A process for preparing fine-grained diamond grinding tools through in-situ solidification

Abstract

This invention discloses a process for in-situ solidification preparation of fine-grained diamond grinding wheels, comprising the following steps: (1) preparation of a microemulsion pore-forming agent; (2) preparation of a diamond forming slurry; (3) in-situ solidification and forming of the diamond grinding wheel; (4) drying of the diamond grinding wheel green; and (5) sintering of the diamond grinding wheel. Compared with ceramic-bonded diamond grinding wheels prepared by the traditional dry pressing method, the ceramic-bonded diamond grinding wheels prepared by this invention have a more uniform microstructure, and the uniformly distributed spherical pores within the sintered body can better accommodate chips and improve the self-sharpening properties of the grinding wheel. The diamond grinding wheels prepared using this invention not only improve grinding efficiency but also reduce the surface roughness of SiC wafers, demonstrating significant potential for promotion and application.

Description

Technical Field

[0001] This invention belongs to the field of superhard material preparation, and relates to a process for preparing fine-grained diamond abrasives by in-situ solidification, and particularly to a process for preparing fine-grained diamond abrasives with a highly uniform microstructure and a large number of regular spherical pores inside. Background Technology

[0002] Ceramic-bonded diamond grinding wheels have advantages such as high elastic modulus, high grinding precision, good self-sharpening properties, easy dressing, sharp grinding edge, and high grinding efficiency. At the same time, the presence of a large number of pores in the grinding wheel structure makes it easy to carry grinding fluid into the grinding zone, resulting in low grinding heat generation. Therefore, they are widely used in the forming and precision grinding of ceramic, glass, and crystal materials.

[0003] In recent years, with the advancement of science and technology, the manufacturing industry has placed increasingly higher demands on the surface dimensional accuracy and roughness of processed workpieces. To adapt to this technological development trend, the diameter of diamond abrasives used in diamond grinding tools for ultra-precision machining of parts has become increasingly finer. For example, the grit size of diamond grinding tools used for ultra-precision thinning grinding of SiC wafers was previously about 2000#, while in recent years, with the increasing requirements for the surface finish of SiC wafers, the grit size of diamond grinding tools has reached 5000#.

[0004] Currently, most fine-grained ceramic-bonded diamond abrasives are formed using the dry pressing method: fine-grained diamond abrasive, ceramic binder powder, and temporary binder are mixed evenly, pressed into shape in a steel mold, and then sintered under a specific heat treatment regime to obtain the finished product. Because the free packing density of the fine-grained diamond abrasive material is low, the material flowability is poor during dry pressing. Furthermore, the friction between the material and the mold during the forming process causes density fluctuations in different parts of the dry-pressed blank, making it difficult to form ceramic-bonded diamond abrasives with a highly uniform microstructure. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a process for preparing fine-grained diamond abrasives by in-situ solidification.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A process for preparing fine-grained diamond grinding tools through in-situ solidification specifically includes the following steps:

[0008] (1) Preparation of microemulsion pore-forming agent

[0009] Isooctane was added to a mixed solution of deionized water, glycerol, and Tween-80 and stirred to obtain an isooctyl microemulsion pore-forming agent;

[0010] (2) Preparation of diamond molding slurry

[0011] Acrylamide, N,N-methylenebisacrylamide and deionized water were weighed according to the formula ratio and stirred to obtain a premixed liquid; diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate and isooctyl microemulsion pore-forming agent obtained in step (1) were weighed according to the formula ratio and added to the premixed liquid, and stirred at high speed to mix evenly to obtain diamond abrasive in-situ solidification molding slurry.

[0012] (3) In-situ solidification forming of diamond grinding tools

[0013] The diamond abrasive in-situ solidification molding slurry obtained in step (2) is injected into the molding mold, then solidified and molded, and after demolding, a diamond abrasive blank is obtained.

[0014] (4) Drying of diamond grinding wheel blanks

[0015] After demolding, the diamond grinding mold blank is placed at room temperature and then dried by programmed temperature increase for later use.

[0016] (5) Sintering of diamond grinding wheels

[0017] The dried diamond blank is placed in a controlled atmosphere furnace and calcined by programmed heating. It is then cooled in the furnace to finally obtain a porous ceramic-bonded diamond abrasive, namely the fine-grained diamond abrasive.

[0018] Optionally, in step (1), the mass ratio of deionized water, glycerol and Tween-80 in the mixed solution is 40-45:22-25:32-35, and the amount of isooctane added is 25-35 wt% of the mass of the mixed solution.

