Method and device for preparing copper-based diamond superhard grinding wheel through spark plasma sintering

Abstract

The invention relates to the technical field of superhard grinding materials, in particular to a method and device for preparing a copper-based diamond superhard grinding wheel through spark plasma sintering. The method for preparing the copper-based diamond super-hard grinding wheel through spark plasma sintering comprises the following steps that spark plasma sintering is conducted on a mixture containing a diamond grinding material and a metal bonding agent, and an integrally-formed grinding material ring is obtained; the metal binding agent is mainly composed of bronze powder and titanium powder; and after the abrasive ring is combined with the steel core, the copper-based diamond superhard grinding wheel is obtained. Binder adding, drying and sieving steps and cold press forming are not needed, the mixture is subjected to spark plasma sintering and then is directly and integrally formed to obtain the abrasive ring, the technological process is short, and the production efficiency is high; meanwhile, spark plasma sintering is adopted, the temperature rising speed is high, the heat preservation time is short, the porosity of the abrasive ring obtained after spark plasma sintering is low, diamond falling is not prone to occurring during part machining, and abrasion weight loss is obviously reduced.

Description

Technical Field

[0001] The invention relates to the technical field of superhard abrasives, and in particular to a method and a device for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering. Background Art

[0002] As modern mechanical processing develops towards high precision, high speed, hard processing, dry processing (without coolant) and cost reduction, very high requirements are placed on the performance of abrasive tools. Traditional silicon carbide and corundum ordinary abrasive molds can no longer fully meet the current high-speed, high-efficiency and high-precision grinding requirements. Therefore, it is an inevitable development trend to develop various superhard grinding materials with excellent wear resistance and long-term stable processing. Currently, the commonly used superhard grinding materials include diamond and cubic boron nitride. Diamond is the hardest material and has extremely strong wear resistance. It is suitable for high-speed grinding and ultra-precision grinding. Diamond grinding wheels are very suitable for grinding harder, brittle, and shorter grinding materials such as non-ferrous metal materials, carbides, glass, ceramics, quartz products, and semiconductor and chip materials. The grinding efficiency, processing accuracy and wear resistance of diamond superhard abrasive tools (grinding wheels) are key issues in high-speed precision grinding.

[0003] The binder used to consolidate abrasive grains in superhard abrasive tools is a key factor affecting the performance of superhard abrasive tools. Traditional superhard abrasive tools (grinding wheels) are mostly manufactured using processes such as resin, ceramic, and metal binder sintering and electroplating. The problem is that the single crystal particles are only mechanically embedded and embedded in the binder and the electroplating layer, and the interaction between the binder and the electroplating layer is weak. Specifically, although the resin binder is relatively easy to process and trim, it has poor heat resistance, low bonding strength, and severe abrasive shedding, which seriously affects efficiency. The ceramic binder is relatively easy to trim and has a high operating temperature, but it is brittle, has poor impact toughness and fatigue resistance, is prone to brittle cracking, and is difficult to use for high-speed processing. Although the metal binder sintering has strong heat resistance, chemical metallurgical bonding cannot usually be produced between the binder and the abrasive grains, so the abrasive grains are only mechanically embedded and embedded in the binder, and the holding force is limited. In metal electroplating, the abrasive grains are only mechanically embedded, so it is easy for the abrasive to fall off in particles and the coating to peel off in pieces, which may lead to the overall failure of the grinding wheel. This is particularly obvious when efficiently grinding materials that are difficult to process. In addition, the coating is thick, the abrasive is exposed at a low height, and the chip space is small, so it is easy for the grinding wheel to fail due to the adhesion and blockage of chips during grinding.

[0004] The traditional method of preparing diamond grinding wheels is usually to prepare the grinding wheel green body by cold pressing, then prepare the grinding wheel abrasive ring by vacuum high temperature sintering, and finally combine the steel core and the abrasive ring to prepare the diamond grinding wheel, see Figure 1As shown, the specific operation is as follows: determine the composition and proportion of the raw materials, weigh the raw materials after determination, and mix them; then pour the evenly mixed powder into a beaker, add a binder and stir, and then place the mixed mixture in a drying oven for drying. After drying, sieve the powder, weigh a certain amount of the mixed powder and put it into a customized mold, use a press to cold press and mold it, and demold it after pressure maintenance to obtain a green body. Put the green body into a vacuum high-temperature furnace for sintering, and then cool it with the furnace to obtain an abrasive ring. Finally, combine the abrasive ring with the steel core for assembly and finishing to obtain a diamond grinding wheel. Although this method improves the method of embedding diamonds with a binder and increases the bonding strength between diamonds and metal substrates, the above method has the following disadvantages: (1) The processing flow is cumbersome, the process flow is long, and the production efficiency is low; (2) During the cold pressing stage, the green body will adhere to the mold surface when demolding, causing shape defects of the green body; (3) During the preparation process, a binder needs to be added, screened, and dried, and the mass loss of the binder during drying is difficult to control; (4) The vacuum high-temperature sintering has a slow heating rate and requires a long insulation time. In addition, the abrasive ring prepared after sintering has a high porosity, which makes it easy for diamonds to fall off when processing parts, resulting in significant wear losses.

