A nano-diamond compact and a preparation method and application thereof

Abstract

The application provides a nano-diamond compact and a preparation method and application thereof, and belongs to the technical field of diamond compacts. The nano-diamond compact provided by the application comprises a hard alloy substrate and superhard material hot-pressed on the surface of the hard alloy substrate, and the superhard material is prepared from raw materials with the following mass percentage: diamond micro powder 85-95.5%; cubic boron nitride 1.5-6%; tungsten carbide 1-3%; cobalt powder 1-5%; tantalum powder 0.5-3%; vanadium powder 0.2-3%; and graphene 0.1-1%. The cubic boron nitride, the tungsten carbide and the graphene can toughen and strengthen the nano-diamond compact; the cobalt powder, the tantalum powder and the vanadium powder can catalyze and bond. The nano-diamond compact has good toughness, and can effectively avoid the cracking of the nano-structure diamond compact.

Description

Technical Field

[0001] This invention relates to the field of diamond composite sheet technology, and particularly to a nanodiamond composite sheet, its preparation method, and its application. Background Technology

[0002] Diamond composite sheets are a type of superhard material composite sheet, polymerized with diamond as the main material on a cemented carbide substrate. They are characterized by high hardness and excellent wear resistance, and are widely used in industries such as oil drilling, geological exploration, coalfield drilling bits, and machining tools. These include commonly used machine tool turning tools, machining drill bits, and milling cutters and profile milling cutters for edge machining. Due to increasing processing demands, the precision requirements of workpieces are becoming increasingly stringent, leading to a greater demand for superhard material cutting tools. Generally, the finer the diamond grain size in the superhard material composite sheet, the lower the surface roughness of the workpiece processed as a cutting tool. This better meets the needs of non-ferrous metal or inorganic material processing industries for cutting instead of grinding, thereby saving time and labor costs in processing industries that require high precision and efficiency.

[0003] Currently, the synthesis of diamond composite sheets mainly involves using three ferrous metal catalysts—iron, cobalt, and nickel—to transform diamond particles into polycrystalline materials through high temperature and pressure. However, as the size of diamond particles decreases, the hardness and brittleness of diamond composite sheets become more severe. The main problem with synthesizing fine-particle diamond composite sheets is that the material has high stress and brittleness, making it extremely prone to cracking. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a nanodiamond composite sheet, its preparation method and application. The nanodiamond composite sheet provided by this invention can effectively prevent the cracking of the nanostructured diamond composite sheet.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a nanodiamond composite sheet, comprising a cemented carbide substrate and a superhard material hot-pressed onto the surface of the cemented carbide substrate, wherein the superhard material is prepared from raw materials comprising the following mass percentages:

[0007]

[0008]

[0009] Preferably, the particle size of the diamond micro powder is 1-200 nm;

[0010] The diameter of the cubic boron nitride sheet is 1–100 nm;

[0011] The particle size of the tungsten carbide is 1–100 nm;

[0012] The cobalt powder has a particle size of 1–100 nm;

[0013] The particle size of the tantalum powder is 1–100 nm;

[0014] The vanadium powder has a particle size of 1–100 nm.

[0015] Preferably, the graphene is one or more of single-layer graphene, multilayer graphene, and graphene-like materials.

[0016] This invention provides a method for preparing the above-mentioned nanodiamond composite sheet, comprising the following steps:

[0017] Diamond micro powder, cubic boron nitride, tungsten carbide, cobalt powder, tantalum powder, vanadium powder and graphene are ball-milled and mixed to obtain mixed micro powder;

[0018] The mixed micro powder was placed in a hydrogen atmosphere to carry out a reduction reaction, thereby obtaining reduced mixed micro powder;

[0019] The cemented carbide sheet and the reduced mixed micro powder are pressed into shape to obtain a pre-assembled composite sheet;

[0020] Under vacuum conditions, the pre-assembled composite sheet is heated, purified, and shaped to obtain a purified and shaped composite sheet.

[0021] The purified and shaped composite sheet is subjected to high temperature and high pressure treatment to obtain a nano-diamond composite sheet.

[0022] Preferably, the ball milling mixing rate is 120-180 r / min and the time is 3-9 h.

[0023] Preferably, the reduction reaction is carried out at a temperature of 350–950°C for 0.5–3 hours; and the hydrogen pressure in the hydrogen atmosphere is 0.02–0.1 MPa.

[0024] Preferably, the pressing pressure is 3 to 5 tons and the time is 3 to 30 seconds.

