Polishing block for diamond polishing and preparation method and application thereof

Abstract

The invention relates to the technical field of diamond grinding tools, and particularly discloses a polishing block for diamond polishing and a preparation method and application thereof. The invention provides a polishing block for diamond polishing. The polishing block is prepared from the following raw materials in parts by weight: 10-15 parts of a resin binder, 50-70 parts of a diamond abrasive, 10-20 parts of a ceramic binder and 1-20 parts of a diamond polishing agent, the ceramic bond comprises silica sol, boric acid and nitrate in a weight ratio of (5-6): 2: (2-3); in the preparation process of the polishing block, firstly, the ceramic bond and the diamond polishing agent are subjected to mixing, spray granulation and presintering, and the nano-diamond polishing particles are obtained. The invention further provides a preparation method of the polishing block and the prepared polishing disc. The polishing disc for diamond polishing has the beneficial effects of being low in cost, high in polishing efficiency, long in service life and the like, and the machining requirement for diamond materials can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diamond polishing tools, in particular to a polishing block for diamond polishing and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of modern science and technology, diamond is widely used in high-tech fields such as petroleum exploration, precision machining, rail transportation, semiconductor materials, aerospace and biomedicine due to its excellent characteristics such as extremely high hardness, stable chemical properties, wide band gap and high thermal conductivity; therefore, the polishing processing of diamond materials is particularly important.

[0003] Diamond material is a typical hard and brittle difficult-to-machine material. Traditional polishing processing of ordinary materials mostly uses ordinary abrasive polishing wheels such as silicon carbide or corundum, or uses free micro-powder diamond polishing solution for chemical mechanical polishing, or uses cerium oxide powder for polishing processing with a polishing disc; however, these polishing methods all have the disadvantages of low polishing efficiency and poor polishing quality; especially, the use of free micro-powder diamond polishing solution has the problems of low diamond utilization rate, difficult shape surface control and environmental pollution; in addition, the cerium oxide abrasive polishing disc needs to use cerium oxide, but cerium oxide is expensive and has high cost, which is difficult to be widely used. In recent years, a grinding block for CVD diamond rough polishing is reported in the related art, which is prepared from diamond-silicon carbide abrasive, high molecular polymer binder, glass fiber and filler; but the high molecular polymer binder used in the grinding block has a certain elasticity, which makes the diamond micro-powder poor in edge out during polishing, resulting in long polishing cycle and poor surface processing quality.

[0004] Therefore, there is an urgent need in the market for a diamond polishing disc with high polishing efficiency, good surface processing quality and long service life. SUMMARY

[0005] In order to overcome the defects of high cost, low polishing efficiency and short service life of the existing diamond polishing disc, the present application provides a polishing block for diamond polishing and a preparation method and application thereof.

[0006] The polishing block for diamond polishing provided by the present application adopts the following technical scheme: A polishing block for diamond polishing, the polishing block is made of raw materials including the following weight parts: resin binder 10-15 parts, diamond abrasive 50-70 parts, ceramic binder 10-20 parts and diamond polishing agent 1-20 parts; The ceramic binder contains silica sol, boric acid and nitrate in a weight ratio of (5-6) : 2 : (2-3) ; The diamond abrasive particle size is 40-60pm; the diamond polishing agent particle size is 50-500nm; In the preparation process of the polishing block, first, the ceramic binder and the diamond polishing agent are mixed, sprayed and granulated, and pre-sintered to obtain nano-diamond polishing particles.

[0007] The resin binder used in the polishing block has good bonding performance and chemical stability, can better bond the raw materials together, and ensure the basic structural stability of the polishing block. The diamond abrasive can quickly remove the diamond machining allowance, providing a basis for efficient polishing; and the larger particle size can ensure sufficient grinding force during polishing, accelerate material removal speed, and improve polishing efficiency. The ceramic binder can improve the bonding strength of the polishing block, has higher overall bonding strength compared to traditional high polymer binder, improves processing efficiency, and also considers the polishing surface quality; on the other hand, the ceramic binder can also enhance the wear resistance and heat resistance of the polishing block, ensure that the polishing block will not be easily damaged during polishing, and prolong its service life. The diamond polishing agent can play a fine polishing role during grinding, reduce scratches, greatly reduce the surface roughness of the ground workpiece, and improve the surface processing quality. In addition, the ceramic binder and the diamond polishing agent are pre-prepared into nano-diamond polishing particles with a larger particle size, and then mixed with diamond abrasive and the like to prepare the polishing block, which can effectively avoid the agglomeration of nano-diamond powder in the wet mixing system, thereby reducing the performance of the polishing block.

