardness, strength, thermal conductivity, and a low coefficient of thermal expansion. Compared to diamond, CBN is chemically more stable and does not react with ferrous metals and their alloys. Therefore, it performs exceptionally well in high-temperature environments, capable of withstanding grinding temperatures of up to 1400-1500°C. This allows CBN to maintain its hardness and structural stability even at high temperatures, making it suitable for machining materials containing ferrous metals such as iron, cobalt, and nickel, and their alloys. CBN abrasives excel in metalworking, particularly in steel processing, where they hold approximately 90% of the market share. Key applications include metal manufacturing, electronics, machinery, and automotive. CBN abrasives are suitable for grinding bearing steel, cast iron, mold steel, tool steel, superalloys, and, in some cases, ceramics. Their superior properties ensure a longer tool life and superior machining results in metalworking.

[0003] CBN crystals synthesized using existing technology are mostly spherical in shape and have high strength. However, they suffer from poor self-sharpening properties during grinding processes. When machining high-speed steel, case-hardened steel, cemented carbide, alloy steel, and nickel- and cobalt-based high-temperature alloys, the grinding effects, such as processing efficiency and lifespan, need to be improved. To this end, the applicant disclosed a method for preparing cubic boron nitride abrasive in a Chinese invention patent application with publication number CN119347654A. This preparation method includes the following steps: mixing raw material powders to form a blank, and then synthesizing cubic boron nitride under high temperature and high pressure; the raw material powders are composed of HBN, a catalyst, and an additive, the catalyst being composed of Mg3N2 and LiH, and the additives being composed of CaB6, Al4C3, and TiN. Although the CBN abrasive disclosed in this invention patent application has further improved self-sharpening properties compared to conventional CBN abrasives, its static pressure strength Ti is below 25, and its service life is limited; and a certain amount of catalyst viscosity will be generated during the grinding process, affecting the surface roughness and precision of the ground product. Summary of the Invention

[0004] In view of this, the main purpose of the present invention is to synthesize flaky CBN with low strength, high sharpness and high self-sharpening properties by designing a catalyst for flaky CBN synthesis and regulating the ratio of various raw materials. As an abrasive, flaky CBN is suitable for grinding high-speed steel and case-hardened steel, cemented carbide, alloy steel, nickel-based and cobalt-based high-temperature alloys, and effectively improves grinding efficiency.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: A catalyst for flaky CBN synthesis is composed of magnesium nitride (Mg3N2), lithium hydride (LiH), calcium boride (CaB6) and titanium nitride (TiN), wherein the mass ratio of magnesium nitride, lithium hydride, calcium boride and titanium nitride is 2.5-4:5.5-9:0.5-2:0.5-1.5.

[0006] The magnesium nitride and lithium hydride in the above-mentioned catalysts are the main components of the catalyst for CBN synthesis. The main functions of magnesium nitride in the CBN synthesis process are solvent catalysis and intermediate phase regulation. The main function of lithium hydride in the CBN synthesis process is to reduce the synthesis conditions and promote structural reorganization. Calcium boride and titanium nitride are used as catalyst additives. The main function of calcium boride in the CBN synthesis process is to reduce and maintain a low-oxygen environment, stabilize active nitrogen, and cooperate with high-pressure conditions to improve product quality. The main function of titanium nitride in the CBN synthesis process is to remove oxygen impurities, maintain a high-purity environment, and balance catalytic activity and process feasibility. Therefore, by rationally controlling the dosage of the four, the four work synergistically, and hexagonal boron nitride can synthesize flaky orange CBN under high temperature and high pressure.

[0007] A sheet-shaped CBN, whose raw materials are composed of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride, and the mass ratio of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride is 80-85: 2.5-4: 5.5-9: 0.5-2: 0.5-1.5.

[0008] A method for preparing flaky CBN comprises the following steps: firstly mixing hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride to prepare a mixed blank; and then subjecting the mixed blank to high temperature and high pressure treatment to prepare orange flaky CBN.

[0009] In order to further improve the CBN synthesis efficiency, in the high temperature and high pressure treatment step, the synthesis temperature is 1600° C. to 1850° C. and the synthesis pressure is 85 to 90 MPa.

