A ceramic diamond grinding wheel, its preparation method and application

Abstract

This invention provides a ceramic diamond grinding wheel, its preparation method, and its application. The ceramic diamond grinding wheel comprises a substrate and an abrasive body tightly bonded to the surface of the substrate. The abrasive body is composed of the following raw materials in weight percentages: 20-40% diamond micron powder, 0-5% green silicon carbide, 24-40% pore-forming agent, 30-50% ceramic binder, and 5-10% water glass. The ceramic binder is composed of the following raw materials in parts by weight: 30-50 parts silicon dioxide, 15-30 parts boric acid, 4-6 parts aluminum oxide, 4-8 parts barium oxide, 5-10 parts aluminum oxide, 5-10 parts zinc oxide, 4-8 parts sodium carbonate, 1-5 parts calcium carbonate, 1-5 parts magnesium oxide, and 1-10 parts lithium carbonate. This invention significantly improves bonding strength by using water glass and ceramic binder in combination. At the same time, due to the combination of diamond micro powder and green silicon carbide, the prepared ceramic diamond grinding wheel has stable current during the silicon carbide wafer thinning process, with no obvious current high point. The grinding wheel has stable sand removal, good self-sharpening properties, and low wear.

Description

Technical Field

[0001] This invention relates to the field of abrasive and grinding wheel technology, specifically to a ceramic diamond grinding wheel, its preparation method, and its application. Background Technology

[0002] Ceramic-bonded diamond wheels are widely used in high-precision grinding of hard and brittle materials such as silicon carbide wafers, sapphire, zirconia ceramics, and optical glass due to their excellent geometry retention, high wear resistance, and good thermal stability. With the large-scale application of silicon carbide, a third-generation semiconductor material, in power devices and 5G communications, the requirements for thinning grinding of silicon carbide wafers are becoming increasingly stringent. This necessitates not only high-efficiency material removal but also ensuring wafer surface integrity, low damage layer thickness, and stability during processing. Therefore, ceramic-bonded diamond wheels, as a key tool in thinning processes, have their grinding performance directly determined by their formulation, microstructure, and manufacturing process.

[0003] Currently, commonly used ceramic diamond grinding wheels in the industry typically employ the following formula system: fine-grained diamond as the main abrasive, white corundum as the auxiliary abrasive, a single-size pore-forming agent added, mixed with a ceramic binder and dextrin liquid, and prepared through granulation, pressing, sintering, and bonding. However, in the actual processing of 8-inch silicon carbide wafers, the use of the above-mentioned traditional grinding wheels has the following drawbacks: firstly, low grinding efficiency and insufficient cutting force; secondly, poor self-sharpening properties and easy clogging; and thirdly, short wheel life and high wear rate. Some technologies have been developed to improve self-sharpening properties by increasing porosity or the amount of pore-forming agent, but this often leads to a decrease in wheel hardness and shape retention. Therefore, how to achieve a systematic improvement in cutting force, self-sharpening properties, and wheel life without reducing wheel hardness has become a pressing problem in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a ceramic diamond grinding wheel, its preparation method, and its application, thus solving the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a ceramic diamond grinding wheel is provided, comprising a substrate and an abrasive body tightly bonded to the surface of the substrate, the abrasive body being composed of the following raw materials in weight percentages: 20-40% diamond micro powder, 0-5% green silicon carbide, 30-40% pore-forming agent, 30-50% ceramic binder and 5-10% water glass. The ceramic binder is composed of the following raw materials in parts by weight: 30-50 parts silicon dioxide, 15-30 parts boric acid, 4-6 parts aluminum oxide, 4-8 parts barium oxide, 5-10 parts aluminum oxide, 5-10 parts zinc oxide, 4-8 parts sodium carbonate, 1-5 parts calcium carbonate, 1-5 parts magnesium oxide and 1-10 parts lithium carbonate.

[0006] Preferably, the pore-forming agent is selected from a mixture of pore-forming agents with particle sizes of 20 μm and 50 μm.

[0007] Specifically, the pore-forming agent is selected from at least one of spherical polymethyl methacrylate, refined naphthalene, coke, walnut shell, and alumina spheres.