[0008] In some embodiments, the weight parts of the ceramic binder can be 10-15 parts or 15-20 parts.

[0009] In a specific embodiment, the weight parts of the ceramic binder can also be 10 parts, 15 parts or 20 parts.

[0010] In some embodiments, the weight parts of the diamond polishing agent can be 1-5 parts, 1-10 parts, 1-15 parts, 1-20 parts, 5-10 parts, 5-15 parts, 5-20 parts, 10-15 parts, 10-20 parts or 15-20 parts.

[0011] In a specific embodiment, the weight parts of the diamond polishing agent can also be 1 part, 5 parts, 10 parts, 15 parts or 20 parts.

[0012] Optionally, the polishing block includes the following weight parts of raw materials: resin binder 10-15 parts, diamond abrasive 50-70 parts, ceramic binder 15-20 parts, diamond polishing agent 5-15 parts.

[0013] Optionally, the preparation method of the nanodiamond polishing particles comprises the following steps: The nanosilica sol, boric acid and nitrate are dissolved in water, and stirred uniformly to obtain a liquid ceramic binder; Then the liquid ceramic binder and diamond polishing agent are mixed, and a dispersant, a binder and a solvent are added and mixed by ball milling to obtain a mixed slurry; The mixed slurry is subjected to spray granulation, pre-sintering and screening to obtain nanodiamond polishing particles; the pre-sintering temperature is 400-600°C, and the holding time is 10-270min.

[0014] Optionally, the pre-sintering adopts a microwave pre-sintering process, and the heating power of the microwave pre-sintering is 1-3kW, and the holding time is 10-30min.

[0015] The application further adopts a microwave pre-sintering process, which can on the one hand enable the ceramic binder to form a reaction layer and fully wrap the diamond polishing agent, and on the other hand can refine the internal grain size and reduce the porosity, so that the nanodiamond polishing particles have excellent mechanical strength. The application can effectively avoid the agglomeration of nanodiamond powder in the wet mixing system, which leads to the decline of various performances of the polishing block, by pre-preparing the ceramic binder and the diamond polishing agent into nanodiamond polishing particles with a larger particle size, and then wet mixing with diamond abrasive to prepare a polishing block.

[0016] In some embodiments, the microwave power can be 1-1.5kW, 1-2kW, 1-2.5kW, 1-3kW, 1.5-2kW, 1.5-2.5kW, 1.5-3kW, 2-2.5kW, 2-3kW or 2.5-3kW.

[0017] In a specific embodiment, the microwave power can also be 1kW, 1.5kW, 2kW, 2.5kW or 3kW.

[0018] In some embodiments, the pre-sintering temperature can be 400-450°C, 400-500°C, 400-600°C, 450-500°C, 450-600°C or 500-600kW.

[0019] In a specific embodiment, the pre-sintering temperature can also be 400°C, 450°C, 500°C or 600°C.

[0020] In some embodiments, the pre-sintering time can be 10-20min or 20-30min.

[0021] In a specific embodiment, the pre-sintering time can also be 10min, 20min or 30min. In some embodiments, the pre-sintering time can be 10-20min or 20-30min.

[0022] In the present application, the dispersant can be sodium cetyl sulfate or polyvinylpyrrolidone or Tween-80, and the addition amount of the dispersant is 0.5%-5% of the total weight of the liquid ceramic binder and the diamond polishing agent; the binder can be one of dextrin, water glass and high molecular adhesive, and the addition amount of the binder is 1-10% of the total weight of the liquid ceramic binder and the diamond polishing agent.