[0025] Preferably, the heating, purification, and shaping temperature is 600–1100℃, and the holding time is 1–3 hours;

[0026] The vacuum level of the vacuum condition is 10. -2 ~10 -4 Pa.

[0027] Preferably, the high temperature and high pressure treatment is performed at a temperature of 1600–1900°C, a pressure of 5–6.5 GPa, and a holding time of 12–25 min.

[0028] This invention provides the application of the above-mentioned nanodiamond composite sheet in cutting tools.

[0029] This invention provides a nanodiamond composite sheet, comprising a cemented carbide substrate and a superhard material hot-pressed onto the surface of the cemented carbide substrate. The superhard material is prepared from raw materials comprising the following mass percentages: 85-95.5% diamond micropowder; 1.5-6% cubic boron nitride; 1-3% tungsten carbide; 1-5% cobalt powder; 0.5-3% tantalum powder; 0.2-3% vanadium powder; and 0.1-1% graphene. This invention adds cubic boron nitride, tungsten carbide, and graphene. The cubic boron nitride and tungsten carbide fill the gaps between diamond particles and form bonds with cobalt, tantalum, and vanadium, preventing diamond growth, reducing material stress, and increasing material toughness. The graphene sheet structure can be converted into diamond during diamond polycrystalline synthesis, resulting in more DD bonds between adjacent diamond particles, increasing the material's strength and toughness, thus strengthening the nanodiamond composite sheet. In this invention, cobalt powder, tantalum powder, and vanadium powder act as catalysts and binders. Compared to iron and cobalt powders, the cobalt, tantalum, and vanadium powders used in this invention are more stable during use, less prone to oxidation, and more suitable for use as catalysts and binders in nano-scale diamond composite sheets. The nanodiamond composite sheet obtained by this invention has good toughness and can effectively prevent cracking of the nanostructured diamond composite sheet.

[0030] This invention provides a method for preparing the aforementioned nanodiamond composite sheets. During high-temperature and high-pressure processing, diamond micropowder forms polycrystalline aggregates, and DD bonds are formed between the diamond micropowder particles, thus connecting the diamond particles into sheets. The preparation method provided by this invention is simple to operate and easy to implement for industrial-scale mass production. Attached Figure Description

[0031] Figure 1 This is a microstructure diagram of the nanodiamond composite sheet obtained in Example 1. Detailed Implementation

[0032] This invention provides a nanodiamond composite sheet, comprising a cemented carbide substrate and a superhard material hot-pressed onto the surface of the cemented carbide substrate, wherein the superhard material is prepared from raw materials comprising the following mass percentages:

[0033]

[0034]

[0035] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0036] In this invention, the cemented carbide is preferably YG16. The thickness of the cemented carbide is preferably 3-6 mm, more preferably 4-5 mm, and even more preferably 3.5 mm.

[0037] In this invention, the thickness of the superhard material on the surface of the cemented carbide is preferably 0.3 to 0.9 mm, more preferably 0.6 mm.

[0038] The superhard material comprises 85-95.5% diamond micropowder, preferably 88-92%, and more preferably 90% by mass percentage. In this invention, the particle size of the diamond micropowder is preferably 1-200 nm, more preferably 10-150 nm, and even more preferably 50-100 nm.

[0039] The superhard material comprises 1.5-6% cubic boron nitride, preferably 2-5%, and more preferably 3-4% by mass percentage. In this invention, the sheet diameter of the cubic boron nitride is preferably 1-100 nm, more preferably 10-80 nm, and even more preferably 30-50 nm.

[0040] The superhard material comprises 1-3% tungsten carbide by mass percentage, preferably 1.5-2.5%, and more preferably 2%. In this invention, the particle size of the tungsten carbide is preferably 1-100 nm, more preferably 10-80 nm, and even more preferably 30-50 nm.

[0041] The superhard material comprises 1-5% cobalt powder by weight, preferably 2-4%, and more preferably 3%. In this invention, the particle size of the cobalt powder is preferably 1-100 nm, more preferably 10-80 nm, and even more preferably 30-50 nm.

[0042] The superhard material comprises 0.5-3% tantalum powder, preferably 1-2.5%, and more preferably 1.5-2%, by mass percentage. In this invention, the particle size of the tantalum powder is preferably 1-100 nm, more preferably 10-80 nm, and even more preferably 30-50 nm.