[0010] To improve CBN quality, the high-temperature, high-pressure treatment step is followed by a further step: crushing the CBN sintered block synthesized at high temperature and high pressure, followed by a purification step to obtain purified CBN crystal particles. The purification step typically involves water soaking, acid washing, and alkaline washing in this order to remove unconverted HBN and impurities.

[0011] In order to obtain the finished CBN abrasive, the purified CBN crystal particles are subjected to size classification and type selection, and are tested under a stereo microscope to be qualified, thereby obtaining the finished orange flaky CBN abrasive.

[0012] In the preparation method of the flaky CBN provided by the present invention, under the action of the catalyst, the conversion rate of HBN into CBN at high temperature and high pressure is 50% to 60%, and the synthesis efficiency is high.

[0013] An application of the above-mentioned flaky CBN as an abrasive in grinding processing.

[0014] A grinding tool comprises the above-mentioned flaky CBN.

[0015] In the technical solution provided by the present invention, the CBN crystals synthesized using the above-mentioned catalyst under high temperature and high pressure are irregular flakes, mostly orange in color, with a small amount of brown particles. This orange flaky CBN abrasive exhibits high sharpness due to its low catalyst viscosity and rich multi-angled design. Furthermore, its high brittleness allows for excellent self-sharpening properties during the grinding process, effectively improving the grinding efficiency and quality of grinding tools using this abrasive when grinding materials such as high-speed steel, case-hardened steel, cemented carbide, alloy steel, and nickel-based or cobalt-based superalloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the synthetic block structure in an embodiment of the present invention, wherein the symbols in the figure are: 1-conductive cap, 2-heating tube, 3-embryo, 4-pyrophyllite; Figure 2 This is a curve diagram of the high temperature and high pressure synthesis process used in Example 1 of the present invention; Figure 3 This is a SEM image of the orange irregular flake CBM synthesized in Example 1 of the present invention; Figure 4 This is a photograph of the morphology of the orange irregular flake CBN synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0019] In the present invention, unless otherwise specified and / or explained, all numerical values ​​involving component amounts are by weight, and "%" means mass percentage. Unless otherwise specified, the terms used in the present invention are commonly used in the relevant field. The preparation processes, testing methods, etc. used in the various embodiments are conventional means well known to those skilled in the art unless otherwise specified. The raw materials and equipment used are all available from public commercial sources.

[0020] The present invention mainly uses magnesium nitride and lithium hydride as the main catalyst components, and calcium boride and titanium nitride as catalyst additives to design a CBN synthesis catalyst with low catalyst viscosity. Using 99% pure HBN as the initial raw material, irregular flaky orange CBN is synthesized under high temperature and high pressure under the action of the catalyst. The CBN has the characteristics of low strength and high sharpness. As an abrasive, it has the characteristics of high self-sharpening properties and can effectively improve the grinding efficiency of materials such as high-speed steel and case-hardened steel, cemented carbide, alloy steel, nickel-based high-temperature alloys and cobalt-based high-temperature alloys.

[0021] Specifically, the CBN synthesis catalyst of the present invention is mainly composed of a uniform mixture of magnesium nitride, lithium hydride, calcium boride and titanium nitride in a mass ratio of 2.5-4: 5.5-9: 0.5-2: 0.5-1.5. For example, the mass ratio of magnesium nitride, lithium hydride, calcium boride and titanium nitride is 2.5 : 5.5 : 2 : 1.5, 3 : 5.5 : 2 : 1.5, 3.5 : 7 : 2 : 1.5, 4 : 5.5 : 2 : 1.5, 3 : 6 : 2 : 1.5, 3 : 8 : 1 : 1.2, 3 : 7.5 : 1.5 : 0.7, 3 : 8 : 1.2 : 1, 3.5 : 7 : 1 : 1, 3.5 : 7.5 : 0.7 : 1, 3.5 : 7.5 : 1 : 1.5, 3.5 : 9 : 0.8 : 0.6, and 4 : 8 : 1.3 : 0.7, 2.5 : 9 : 0.5 : 0.5, etc. Among them, the mass ratio of the four is preferably 2.5-4 : 6-9 : 1-1.5 : 0.7-1.2, so as to further improve the CBN conversion rate and particle size concentration of the flaky CBN abrasive.