[0019] Optionally, the raw material formula of the diamond molding slurry is as follows:

[0020]

[0021] The formula for commercially available ceramic binders is as follows: SiO2 55-60wt%; B2O3 15-20wt%; Al2O3 12-15wt%; ZnO 5-10wt%; Na2O 5-8wt%; Li2O 2-3wt%.

[0022] Optionally, the curing temperature in step (3) is 75-85℃ and the molding temperature is 45-60min.

[0023] The reaction and its underlying principle at this point are as follows:

[0024] Under the action of the initiator cerium ammonium nitrate, acrylamide acts as a monomer, and N,N-methylenebisacrylamide acts as a crosslinking agent. At a water bath temperature, N,N-methylenebisacrylamide undergoes a grafting reaction between acrylamide monomer molecules, causing the linear N,N-methylenebisacrylamide monomer molecules to form a three-dimensional network structure. At this time, most of the water molecules in the diamond abrasive molding slurry are fixed in the three-dimensional network, thereby enabling the slurry to solidify rapidly in situ. The solid particles of the green body retain the high dispersibility of the liquid-based dispersion system, and there are also large-sized isooctane emulsion microspheres in the green body. After demolding, the diamond abrasive green body is obtained.

[0025] Optionally, in step (4), the demolded diamond abrasive blank is placed at room temperature for 12-16 hours, then placed in a 45°C drying oven for 12-16 hours, then the temperature of the drying oven is raised to 80°C for 8-10 hours, and finally raised to 120°C for 4-6 hours.

[0026] It should be noted that segmented heat preservation and drying are adopted, and the drying speed is controlled to prevent the green body from cracking.

[0027] Optionally, the programmed temperature rise calcination process in step (5) is as follows:

[0028] At 2℃·min in air atmosphere -1 The temperature is increased to 400℃ at a rate of 3℃·min and held for 30-60 minutes, then increased at a rate of 3℃·min. -1 The temperature is rapidly increased to 700-730℃ and held for 1-2 hours.

[0029] It should be noted that the phase changes during the above-mentioned temperature-increasing calcination process are as follows:

[0030] At 2℃·min in air atmosphere -1 The temperature was increased to 400℃ at a rate of [missing information] and held for 30-60 min. During this heating range, the organic matter in the green body began to decompose and carbonize. Specifically, after the isooctane emulsion microspheres in the green body decomposed, uniformly distributed spherical pores were left in the green body. Because a large amount of organic matter decomposed in this temperature range, the heating rate was relatively slow. Subsequently, the temperature was increased at 3℃·min [missing information]. -1 The temperature is rapidly increased to 700-730℃ and held for 1-2 hours. During the holding period at 700-730℃, the ceramic binder softens into a viscous fluid, which, under capillary force, fills the spaces between diamond particles, wetting and encapsulating the diamond abrasive. During furnace cooling, the binder forms a solid with a certain strength, ultimately yielding a porous ceramic-bonded diamond abrasive.

[0031] Furthermore, in the preparation of the microemulsion pore-forming agent, deionized water, glycerol and Tween-80 were added simultaneously and stirred for 30-60 minutes with a magnetic stirrer at a stirring speed of 300-400 r / min to prepare a mixed solution. Then, isooctane was added under stirring conditions and stirred for 1-2 hours to finally obtain the isooctyl microemulsion pore-forming agent.

[0032] It should be noted that Tween-80 is a surface surfactant for isooctane and glycerol is a co-surfactant. Under stirring conditions, they adsorb onto the surface of isooctane droplets to form a surface coating structure, which helps the isooctane droplets to be stably suspended and dispersed in deionized water, forming a microemulsion pore-forming agent.

[0033] Further, acrylamide, N,N-methylenebisacrylamide and deionized water are mixed evenly by magnetic stirring for 30-60 minutes to obtain a premixed liquid; then diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate and isooctyl microemulsion pore-forming agent obtained in step (1) are weighed according to the formula ratio and added to the premixed liquid, and stirred at high speed for 2-3 hours at a stirring speed of 8000-10000 r / min. After being mixed evenly, the diamond abrasive in-situ solidification molding slurry is obtained.

[0034] It should be noted that during the stirring process, polyethylene glycol will be adsorbed on the surface of diamond abrasive and ceramic binder powder, generating a steric hindrance effect, which helps the diamond abrasive and ceramic binder to be suspended and dispersed in the molding slurry.