[0008] Preferably, the diamond micropowder has a particle size of 7~20μm.

[0009] Preferably, the particle size of the green silicon carbide is 14~20μm.

[0010] According to a second aspect of the present invention, a method for preparing a ceramic diamond grinding wheel is provided, comprising the following steps: S1. The diamond micro powder, green silicon carbide, pore-forming agent, ceramic binder and water glass are mixed, kneaded and granulated to obtain uniform particles; S2. The uniform particles are loaded into a mold and cold-pressed to obtain a green body; S3. The green body is first sintered in air atmosphere, and then sintered a second time in inert atmosphere. After cooling to room temperature, a polishing body is obtained. S4. After the grinding body is bonded to the substrate with an adhesive and then shaped and sharpened, the ceramic diamond grinding wheel is obtained.

[0011] Preferably, in step S2, the pressure of the cold pressing is 25~35MPa.

[0012] Preferably, in step S3, the conditions for the first sintering are: first, the temperature is raised to 100-150°C at a heating rate of 1-2°C / min and held for 1-2 hours, then the temperature is raised to 300-400°C at a heating rate of 1-2°C / min and held for 1-2 hours.

[0013] Preferably, in step S3, the conditions for the secondary sintering are as follows: first, the temperature is raised to 600-700℃ at a heating rate of 1-2℃ / min and held for 3-4 hours, then the temperature is raised to 800-900℃ at a heating rate of 1-2℃ / min and held for 2-3 hours.

[0014] Preferably, in step S4, the adhesive is a two-component adhesive.

[0015] According to a third aspect of the present invention, a ceramic diamond wheel or a ceramic diamond wheel prepared by the above-described method is provided for use in the thinning of silicon carbide wafers.

[0016] This invention provides a ceramic diamond grinding wheel, its preparation method, and its application. Compared with the prior art, it has the following advantages: (1) The ceramic diamond grinding wheel provided in this solution can significantly improve the bonding strength by using water glass and ceramic binder. At the same time, due to the combination of diamond micro powder and green silicon carbide, the ceramic diamond grinding wheel prepared has stable current during the silicon carbide wafer thinning process, with no obvious current high point. The grinding wheel has stable sand removal, good self-sharpening properties, and low wear.

[0017] (2) The ceramic diamond grinding wheel provided in this solution enhances the cutting force and reduces the concentration of diamond powder by selecting diamond micro powder with a larger particle size and green silicon carbide and reducing the amount used, thereby reducing the number of active abrasive grains and promoting micro-generation by increasing the force on the abrasive grains, thus improving the service life.

[0018] (3) The ceramic diamond grinding wheel provided in this solution forms a complex and uniformly distributed channel in the abrasive layer by selecting two pore-forming agents with different particle sizes. The ceramic binder and the grinding layer formed by the abrasive particles form a uniformly thick channel wall, which improves the self-sharpening property of the ceramic diamond grinding wheel.

[0019] (4) The ceramic diamond grinding wheel provided in this solution has high porosity and hardness through the compounding of raw materials and sintering process. When applied to the silicon carbide thinning process, it has excellent sharpness and shedding stability, and has a longer service life, avoiding equipment alarm shutdown caused by high current. Attached Figure Description

[0020] Figure 1 The images show the surface morphology of the ceramic diamond grinding wheel prepared in Example 1 of this invention. Image a is a microscope image at 5×5, image b is a microscope image at 5×10, and image c is a magnified image at 150x magnification. Figure 2 The images show the surface morphology of the ceramic diamond grinding wheel prepared in Comparative Example 1 of this invention. Image a is a microscope image at 5×5, image b is a microscope image at 5×10, and image c is a magnified image at 150x magnification. Figure 3 This is a current load diagram of the ceramic diamond grinding wheel prepared in Example 1 of the present invention during silicon carbide wafer thinning; Figure 4 This is a current load diagram of the ceramic diamond grinding wheel prepared in Comparative Example 1 of the present invention during the thinning of silicon carbide wafers. Detailed Implementation

[0021] To better illustrate the content of this invention, the following description is provided in conjunction with specific embodiments.