[0043] The superhard material comprises 0.2-3% vanadium powder by weight percentage, preferably 0.5-2.5%, more preferably 1-2%. In this invention, the particle size of the vanadium powder is preferably 1-100 nm, more preferably 10-80 nm, and even more preferably 30-50 nm.

[0044] The superhard material comprises 0.1-1% graphene by weight, preferably 0.3-0.8%, and more preferably 0.5%. In this invention, the graphene is one or more of single-layer graphene, multilayer graphene, and graphene-like materials. In this invention, the number of graphene layers is preferably 1-20, and more preferably 3-10.

[0045] This invention provides a method for preparing the above-mentioned nanodiamond composite sheet, comprising the following steps:

[0046] Diamond micro powder, cubic boron nitride, tungsten carbide, cobalt powder, tantalum powder, vanadium powder and graphene are ball-milled and mixed to obtain mixed micro powder;

[0047] The mixed micro powder was placed in a hydrogen atmosphere to carry out a reduction reaction, thereby obtaining reduced mixed micro powder;

[0048] The cemented carbide sheet and the reduced mixed micro powder are pressed into shape to obtain a pre-assembled composite sheet;

[0049] Under vacuum conditions, the pre-assembled composite sheet is heated, purified, and shaped to obtain a purified and shaped composite sheet.

[0050] The purified and shaped composite sheet is subjected to high temperature and high pressure treatment to obtain a nano-diamond composite sheet.

[0051] This invention involves ball milling and mixing diamond micropowder, cubic boron nitride, tungsten carbide, cobalt powder, tantalum powder, vanadium powder, and graphene to obtain a mixed micropowder. In this invention, the ball milling is preferably wet ball milling; the ball milling medium is preferably stainless steel balls; and the dispersion medium is preferably an organic solvent, preferably one or more of ethanol, ethylene glycol, propanol, acetone, and n-heptane, more preferably ethanol.

[0052] In this invention, the ball milling mixing rate is preferably 120-180 r / min, more preferably 120-150 r / min, and the time is preferably 3-9 h, more preferably 6 h.

[0053] In this invention, after ball milling and mixing, the resulting mixed powder is preferably dried and sieved. The drying temperature is preferably 80°C; the sieving is preferably performed through a 100-mesh sieve.

[0054] After obtaining the mixed micropowder, the present invention places the mixed micropowder in a hydrogen atmosphere and carries out a reduction reaction to obtain reduced mixed micropowder. In the present invention, the pressure of the hydrogen in the hydrogen atmosphere is preferably 0.02–0.1 MPa, more preferably 0.04–0.08 MPa. In the present invention, the temperature of the reduction reaction is preferably 350–950°C, more preferably 500–700°C; the time is preferably 0.5–3 h, more preferably 2 h. In the present invention, metal powder is easily oxidized to oxides, thereby reducing catalyst activity. The present invention, through the reduction reaction, can reduce the oxidized metal catalyst, thereby restoring catalytic activity.

[0055] After obtaining the reduced mixed micro powder, the present invention presses the cemented carbide sheet and the reduced mixed micro powder together to obtain a pre-assembled composite sheet. In this invention, the pressing is preferably performed in a niobium cup. Specifically, the reduced mixed micro powder is preferably spread evenly in a niobium cup, covered with a cemented carbide sheet, and fitted with a suitable molybdenum cup as a lid before pressing. In this invention, based on a niobium cup with a diameter of 35 mm, the mass of the reduced mixed micro powder used in a single pressing is preferably 3-5 g, more preferably 3.5 g.

[0056] The present invention preferably uses a hydraulic press for the pressing and molding process. In this invention, the pressing pressure is preferably 3 to 5 tons, more preferably 5 tons; the pressing time is preferably 3 to 30 seconds, more preferably 5 to 20 seconds. In this invention, the pressing and molding process is preferably carried out indoors at room temperature and humidity below 45%.

[0057] After obtaining the pre-assembled composite sheet, the present invention heats and purifies the pre-assembled composite sheet under vacuum conditions to obtain a purified and shaped composite sheet. Preferably, the heating and purification is performed in a vacuum furnace. In the present invention, the vacuum degree is preferably 10. -2 ~10 -4 Pa, more preferably 10 Pa -4 Pa. In this invention, the preferred temperature for heating, purifying, and shaping is 600–1100°C, more preferably 600–800°C; the preferred holding time is 1–3 hours, more preferably 2 hours. In this invention, the preferred heating rate to the heating, purifying, and shaping temperature is 20°C / min. In this invention, during the heating and purifying process, the air adsorbed in the powder is released under vacuum and high temperature, while the binder slightly melts at high temperature, causing the material to solidify from powder into a block.