[0023] Optionally, the pressure of the spray granulation is 0.2-0.3Mpa, and the temperature is 180-220℃. Optionally, in the mixing and ball milling step, the weight ratio of the ball and the material is (1-10):1, and the weight ratio of the material and the solvent is 1:(1-5); the ball milling speed is 200-400r / min, and the ball milling time is 10-100h.

[0024] Optionally, the solvent in the mixing and ball milling step is water. Optionally, the resin binder is selected from one or more of phenolic resin, epoxy resin and polyurethane resin. The nitrate salt includes aluminum nitrate, lithium nitrate, sodium nitrate, potassium nitrate and calcium nitrate. The diamond polishing agent contains nano-diamond, and the mass percentage of the nano-diamond in the diamond polishing agent is 50-100%.

[0025] Optionally, the diamond polishing agent further contains nano-alumina and / or nano-silica; and the particle size of the nano-diamond polishing particle is <100 mesh.

[0026] In a second aspect, the present application provides a preparation method of a polishing block for diamond polishing, which comprises the following steps: preparing nano-diamond polishing particles, mixing, hot pressing, and sintering. The sintering step adopts a two-stage sintering process: the first stage has a temperature rising rate of 0.8-1.5℃ / min, the temperature is raised to 200-220℃ and kept for 200-240min; and the second stage has a temperature rising rate of 2-3℃ / min, the temperature is raised to 600-700℃ and kept for 360-420min.

[0027] Optionally, the hot pressing temperature in the hot pressing step is 200-220℃, and the pressure keeping time is 5-10min.

[0028] In summary, the present application has the following beneficial effects: 1.The polishing block for diamond polishing is prepared by using a resin binder, a diamond abrasive, a ceramic binder and a diamond polishing agent, etc., and the polishing block has excellent polishing efficiency and service life, and the surface quality of the diamond material obtained by polishing is good, which can meet the processing requirements of the diamond material.

[0029] 2.The pre-sintering is performed by using a microwave pre-sintering process, which can further optimize the internal grains and performance of the nano-diamond polishing particles, so that the polishing block has higher polishing efficiency and longer service life.

[0030] 3.The microwave power in the microwave pre-sintering process is controlled at 1.5-2.5 kW, the pre-sintering temperature is controlled at 450-500 ℃, and the pre-sintering time is controlled at 10-20 min, so that the polishing block has higher processing efficiency and longer service life, and the average processing time of the 2-inch polycrystalline diamond wafer can be shortened to within 100 min, and the wear ratio G can reach more than 1200. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a preparation method flow chart of the polishing block for diamond polishing provided by the application. DETAILED DESCRIPTION

[0032] The polishing block for diamond polishing is prepared by using a resin binder, a diamond abrasive, a ceramic binder and a diamond polishing agent, etc., and the polishing block has excellent polishing efficiency and service life, and the surface quality of the diamond material obtained by polishing is good, which can meet the processing requirements of the diamond material.

[0033] The preparation method of the nano-diamond polishing particles comprises the following steps: (1) Dissolve nano-silica sol, boric acid and nitrate in water, and stir uniformly to obtain a liquid ceramic binder; (2) Then the liquid ceramic binder, diamond polishing agent is mixed, and a dispersing agent, a binder and water are added to mix and ball mill to obtain a mixed slurry; in the ball milling, the weight ratio of balls to material is (1-10):1, and the weight ratio of material to deionized water is 1:(1-5); the ball milling speed is 200-400 r / min, and the ball milling time is 10-100 h; (3) The mixed slurry is subjected to spray granulation, microwave pre-sintering and screening to obtain nano-diamond polishing particles; the spray granulation pressure is 0.2-0.3 MPa, and the temperature is 180-220℃; the microwave pre-sintering heating power is 1-3 kW, the pre-sintering temperature is 400-600℃, and the holding time is 240-360 min.

[0034] The application provides a preparation method of a polishing block for diamond polishing, which comprises the following steps: (1) Preparing nano-diamond polishing particles; (2) Mixing: the resin binder, diamond abrasive and nano-diamond polishing particles are put into a three-dimensional mixer to mix for 30 min; then the mixed powder is screened through a 60-mesh screen for 2 times to obtain uniformly mixed powder; the temporary binder (dextrin) is added to the powder to mix, so that the raw materials are fully wetted, and a molding material is obtained.