[0005] In addition, the patent with application number CN201710819270.9 discloses a method for a composite material of a high entropy alloy holding abrasive particles, the method is as follows: after heating and melting each raw material, a high entropy alloy powder is obtained by atomization powder making, and the obtained powder is mechanically ball milled to activate the alloy powder particles. Then the activated high entropy alloy powder is mixed with the abrasive particles to obtain a uniform powder. Then the powder is poured into a mold for discharge plasma sintering to obtain a composite material. However, the composite material obtained by this patent is often used for cutting stone, refractory materials, glass, etc., and belongs to the field of high entropy alloys, but not to the field of superhard abrasives, and is not suitable for steel parts processing and semiconductor silicon wafer processing. This patent is a combination of high entropy alloys and abrasives by inlaying and holding. If this form of combination is used in processing parts or rust removal, it is easy for the abrasive to detach from the metal matrix, causing damage to the abrasive, and this combination form has poor wear performance. In addition, the patent has the following disadvantages: (1) The high entropy alloy powder particles produced by the gas atomization method are large, resulting in uneven contact with the abrasive particles during the sintering process, which easily leads to the formation of pores; (2) The high entropy alloy powder particles need to be mechanically ball milled for activation treatment, which makes the process complicated; (3) The composite cylindrical blank obtained after the discharge plasma sintering needs other treatments to obtain the abrasive ring for the grinding wheel; (4) The high entropy alloy and the abrasive are combined by inlay bonding, and Mo reacts with the abrasive but is not strong.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for preparing copper-based diamond superhard grinding wheels by spark plasma sintering, which does not require the addition of a binder, drying and sieving steps, or cold pressing. The present invention directly pours the mixture into a mold for spark plasma sintering and then directly integrally forms an abrasive ring, which has a simple process, a short process, and high production efficiency. At the same time, the present invention adopts spark plasma sintering, which has a fast heating rate and a short heat preservation time, and the abrasive ring obtained after spark plasma sintering has a low porosity, and diamonds are not easy to fall off when processing parts, and the weight loss due to wear is significantly reduced. The method solves the problems of the traditional method of preparing diamond grinding wheels by first cold pressing to prepare grinding wheel green blanks and then preparing grinding wheel abrasive rings by vacuum high temperature sintering, such as long process, low production efficiency, green blank defects, and high porosity of the prepared abrasive rings.

[0008] The second purpose of the present invention is to provide a device with a simple structure and easy to manufacture. The mixed material can be directly integrally formed into an abrasive ring with low porosity after spark plasma sintering in the device, thereby avoiding the possibility of demolding failure during cold pressing, saving processing time and improving production efficiency.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] The present invention first provides a method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering, comprising the following steps: spark plasma sintering a mixture containing diamond abrasive and a metal binder to obtain an integrally formed abrasive ring; the metal binder is mainly composed of bronze powder and titanium powder; after the abrasive ring is combined with a steel core, the copper-based diamond superhard grinding wheel is obtained.

[0011] Furthermore, the mass ratio of the diamond abrasive to the metal binder is 40-48:52-60.

[0012] Furthermore, the metal binder is composed of bronze powder and titanium powder in a mass ratio of 90-95:5-10.

[0013] Furthermore, the bronze powder is Cu60Sn40 bronze powder.

[0014] Furthermore, the preparation method of the mixture includes: uniformly mixing the diamond abrasive, the bronze powder and the titanium powder; or, plasma atomizing the bronze powder to obtain ultrafine bronze powder, mixing the titanium powder and the diamond abrasive and ball milling to obtain titanium-coated diamond powder, and uniformly mixing the ultrafine bronze powder and the titanium-coated diamond powder.

[0015] Furthermore, the plasma gas used for the plasma atomization includes argon gas.

[0016] Furthermore, the median particle size of the bronze powder is 40 to 80 μm.

[0017] Furthermore, the median particle size of the ultrafine bronze powder is 25 to 40 μm.

[0018] Furthermore, the ball milling time is 10 to 24 hours, the ball milling speed is 150 to 280 r / min, and the ball-to-material ratio of the ball milling is 5 to 18:1.

[0019] Furthermore, the spark plasma sintering pressure is 25-30 MPa.

[0020] Furthermore, the reaction temperature of the spark plasma sintering is 930-980°C.

[0021] Furthermore, the heating rate of the spark plasma sintering is 50-100° C. / min.

[0022] Furthermore, the spark plasma sintering has a heat preservation time of 1 to 10 minutes.

[0023] Furthermore, the atmosphere of the spark plasma sintering is an argon atmosphere.

[0024] Furthermore, the DC pulse output current of the spark plasma sintering is 4500-5500A.

[0025] Furthermore, the pulse frequency of the spark plasma sintering is 20 to 30 ms.

[0026] Furthermore, the density of the abrasive ring is 80% to 85%.

[0027] The present invention further provides a device suitable for the method of preparing copper-based diamond superhard grinding wheel by spark plasma sintering, the device is used as a mold for spark plasma sintering of the mixture, and the device includes an inner graphite column, an outer graphite sleeve, an upper pressure head base and a lower pressure head base; wherein the upper pressure head base includes an integrally formed non-detachable upper pressure plate and an upper pressure ring, and the lower pressure head base includes an integrally formed non-detachable lower pressure plate and a lower pressure ring, and the upper pressure ring and the lower pressure ring are annular in shape; the inner graphite column is shaped like a cylinder, and the outer graphite sleeve is shaped like an annular, the outer graphite sleeve is sleeved on the outside of the inner graphite column, and there is a accommodating space between the outer graphite sleeve and the inner graphite column for accommodating the upper pressure ring and the lower pressure ring; the inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base surround to form a reaction chamber, and the mixture forms an abrasive ring after spark plasma sintering in the reaction chamber.

[0028] Furthermore, at least one layer of graphite paper is provided on the inner wall of the outer graphite sleeve, at least one layer of graphite paper is provided on the outer wall of the inner graphite column, at least one layer of graphite paper is provided on the outer surface of the lower pressure head base, and at least one layer of graphite paper is provided on the outer surface of the upper pressure head base.

[0029] Furthermore, the outer surface of the graphite paper is coated with at least one graphite insulation layer having pores.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The method for preparing copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention does not require the addition of a binder during the preparation of abrasives, and there is no drying and sieving step, and no cold pressing is required. The mixed material is directly poured into a mold for spark plasma sintering. The process is simple, the flow is short, and the production efficiency is high. At the same time, the spark plasma sintering has a fast heating speed, and the processing can be completed with a short insulation time; and the abrasive ring obtained after spark plasma sintering has a low porosity, can withstand a large load during high-speed grinding, and is not prone to diamond shedding when processing parts. At the same time, it has excellent impact resistance and good shape retention.

[0032] (2) The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention uses a plasma atomization method to prepare powder. The obtained metal bronze powder has fine particles, which is half the particle size of the powder obtained by the atomization method. During the sintering process, it is fully combined with the diamond abrasive and has a low porosity.

[0033] (3) The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention has a stronger metallurgical bond between the diamond and the metal matrix, and the abrasive is not easy to fall off during the processing.