[0022] The raw materials of the flaky CBN of the present invention are composed of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride in a mass ratio of 80-85: 2.5-4: 5.5-9: 0.5-2: 0.5-1.5. The raw materials can be synthesized into flaky orange CBN by high temperature and high pressure treatment. The mass ratio of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride in the above raw materials can be 80:4:9:0.5:1.5, 82:4:8:1:1, 81:3.5:7.5:1.2:1, 83:3.2:7.8:1.2:0.8, 84:3.5:7.5:1.2:1, 85:3:7:1.5:1.2, 85:4:9:0.5:0.5, etc. The mass ratio of each component in the above raw materials is preferably 80-85:2.5-4:6-9:1-1.5:0.7-1.2.

[0023] The preparation method of the sheet-like CBN of the present invention is as follows: Mixing of raw materials: First, mix the above raw materials evenly in a sealed container for 0.5 to 1 hour to make the raw materials evenly mixed, then use a press to press the mixed raw materials into a mixed blank, and assemble it according to the requirements for use. Figure 1 As shown, the conductive cap 1, the heating tube 2, the embryo 3, and the pyrophyllite 4 are assembled into a composite block for later use.

[0024] Synthesis of CBN: The synthesis block is loaded into the high-pressure chamber of a six-sided top press, and an orange CBN sintered block is synthesized under high temperature and high pressure conditions. During the high temperature and high pressure synthesis, the pressure of the six-sided top press is first increased to 25-35 MPa before heating begins. The pressure is then increased to 50-60 MPa and maintained for 3-5 minutes. During this period, the temperature is raised to 1600℃-1850℃ after being maintained for 0.5-2 minutes. The pressure is then further increased to a synthesis pressure of 85-90 MPa, maintained for 20-35 minutes, and then naturally cooled. After cooling naturally for 10-15 minutes, the pressure is released to synthesize the orange CBN sintered block.

[0025] Crushing and Purifying CBN: The synthesized CBN sintered block is removed from the high-pressure chamber, crushed, and soaked in water to remove unconverted HBN. It is then boiled in a mixed acid at 150°C to 180°C for 6 to 8 hours to remove impurities. It is then boiled in an industrial caustic soda solution at 250°C to 350°C for 4 to 6 hours. After rinsing and drying, orange CBN crystals are obtained. The mixed acid is composed of 95% to 98% concentrated sulfuric acid and 63% to 65% concentrated nitric acid, with a volume ratio of (2 to 4):(0.5 to 1.5).

[0026] Grading and Selection: After acid and alkali purification, the cubic boron nitride undergoes particle size grading and selection, and then undergoes stereomicroscope inspection to obtain a finished orange flake CBN abrasive. The orange flake CBN abrasive has a compressive strength Ti of 28 to 38, such as 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, and preferably 30 to 35. The HBN conversion rate is 50% to 58%, such as 50%, 52%, 53%, 55%, 57%, 58%, 59%, 60%, and preferably 50% to 55%.

[0027] The flaky CBN of the present invention can be used as abrasive particles in a grinding tool and applied in grinding high-speed steel, surface-hardened steel, cemented carbide, alloy steel, nickel-based high-temperature alloy or cobalt-based high-temperature alloy.

[0028] The abrasive tool of the present invention includes the aforementioned flaky CBN. The abrasive tool can be a grinding wheel, grinding head, or grindstone, and can be used for grinding processes such as rough grinding, fine grinding, mirror grinding, profile grinding, tool sharpening, and honing on materials such as high-speed steel, case-hardened steel, cemented carbide, alloy steel, and nickel-based or cobalt-based superalloys. Due to the high brittleness and low catalyst viscosity of the aforementioned orange CBN flake, the abrasive tool exhibits high grinding efficiency, excellent grinding quality, and a long service life.