[0022] Example 1 A method for preparing a ceramic diamond grinding wheel includes the following steps: Materials: By mass percentage, it includes 30% diamond micro powder of type W20 (particle size 14~20μm), 3% green silicon carbide of type W20 (particle size 14~20μm), 30% spherical polymethyl methacrylate mixed pore-forming agent with particle size of 50μm and 20μm, 30% ceramic binder, and 7% water glass. The ceramic pore-forming agent is composed of 30 parts silicon dioxide, 15 parts boric acid, 4 parts aluminum oxide, 4 parts barium oxide, 5 parts aluminum oxide, 5 parts zinc oxide, 4 parts sodium carbonate, 1 part calcium carbonate, 1 part magnesium oxide, and 1 part lithium carbonate. Mixing: Diamond micro powder, green silicon carbide, pore-forming agent, ceramic binder and water glass were mixed for 20 minutes using an acoustic resonance mixer to obtain the mixture; Granulation: The mixture is first placed in an internal mixer for 2 hours of internal mixing, and then fed into a granulator for 5 hours of granulation to obtain uniform granules; Cold pressing: Uniform particles are loaded into a mold and pressed by a press at a pressure of 30MPa to obtain a green body; Sintering: The green blank is placed in a muffle furnace and heated to 100°C at a heating rate of 1.6°C / min under an air atmosphere, and held for 1 hour. Then, it is heated to 300°C at a heating rate of 1.6°C / min and held for 1 hour. Then, nitrogen is introduced to purge the air in the muffle furnace. Under a nitrogen atmosphere, it is heated to 600°C at a heating rate of 1.6°C / min and held for 3 hours. Then, it is heated to 800°C at a heating rate of 1.6°C / min and cooled naturally to room temperature to obtain the grinding media. Bonding: The grinding media is bonded to the aluminum substrate with adhesive. After shaping and sharpening, it is ultrasonically cleaned to obtain a ceramic diamond grinding wheel.

[0023] The surface morphology of the ceramic diamond grinding wheel prepared in this embodiment is as follows: Figure 1 As shown, the porosity of the ceramic diamond grinding wheel was 61.5% as measured by a porosity meter, and the Shore A hardness of the ceramic diamond grinding wheel was 68.75 as measured by a hardness tester.

[0024] Example 2 The preparation method in this embodiment is the same as that in Example 1. The difference is that the diamond micro powder is selected from W10 (particle size of 7~10μm) during the material preparation process.

[0025] Example 3 The preparation method in this embodiment is the same as that in Example 1, except that the diamond used in the preparation process is selected from W15 (particle size of 10~14μm).

[0026] Example 4 The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation process, by mass percentage, it includes 40% diamond micro powder of type W20 (particle size of 14~20μm), 25% spherical polymethyl methacrylate mixed pore-forming agent with particle size of 50μm and 20μm, 30% ceramic binder, and 5% water glass.

[0027] Example 5 The preparation method of this embodiment is the same as that of Example 1. The difference is that, in the preparation process, by mass percentage, it includes 20% diamond micro powder of type W20 (particle size of 14~20μm), 5% green silicon carbide of type W20 (particle size of 14~20μm), 40% spherical polymethyl methacrylate mixed pore-forming agent with particle size of 50μm and 20μm, 30% ceramic binder, and 10% water glass.

[0028] Comparative Example 1 A method for preparing a ceramic diamond grinding wheel, the preparation process of which is the same as that in Example 1, the difference being that the raw materials and amounts used are different. By mass percentage, it includes 50% diamond micro powder of type W5 (particle size of 3.5~5μm), 10% diamond of type W15 (particle size of 10~14μm), 20% pore-forming agent spherical polymethyl methacrylate with a particle size of 80μm, 15% ceramic binder, and 5% dextrin solution.

[0029] The surface morphology of the ceramic diamond grinding wheel prepared in this comparative example is as follows: Figure 2 As shown, the porosity of the ceramic diamond grinding wheel was 55.3% as measured by a porosity meter, and the Shore A hardness of the ceramic diamond grinding wheel was 61.89 as measured by a hardness tester.