[0034] (4) The device for spark plasma sintering provided by the present invention can be integrally formed to produce an abrasive ring with low porosity, and avoids the possibility of demolding failure during cold pressing, thereby saving processing time and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of a conventional method for preparing a diamond grinding wheel;

[0037] Figure 2 A schematic flow chart of a method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention;

[0038] Figure 3 A schematic diagram of the structure of the abrasive ring provided by the present invention;

[0039] Figure 4 A schematic diagram of the structure of a copper-based diamond superhard grinding wheel provided by the present invention;

[0040] Figure 5 A schematic diagram of the structure of the device provided by the present invention. DETAILED DESCRIPTION

[0041] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0042] If there is no special explanation, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0043] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0044] If there is no special explanation, in the present invention, "one or more" or "at least one" refers to any one, any two or more of the listed items. Among them, "several" refers to any two or more of the listed items.

[0045] In a first aspect, the present invention provides a method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering, comprising the following steps:

[0046] A mixture containing diamond abrasive and metal binder is placed in a mold, and the mold is placed in a spark plasma sintering furnace for spark plasma sintering. After sintering, the mixture is cooled in the furnace to obtain an integrally formed abrasive ring.

[0047] Wherein, the metal binder is mainly composed of bronze powder and titanium powder (metal titanium powder).

[0048] After the abrasive ring is combined with the steel core, the copper-based diamond superhard grinding wheel is obtained.

[0049] The method for preparing copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention does not need to add a binder during the preparation of abrasives, and there is no drying and sieving step, and no cold pressing is required. The mixed material is directly poured into a mold for spark plasma sintering, and the process is simple, the process is short, and the production efficiency is high. At the same time, the spark plasma sintering has a fast heating speed, and the processing can be completed with a short insulation time; and the abrasive ring obtained after spark plasma sintering has a low porosity, can withstand a large load during high-speed grinding, and is not easy to fall off when processing parts, and has excellent impact resistance and good shape retention.

[0050] Compared with the superhard grinding wheel abrasive ring prepared by vacuum high temperature sintering, the superhard grinding wheel abrasive ring prepared by spark plasma sintering in the present invention has the same reaction layer thickness, but the porosity and mass loss due to wear are significantly lower than that.

[0051] Specifically, the microstructure of the copper-based diamond superhard grinding wheel abrasive ring prepared by discharge plasma sintering was analyzed by SEM, EDS and XRD, and its phase composition, element distribution, and interface reaction layer thickness were basically consistent with those of the copper-based diamond superhard grinding wheel abrasive ring prepared by vacuum high temperature sintering. The copper-based diamond superhard grinding wheel abrasive ring prepared by the present invention was tested for performance. The porosity of the abrasive ring prepared by discharge plasma sintering was 15% to 20%, and the friction and wear loss was 1 to 5 mg. The porosity of the abrasive ring prepared by vacuum high temperature sintering was about 35% to 40%, and the friction and wear loss was 35 to 40 mg. Therefore, the method provided by the present invention not only greatly improves the wear performance and density of the grinding wheel abrasive ring, but also greatly shortens the processing time and improves production efficiency.

[0052] The schematic diagram of the process of the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided by the present invention is shown in Figure 2 shown.

[0053] The structural schematic diagram of the abrasive ring prepared by the present invention is shown in Figure 3 shown.

[0054] The structural schematic diagram of the copper-based diamond superhard grinding wheel prepared by the present invention is shown in Figure 4shown.

[0055] In some specific embodiments, the mass ratio of the diamond abrasive to the metal binder is 40-48:52-60, for example, 40:60, 41:59, 42:58, 43:57, 44:56, 45:55, 46:54, 47:53, 48:52, 49:51, 50:50, 51:49 or 52:48. Diamond abrasives are particles that play a wear-resistant role, and the content of the components cannot be too low. If it is too low, the wear resistance of the grinding wheel will be reduced and the weight loss due to wear will be too high. The content of diamond abrasives cannot be too high either, as diamond abrasives will form agglomerations in the metal matrix, which will also cause a large number of diamond particles to fall off as a whole during processing, reducing the wear resistance of the grinding wheel.

[0056] In some specific embodiments, the metal binder is composed of bronze powder and titanium powder in a mass ratio of 90-95:5-10. The mass ratio of bronze powder to titanium powder can be 90:10, 91:9, 92:8, 93:7, 94:6 or 95:5.

[0057] In some specific implementations, the bronze powder is Cu60Sn40 bronze powder.

[0058] The bronze powder is bronze powder (Cu60Sn40), which is mainly composed of Cu-Sn intermetallic compounds and does not react with pure titanium powder. The metal binder adopts the above ratio, and the titanium powder can completely react with the diamond particles, and a high-strength metallurgical bond is formed at the interface. There will be no excess titanium powder in the metal matrix to reduce the strength of the metal matrix. At this time, the metal matrix is ​​only composed of bronze powder, with good hardness and brittleness matching, high strength and good wear resistance.

[0059] In some specific implementations, the method for preparing the mixture includes: uniformly mixing the diamond abrasive, the bronze powder and the titanium powder.

[0060] Different from vacuum high-temperature sintering, the present invention does not need to screen and add a bonding agent after the raw materials are evenly mixed. The present invention reduces the steps of screening, adding a bonding agent and drying, which can save time and improve efficiency.

[0061] Alternatively, the preparation method of the mixture includes: plasma atomizing the bronze powder to obtain ultrafine bronze powder; drying the titanium powder and the diamond abrasive to remove moisture, mixing and ball milling to obtain titanium-coated diamond powder, that is, the titanium powder is coated on the outer surface of the diamond abrasive; and then uniformly mixing the ultrafine bronze powder and the titanium-coated diamond powder.

[0062] The abrasive ring and grinding wheel prepared by the method are suitable for superhard abrasive tool fields such as steel parts processing and semiconductor silicon wafer processing, and have obvious requirements on the strength of the holding force between the metal matrix and the abrasive.

[0063] The present invention prepares powder by plasma atomization, and the obtained metal bronze powder has fine particles, which is half the particle size of the powder obtained by atomization. During the sintering process, the powder is fully combined with diamond abrasive and has low porosity.

