Preparation method of diamond abrasive

Abstract

The invention belongs to the technical field of diamond materials, and particularly relates to a preparation method of a diamond abrasive, which comprises the following steps: dispersing ultrafine diamond micro-powder in an oil phase of a resorcinol-formaldehyde sol precursor, stirring a polyethylene glycol alcohol solution and the oil phase to form an emulsion, spontaneously dispersing into countless spherical liquid drops in an emulsion system, and preparing the diamond abrasive by using the spherical liquid drops. After full stirring, resorcinol-formaldehyde in the spherical liquid drops is subjected to a gel reaction to form spherical gel particles, and meanwhile, the diamond micro-powder is also uniformly distributed in the gel particles. After the gel particles are subjected to drying and high-temperature calcination, organic matters such as wax and polyethylene glycol are fully decomposed and volatilized, finally, the granulated diamond abrasive material with uniform particle size distribution is obtained, spherical gel particles with stable shapes can be obtained without a traditional large-scale high-temperature spray drying device, and the advantages of high grinding efficiency, stable grinding performance and the like are achieved. And the grinding precision is good, and the service life is long.

Description

Technical Field

[0001] The invention belongs to the technical field of diamond materials, in particular to a method for preparing diamond abrasive. Background Art

[0002] However, traditional diamond abrasives have problems such as poor self-sharpening, low polishing efficiency and poor surface consistency of workpieces. Stacked abrasives are a new type of abrasive developed and used in the process of industrial development. Wang Zhaowu et al. used the rolling method to prepare spherical stacked abrasives. Fang Wenjun et al. of Hunan University used the spray drying method to prepare ultrafine diamond stacked abrasives with good sphericity and uniform internal structure. Cellulose, polyvinyl alcohol and starch were also used. At present, the spray drying method is more mature and widely used, but spray drying requires a high-temperature heating device, which places very high requirements on the spray drying tower, and the particle size distribution range of the stacked abrasive obtained by the spray drying method is also relatively wide. However, the appearance of the granulated diamond stacked abrasive on the market is generally off-white powder with low whiteness. From the naked eye, it can be found that the granulated diamond stacked abrasive contains some impurities, and its precision grinding performance is also affected. Because in the granulation process, the binders such as cellulose, polyvinyl alcohol, starch, etc. will decompose and generate impurities after pyrolysis or high-temperature aging, or the binder itself is an impurity. For example, starch molecules first decompose and then polycondense during the pyrolysis process to form an amorphous carbon encapsulation structure with aromatic carbon as the core. As the temperature rises, cellulose decomposes violently and gradually converts from an amorphous carbon structure to a graphite carbon structure. The carbon generated by the pyrolysis of polyvinyl alcohol at high temperature is amorphous carbon. For another example, the granulated diamond stacked abrasive containing ceramic binders such as pyrophyllite has a yellowish appearance and low whiteness. The graphite carbon and amorphous carbon introduced by the above binders are the main impurities of diamond micropowder. However, the level of impurity content can reduce the overall hardness of diamond and affect the performance of deep processing and precision grinding. Granulation technologies such as spray drying have many disadvantages in themselves, and there are also problems such as environmental pollution and high energy consumption in the actual production process. It can be seen that the current technical solutions for granulated diamond stacked abrasives are mixed. In order to solve the above problems, those skilled in the art are in urgent need of developing a method for preparing diamond abrasives to meet the existing market demand and performance requirements. Summary of the invention

[0003] In view of the above problems, the present invention aims to provide a method for preparing diamond abrasive.

[0004] A method for preparing a diamond abrasive comprises the following steps: a first step, mixing wax, resorcinol, polyformaldehyde and ultrafine diamond powder to form a uniform oil phase by heating and stirring; a second step, dissolving an emulsifier polyethylene glycol in alcohol, keeping the temperature at 65 DEG C in a water bath, adding the oil phase, and emulsifying for 5 minutes at 12000-15000 rpm by a high-speed shearing machine to obtain a uniform emulsion; a third step, transferring the emulsion to a reaction kettle, controlling the stirring speed at 300-350 rpm, the temperature at 90-95 DEG C, reacting for 3-5 hours, filtering, washing and drying to obtain spherical gel particles; and then washing and filtering with anhydrous ethanol to obtain the spherical gel particles, placing the gel particles in a drying oven at 80-90 DEG C to dry for 3-4 hours, calcining at 640-660 DEG C, keeping the temperature for 1 hour, and sieving to obtain the diamond abrasive.

[0005] Furthermore, the ultrafine diamond powder in the first step accounts for 60% to 70% of the mass of the uniform oil phase, the wax accounts for 3% to 5% of the mass of the uniform oil phase, and the uniform oil phase contains 25 to 26 parts of resorcinol and 13 to 13.5 parts of polyformaldehyde by weight.