[0058] After obtaining the purified and shaped composite sheet, the present invention subjectes the purified and shaped composite sheet to high-temperature and high-pressure treatment to obtain nanodiamond composite sheets. Preferably, the high-temperature and high-pressure treatment is performed using a six-sided press. In the present invention, the temperature of the high-temperature and high-pressure treatment is preferably 1600–1900℃, more preferably 1750–1800℃; the pressure is preferably 5–6.5 GPa, more preferably 6 GPa; and the holding time is preferably 12–25 min, more preferably 18–20 min. In the present invention, the heating rate of the high-temperature and high-pressure treatment is preferably 400℃ / min, and the pressure rate is preferably 10 GPa / min. In the present invention, during the high-temperature and high-pressure treatment, diamond micropowder forms polycrystalline crystals, and DD bonds are formed between the diamond micropowder particles, causing the diamond particles to be linked into sheets.

[0059] This invention provides the application of the aforementioned nanodiamond composite sheet in cutting tools. In this invention, the cutting tool is preferably one or more of the following: machining tools, solid diamond end mills, solid diamond drills, micro drills, and twist end mills.

[0060] The following detailed description of the nanodiamond composite sheet, its preparation method, and its application provided by the present invention, with reference to specific embodiments, should not be construed as limiting the scope of protection of the present invention.

[0061] Example 1

[0062] (1) 93.0 g of 200 nm diamond powder, 2.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0063] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0064] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0065] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0066] (5) The purified and shaped composite sheet is matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided top press. The pressure is 6.0 GPa, the temperature is 1750℃, and the heat and pressure holding time is 18 min to obtain a nano diamond composite sheet with no cracks in appearance.

[0067] The microstructure of the obtained nanodiamond composite sheet is shown in the figure below. Figure 1 As shown, by Figure 1 As can be seen, the main material is black, which is nanodiamond with poor conductivity. The whiter part between the nanodiamond particles is a mixture of cobalt, tantalum, and vanadium with better conductivity. The gray part in the gaps is cubic boron nitride or tungsten carbide. The particles in the figure are interconnected.

[0068] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.8 × 10⁻⁶. 4 .

[0069] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.65 mm, showing dimple fracture.

[0070] Example 2

[0071] (1) 93.0 g of 200 nm diamond powder, 1.0 g of 100 nm cubic boron nitride, 2.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled in a stainless steel container with organic solvent at a rate of 120 r / min for 6 hours. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0072] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0073] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0074] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0075] (5) The purified and shaped composite sheet is matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided top press. The pressure is 6.0 GPa, the temperature is 1750℃, and the heat and pressure holding time is 18 min to obtain a nano diamond composite sheet with no cracks in appearance.

[0076] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.7 × 10⁻⁶. 4 .

[0077] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.52 mm, showing dimple fracture.

[0078] Example 3

[0079] (1) 94.0 g of 200 nm diamond powder, 1.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0080] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0081] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0082] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0083] (5) The purified and shaped composite sheet is matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided top press. The pressure is 6.0 GPa, the temperature is 1750℃, and the heat and pressure holding time is 18 min to obtain a nano diamond composite sheet with no cracks in appearance.

[0084] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.8 × 10⁻⁶. 4 .

[0085] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was processed into a sample with a diameter of 13.8 mm by wire electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.68 mm, showing dimple fracture.

[0086] Example 4

[0087] (1) 94.0 g of 200 nm diamond powder, 1.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0088] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0089] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0090] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0091] (5) The purified and shaped composite sheet was matched with a suitable traditional carbonate tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 5.5 GPa, the temperature was 1750℃, and the holding time was 18 min, to obtain a nano-diamond composite sheet. There were no cracks in the appearance.

[0092] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Method for Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.5 × 10⁻⁶. 4 .

[0093] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.75 mm, showing dimple fracture.

[0094] Example 5

[0095] (1) 94.0 g of 200 nm diamond powder, 1.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled in a stainless steel container with organic solvent at a rate of 120 r / min for 6 hours. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0096] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0097] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0098] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0099] (5) The purified and shaped composite sheet was matched with a suitable traditional carbonate tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 6.0 GPa, the temperature was 1600℃, and the holding time was 18 min to obtain a nano-diamond composite sheet. There were no cracks in the appearance.