[0030] go through Figure 1 and Figure 2 As can be seen from the comparison, the pores in Comparative Example 1 are independent of each other, with only a small number of pores connected. The main body of the abrasive layer is ceramic binder and abrasive grains. In Example 1, individual pores appear. In the abrasive layer, the pores form a complex and evenly distributed channel. The grinding layer composed of ceramic binder and abrasive grains forms a thin wall of channel with uniform wall thickness.

[0031] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 1, except that the diamond micro powder is selected from W5 (particle size 3.5~5) during the preparation process.

[0032] Comparative Example 3 The preparation method of this comparative example is the same as that of Example 1, except that the diamond micro powder is selected from W28 (particle size of 20~28μm) during the preparation process.

[0033] Comparative Example 4 The preparation method of this comparative example is the same as that of Example 1, except that only a pore-forming agent with a particle size of 50 μm is selected during the material preparation process.

[0034] Comparative Example 5 The preparation method of this comparative example is the same as that of Example 1, except that only a pore-forming agent with a particle size of 20 μm is selected during the material preparation process.

[0035] Comparative Example 6 The preparation method of this comparative example is the same as that of Example 1, except that, in the preparation process, by mass percentage, it includes 10% diamond micro powder of type W20 (particle size of 14~20μm), 5% green silicon carbide of type W20 (particle size of 14~20μm), 30% spherical polymethyl methacrylate mixed pore-forming agent with particle size of 50μm and 20μm, 45% ceramic binder, and 10% water glass.

[0036] Comparative Example 7 The preparation method of this comparative example is the same as that of Example 1, except that, in the preparation process, by mass percentage, it includes 50% diamond micro powder of type W20 (particle size of 14~20μm), 5% green silicon carbide of type W20 (particle size of 14~20μm), 20% spherical polymethyl methacrylate mixed pore-forming agent with particle size of 50μm and 20μm, 20% ceramic binder, and 5% water glass.

[0037] The porosity and hardness of the ceramic diamond grinding wheels prepared in Examples 1 to 5 and Comparative Examples 1 to 7 were tested respectively, as shown in Table 1.

[0038] Table 1

[0039] As shown in Table 1, Examples 1-3 and Comparative Examples 2-3, when the particle size of diamond micron powder decreases, the specific surface area increases, which can lead to insufficient binder in some areas, resulting in decreased strength and slightly decreased hardness. At the same time, the fine powder will partially fill the gaps in the pore-forming agent, causing a slight decrease in total porosity. However, if the particle size of diamond micron powder is too small, agglomeration will occur, resulting in a severe lack of binder, which will significantly reduce the hardness during grinding wheel feeding. On the other hand, if the particle size of diamond micron powder is too large, the particle packing voids will increase, resulting in excessive binder, decreased hardness, and increased porosity. By comparing Example 1 with Comparative Examples 4-5, the single-size pore-forming agent forms independent spherical pores after sintering, but the inter-pore connectivity is poor, the porosity will decrease, and the hardness will be slightly higher. By comparing Examples 1, 4-5 and Comparative Examples 6-7, it was found that when the content of diamond micron powder was too low, the content of binder increased, the effective porosity decreased, and the hardness of the grinding wheel also decreased slightly; when the diamond content was too high, the content of pore-forming agent and binder was too low, which resulted in weak interparticle bonding force, reduced porosity, but higher hardness.

[0040] Application examples The ceramic diamond grinding wheels prepared in Example 1 and Comparative Example 1 were applied to the thinning of silicon carbide wafers. Specifically, an 8-inch bare silicon carbide wafer (wafer number: BE025016JRE5) was ground using a fully automatic grinding machine (model: DISCO8640). The spindle power of the machine was set to 6.3 kW, the spindle forming resolution to 0.01 μm / s, the grinding fluid outlet method to be center outlet / outer bamboo tube outlet, the grinding fluid flow rate (L / min) to be 4.8 / 4.8, and the no-load current / alarm current to be 6 / 36 A. The spindle speed for grinding was 2250 rpm, the carrier plate speed was 254 rpm, and the spindle feed was 0.3 μm. The test data are shown in Table 2.

[0041] Table 2

[0042] As can be seen from the data comparison in Table 2, the ceramic diamond grinding wheel prepared in Example 1 of the present invention has self-sharpening and uniform shedding, low grinding wheel consumption, low wear rate, and long service life.