[0035] (3) Hot pressing: the molding material is slowly and uniformly poured into a mold, and a scraper is used to scrape it flat; hot pressing is performed at 200-220℃ for 5-10 min to obtain a secondary solidified polishing block body.

[0036] (4) Sintering: the polishing block body is put into a sintering furnace to perform sintering by adopting a two-stage sintering process; after deburring and contour trimming, a polishing block is obtained; the two-stage sintering process is as follows: the first stage has a temperature rising rate of 0.8-1.5℃ / min, the temperature is raised to 200-220℃ and is kept for 200-240 min; the second stage has a temperature rising rate of 2-3℃ / min, the temperature is raised to 600-700℃ and is kept for 360-420 min.

[0037] The particle size of the silica sol used in the embodiments of the application is 20-50 nm; the phenolic resin is PF-8012, which is purchased from Jinan Shengquan Group; the diamond abrasive is diamond single crystal, and the particle size is 40-60 μm; the nano-diamond particle size is 50-500 nm; the dispersing agent is polyvinylpyrrolidone; the binder is water glass; the raw materials, reagents and solvents used in the application can be obtained by commercial purchase.

[0038] The application will be further described in detail in combination with the preparation examples, embodiments, performance detection tests and the accompanying drawings.

[0039] Preparation Example 1 Preparation Example 1 provides a kind of nano-diamond polishing particles.

[0040] The preparation method of the nanodiamond polishing particles provided in Preparation Example 1 comprises the following steps: (1) Dissolve 100 g of nanosilica sol, 40 g of boric acid, 20 g of aluminum nitrate, 10 g of lithium nitrate, 10 g of sodium nitrate, 10 g of potassium nitrate, and 10 g of calcium nitrate in 100 g of water, and stir to obtain a liquid ceramic binder; that is, the weight ratio of the nanosilica sol, the boric acid, and the nitrate salts is 5:2:3; (2) Then, mix 150 g of the liquid ceramic binder, 100 g of diamond polishing agent (containing 80 wt% nanodiamond and the rest being nanometer alumina), 2 g of polyvinylpyrrolidone, 15 g of water glass, and deionized water, and perform mixing ball milling to obtain a mixed slurry; in the mixing ball milling, the weight ratio of the balls to the material is 5:1, and the weight ratio of the material to the deionized water is 1:2; the ball milling speed is 300 r / min, and the ball milling time is 24 h; (3) Perform spray granulation, pre-sintering, and screening on the mixed slurry to obtain nanodiamond polishing particles with a particle size of <100 μm; the spray granulation is performed at a pressure of 0.2 MPa and a temperature of 200 ℃; the pre-sintering is performed using a sintering furnace, the pre-sintering temperature is 500 ℃, and the holding time is 240 min.

[0041] Preparation Example 2 Preparation Example 2 provides a nanodiamond polishing particle.

[0042] The above preparation example is different from Preparation Example 1 in that the pre-sintering is performed using a microwave sintering furnace, the heating power is 2 kW, the pre-sintering temperature is 500 ℃, and the holding time is 20 min.

[0043] Preparation Example 3 Preparation Example 3 provides a nanodiamond polishing particle.

[0044] The above preparation example is different from Preparation Example 2 in that the amounts of the raw materials in the liquid ceramic binder are as follows: 110 g of nanosilica sol, 40 g of boric acid, 15 g of aluminum nitrate, 10 g of lithium nitrate, 10 g of sodium nitrate, 10 g of potassium nitrate, and 5 g of calcium nitrate; that is, the weight ratio of the nanosilica sol, the boric acid, and the nitrate salts is 5.5:2:2.5.

[0045] Preparation Example 4 Preparation Example 4 provides a nanodiamond polishing particle.