[0100] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.7 × 10⁻⁶. 4 .

[0101] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.66 mm, showing dimple fracture.

[0102] Comparative Example 1

[0103] (1) 94.0 g of 200 nm diamond powder, 5.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 0–100 nm vanadium powder were ball-milled in a stainless steel container with organic solvent at a rate of 120 r / min for 6 hours. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0104] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0105] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0106] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0107] (5) The purified and shaped composite sheet was matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided top press. The pressure was 6.0 GPa, the temperature was 1750℃, and the heat and pressure holding time was 18 min. The resulting nanodiamond composite sheet polycrystalline layer had cracks on its appearance.

[0108] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.8 × 10⁻⁶. 4 .

[0109] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 2.37 mm, showing dimple fracture.

[0110] Comparative Example 2

[0111] (1) 94.0 g of 200 nm diamond powder, 1.5 g of 1–100 nm tungsten carbide powder, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0112] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0113] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0114] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0115] (5) The purified and shaped composite sheet was matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 6.0 GPa, the temperature was 1750℃, and the heat and pressure holding time was 18 min. The resulting nanodiamond composite sheet polycrystalline layer had obvious cracks.

[0116] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.8 × 10⁻⁶. 4 .

[0117] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 2.36 mm, showing dimple fracture.

[0118] Comparative Example 3

[0119] (1) 94.0 g of 200 nm diamond powder, 2.0 g of 100 nm cubic boron nitride, 0.2 g of 3-10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1-100 nm vanadium powder were ball-milled in a stainless steel container with organic solvent at a rate of 120 r / min for 6 hours. The mixture was dried at 80 °C and sieved through a 100 mesh sieve to obtain a mixed powder.

[0120] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0121] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0122] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0123] (5) The purified and shaped composite sheet was matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 6.0 GPa, the temperature was 1750℃, and the heat and pressure holding time was 18 min. The resulting nanodiamond composite sheet polycrystalline layer had obvious cracks.

[0124] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.7 × 10⁻⁶. 4 .

[0125] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.82 mm, showing dimple fracture.

[0126] Comparative Example 4

[0127] (1) 94.0 g of 200 nm diamond powder, 2.0 g of 100 nm cubic boron nitride, 1.5 g of 1-100 nm tungsten carbide, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1-100 nm vanadium powder were ball-milled in a stainless steel container with organic solvent at a rate of 120 r / min for 6 hours. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0128] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0129] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0130] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0131] (5) The purified and shaped composite sheet was matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 6.0 GPa, the temperature was 1750℃, and the holding time was 18 min. 50% of the samples of the obtained nanodiamond composite sheet had obvious cracks in the polycrystalline layer.

[0132] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.7 × 10⁻⁶. 4 .

[0133] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.96 mm, showing dimple fracture.

[0134] Comparative Example 5

[0135] (1) 93.0 g of 200 nm diamond powder, 2.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0136] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0137] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0138] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0139] (5) The purified and shaped composite sheet was matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided press. The pressure was 4.5 GPa, the temperature was 1750℃, and the heat and pressure holding time was 18 min. The resulting nano-diamond composite sheet had obvious cracks, most of the polycrystalline layer surface was graphitized and blackened, and most of the polycrystalline layer of the composite sheet was delaminated.

[0140] Undelaminated samples were selected, and the wear ratio of the obtained nanodiamond composite sheets was tested using the method specified in JB / T 3235-2013: Test Method for Wear Ratio of Polycrystalline Diamond. The wear ratio of the nanodiamond composite sheets obtained by testing with a silicon carbide grinding wheel was 1.2 × 10⁻⁶. 4 .

[0141] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 3.61 mm, showing dimple fracture.

[0142] Comparative Example 6

[0143] (1) 93.0 g of 200 nm diamond powder, 2.0 g of 100 nm cubic boron nitride, 1.5 g of 1–100 nm tungsten carbide, 0.2 g of 3–10 layer graphene, 2.0 g of 100 nm cobalt powder, 0.8 g of 200 nm tantalum powder, and 0.4 g of 1–100 nm vanadium powder were ball-milled for 6 hours at a rate of 120 r / min in a stainless steel container with organic solvent. The mixture was dried at 80 °C and sieved through a 100-mesh sieve to obtain a mixed powder.

[0144] (2) The mixed micro powder was reduced in hydrogen at 500℃ for 2 hours at a hydrogen pressure of 0.08MPa to obtain the reduced mixed micro powder.