[0064] In some specific implementations, the porosity of the abrasive ring prepared by the present invention is 15% to 20%.

[0065] In addition, the present invention mixes diamond abrasive and titanium powder for ball milling to obtain titanium-coated diamond, which can not only refine diamond particles, but also allow the diamond to fully contact with the titanium powder, so that the diamond is sintered densely and evenly with the metal matrix during the sintering process, and titanium carbide is formed on the surface of the diamond after sintering.

[0066] In addition, the reaction layer thickness of the superhard grinding wheel prepared by the present invention is 1.7 μm, and the diamond and the metal matrix are combined in the form of a compound, which is much more firmly held than inlaying, and the abrasive is not easy to fall off during the processing.

[0067] In some specific embodiments, the mixing is carried out in a mixer, such as a TD-6 three-dimensional vortex mixer. The rotation speed during mixing can be 18 to 40 r / min, the operation mode is unidirectional operation, and the mixing time can be 8 to 14 hours, but is not limited thereto.

[0068] In some specific embodiments, the plasma gas used for the plasma atomization includes argon or helium, preferably argon, which has lower cost.

[0069] In some specific embodiments, the median particle size of the bronze powder is 40-80 μm, including but not limited to any point value of 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, or a range value between any two of them.

[0070] In some specific embodiments, the median particle size of the ultrafine bronze powder is 25 to 40 μm, including but not limited to any point value of 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 37 μm, and 40 μm, or a range value between any two of them. Specifically, the bronze powder is injected into an inert gas plasma, completely evaporated and converted into steam under high temperature, and then rapidly cooled using a gas quenching cooling technique to obtain an ultrafine bronze powder. The present invention adopts a plasma atomization method to prepare the powder, and the median particle size of the obtained powder is smaller. The use of ultrafine bronze powder can be more evenly mixed with titanium powder, the metal matrix composition formed after the reaction is more uniform, and the wear resistance of the abrasive tool is better.

[0071] In some specific embodiments, the median particle size of the titanium powder is 40-80 μm, including but not limited to any point value of 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm or a range value between any two of them.

[0072] In some specific embodiments, the ball milling time is 10 to 24 hours, such as 12 hours, 15 hours, 18 hours or 20 hours; the ball milling speed is 150 to 280 r / min, such as 180 r / min, 200 r / min, or 240 r / min; the ball-to-material ratio of the ball milling is 5 to 18:1, such as 6:1, 8:1, 10:1, 12:1 or 15:1. Preferably, after the diamond abrasive and titanium powder are dried to remove moisture, they are poured into a planetary ball mill for ball milling. The ball milling equipment can be any equipment commonly used in the art, such as a planetary ball mill, but is not limited thereto.

[0073] In some specific embodiments, the pressure of the spark plasma sintering is 25 to 30 MPa; including but not limited to any point value of 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa or the range value between any two. Under this pressure condition, the wear resistance, chip capacity and heat dissipation of the diamond grinding wheel can be well balanced. Among them, if the pressure is too large, the grinding wheel is too dense, the porosity is low, it is not conducive to the removal of workpiece debris and heat during processing, burns the workpiece surface, and affects the quality; if the pressure is too small, the grinding wheel porosity is large, and the wear resistance of the grinding wheel will be reduced. Therefore, the above pressure range can take into account the excellent wear resistance of the grinding wheel, as well as the advantages of good chip capacity and heat dissipation.

[0074] In some specific embodiments, the reaction temperature of the spark plasma sintering is 930-980°C; including but not limited to any point value of 940°C, 950°C, 960°C, 970°C or any range value between two of them. Within this temperature range, the interface between the diamond particles and the metal matrix in the grinding wheel can form a good interface bonding strength. However, too high a temperature can cause thermal damage such as graphitization to the diamond particles, reduce the strength of the diamond particles, and further reduce the wear resistance. If the temperature is too low, the interface reaction is not thorough enough, the interface bonding strength is low, and the wear resistance is reduced.

[0075] In some specific embodiments, the heating rate of the spark plasma sintering is 50-100°C / min, including but not limited to any one of 60°C / min, 70°C / min, 80°C / min, 90°C / min or a range between any two of them.

[0076] In some specific embodiments, the holding time of the spark plasma sintering is 1 to 10 min, including but not limited to any one of 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or a range between any two of them.

[0077] In some specific embodiments, the spark plasma sintering atmosphere is an argon atmosphere or a helium atmosphere, preferably an argon atmosphere, which has lower cost.

[0078] In some specific embodiments, during the spark plasma sintering process, the pressure of argon gas is lower than 0.5 MPa.

[0079] In some specific embodiments, the DC pulse output current of the spark plasma sintering is 4500-5500A; including but not limited to any point value of 4500A, 4600A, 4800A, 5000A, 5200A, 5500A or the range value between any two. The magnitude of the current output is directly related to the output heat. Among them, if the output current is too small, the heat is low, and the effect of quickly heating the inside of the sample cannot be achieved. Not only will the interface reaction proceed slowly and the interface bonding strength be low, but also the fluidity of the metal matrix will deteriorate after melting, and the porosity will increase, which will eventually lead to a decrease in the wear resistance of the grinding wheel. If the output current is too large, the temperature inside the sample rises too quickly, which may cause adverse effects such as graphitization of diamond particles and overmelting of the metal matrix, and may also cause a decrease in the wear resistance of the grinding wheel.

[0080] In some specific embodiments, the pulse frequency of the spark plasma sintering is 20 to 30 ms, including but not limited to any point value of 20ms, 22ms, 23ms, 25ms, 28ms, and 30ms or a range value between any two of them. The magnitude of the pulse frequency is also related to the output heat. Among them, if the pulse frequency is too low, the heat input is slow, and the effect of rapid heating inside the sample cannot be achieved, which will cause the interface reaction to proceed slowly and the fluidity of the metal matrix to deteriorate after melting, resulting in lower interface bonding strength and increased porosity, which will eventually lead to a decrease in the wear resistance of the grinding wheel. If the pulse frequency is too large, the temperature inside the sample rises too quickly, which may cause adverse effects such as graphitization of diamond particles and overmelting of the metal matrix, and may also cause a decrease in the wear resistance of the grinding wheel.