[0035] Furthermore, before the diamond abrasive is solidified in situ, petroleum jelly needs to be applied to the surface of the plastic molding aluminum mold. Then, the excess petroleum jelly on the surface is wiped off with gauze. After the diamond abrasive solidification molding slurry obtained in step (2) is left to stand at room temperature for 2-3 hours, it is injected into the molding mold.

[0036] It should be noted that Vaseline is used as a release agent to prevent the mold from sticking to the molded blank during demolding; and the in-situ solidification of the diamond abrasive slurry is left to stand at room temperature to remove large air bubbles introduced during the high-speed stirring process.

[0037] As can be seen from the above technical solution, compared with the prior art, the in-situ solidification process for preparing fine-grained diamond abrasives provided by the present invention has the following superior effects:

[0038] The process of this invention involves uniformly dispersing diamond and a ceramic binder under liquid conditions to obtain a liquid diamond abrasive slurry. Simultaneously, a microemulsion pore-forming agent is added during diamond forming. Then, through the cross-linking effect of organic monomers and a cross-linking agent, the slurry rapidly solidifies to form a diamond abrasive blank. This blank is then sintered to obtain a diamond abrasive with a highly uniform microstructure and a large number of uniformly distributed spherical pores. When processing SiC ceramic materials, the diamond abrasive prepared by this method exhibits more uniform grinding patterns and lower surface roughness. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 The microstructure of ceramic-bonded diamond abrasives with a diamond particle size of 5-8 μm, prepared by the currently commercially available dry pressing method.

[0041] Figure 2 The microstructure of ceramic-bonded diamond abrasives with a diamond particle size of 5-8 μm prepared by the process of this invention.

[0042] Figure 3 White light interference image of a 6-inch SiC wafer after single-sided grinding and thinning using a commercially available ceramic-bonded diamond abrasive with 5-8 μm diamond particles.

[0043] Figure 4 White light interference image of a 6-inch SiC wafer after single-sided grinding and thinning using a ceramic-bonded diamond abrasive with diamond particles of 5-8 μm prepared by the process of this invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] This invention discloses a process for preparing fine-grained diamond abrasives through in-situ solidification, specifically including the following steps:

[0046] (1) Preparation of microemulsion pore-forming agent

[0047] Deionized water, glycerin, and Tween-80 were accurately weighed, with a mass ratio of 40-45:22-25:32-35. The three reagents were then added to a beaker to prepare a mixed solution, which was stirred for 30-60 minutes using a magnetic stirrer at a speed of 300-400 rpm. After thorough mixing, 25-35 wt% of isooctane was added to the mixed solution under stirring conditions, and then stirred for 1-2 hours using a magnetic stirrer to obtain the isooctyl microemulsion pore-forming agent.

[0048] (2) Preparation of diamond molding slurry

[0049] The raw material formula (wt%) for diamond forming slurry is as follows:

[0050]

[0051] The formula of commercially available ceramic binders is (wt%): SiO2 55-60; B2O3 15-20; Al2O3 12-15; ZnO 5-10; Na2O 5-8; Li2O 2-3.

[0052] Acrylamide, N,N-methylenebisacrylamide, and deionized water were weighed according to a certain formula ratio and mixed evenly with magnetic stirring for 30-60 minutes to obtain a premix. Then, diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate, and isooctyl microemulsion pore-forming agent obtained in step one were weighed according to the formula ratio and added to the premix. The mixture was stirred at high speed for 2-3 hours at a stirring speed of 8000-10000 r / min until it was evenly mixed to obtain a diamond abrasive in-situ solidification molding slurry.

[0053] (3) In-situ solidification forming of diamond grinding tools

[0054] Apply petroleum jelly to the surface of the plastic-molded aluminum mold, then wipe off any excess petroleum jelly with gauze. After the diamond abrasive in-situ solidification molding slurry obtained in step 2 has been left to stand at room temperature for 2-3 hours, it is then injected into the molding mold. The aluminum mold containing the molding slurry is then placed in a water bath at 75-85℃ and heated for 45-60 minutes to solidify and shape. After demolding, the diamond abrasive green blank is obtained.

[0055] (4) Drying of diamond grinding wheel blanks

[0056] After demolding, the diamond grinding blank is placed at room temperature for 12-16 hours, then placed in a 45℃ drying oven for 12-16 hours, then the temperature of the drying oven is raised to 80℃ for 8-10 hours, and finally raised to 120℃ for 4-6 hours.