[0006] Furthermore, the particle size of the ultrafine diamond powder in the first step is marked as 20 / 25 or 30 / 35 or 35 / 40 or 40 / 45 or 50 / 60 or 60 / 70 or 20 / 30 or 30 / 40 or 40 / 50 or 60 / 80.

[0007] Furthermore, the grade of the diamond abrasive in the third step is SMD or SMD25 or SMD30 or SMD35 or SMD40.

[0008] Furthermore, the first step wax is beeswax.

[0009] Furthermore, the first step has a stirring speed of 600-800 rpm, a stirring time of 15-20 min, and a heating temperature of 64-66°C.

[0010] Furthermore, the average molecular weight of the polyethylene glycol in the second step is 600-1000.

[0011] Furthermore, the alcohol in the second step is alcohol with a volume concentration of 40% to 50%.

[0012] Diamond itself does not have plasticity and is difficult to form into balls by the wetting effect of water alone. In order to avoid the influence of the residue produced by the inorganic binder on the diamond particles, resorcinol-formaldehyde sol-gel is used to produce no residue after sintering.

[0013] Beneficial effects of the present invention: The invention discloses a patented method for preparing diamond abrasive. The diamond abrasive is in the form of white powder, wherein ultrafine diamond micropowder is dispersed in an oil phase, and then a polyethylene glycol alcohol solution is mixed with the oil phase to form an emulsion. After sufficient stirring, the resorcinol-formaldehyde gel in the emulsion system reacts to form spherical gel particles, and the diamond micropowder is evenly distributed in the gel particles. After the gel particles are dried and calcined at high temperature, organic substances such as wax and polyethylene glycol are fully decomposed and volatilized, and finally granulated diamond abrasives with uniform particle size distribution are obtained, and spherical gel particles with stable shape can be obtained without using a traditional large-scale high-temperature spray drying device. These abrasives can be used to manufacture grinding tools or directly used for grinding and polishing, have high efficiency, stable performance and good service life, and are suitable for grinding and polishing of various high-density materials and metals and alloys. DETAILED DESCRIPTION

[0014] The present invention is described below with specific examples, but is not intended to be limiting of the present invention. Example 1

[0015] Raw materials and equipment: Ultrafine diamond powder with particle size marked as 20 / 25, 30 / 35, 35 / 40, 40 / 45, 50 / 60, 60 / 70, 20 / 30, 30 / 40, 40 / 50, 60 / 80; Mengcheng Kunpengyun Biological Natural Beeswax; Anqing Yake Technology D0514 Polyformaldehyde; Yuanli Chemical Polyethylene Glycol PEG600.

[0016] The method for preparing diamond abrasive comprises the following steps: The first step is to prepare 25 parts of resorcinol, 13 parts of paraformaldehyde and beeswax by weight, which account for 5% of the mass of the uniform oil phase; the wax, resorcinol, paraformaldehyde and ultrafine diamond powder are mixed and stirred at 64°C to form a uniform oil phase, and the ultrafine diamond powder accounts for 70% of the mass of the uniform oil phase; the second step is to dissolve the emulsifier polyethylene glycol PEG600 in 40% alcohol by volume, maintain a constant temperature of 65°C, add the uniform oil phase obtained in the previous step, and emulsify it at 12000rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 300rpm, the temperature at 90°C, react for 3 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain spherical gel particles, place the above gel particles in a 90°C drying oven for 4 hours, and then calcine at 660°C in a box-type resistance furnace, and keep warm for 1 hour, sieve, and obtain diamond abrasive. The diamond abrasive grade reaches SMD grade.

[0017] Product: Bulk density 2.38g / cm 3, no visible agglomerates or other foreign matter, the micro powder is white powder. a) The particle size of 120 / 140 and coarser is not more than 0.1% (particle percentage); the particle size of 140 / 170 and finer is not more than 0.3% (particle percentage). Example 2

[0018] Raw materials and equipment: Ultrafine diamond powder with particle size marked as 20 / 25, 30 / 35, 35 / 40, 40 / 45, 50 / 60, 60 / 70, 20 / 30, 30 / 40, 40 / 50, 60 / 80; Mengcheng Kunpengyun Biological Natural Beeswax; Anqing Yake Technology D0514 Polyformaldehyde; Yuanli Chemical Polyethylene Glycol PEG600.