[0081] In some specific embodiments, the density of the abrasive ring is 80% to 85%, including but not limited to any point value of 81%, 82%, 83%, 84%, 85% or a range value between any two of them.

[0082] The components of the abrasive ring prepared by the present invention are diamond, metal matrix and interface reaction layer, wherein the interface reaction layer is titanium carbide. It can be understood that the bronze powder is Cu60Sn40, so the metal matrix is ​​mainly composed of copper-tin intermetallic compounds Cu3Sn and Cu6Sn5 which are both hard and brittle.

[0083] In some specific embodiments, the abrasive ring is bonded to the steel core by a special bonding agent, wherein the bonding agent can be any reagent commonly used in the art, and the present invention does not limit this. Afterwards, the burrs are removed and the shape is trimmed to obtain the copper-based diamond superhard grinding wheel.

[0084] The size of the copper-based superhard diamond grinding wheel prepared by the present invention can be set as needed. For example, the inner diameter of the copper-based superhard diamond grinding wheel is 85 mm, the outer diameter is 95 mm, and the width is 10 mm, but it is not limited thereto.

[0085] In some specific implementations, the dry friction load of the copper-based diamond superhard grinding wheel is 50N, the friction time is 60min, and the mass loss is 1-5mg.

[0086] In a second aspect, the present invention provides a device suitable for the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering, wherein the device is used as a mold for spark plasma sintering of a mixture, see Figure 3 As shown, the device includes an inner graphite column, an outer graphite sleeve, an upper pressure head base and a lower pressure head base.

[0087] Wherein, the materials of the inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base are all graphite materials, preferably high-strength graphite materials, and the compressive strength of the high-strength graphite materials is 600-800MPa. Wherein, the upper pressure head base includes an upper pressure plate and an upper pressure ring that are integrally formed and cannot be disassembled. They are respectively referred to as the upper pressure plate and the upper pressure ring here for the convenience of describing the shape, size and positional relationship of the upper pressure head base, wherein the shape of the upper pressure ring is annular, and the shape of the upper pressure plate is disc-shaped. The lower pressure head base includes an integrally formed and non-detachable lower pressure plate and a lower pressure ring, which are respectively referred to as the lower pressure plate and the lower pressure ring here for the convenience of describing the shape, size and positional relationship of the lower pressure head base, wherein the shape of the lower pressure ring is annular, and the shape of the lower pressure plate is disc-shaped, and the inner diameter and outer diameter of the upper pressure ring and the lower pressure ring are the same.

[0088] It is understandable that the heights of the upper pressure ring and the lower pressure ring may be the same or different.

[0089] The inner graphite column is in the shape of a solid cylinder, the outer graphite sleeve is in the shape of a hollow ring, the outer graphite sleeve is sleeved on the outside of the inner graphite column, and there is a accommodating space between the outer graphite sleeve and the inner graphite column; the accommodating space is used to accommodate the upper pressure ring and the lower pressure ring, and form a reaction chamber for adding a mixed material and performing spark plasma sintering.

[0090] The inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base surround and form a reaction chamber. When in use, the inner graphite column, the outer graphite sleeve and the lower pressure head base are assembled and then a mixture is added into the enclosed gap, i.e., the reaction chamber. The shape of the reaction chamber is annular, and the size of the reaction chamber is adapted to the size of the prepared abrasive ring. Then, the upper pressure head base is placed and pressed, and the mixture forms an abrasive ring after spark plasma sintering in the reaction chamber.

[0091] It is understood that the size of the reaction chamber can be adjusted by the sizes of the inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base.

[0092] The device provided by the present invention is a mold used for spark plasma sintering in the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering. It has a simple structure and is easy to prepare. The mixed material can be directly integrally formed into an abrasive ring with a low porosity after spark plasma sintering in the device, thereby avoiding the possibility of demolding failure during cold pressing, saving processing time, and improving production efficiency.

[0093] It is understandable that the mixture is placed in a spark plasma sintering furnace, and the upper pressure head base and the lower pressure head base are respectively connected to the oil pressure device of the spark plasma sintering furnace, and the upper pressure head base and the lower pressure head base are pressurized by the oil pressure device, so as to achieve pressure on the mixture. During the spark plasma sintering process, a pulse current is passed, and the upper pressure head base and the lower pressure head base are respectively connected to the pulse current generator of the spark plasma sintering furnace. Under the action of the pulse current, discharge is generated between the material particles, plasma is excited, and rapid sintering of the mixture is achieved.

[0094] The structural schematic diagram of the abrasive ring made by the device provided by the present invention, i.e., the mold, is shown in FIG. Figure 3 As shown, the abrasive ring is in the shape of a circular ring.

[0095] In some specific embodiments, at least one layer of graphite paper is disposed on the inner wall of the outer graphite sleeve, at least one layer of graphite paper is disposed on the outer wall of the inner graphite column, at least one layer of graphite paper is disposed on the outer surface of the lower pressure head base, and at least one layer of graphite paper is disposed on the outer surface of the upper pressure head base. The graphite paper disposed at each location is at least one layer, for example, two layers, three layers or more.

[0096] Graphite paper can isolate the mixture placed inside the device from the upper pressure head base, the lower pressure head base, the inner graphite column and the outer graphite sleeve, so that the current does not pass through the mixture and a temperature gradient is generated above and below the outer graphite sleeve. That is, the graphite paper mainly plays the role of insulation, preventing the current from passing through the material and avoiding short circuits. In addition, graphite paper has a high thermal conductivity, which can generate uniform Joule heat between powder particles, can quickly heat up, and accelerate the sintering process.

[0097] In some specific embodiments, the outer surface of the graphite paper is coated with at least one graphite insulating layer having pores. The graphite insulating layer is at least one layer, for example, two layers, three layers or more. The graphite insulating layer mainly plays the role of electrical insulation, preventing the current from being conducted on an unexpected path during plasma discharge, avoiding the occurrence of short circuit, thereby ensuring the normal operation of the equipment and the stability of the sintering process. The graphite insulating layer has a certain thermal insulation performance, which can reduce the loss of heat from the sintering area to the surrounding environment and play a role in heat preservation. The main function of the pores is to effectively discharge the air between the powder particles during sintering. During the sintering process, the sample and the graphite insulating layer will release gases, such as adsorbed air, moisture, and gases generated by the decomposition of the material itself. These pores provide a discharge channel for the gas, preventing the gas from accumulating in the sintering chamber to form high pressure, affecting the quality of the sintered body, and preventing defects such as pores and cracks.