[0029] The technical solution of the present invention is further described in detail below through specific embodiments. In the following examples and comparative examples, HBN is prepared from 99% pure HBN raw material powder that has been purified and treated to remove moisture and surface-adsorbed gaseous impurities. The mixed acid used for acid purification is composed of 98% concentrated sulfuric acid and 65% concentrated nitric acid, prepared in a volume ratio of 3:1.

[0030] In the present invention, the static compressive strength test of the CBN abrasive is carried out in accordance with the provisions of "JB / T10985-2020 Determination of compressive strength of superhard abrasives"; and the thermal shock toughness test of each CBN abrasive is carried out with reference to "GB / T 33144-2016 Determination of impact toughness of superhard abrasives".

[0031] Example 1 This embodiment provides a method for preparing a flaky CBN abrasive, comprising the following steps: Raw material mixing: First, place 80 parts of hexagonal boron nitride, 2.5 parts of magnesium nitride, 9 parts of lithium hydride, 1 part of calcium boride, and 1.5 parts of titanium nitride in a sealed container and mix them evenly for 45 minutes to ensure that the raw materials are evenly mixed. Then, use a press to press the mixed raw materials into a mixed blank, and assemble it according to the requirements for use; Synthetic CBN: The synthetic block is loaded into the high-pressure chamber of the six-sided top press, and the temperature is started after the pressure is increased to 25 MPa. When the pressure is increased to 55 MPa, it is maintained for about 4 minutes. During this period, the temperature is increased to 1650℃ after maintaining for 1 minute and then kept warm. Then the pressure is continued to be increased to the synthetic pressure of 88 MPa, maintained for 25 minutes, and then cooled naturally. After cooling naturally for 10 minutes, the pressure is released. Figure 2 As shown; Crushing and purifying CBN: The synthesized CBN sintered block is taken out of the high-pressure chamber, crushed, and soaked in water to remove unconverted HBN. Then, it is boiled in mixed acid at 155°C for 8 hours to remove impurities. Then, it is boiled in industrial caustic soda solution at 350°C for 4 hours. After rinsing and drying, orange CBN crystals are obtained. Grading and selection: After acid and alkali purification, the cubic boron nitride is graded and selected, and then tested under a stereo microscope to obtain the orange flake crystal CBN abrasive product. Figure 3 and Figure 4 Calculations show that the CBN crystal conversion rate of this example is 55%, with most of the crystals being irregular smooth flakes and blocks, with a small amount of polyhedrons. The crystals are highly complete, with peak particle sizes concentrated, with 140 / 170 being the majority, accounting for 35%, and an average compressive strength of 30.

[0032] Example 2 This embodiment provides a method for preparing a flaky CBN abrasive, comprising the following steps: Raw material mixing: First, 83 parts of hexagonal boron nitride, 3 parts of magnesium nitride, 7.5 parts of lithium hydride, 1.2 parts of calcium boride, and 1 part of titanium nitride are placed in a sealed container and uniformly mixed for 45 minutes to ensure that the raw materials are evenly mixed. Then, the mixed raw materials are pressed into a mixed blank using a press and assembled as required for use; Synthesis of CBN: The synthetic block is loaded into the high-pressure chamber of the six-sided top press. After the pressure is increased to 28 MPa, the temperature is started. When the pressure is increased to 60 MPa, it is maintained for about 4 minutes. During this period, the temperature is raised to 1720℃ after being maintained for 1 minute and then kept warm. Then the pressure is further increased to the synthesis pressure of 88 MPa. After maintaining for 25 minutes, the temperature is naturally lowered. After naturally cooling for 12 minutes, the pressure is released. Crushing and purifying CBN: The synthesized CBN sintered block is taken out of the high-pressure chamber, crushed, and soaked in water to remove unconverted HBN. Then, it is boiled in mixed acid at 170°C for 7 hours to remove impurities. Then, it is boiled in industrial caustic soda solution at 300°C for 5 hours. After rinsing and drying, orange CBN crystals are obtained. Grading and Selection: After acid and alkali purification, the cubic boron nitride was subjected to particle size grading and selection, and qualified under stereomicroscope inspection to obtain the finished CBN abrasive in the form of orange flake crystals. Calculations show a 53% conversion rate for the CBN crystals in this example. The crystals are mostly irregular, smooth flakes and blocks, with a small amount of polyhedrons, demonstrating high crystal integrity. The peak particle size is highly concentrated, with 140 / 170 being the most common, accounting for 35%. The average compressive strength is Ti 32.