[0019] The method for preparing diamond abrasive comprises the following steps: The first step is to add 25 parts of resorcinol and 13.5 parts of polyformaldehyde by weight; the ultrafine diamond powder accounts for 65% of the mass of the uniform oil phase, and the wax accounts for 4% of the mass of the uniform oil phase. The wax, resorcinol, polyformaldehyde and ultrafine diamond powder are mixed and stirred at 64°C to form a uniform oil phase; the second step is to dissolve the emulsifier polyethylene glycol PEG600 in 40% alcohol by volume, maintain a constant temperature of 65-70°C, add the uniform oil phase obtained in the previous step, and emulsify it at 13000rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 320rpm, the temperature at 92°C, react for 4 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain spherical gel particles, place the above gel particles in a 90°C drying oven for 4 hours, and then calcine at 660°C in a box-type resistance furnace, and keep warm for 1 hour, sieve, and obtain diamond abrasive. The grade of diamond abrasive reaches grade SMD25.

[0020] Product: Bulk density 2.45g / cm 3 , no visible agglomerates or other foreign matter, the micro powder is white powder. a) The particle size of 120 / 140 and coarser is not more than 0.1% (particle percentage); the particle size of 140 / 170 and finer is not more than 0.3% (particle percentage). Example 3

[0021] Raw materials and equipment: Ultrafine diamond powder with particle sizes marked as 20 / 25, 30 / 35, 35 / 40, 40 / 45, 50 / 60, 60 / 70, 20 / 30, 30 / 40, 40 / 50, 60 / 80; Mengcheng Kunpengyun Biological Natural Beeswax; Anqing Yake Technology D0514 polyformaldehyde; Yuanli Chemical Polyethylene Glycol PEG1000.

[0022] The method for preparing diamond abrasive comprises the following steps: The first step is to add 25 parts of resorcinol and 13.5 parts of polyformaldehyde by weight; the ultrafine diamond powder accounts for 70% of the mass of the uniform oil phase, and the wax accounts for 5% of the mass of the uniform oil phase; the wax, resorcinol, polyformaldehyde and ultrafine diamond powder are mixed and stirred at 65°C to form a uniform oil phase; the second step is to dissolve the emulsifier polyethylene glycol PEG1000 in 45% alcohol by volume, maintain a constant temperature of 68°C, add the uniform oil phase obtained in the previous step, and emulsify it at 13000rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 320rpm, the temperature at 92°C, react for 4 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain spherical gel particles, place the above gel particles in a 90°C drying oven for 4 hours, and then calcine at 660°C in a box-type resistance furnace, and keep warm for 1 hour, sieve, and obtain diamond abrasive. The grade of diamond abrasive reaches grade SMD30.

[0023] Product: Bulk density 2.32g / cm 3 , no visible agglomerates or other foreign matter, the micro powder is white powder. a) The particle size of 120 / 140 and coarser is not more than 0.1% (particle percentage); the particle size of 140 / 170 and finer is not more than 0.4% (particle percentage). Example 4

[0024] Raw materials and equipment: Ultrafine diamond powder with particle size marked as 20 / 25, 30 / 35, 35 / 40, 40 / 45, 50 / 60, 60 / 70, 20 / 30, 30 / 40, 40 / 50, 60 / 80; Mengcheng Kunpengyun Biological Natural Beeswax; Anqing Yake Technology D0514 Polyformaldehyde; Yuanli Chemical Polyethylene Glycol PEG600.

[0025] The method for preparing diamond abrasive comprises the following steps: The first step is to add 25 parts of resorcinol and 13 parts of D0514 polyformaldehyde by weight; the ultrafine diamond powder accounts for 60% of the mass of the uniform oil phase, and the wax accounts for 3% of the mass of the uniform oil phase. The wax, resorcinol, polyformaldehyde and ultrafine diamond powder are mixed and stirred at 66°C to form a uniform oil phase; the second step is to dissolve the emulsifier polyethylene glycol in alcohol with a volume fraction of 40, maintain a constant temperature of 65°C, add the uniform oil phase obtained in the previous step, and emulsify it at 12000rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 350rpm, the temperature at 95°C, react for 5 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain spherical gel particles, place the above gel particles in a 90°C drying oven for 4 hours, and then calcine at 660°C in a box-type resistance furnace, and keep warm for 1 hour, sieve, and obtain diamond abrasive. The grade of diamond abrasive reaches grade SMD35.

[0026] Product: Bulk density 2.18g / cm 3 , no visible agglomerates or other foreign matter, the micro powder is white powder. a) The particle size of 120 / 140 and coarser is not more than 0.2% (particle percentage); the particle size of 140 / 170 and finer is not more than 0.5% (particle percentage). Example 5

[0027] Raw materials and equipment: Ultrafine diamond powder with particle sizes marked as 20 / 25, 30 / 35, 35 / 40, 40 / 45, 50 / 60, 60 / 70, 20 / 30, 30 / 40, 40 / 50, 60 / 80; Mengcheng Kunpengyun Biological Natural Beeswax; Anqing Yake Technology D0514 polyformaldehyde; Yuanli Chemical Polyethylene Glycol PEG1000.