[0098] The sizes of the inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base in the present invention can be set according to the size of the required abrasive ring. For example, the diameter of the inner graphite column is 80 mm, the inner diameter of the outer graphite sleeve is 100 mm, and the width of the upper pressure ring and the lower pressure ring is 20 mm (i.e., the width of the reaction chamber is 20 mm, and the width of the abrasive ring is 20 mm), but it is not limited thereto.

[0099] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0100] Example 1

[0101] The device (i.e., mold) for spark plasma sintering provided in this embodiment is shown in FIG. Figure 5As shown, it includes an inner graphite column, an outer graphite sleeve, an upper pressure head base and a lower pressure head base. Among them, the upper pressure head base includes an integrally formed non-detachable upper pressure plate and an upper pressure ring, and the lower pressure head base includes an integrally formed non-detachable lower pressure plate and a lower pressure ring, the upper pressure ring and the lower pressure ring are in the shape of annular rings, the inner diameter and outer diameter of the upper pressure ring and the lower pressure ring are the same, and the upper pressure plate and the lower pressure plate are in the shape of a disc. The material of the inner graphite column and the outer graphite sleeve is a graphite material with a compressive strength of 600Mpa. The shape of the inner graphite column is a solid cylinder, the shape of the outer graphite sleeve is a hollow ring, the outer graphite sleeve is sleeved on the outside of the inner graphite column, and there is a holding space for accommodating the upper pressure ring and the lower pressure ring between the outer graphite sleeve and the inner graphite column. The inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base surround and form a reaction chamber. A layer of graphite paper is arranged on the inner wall of the outer graphite sleeve, a layer of graphite paper is arranged on the outer wall of the inner graphite column, a layer of graphite paper is arranged on the outer surface of the lower pressure head base, and a layer of graphite paper is arranged on the outer surface of the upper pressure head base; and the outer surface of each graphite paper is covered with a graphite insulation layer with pores.

[0102] Example 2

[0103] Using the device (i.e., mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this embodiment comprises the following steps:

[0104] (1) Pour diamond abrasive, bronze powder (Cu60Sn40, purity ≥ 99.9%) and pure titanium powder (purity ≥ 99.9%) into a TD-6 three-dimensional vortex mixer and mix for 12 hours to obtain a mixture, wherein the mass ratio of diamond abrasive to metal binder is 45:55, the mass ratio of bronze powder to pure titanium powder is 93:7, and the median particle size of bronze powder and pure titanium powder is 40 μm.

[0105] (2) pouring the mixture into a reaction chamber surrounded by a lower pressure head base, an inner graphite column and an outer graphite sleeve, and covering the upper pressure head base; then placing the mold in a spark plasma sintering furnace for spark plasma sintering, wherein the upper pressure head base and the lower pressure head base are respectively connected to the oil pressure device of the spark plasma sintering furnace, and the upper pressure head base and the lower pressure head base are pressurized by the oil pressure device to apply pressure to the mixture, the pressurized pressure is 28MPa, the sintering reaction temperature is 950℃, the heating rate is 80℃ / min, and the pressure is maintained at 100℃. The heating time is 10 min, the sintering atmosphere is argon, and the pressure of argon is always set to be lower than 0.5 MPa during the sintering process; at the same time, a pulse current is introduced, and the upper pressure head base and the lower pressure head base are respectively connected to the pulse current generator of the spark plasma sintering furnace. The DC pulse output current is 5000 A, and the pulse frequency is 25 ms. Under the action of the pulse current, discharge is generated between the material particles, and plasma is excited to achieve rapid sintering of the mixture. After the insulation is completed, it is naturally cooled to obtain a copper-based diamond superhard grinding wheel abrasive ring.

[0106] After testing, the density of the copper-based diamond superhard grinding wheel abrasive ring prepared in this embodiment is 84.6% (high density means low porosity), and the components of the copper-based diamond superhard grinding wheel abrasive ring are diamond, metal matrix and interface reaction layer, and the interface reaction layer is titanium carbide.

[0107] (3) The abrasive ring prepared above is combined with the steel core through a special bonding agent (epoxy resin) for grinding wheels, and the burrs are removed and trimmed to obtain a copper-based diamond superhard grinding wheel.

[0108] Example 3

[0109] Using the device (i.e., mold) of Example 1, the method for preparing copper-based diamond superhard grinding wheel by spark plasma sintering provided in this embodiment is basically the same as that in Example 2, except that step (1) is different. Step (1) of this embodiment is: using plasma atomization method, bronze powder with a median particle size of 40 μm is injected into argon plasma, and it is completely evaporated and converted into steam under high temperature, and then gas quenching cooling technology is used to achieve rapid cooling, thereby obtaining ultrafine copper-based metal powder with a median particle size of 25 μm. After the diamond abrasive and pure titanium powder are dried to remove moisture, they are poured into a planetary ball mill for ball milling. Among them, the ball milling time is 12h, the ball milling speed is 200r / min, and the ball-to-material ratio is 10:1. Titanium-coated diamond powder is obtained after ball milling. Then the above-mentioned ultrafine copper-based metal powder and the above-mentioned titanium-coated diamond powder are added to a TD-6 three-dimensional vortex mixer and mixed for 12h to obtain a mixture.

[0110] Example 4

[0111] Using the device (i.e., mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this embodiment comprises the following steps:

[0112] (1) Using plasma atomization method, bronze powder (Cu60Sn40, purity ≥99.9%) with a median particle size of 80 μm was injected into argon plasma, and completely evaporated and converted into steam under high temperature, and then rapidly cooled by gas quenching cooling technology to obtain ultrafine copper-based metal powder with a median particle size of 35 μm. Diamond abrasive and pure titanium powder were dried to remove moisture and poured into a planetary ball mill for ball milling. The ball milling time was 10 h, the ball milling speed was 280 r / min, and the ball-to-material ratio was 15:1. Titanium-coated diamond powder was obtained after ball milling. Then the ultrafine copper-based metal powder and the titanium-coated diamond powder were added to a TD-6 three-dimensional vortex mixer and mixed for 12 h to obtain a mixture. The mass ratio of diamond abrasive to metal binder was 48:52, the mass ratio of bronze powder to pure titanium powder was 95:5, and the median particle size of bronze powder and pure titanium powder was 60 μm.