[0043] pass Figure 3 , Figure 4 The comparison shows that the ceramic diamond grinding wheel prepared in Example 1 has a stable current with no obvious current spikes, while the ceramic diamond grinding wheel prepared in Comparative Example 1 has large current fluctuations and significant current spikes.

[0044] The flatness and surface condition of the ceramic diamond grinding wheels prepared in Examples 1-5 and Comparative Examples 1-7 were tested using an FM200 tester. The grinding wheel wear and wear rate were also tested. The results are shown in Table 3. Table 3

[0045] As shown in Table 3, the ceramic diamond grinding wheel prepared in Example 1 achieves the best performance by balancing wear rate, surface quality, TTV, and warpage. While excessively high diamond powder content reduces wear rate, it worsens surface roughness and TTV. Excessively fine diamond powder results in better surface roughness but extremely high wear rate, severely shortening the wheel's lifespan. Ceramic diamond grinding wheels prepared with a single-size pore-forming agent exhibit poor chip removal and cooling performance, leading to poor surface roughness.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A ceramic diamond grinding wheel, characterized in that: The invention includes a substrate and an abrasive body tightly bonded to the surface of the substrate, the abrasive body being composed of the following raw materials in weight percentages: 20-40% diamond micro powder, 0-5% green silicon carbide, 24-40% pore-forming agent, 30-50% ceramic binder and 5-10% water glass. The ceramic binder is composed of the following raw materials in parts by weight: 30-50 parts silicon dioxide, 15-30 parts boric acid, 4-6 parts aluminum oxide, 4-8 parts barium oxide, 5-10 parts aluminum oxide, 5-10 parts zinc oxide, 4-8 parts sodium carbonate, 1-5 parts calcium carbonate, 1-5 parts magnesium oxide and 1-10 parts lithium carbonate.

2. The ceramic diamond grinding wheel according to claim 1, characterized in that: The pore-forming agent is selected from a mixture of pore-forming agents with particle sizes of 20 μm and 50 μm.

3. The ceramic diamond grinding wheel according to claim 1, characterized in that: The diamond micron powder has a particle size of 7~20μm.

4. The ceramic diamond grinding wheel according to claim 1, characterized in that: The green silicon carbide has a particle size of 14~20μm.

5. A method for preparing a ceramic diamond grinding wheel according to any one of claims 1 to 4, characterized in that: Includes the following steps: S1. The diamond micro powder, green silicon carbide, pore-forming agent, ceramic binder and water glass are mixed, kneaded and granulated to obtain uniform particles; S2. The uniform particles are loaded into a mold and cold-pressed to obtain a green body; S3. The green body is first sintered in air atmosphere, and then sintered a second time in inert atmosphere. After cooling to room temperature, a polishing body is obtained. S4. After the grinding body is bonded to the substrate with an adhesive and then shaped and sharpened, the ceramic diamond grinding wheel is obtained.

6. The method for preparing a ceramic diamond grinding wheel according to claim 5, characterized in that: In step S2, the pressure of the cold pressing is 25~35MPa.

7. The method for preparing a ceramic diamond grinding wheel according to claim 5, characterized in that: In step S3, the conditions for the first sintering are as follows: first, the temperature is raised to 100-150℃ at a heating rate of 1-2℃ / min and held for 1-2 hours; then, the temperature is raised to 300-400℃ at a heating rate of 1-2℃ / min and held for 1-2 hours.

8. The method for preparing a ceramic diamond grinding wheel according to claim 1, characterized in that: In step S3, the conditions for the secondary sintering are as follows: first, the temperature is raised to 600-700℃ at a heating rate of 1-2℃ / min and held for 3-4 hours; then, the temperature is raised to 800-900℃ at a heating rate of 1-2℃ / min and held for 2-3 hours.

9. The method for preparing a ceramic diamond grinding wheel according to claim 5, characterized in that: In step S4, the adhesive is a two-component adhesive.

10. The application of a ceramic diamond grinding wheel according to any one of claims 1 to 4 or a ceramic diamond grinding wheel obtained by the preparation method according to any one of claims 5 to 9 in the thinning of silicon carbide wafers.

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