[0145] (3) Spread 3.5g of reduced mixed micro powder into a 35mm diameter niobium cup and cover it with a 3mm thick hard alloy (grade YG16). Match a suitable molybdenum cup as a lid, and use a hydraulic press to compact the powder at a pressure of 5 tons to obtain a pre-assembled composite sheet.

[0146] (4) Place the pre-assembled composite sheet into a vacuum furnace and heat it at 10°C. -4 The material is heated, purified, and shaped under vacuum conditions at 600℃, and kept at that temperature for 2 hours to obtain a purified and shaped composite sheet.

[0147] (5) The purified and shaped composite sheet is matched with a suitable traditional carbon salt tube and pyrophyllite block, and subjected to high temperature and high pressure treatment in a six-sided top press. The pressure is 6.0 GPa, the temperature is 1500℃, and the heat and pressure holding time is 18 min to obtain the nano diamond composite sheet.

[0148] The wear ratio of the obtained nanodiamond composite sheet was tested according to "JB / T 3235-2013: Determination of Wear Ratio of Polycrystalline Diamond". The wear ratio of the nanodiamond composite sheet obtained by testing with a silicon carbide grinding wheel was 1.7 × 10⁻⁶. 4 .

[0149] The impact toughness of the nanodiamond composite sheet was tested using an impact toughness tester. The nanodiamond composite sheet was wire-cut into a sample with a diameter of 13.8 mm by electrical discharge machining. The hammer height was 13.5 cm, the hammer weight was 0.6 kg, the single impact energy was 0.7938 J, and after 30 consecutive impacts, the edge breakage length was 1.79 mm, showing dimple fracture.

[0150] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A nanodiamond composite sheet, comprising a cemented carbide substrate and a superhard material hot-pressed onto the surface of the cemented carbide substrate, wherein the superhard material is prepared from raw materials in the following mass percentages: Diamond micron powder 85~95.5%; Cubic boron nitride 1.5~6%; Tungsten carbide 1~3%; Cobalt powder 1~5%; Tantalum powder 0.5~3%; Vanadium powder 0.2~3%; Graphene 0.1~1%; The diamond micro powder has a particle size of 200 nm; The cubic boron nitride has a sheet diameter of 100 nm; The particle size of the tungsten carbide is 1~100nm; The cobalt powder has a particle size of 100 nm; The tantalum powder has a particle size of 200 nm; The vanadium powder has a particle size of 1~100nm.

2. The nanodiamond composite sheet according to claim 1, characterized in that, The graphene is one or both of single-layer graphene and multi-layer graphene.

3. A method for preparing the nanodiamond composite sheet according to claim 1 or 2, comprising the following steps: Diamond micro powder, cubic boron nitride, tungsten carbide, cobalt powder, tantalum powder, vanadium powder and graphene are ball-milled and mixed to obtain mixed micro powder; The mixed micro powder was placed in a hydrogen atmosphere to carry out a reduction reaction, thereby obtaining reduced mixed micro powder; The cemented carbide sheet and the reduced mixed micro powder are pressed into shape to obtain a pre-assembled composite sheet; Under vacuum conditions, the pre-assembled composite sheet is heated, purified, and shaped to obtain a purified and shaped composite sheet; the heating and purification temperature is 600~1100℃, and the holding time is 1~3h; the vacuum degree is 10. -2 ~10 -4 Pa; The purified and shaped composite sheet is subjected to high temperature and high pressure treatment to obtain a nano-diamond composite sheet.

4. The preparation method according to claim 3, characterized in that, The ball milling mixing rate is 120~180 r / min, and the time is 3~9 h.

5. The preparation method according to claim 3, characterized in that, The reduction reaction is carried out at a temperature of 350~950℃ for a time of 0.5~3h; the hydrogen pressure in the hydrogen atmosphere is 0.02~0.1MPa.

6. The preparation method according to claim 3 or 5, characterized in that, The pressing pressure is 3-5 tons, and the time is 3-30 seconds.

7. The preparation method according to claim 3, characterized in that, The high-temperature and high-pressure treatment is carried out at a temperature of 1600~1900℃, a pressure of 5~6.5GPa, and a holding time of 12~25min.

8. The application of the nanodiamond composite sheet according to claim 1 or 2 or the nanodiamond composite sheet prepared by the preparation method according to any one of claims 3 to 7 in cutting tools.

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