[0028] The method for preparing diamond abrasive comprises the following steps: The first step is to add 25 parts of resorcinol and 13.5 parts of D0514 polyformaldehyde by weight; the ultrafine diamond powder accounts for 60% of the mass of the uniform oil phase, and the wax accounts for 3% of the mass of the uniform oil phase. The wax, resorcinol, polyformaldehyde and ultrafine diamond powder are mixed and stirred at 66°C to form a uniform oil phase; the second step is to dissolve the emulsifier polyethylene glycol in 50% alcohol by volume, maintain a constant temperature of 70°C, add the uniform oil phase obtained in the previous step, and emulsify it at 15000rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 350rpm, the temperature at 95°C, react for 5 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain spherical gel particles, place the above gel particles in a 90°C drying oven for 4 hours, and then calcine at 660°C in a box-type resistance furnace, and keep warm for 1 hour, sieve, and obtain diamond abrasive. The grade of diamond abrasive reaches grade SMD40.

[0029] Product: Bulk density 2.25g / cm 3 , no visible agglomerates or other foreign matter, the micro powder is white powder. a) The particle size of 120 / 140 and coarser is not more than 0.2% (particle percentage); the particle size of 140 / 170 and finer is not more than 0.5% (particle percentage).

[0030] The compressive strength and impact toughness of the diamond abrasives of Examples 1 to 5 were tested. Table 1 shows the compressive strength of the diamond abrasives of Examples 1 to 5, and Table 2 shows the compressive strength of the diamond abrasives of Examples 1 to 5.

[0031] Table 1 Compressive strength of diamond abrasives of Examples 1 to 5

[0032] Table 2 Impact toughness of diamond abrasives of Examples 1 to 5

[0033] Note: The particle size composition shall be tested in accordance with GB / T6406-2016. The impact toughness shall be tested in accordance with GB / T33144-2016. The compressive strength shall be tested in accordance with JB / T10985-2020. The carbide indenter and gasket are made of YG6x, with a hardness of not less than 91HRA, and the surface roughness: a) Ra for the test particle size of 70 / 80 and its coarser is not more than 0.80μm; b) Ra for the test particle size of 80 / 100 and its finer is not more than 0.20μm. The bulk density shall be tested in accordance with JB / T3584-2012. The impurity content shall be tested in accordance with JB / T10986-2023.

Claims

1. A method for preparing a diamond abrasive, characterized in that: The following steps are involved: The first step is to mix wax, resorcinol, polyformaldehyde and ultrafine diamond powder to form a uniform oil phase by heating and stirring; the second step is to dissolve the emulsifier polyethylene glycol in alcohol, keep the temperature at 65°C in a water bath, add the oil phase, and emulsify it at 12000-15000 rpm for 5 minutes through a high-speed shearing machine to obtain a uniform emulsion; the third step is to transfer the emulsion to a reactor, control the stirring speed at 300-350 rpm, the temperature at 90-95°C, react for 3-5 hours, and then filter, wash and dry to obtain spherical gel particles; then wash and filter with anhydrous ethanol to obtain the spherical gel particles, place the above gel particles in a drying oven at 80-90°C for 3-4 hours, calcine at 640-660°C, keep warm for 1 hour, and sieve to obtain diamond abrasive.

2. The method for preparing a diamond abrasive according to claim 1, characterized in that: In the first step, the ultrafine diamond powder accounts for 60% to 70% of the mass of the uniform oil phase, and the wax accounts for 3% to 5% of the mass of the uniform oil phase.

3. The method for preparing diamond abrasive according to claim 1, characterized in that: The first step ultrafine diamond powder particle size is marked as 20 / 25 or 30 / 35 or 35 / 40 or 40 / 45 or 50 / 60 or 60 / 70 or 20 / 30 or 30 / 40 or 40 / 50 or 60 / 80.

4. The method for preparing diamond abrasive according to claim 1, characterized in that: In the third step, the grade of the diamond abrasive is SMD or SMD25 or SMD30 or SMD35 or SMD40.

5. The method for preparing diamond abrasive according to claim 1, characterized in that: The first step wax is beeswax.

6. The method for preparing diamond abrasive according to claim 1, characterized in that: The first step has a stirring speed of 600-800 rpm, a stirring time of 15-20 min, and a heating temperature of 64-66°C.

7. The method for preparing diamond abrasive according to claim 1, characterized in that: The average molecular weight of the polyethylene glycol in the second step is 600-1000.

8. The method for preparing diamond abrasive according to claim 1, characterized in that: The alcohol in the second step is alcohol with a volume concentration of 40% to 50%.

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