[0046] The above preparation example is different from Preparation Example 2 in that the amounts of the raw materials in the liquid ceramic binder are as follows: 120 g of nanosilica sol, 40 g of boric acid, 10 g of aluminum nitrate, 10 g of lithium nitrate, 10 g of sodium nitrate, 6 g of potassium nitrate, and 4 g of calcium nitrate; that is, the weight ratio of the nanosilica sol, the boric acid, and the nitrate salts is 6:2:2.

[0047] Preparation Example 5-10 Preparation Example 5-10 respectively provides a nano-diamond polishing particle.

[0048] The above preparation example is different from Preparation Example 2 in the amount of ceramic binder and diamond polishing agent, which is shown in Table 1 below.

[0049] Table 1 Amount of ceramic binder and diamond polishing agent in Preparation Example 2, Preparation Example 5-10 Preparation Example 11-19 Preparation Example 11-19 respectively provides a nano-diamond polishing particle.

[0050] The above preparation example is different from Preparation Example 5 in the temperature and time of pre-sintering, which is shown in Table 2 below.

[0051] Table 2 Temperature and time of pre-sintering in Preparation Example 5, Preparation Example 11-19 Example 1-19 Example 1-19 respectively provides a polishing block for diamond polishing.

[0052] The above examples are different in that the nano-diamond polishing particles used in Example 1-19 are respectively derived from Preparation Example 1-19.

[0053] The preparation method of the polishing block for diamond polishing provided by Example 1-19 comprises the following steps: (1) Prepare nano-diamond polishing particles according to Preparation Example 1-19 respectively; (2) Mixing: Put 100g of phenolic resin, 600g of diamond abrasive, and nano-diamond polishing particles obtained from Preparation Example 1-19 into a three-dimensional mixer and mix for 30min; then pass through a 60-mesh sieve twice to obtain uniformly mixed powder; add 20g of water glass to the powder and mix to fully wet the raw materials, obtaining a molding material.

[0054] (3) Hot pressing molding: slowly and uniformly pour the molding material into the mold and scrape it flat with a scraper; hot press at 200℃ for 8min to obtain a secondary consolidated polishing block body blank.

[0055] (4) Sintering: Put the polishing block body blank into a sintering furnace and sinter it using a two-stage sintering process; after deburring and contour trimming, obtain a polishing block; the two-stage sintering process is as follows: the first stage has a temperature rising rate of 1℃ / min, the temperature rises to 200℃ and is kept for 200min; the second stage has a temperature rising rate of 2.5℃ / min, the temperature rises to 650℃ and is kept for 380min.

[0056] Comparative Example 1 Comparative Example 1 provides a polishing block for diamond polishing.

[0057] The above comparative example differs from Example 1 in that the ceramic binder is replaced with an equal amount of resin binder.

[0058] The method for preparing the polishing block for diamond polishing provided by Comparative Example 1 includes the following steps: (1) Mixing: 200 g of resin binder, 600 g of diamond abrasive, and 100 g of diamond polishing agent are placed into a three-dimensional mixer and mixed for 30 min; then passed through a 60-mesh sieve twice to obtain uniformly mixed powder; 20 g of water glass is added to the powder to fully wet the raw materials, and a molding material is obtained.

[0059] (2) Hot pressing: the molding material is slowly and uniformly poured into a mold and leveled with a scraper; hot pressing at 200°C for 8 min to obtain a twice-solidified polishing block body blank.

[0060] (3) Sintering: the polishing block body blank is placed in a sintering furnace and sintered using a two-stage sintering process; after deburring and contour trimming, a polishing block is obtained; the two-stage sintering process is as follows: the first stage has a temperature rising rate of 1°C / min, the temperature is raised to 200°C and held for 200 min; the second stage has a temperature rising rate of 2.5°C / min, the temperature is raised to 650°C and held for 380 min.

[0061] Comparative Example 2 Comparative Example 2 provides a polishing block for diamond polishing.

[0062] The above comparative example differs from Example 1 in that the ceramic binder and diamond polishing agent are directly used for wet mixing.