[0113] (2) pouring the mixture into a reaction chamber surrounded by a lower pressure head base, an inner graphite column and an outer graphite sleeve, and covering the upper pressure head base; then placing the mold in a spark plasma sintering furnace for spark plasma sintering, wherein the upper pressure head base and the lower pressure head base are respectively connected to the oil pressure device of the spark plasma sintering furnace, and the upper pressure head base and the lower pressure head base are pressurized by the oil pressure device to achieve pressure on the mixture, the pressurized pressure is 25MPa, the sintering reaction temperature is 930°C, and the heating rate is 50°C / min. The holding time is 5 minutes, the sintering atmosphere is argon, and the pressure of argon is always set to be lower than 0.5MPa during the sintering process; at the same time, a pulse current is introduced, and the upper pressure head base and the lower pressure head base are respectively connected to the pulse current generator of the spark plasma sintering furnace. The DC pulse output current is 4500A, and the pulse frequency is 20ms. Under the action of the pulse current, discharge is generated between the material particles, and plasma is excited to achieve rapid sintering of the mixture. After the holding period is completed, it is naturally cooled to obtain a copper-based diamond superhard grinding wheel abrasive ring.

[0114] After testing, the density of the copper-based diamond superhard grinding wheel abrasive ring prepared in this embodiment is 82.6%. The copper-based diamond superhard grinding wheel abrasive ring is composed of diamond, metal matrix and interface reaction layer, and the interface reaction layer is titanium carbide.

[0115] (3) The abrasive ring prepared above is combined with the steel core through a special bonding agent (epoxy resin) for grinding wheels, and the burrs are removed and trimmed to obtain a copper-based diamond superhard grinding wheel.

[0116] Example 5

[0117] Using the device (i.e., the mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this example is basically the same as that of Example 4, except that in step (1), the mass ratio of diamond abrasive to metal binder is 40:60.

[0118] The density of the copper-based diamond superhard grinding wheel abrasive ring prepared in this embodiment is 83.6%.

[0119] Example 6

[0120] Using the apparatus (i.e., mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this example is basically the same as that of Example 4, except that in step (1), the mass ratio of bronze powder to pure titanium powder is 90:10.

[0121] The density of the copper-based diamond superhard grinding wheel abrasive ring prepared in this embodiment is 82.0%.

[0122] Example 7

[0123] Using the device (i.e., the mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this embodiment is basically the same as that of Example 4, except that: in step (2), the parameters of spark plasma sintering are as follows: the pressure is 30 MPa, the sintering reaction temperature is 980°C, the heating rate is 50°C / min, the holding time is 1 min, the DC pulse output current is 5500A, and the pulse frequency is 30 ms.

[0124] The density of the copper-based diamond superhard grinding wheel abrasive ring prepared in this embodiment is 82.2%.

[0125] Comparative Example 1

[0126] This comparative example adopts a traditional method for preparing a diamond grinding wheel, which specifically includes the following steps:

[0127] (1) Pour diamond abrasive, bronze powder (Cu60Sn40, purity ≥ 99.9%) and pure titanium powder (purity ≥ 99.9%) into a TD-6 three-dimensional vortex mixer and mix for 12 hours to obtain a mixture, wherein the mass ratio of diamond abrasive to metal binder is 45:55, the mass ratio of bronze powder to pure titanium powder is 93:7, and the median particle size of bronze powder and pure titanium powder is 40 μm.

[0128] (2) Pour the mixture into a beaker, add a binder (acrylic acid solution, the mass of which is 5% of the mass of the mixture) and stir evenly, then place the mixed material in a drying oven for drying. After drying, sieve the powder (300 mesh), weigh a certain amount of the mixture powder and put it into a mold, use a press to perform cold pressing (40t, 2min), maintain the pressure and demold, and obtain a green body.

[0129] (3) The green body is placed in a vacuum high-temperature furnace for sintering (950°C, 30 min), and then cooled in the furnace to obtain an abrasive ring.

[0130] (4) The abrasive ring and the steel core are combined with a special bonding agent for grinding wheels (the same type as in Example 2), and the burrs are removed and trimmed to obtain a diamond grinding wheel.

[0131] The density of the abrasive ring prepared in this comparative example is 64.0%.

[0132] Comparative Example 2

[0133] Using the device (i.e., the mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this comparative example is basically the same as that of Example 4, except that: no pure titanium powder is added, i.e., only bronze powder is used as the metal binder, and the amount of the metal binder remains unchanged.

[0134] The density of the abrasive ring prepared in this comparative example is 78.4%.

[0135] Comparative Example 3

[0136] Using the device (i.e., the mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this comparative example is basically the same as that of Example 4, except that the mass ratio of diamond abrasive to metal binder is 70:30, and the mass ratio of bronze powder to pure titanium powder is 80:20.

[0137] The density of the abrasive ring prepared in this comparative example is 45.0%.

[0138] Comparative Example 4

[0139] Using the device (i.e., the mold) of Example 1, the method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering provided in this comparative example is basically the same as that of Example 4, except that: in step (2), the parameters of spark plasma sintering are as follows: the pressure is 10 MPa, the sintering reaction temperature is 900°C, the heating rate is 100°C / min, the holding time is 1 min, the DC pulse output current is 3500A, and the pulse frequency is 10 ms.

[0140] The density of the abrasive ring prepared in this comparative example is 75.0%.

[0141] Experimental example

[0142] The performance tests were performed on the grinding wheels prepared in each embodiment and each comparative example, and the results are shown in Table 1.