[0057] (5) Sintering of diamond grinding wheels

[0058] The dried diamond blank was placed in a controlled atmosphere furnace and heated at 2°C / min in an air atmosphere. -1 The temperature is increased to 400℃ at a rate of 3℃·min and held for 30-60 minutes, then increased at a rate of 3℃·min. -1 The temperature is rapidly increased to 700-730℃ and held for 1-2 hours, then cooled in the furnace to finally obtain porous ceramic-bonded diamond abrasives.

[0059] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0061] Example 1

[0062] This embodiment provides a process for preparing fine-grained diamond grinding tools using an in-situ solidification method, with the following specific steps:

[0063] (1) Preparation of microemulsion pore-forming agent

[0064] Deionized water, glycerin, and Tween-80 were accurately weighed in a mass ratio of 45:25:30. The three reagents were then simultaneously added to a beaker to prepare a mixed solution. The solution was stirred for 60 minutes at 400 rpm using a magnetic stirrer. After thorough mixing, 30 wt% of isooctane was added to the mixture while stirring. The mixture was then stirred for 1 hour using a magnetic stirrer to obtain the isooctane microemulsion pore-forming agent.

[0065] (2) Preparation of diamond molding slurry

[0066] The raw material formula (wt%) for diamond forming slurry is as follows:

[0067]

[0068] Acrylamide, N,N-methylenebisacrylamide, and deionized water were weighed according to a certain formula ratio and mixed evenly with magnetic stirring for 60 minutes to obtain a premix. Then, diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate, and isooctyl microemulsion pore-forming agent obtained in step one were weighed according to the formula ratio and added to the premix. The mixture was stirred at high speed for 3 hours at a stirring speed of 8000 r / min until it was evenly mixed to obtain a diamond abrasive in-situ solidification molding slurry.

[0069] (3) In-situ solidification forming of diamond grinding tools

[0070] Apply petroleum jelly to the surface of the plastic-molded aluminum mold, and then wipe off the excess petroleum jelly with gauze. After the diamond abrasive in-situ solidification molding slurry obtained in step 2 is left to stand at room temperature for 3 hours, it is injected into the molding mold. Then, the aluminum mold containing the molding slurry is placed in an 80°C water bath and heated for 60 minutes to solidify and shape. After demolding, the diamond abrasive green blank is obtained.

[0071] (4) Drying of diamond grinding wheel blanks

[0072] After demolding, the diamond grinding blank was placed at room temperature for 16 hours, then placed in a 45°C drying oven for 12 hours, then the temperature of the drying oven was raised to 80°C for 8 hours, and finally raised to 120°C for 6 hours.

[0073] (5) Sintering of diamond grinding wheels

[0074] The dried diamond blank was placed in a controlled atmosphere furnace and heated at 2°C / min in an air atmosphere. -1 The temperature was increased to 400℃ at a rate of 3℃·min and held for 60 minutes, then increased to 400℃ at a rate of 3℃·min. -1 The temperature is rapidly increased to 730℃ and held for 1 hour, then cooled in the furnace to finally obtain a porous ceramic-bonded diamond abrasive.

[0075] The following will further verify and illustrate the superior effects of this invention compared to existing technologies through specific characterization and measurement.

[0076] Fine-grained diamond and ceramic binders are dispersed in a liquid medium through high-speed stirring, resulting in a more uniform mixture than traditional dry-mixing methods. The highly dispersed slurry is then rapidly solidified in situ under a water bath at 75-85℃, preserving the high dispersibility of the fine-grained diamond and ceramic binders. The sintered ceramic-bonded abrasive blank exhibits a more uniform microstructure compared to ceramic-bonded diamond abrasives prepared by traditional dry pressing, with uniformly distributed spherical pores within the sintered body (see [link to product description]). Figure 1 , Figure 2 ).

[0077] Specifically, Figure 1 This indicates that the ceramic-bonded diamond abrasive prepared by dry pressing exhibits localized binder enrichment and uneven microstructure. Figure 2 This indicates that the ceramic-bonded diamond abrasive prepared in Example 1 of the present invention has a more uniform microstructure and uniformly distributed spherical pores in the sintered body. These pores can better accommodate chips and improve the self-sharpening property of the abrasive when grinding SiC materials.