[0063] The method for preparing the polishing block for diamond polishing provided by Comparative Example 2 includes the following steps: (1) Mixing: 100 g of resin binder, 600 g of diamond abrasive, 150 g of ceramic binder, and 100 g of diamond polishing agent are placed into a three-dimensional mixer and mixed for 30 min; then passed through a 60-mesh sieve twice to obtain uniformly mixed powder; 20 g of water glass is added to the powder to fully wet the raw materials, and a molding material is obtained.

[0064] (2) Hot pressing: the molding material is slowly and uniformly poured into a mold and leveled with a scraper; hot pressing at 200°C for 8 min to obtain a twice-solidified polishing block body blank.

[0065] (3) Sintering: the polished block body blank is put into a sintering furnace for sintering by using a two-stage sintering process, and after deburring and contour finishing, a polished block is obtained; the two-stage sintering process is as follows: the temperature is increased to 200℃ at a first-stage heating rate of 1℃ / min, and the temperature is kept for 200min; the temperature is increased to 650℃ at a second-stage heating rate of 2.5℃ / min, and the temperature is kept for 380min.

[0066] Comparative Example 3 Comparative Example 3 provides a polishing block for diamond polishing.

[0067] The above comparative example differs from Example 1 in that the amounts of the raw materials in the liquid ceramic binder used for preparing the nanodiamond polishing particles are as follows: nanosilica sol 80g, boric acid 40g, aluminum nitrate 20g, lithium nitrate 20g, sodium nitrate 20g, potassium nitrate 10g, and calcium nitrate 10g; that is, the weight ratio of the silica sol, boric acid, and nitrate is 4:2:4.

[0068] Comparative Example 4 Comparative Example 4 provides a polishing block for diamond polishing.

[0069] The above comparative example differs from Example 1 in that the sintering step is as follows: (4) Sintering: the polished block body blank is put into a sintering furnace, and then the temperature is increased to 650℃ at a heating rate of 1℃ / min, and the temperature is kept for sintering for 580min, and after deburring and contour finishing, a polished block is obtained.

[0070] Comparative Example 5 Comparative Example 5 provides a polishing block for diamond polishing.

[0071] The above comparative example differs from Example 1 in that the sintering step is as follows: (4) Sintering: the polished block body blank is put into a sintering furnace for sintering by using a two-stage sintering process, and after deburring and contour finishing, a polished block is obtained; the two-stage sintering process is as follows: the temperature is increased to 350℃ at a first-stage heating rate of 2℃ / min, and the temperature is kept for 200min; the temperature is increased to 800℃ at a second-stage heating rate of 4℃ / min, and the temperature is kept for 380min.

[0072] Performance detection test The polished blocks obtained in Examples 1-19 and Comparative Examples 1-5 are adhered to metal bases to form polishing discs, and then the polishing discs are used to test the polishing performance of polycrystalline diamond wafers (the initial surface roughness is 200-300nm); the polishing machine is SPG40, and the speed of the grinding wheel is 2000r / min; the specific test results are shown in Table 3.

[0073] (1) Processing effect: the polycrystalline diamond wafer with a diameter of 2 inches is polished by using the polishing disc, and the polishing time is 3 h, and then the surface roughness of the polycrystalline diamond wafer after polishing is detected.

[0074] (2) Average processing time: the polycrystalline diamond wafer with a diameter of 2 inches is polished by using the polishing disc, and the time required from the beginning of polishing until the wafer surface has no scratches and color difference and reaches the mirror surface roughness (<20 nm) is counted; 5 groups are detected for each kind, and the average value is taken.

[0075] (3) Wear ratio: refers to the ratio of the volume of workpiece material removed to the volume of grinding wheel wear during grinding, and the calculation formula is G=Vwc / Vsc (Vwc is the volume of workpiece removed, and Vsc is the volume of grinding wheel wear), which is used to measure the economy and wear resistance of the grinding wheel.