[0033] Example 3 This embodiment provides a method for preparing a flaky CBN abrasive, comprising the following steps: Raw material mixing: First, place 85 parts of hexagonal boron nitride, 3.8 parts of magnesium nitride, 6 parts of lithium hydride, 1.5 parts of calcium boride, and 0.7 parts of titanium nitride in a sealed container and mix them evenly for 45 minutes to ensure that the raw materials are evenly mixed. Then, use a press to press the mixed raw materials into a mixed blank, and assemble them as required for use; Synthesis of CBN: The synthetic block is loaded into the high-pressure chamber of the six-sided top press. After the pressure is increased to 30 MPa, the temperature is started. When the pressure reaches 65 MPa, it is maintained for about 3 minutes. During this period, the temperature is raised to 1820℃ after being maintained for 1 minute and then kept warm. Then the pressure is further increased to the synthesis pressure of 90 MPa. After maintaining for 28 minutes, the temperature is naturally lowered. After naturally cooling for 15 minutes, the pressure is released. Crushing and purifying CBN: The synthesized CBN sintered block is taken out of the high-pressure chamber, crushed, and soaked in water to remove unconverted HBN. Then, it is boiled in mixed acid at 180°C for 6 hours to remove impurities. Then, it is boiled in industrial caustic soda solution at 250°C for 6 hours. After rinsing and drying, orange CBN crystals are obtained. Grading and Selection: After acid and alkali purification, the cubic boron nitride was subjected to particle size grading and selection, and qualified under stereomicroscope inspection to obtain the finished CBN abrasive in the form of orange flake crystals. Calculations show a 50% conversion rate of the CBN crystals in this example. The crystals are mostly irregular, smooth flakes and blocks, with a small amount of polyhedrons, and exhibit high crystal integrity. The peak particle sizes are highly concentrated, with 140 / 170 being the majority, accounting for 30%. The average compressive strength is Ti 35.

[0034] Comparative Example 1 This comparative example provides a method for preparing CBN abrasive, which is essentially the same as the method provided in Example 1, with the primary difference being that the catalyst in this comparative example consists solely of magnesium nitride and lithium hydride, omitting calcium boride and titanium nitride. All other preparation conditions were the same. The resulting synthesized CBN crystals were pale yellow, predominantly blocky, with uneven particle size and a small amount of translucent, pale white crystals. The CBN crystal conversion rate in this comparative example was 55%, and the average compressive strength was Ti 25.

[0035] Comparative Example 2 This comparative example provides a method for preparing CBN abrasive, which is essentially the same as the method provided in Example 1. The main difference is that the catalyst in this comparative example is composed of magnesium nitride, lithium hydride, and calcium boride, but no titanium nitride. All other preparation conditions are the same. The resulting CBN crystals have a slightly brown and orange color, are mostly blocky, and have uneven particle size. The CBN crystal conversion rate in this comparative example is 52%, and the average compressive strength is Ti 28. Experimental results show that the crystal conversion rate decreases with increasing calcium boride content.

[0036] Comparative Example 3 This comparative example provides a method for preparing CBN abrasive, which is essentially the same as the method provided in Example 1, with the primary difference being that the catalyst in this comparative example is composed of magnesium nitride, lithium hydride, and titanium nitride, and no calcium boride. All other preparation conditions are the same. The resulting CBN crystals have a slightly brownish-orange color, are mostly blocky, and have uneven particle size. The CBN crystal conversion rate in this comparative example is 50%, and the average compressive strength is Ti 28.

[0037] Comparative Example 4 This comparative example provides a method for preparing CBN abrasive, which is essentially the same as the method provided in Example 1, with the primary difference being that the raw materials in this comparative example consist of 87 parts hexagonal boron nitride, 4.5 parts magnesium nitride, 5 parts lithium hydride, 2.5 parts calcium boride, and 1 part titanium nitride. All other preparation conditions were the same. The resulting synthesized CBN crystals were mostly orange in color, with a small amount of fine yellow particles. The crystals were mostly blocky, with a rough surface and uneven particle size. The CBN crystal conversion rate in this comparative example was 50%, and the average compressive strength was Ti 30.