[0143] Table 1 Superhard grinding wheel performance test results

[0144] Group Thickness of interface reaction layer Wear weight loss Porosity Impact toughness Example 2 1.70μm 5.0mg 15.4％ <![CDATA[4.31J / cm 2 ]]> Example 3 1.75μm 3.0mg 15.2％ <![CDATA[4.36J / cm 2 ]]> Example 4 1.38μm 15.8mg 17.4％ <![CDATA[3.74J / cm 2 ]]> Example 5 1.38μm 14.2mg 16.4％ <![CDATA[3.88J / cm 2 ]]> Example 6 1.38μm 19.6mg 18.0％ <![CDATA[3.58J / cm 2 ]]> Example 7 0.86μm 24.6mg 17.8％ <![CDATA[3.72J / cm 2 ]]> Comparative Example 1 1.70μm 31.4mg 36.0％ <![CDATA[3.24J / cm 2 ]]> Comparative Example 2 0μm 76.4mg 21.6％ <![CDATA[3.41J / cm 2 ]]> Comparative Example 3 1.38μm 58.7mg 55.0％ <![CDATA[2.7J / cm 2 ]]> Comparative Example 4 0.67μm 28.4mg 25.0％ <![CDATA[3.2J / cm 2 ]]>

[0145] It can be seen from Table 1 that the diamond / Cu-based superhard grinding wheels prepared by plasma spark sintering obtained in each embodiment have lower porosity, lower wear weight loss and higher impact toughness.

[0146] In Comparative Example 1, conventional vacuum high-temperature sintering is performed by cold pressing before sintering. The grinding wheel produced by this method has a large porosity, resulting in a large loss due to wear. In Example 2, spark plasma sintering is performed while heating in the reaction chamber, resulting in a lower porosity, less loss due to wear, and better impact toughness. The thickness of the interface reaction layer of the two methods is consistent.

[0147] In Comparative Example 2, Ti powder was not added. Since diamond and bronze powder do not react, this method causes diamond to be buried in the metal matrix, resulting in a large loss in weight due to wear. However, since spark plasma sintering is used and the bronze powder is dense, the porosity is small and the impact toughness is poor.

[0148] In Comparative Example 3, since the proportion of diamond abrasive is too high, agglomeration is likely to occur during the sintering process, resulting in a larger porosity, a larger wear weight loss, and poor impact toughness.

[0149] In Comparative Example 4, the spark plasma sintering process parameters are not suitable, so that the reaction time of the mixture in the reaction chamber is too short, resulting in a thin interface reaction layer, a large porosity, a large wear weight loss, and poor impact toughness.

[0150] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering, characterized in that: The steps include: The mixture containing diamond abrasive and metal binder is subjected to spark plasma sintering to obtain an integrally formed abrasive ring; the metal binder is mainly composed of bronze powder and titanium powder; After the abrasive ring is combined with the steel core, the copper-based diamond superhard grinding wheel is obtained.

2. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 1, characterized in that: The mass ratio of the diamond abrasive to the metal binder is 40-48:52-60.

3. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 1, characterized in that: The metal binder is composed of bronze powder and titanium powder in a mass ratio of 90-95:5-10; And / or, the bronze powder is Cu60Sn40 bronze powder.

4. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 1, characterized in that: The preparation method of the mixture comprises: uniformly mixing the diamond abrasive, the bronze powder and the titanium powder; or, plasma atomizing the bronze powder to obtain ultrafine bronze powder, mixing the titanium powder and the diamond abrasive and ball milling to obtain titanium-coated diamond powder, and uniformly mixing the ultrafine bronze powder and the titanium-coated diamond powder.

5. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 4, characterized in that: The plasma gas used for the plasma atomization includes argon; Preferably, the median particle size of the bronze powder is 40 to 80 μm; More preferably, the median particle size of the ultrafine bronze powder is 25 to 40 μm.

6. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 4, characterized in that: The ball milling time is 10 to 24 hours, the ball milling speed is 150 to 280 r / min, and the ball-to-material ratio of the ball milling is 5 to 18:

1.

7. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to claim 1, characterized in that: At least one of the following conditions is met: (1) The spark plasma sintering pressure is 25-30 MPa; (2) The reaction temperature of the spark plasma sintering is 930-980° C.; (3) The heating rate of the spark plasma sintering is 50 to 100° C. / min; (4) The holding time of the spark plasma sintering is 1 to 10 minutes; (5) The atmosphere of the spark plasma sintering is an argon atmosphere; (6) The DC pulse output current of the spark plasma sintering is 4500-5500A; (7) The pulse frequency of the spark plasma sintering is 20 to 30 ms.

8. The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering according to any one of claims 1 to 7, characterized in that: The density of the abrasive ring is 80% to 85%.

9. A device, characterized in that: The method for preparing a copper-based diamond superhard grinding wheel by spark plasma sintering as claimed in any one of claims 1 to 8, wherein the device is used as a mold for spark plasma sintering of a mixture, and the device comprises an inner graphite column, an outer graphite sleeve, an upper pressure head base and a lower pressure head base; Wherein, the upper pressure head base includes an upper pressure plate and an upper pressure ring which are integrally formed and cannot be disassembled, and the lower pressure head base includes a lower pressure plate and a lower pressure ring which are integrally formed and cannot be disassembled, and the upper pressure ring and the lower pressure ring are in the shape of rings; The inner graphite column is in the shape of a cylinder, the outer graphite sleeve is in the shape of a ring, the outer graphite sleeve is sleeved on the outside of the inner graphite column, and there is an accommodating space between the outer graphite sleeve and the inner graphite column for accommodating the upper pressure ring and the lower pressure ring; The inner graphite column, the outer graphite sleeve, the upper pressure head base and the lower pressure head base surround and form a reaction chamber, and the mixed material forms an abrasive ring after spark plasma sintering in the reaction chamber.

10. The device according to claim 9, characterized in that: At least one layer of graphite paper is disposed on the inner wall of the outer graphite sleeve, at least one layer of graphite paper is disposed on the outer wall of the inner graphite column, at least one layer of graphite paper is disposed on the outer surface of the lower pressure head base, and at least one layer of graphite paper is disposed on the outer surface of the upper pressure head base; Preferably, the outer surface of the graphite paper is coated with at least one graphite insulation layer having pores.

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