[0076] Table 3: Performance detection results of the polishing blocks obtained in Examples 1-19 and Comparative Examples 1-5 According to the detection results of Table 3 of the present application, the polishing blocks for diamond polishing obtained in Examples 1-19 can reduce the surface roughness of the polycrystalline diamond wafer from 200-300 nm to 13-19 nm after processing for 3 h; the time required for processing the polycrystalline diamond wafer to mirror surface roughness is 83-124 min, and the wear ratio of the polishing block is 1062-1287. The polishing blocks for diamond polishing obtained in Comparative Examples 1-5 can only reduce the surface roughness of the polycrystalline diamond wafer from 200-300 nm to 27-48 nm after processing for 3 h; the time required for processing the polycrystalline diamond wafer to mirror surface roughness is as long as 220-345 min, and the wear ratio of the polishing block is 527-695. Therefore, it is shown that the polishing blocks for diamond polishing are prepared by using the resin bond, diamond abrasive, ceramic bond and diamond polishing agent as raw materials, and by controlling the weight ratio of the silica sol, boric acid and nitrate in the ceramic bond within a specific range, the processing efficiency of the polishing block is high, the surface processing quality of the diamond is good, and the service life is long.

[0077] Although the present application has been described in detail by the general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of protection claimed by the present application.

Claims

1. A polishing block for diamond polishing, characterized in that, The polishing block is made from the following raw materials in parts by weight: 10-15 parts resin binder, 50-70 parts diamond abrasive, 10-20 parts ceramic binder and 1-20 parts diamond polishing agent. The ceramic binder comprises silica sol, boric acid, and nitrate in a weight ratio of (5-6):2:(2-3); The diamond abrasive has a particle size of 40-60 μm; the diamond polishing agent has a particle size of 50-500 nm. In the preparation process of the polishing block, the ceramic binder and the diamond polishing agent are first mixed, sprayed and granulated, and pre-sintered to obtain nano-diamond polishing particles.

2. The polishing block according to claim 1, characterized in that, The polishing block comprises the following raw materials in parts by weight: 10-15 parts resin binder, 50-70 parts diamond abrasive, 15-20 parts ceramic binder, and 5-15 parts diamond polishing agent.

3. The polishing block according to claim 1, characterized in that, The preparation method of the nanodiamond polishing particles includes the following steps: Nano-silica sol, boric acid, and nitrate are dissolved in water and stirred evenly to obtain a liquid ceramic binder; Then, the liquid ceramic binder and diamond polishing agent are mixed, and dispersant, binder and solvent are added and ball-milled to obtain a mixed slurry; The mixed slurry is spray-granulated, pre-sintered, and sieved to obtain nano-diamond polishing particles; the pre-sintering temperature is 400-600℃, and the holding time is 10-270min.

4. The polishing block according to claim 3, characterized in that, The pre-sintering process employs microwave pre-sintering technology, with a heating power of 1-3kW and a holding time of 10-30min.

5. The polishing block according to claim 3, characterized in that, The spray granulation pressure is 0.2-0.3 MPa, and the temperature is 180-220℃.

6. The polishing block according to claim 1, characterized in that, The resin binder is selected from one or more of phenolic resin, epoxy resin and polyurethane resin; The nitrates include aluminum nitrate, lithium nitrate, sodium nitrate, potassium nitrate, and calcium nitrate; The diamond polishing agent contains nanodiamonds, and the mass percentage of nanodiamonds in the diamond polishing agent is 50-100%.

7. The polishing block according to claim 6, characterized in that, The diamond polishing agent also contains nano-alumina and / or nano-silicon oxide; The particle size of the nanodiamond polishing particles is <100 mesh.

8. The method for preparing a polishing block for diamond polishing as described in any one of claims 1-7, characterized in that, Includes the following steps: Preparation of nanodiamond polishing particles, mixing, hot pressing, and sintering; The sintering process adopts a two-stage sintering process: the first stage has a heating rate of 0.8-1.5℃ / min, and the temperature is raised to 200-220℃ and held for 200-240min; the second stage has a heating rate of 2-3℃ / min, and the temperature is raised to 600-700℃ and held for 360-420min.

9. The method for preparing a polishing block according to claim 8, characterized in that, The hot pressing temperature in the hot pressing molding step is 200-220℃, and the holding time is 5-10 minutes.

10. A polishing disc for diamond polishing, comprising a polishing block for diamond polishing as described in any one of claims 1-6 and a metal substrate.

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