[0038] Comparative Example 5 This comparative example provides a method for preparing CBN abrasive, which is essentially the same as the method provided in Example 1, with the primary difference being that the raw materials in this comparative example consist of 90 parts hexagonal boron nitride, 2 parts magnesium nitride, 6 parts lithium hydride, 1 part calcium boride, and 1 part titanium nitride. All other preparation conditions were the same. The resulting synthesized CBN crystals were primarily orange in color, with irregular and thick plate-like shapes and uniform particle size. The CBN crystal conversion rate in this comparative example was 52%, and the average compressive strength was Ti 32.

[0039] Example 4 This embodiment provides a grinding wheel, which includes CBN abrasives uniformly distributed in a vitrified binder, wherein the CBN abrasives can be the flaky orange CBN abrasives prepared in any one of Embodiments 1 to 4.

[0040] This embodiment also provides an application of the above-mentioned grinding wheel in fine grinding of nickel-based high-temperature alloy GH4169.

[0041] In summary, by using the catalyst provided in the embodiments of the present invention and regulating the raw material ratio of hexagonal boron nitride and the catalyst, orange flaky CBN can be synthesized through high temperature and high pressure treatment with a high CBN conversion rate. The flaky CBN has good brittleness, high static pressure strength, and more edges and corners as an abrasive, thereby making the CBN grinding tool have high self-sharpening properties during the grinding process, which can effectively improve the grinding efficiency and grinding quality, as well as the service life of the grinding tool.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A flaky CBN synthesis catalyst, characterized in that: The invention is composed of magnesium nitride, lithium hydride, calcium boride and titanium nitride, and the mass ratio of magnesium nitride, lithium hydride, calcium boride and titanium nitride is 2.5-4: 5.5-9: 0.5-2: 0.5-1.

5.

2. A sheet-shaped CBN, characterized in that: Its raw materials consist of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride, wherein the mass ratio of hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride and titanium nitride is 80-85: 2.5-4: 5.5-9: 0.5-2: 0.5-1.

5.

3. A method for preparing the flaky CBN according to claim 2, comprising the steps of: first mixing hexagonal boron nitride, magnesium nitride, lithium hydride, calcium boride, and titanium nitride to form a mixed blank; and then subjecting the mixed blank to a high temperature and high pressure treatment to produce orange flaky CBN.

4. The preparation method according to claim 3, wherein In the high temperature and high pressure treatment step, the synthesis high temperature is 1600° C. to 1850° C., and the synthesis pressure is 85 to 90 MPa.

5. The preparation method according to claim 4, wherein The high-temperature and high-pressure treatment steps include: first increasing the pressure of the six-sided top press to 25-35 MPa and then starting to heat, then increasing the pressure to 50-60 MPa and maintaining it for 3-5 minutes, during which time the temperature is increased to 1600°C-1850°C after maintaining it for 0.5-2 minutes and then maintaining the temperature, then continuing to increase the pressure to a synthetic pressure of 85-90 MPa, maintaining it for 20-35 minutes, and then naturally cooling it down, and then releasing the pressure after naturally cooling it down for 10-15 minutes.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The high temperature and high pressure treatment step further includes the following steps: firstly crushing the CBN sintered block synthesized at high temperature and high pressure, and then purifying it to obtain purified CBN crystal particles.

7. The preparation method according to claim 6, characterized in that The method also includes subjecting the purified CBN crystal particles to particle size classification and type selection, and inspecting them under a stereo microscope to obtain orange flaky CBN abrasive products.

8. Use of the flaky CBN according to claim 2 in grinding.

9. The use according to claim 8, characterized in that The flaky CBN is used in grinding high-speed steel, surface-hardened steel, cemented carbide, alloy steel, nickel-based high-temperature alloy or cobalt-based high-temperature alloy.

10. A grinding tool, characterized in that: The present invention comprises the sheet-shaped CBN as described in claim 2.

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