[0078] A 6-inch SiC wafer was thinned using a commercially available ceramic-bonded diamond abrasive with 5-8 μm diamond particles on a single-sided grinding machine. The operating speed was 1200 r / min, the working pressure of the abrasive was 120 N, and the coolant was deionized water. The SiC wafer thickness reduction was 8.7 μm per minute, and the wafer surface roughness was Ra 0.105 μm (see [link to relevant documentation]). Figure 3 Under the same grinding conditions, a ceramic-bonded diamond abrasive tool prepared using the process of this invention was used for single-sided grinding and thinning of a 6-inch SiC wafer. The SiC wafer thickness reduction was 10.2 μm per minute, and the SiC wafer surface roughness was Ra 0.054 μm (see [link to invention]). Figure 4 The grinding efficiency was increased by 17.1%, and the surface roughness of SiC wafers was reduced by 48.6%.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for preparing fine-grained diamond abrasives through in-situ solidification, characterized in that, The process specifically includes the following steps: (1) Preparation of microemulsion pore-forming agent Isooctane was added to a mixed solution of deionized water, glycerol, and Tween-80 and stirred to obtain an isooctyl microemulsion pore-forming agent; (2) Preparation of diamond molding slurry Acrylamide, N,N-methylenebisacrylamide and deionized water were weighed according to the formula ratio and stirred to obtain a premixed liquid; diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate and isooctyl microemulsion pore-forming agent obtained in step (1) were weighed according to the formula ratio and added to the premixed liquid, and stirred at high speed to mix evenly to obtain diamond abrasive in-situ solidification molding slurry. (3) In-situ solidification forming of diamond grinding tools The diamond abrasive in-situ solidification molding slurry obtained in step (2) is injected into the molding mold, then solidified and molded, and after demolding, a diamond abrasive blank is obtained. (4) Drying of diamond grinding wheel blanks After demolding, the diamond grinding mold blank is placed at room temperature and then dried by programmed temperature increase for later use. (5) Sintering of diamond grinding wheels The dried diamond green blank is placed in a controlled atmosphere furnace and calcined by programmed heating and cooling, and finally a porous ceramic bonded diamond abrasive is obtained, namely the fine-grained diamond abrasive. The raw material formula for the diamond molding slurry is as follows: The formula for commercially available ceramic binders is as follows: SiO2 55-60wt%; B2O3 15-20wt%; Al2O3 12-15wt%; ZnO 5-10wt%; Na2O 5-8wt%; Li2O 2-3wt%; The programmed temperature rise calcination process in step (5) is as follows: At 2℃·min in air atmosphere -1 The temperature is increased to 400℃ at a rate of 3℃·min and held for 30-60 minutes, then increased at a rate of 3℃·min. -1 The temperature is rapidly increased to 700-730℃ and held for 1-2 hours.

2. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1, characterized in that, In step (1), the mass ratio of deionized water, glycerol and Tween-80 in the mixed solution is 40-45:22-25:32-35, and the amount of isooctane added is 25-35 wt% of the mass of the mixed solution.

3. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1, characterized in that, The curing temperature in step (3) is 75-85℃, and the molding temperature is 45-60min.

4. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1, characterized in that, In step (4), the demolded diamond abrasive blank is placed at room temperature for 12-16 hours, then placed in a 45°C drying oven for 12-16 hours, then the temperature of the drying oven is raised to 80°C for 8-10 hours, and finally raised to 120°C for 4-6 hours.

5. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1 or 2, characterized in that, In the preparation of the microemulsion pore-forming agent, deionized water, glycerol and Tween-80 were added simultaneously and mixed into a solution by mechanical stirring for 30-60 minutes at a stirring speed of 300-400 r / min. Then, isooctane was added under stirring conditions and stirred for 1-2 hours to finally obtain the isooctyl microemulsion pore-forming agent.

6. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1, characterized in that, Acrylamide, N,N-methylenebisacrylamide and deionized water were mixed evenly by magnetic stirring for 30-60 minutes to obtain a premixed liquid. Then, diamond abrasive, ceramic binder, polyethylene glycol, cerium ammonium nitrate and isooctyl microemulsion pore-forming agent obtained in step (1) were added to the premixed liquid and stirred at high speed for 2-3 hours at a stirring speed of 8000-10000 r / min. After being mixed evenly, the diamond abrasive in-situ solidification molding slurry was obtained.

7. The process for preparing fine-grained diamond abrasives by in-situ solidification according to claim 1 or 3, characterized in that, Before the diamond abrasive is solidified in situ, Vaseline needs to be applied to the surface of the plastic molding aluminum mold. Then, the excess Vaseline reagent on the surface is wiped off with gauze. After the diamond abrasive solidification slurry obtained in step (2) is left to stand at room temperature for 2-3 hours, it is injected into the molding mold.

Images