A method for preparing a porous ceramic diamond grinding wheel tooth

Abstract

The present application relates to the technical field of grinding wheel preparation, and particularly relates to a preparation method of porous ceramic diamond grinding wheel teeth, which comprises the following steps: S1: preparing a binder solution by mixing binders; S2: mixing the binder solution, diamond abrasive, ceramic binder and dispersant to obtain a first mixture; S3: mixing the first mixture and thickening agent to obtain a second mixture; S4: mixing the second mixture, initiator and foaming agent, and then freezing, drying and sintering to obtain the porous ceramic diamond grinding wheel teeth; wherein the weight proportions of raw materials of the porous ceramic diamond grinding wheel teeth are as follows: diamond abrasive 30-54%, binder 7-8%, dispersant 2-3%, thickening agent 1-4%, initiator 3-5% and foaming agent 6-10%, and the rest is ceramic binder; the grinding wheel teeth prepared by the preparation method have the characteristic of high porosity.

Description

Technical Field

[0001] This invention relates to the field of grinding wheel manufacturing technology, and in particular to a method for preparing porous ceramic diamond grinding wheel teeth. Background Technology

[0002] Currently, ceramic grinding wheels manufactured using traditional forming processes are mature technologies, exhibiting high strength and good wear resistance, and are widely used in the grinding of various conventional materials. However, the ever-increasing demand for microscopic and nanoscale structures in semiconductor wafers has exceeded the capabilities of traditional grinding processes, making it difficult to meet requirements in terms of machining accuracy and surface integrity. Traditional forming technologies such as cold pressing remain the dominant processes in the production of diamond ultra-precision grinding tools, which has become a bottleneck restricting further performance improvements.

[0003] In the grinding process of semiconductor wafers, on the one hand, because the pores are closed or not connected, it is impossible to guarantee the consistency of the processed surface quality, and the diamond in the mold is prone to oxidation or graphitization due to the high temperature of grinding; on the other hand, the limited space to accommodate debris may cause the pores of the grinding wheel to become blocked, reducing the grinding performance of the grinding wheel, thereby causing damage to the workpiece. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for preparing porous ceramic diamond grinding wheel teeth, which solves the problems of easy clogging of grinding wheels, poor heat dissipation, and poor grinding performance and surface finish in the prior art.

[0005] This invention first provides a method for preparing porous ceramic diamond grinding wheel teeth, the method comprising the following steps: S1: Prepare the adhesive into an adhesive solution; S2: The binder solution is mixed with diamond abrasive, ceramic binder and dispersant to obtain a first mixture; S3: Vacuum mix the first mixture and the thickener to obtain the second mixture; S4: The second mixture is mixed with the initiator and foaming agent, and then frozen, dried and sintered to obtain the porous ceramic diamond grinding wheel teeth; The porous ceramic diamond grinding wheel teeth are made of the following raw materials by weight: 30%~54% diamond abrasive, 7%~8% binder, 2%~3% dispersant, 1%~4% thickener, 3%~5% initiator, 6%~10% foaming agent, and the remainder is ceramic binder.

[0006] In one embodiment, the diamond abrasive has a particle size of 8000~30000 mesh.

[0007] In one embodiment, the binder is polyvinyl alcohol, the dispersant is ammonium citrate, the thickener is methylcellulose, the initiator is ammonium persulfate, the foaming agent is ammonium dodecyl sulfate, and the ceramic binder is borosilicate low-melting-point glass powder.

[0008] In one embodiment, in step S4, the mixing includes magnetic stirring, and the magnetic stirring time is 30-35 minutes.

[0009] In one embodiment, in step S2, the mixing includes ball milling, and the ball milling time is 4 to 5 hours.

[0010] In one embodiment, in step S3, the vacuum mixing is performed using a planetary vacuum degassing machine, and the vacuum mixing time is at least 5 minutes.

[0011] In one embodiment, in step S4, the freezing and drying are carried out using a vacuum freeze dryer, the freezing time is 2 to 3 hours, the drying time is 15 to 18 hours, the freezing temperature is -40°C to -30°C, and the drying temperature is 10°C to 17°C.

[0012] In one embodiment, step S4 further includes a water bath step before freezing.

[0013] In one embodiment, in step S4, the sintering includes holding at a temperature of 600~810°C for 3~4 hours.

[0014] In one embodiment, the porous ceramic diamond grinding wheel teeth have a porosity of 43-76% and a pore size of 20-1000 μm.

[0015] The present invention provides a method for preparing porous ceramic diamond grinding wheel teeth, which has the following beneficial effects: the diamond abrasive continuously maintains the sharpness of the cutting edge during the grinding process, without scratching the workpiece; the binder completely wets the diamond abrasive; the pore structure is firmly held by the ceramic binder and adhesive, ensuring the consistency of the processed surface quality; the high porosity of the grinding layer increases the space for accumulating debris, which can reduce debris blockage and keep the grinding wheel self-sharpening, thereby improving grinding performance. Attached Figure Description

[0016] Figure 1 A process flow diagram of the preparation method in this invention; Figure 2 This is a SEM image of the ceramic diamond grinding wheel teeth in Example 1 of this invention; Figure 3 This is a SEM image of the ceramic diamond grinding wheel teeth in Example 2 of this invention; Figure 4This is a SEM image of the ceramic diamond grinding wheel teeth in Example 3 of this invention; Figure 5 This is a SEM image of the ceramic diamond grinding wheel teeth in Comparative Example 1 of this invention. Figure 6 This is a SEM image of the ceramic diamond grinding wheel teeth in Comparative Example 2 of this invention; Figure 7 This is a SEM image of the ceramic diamond grinding wheel teeth in Comparative Example 3 of this invention; Figure 8 This is a photograph of a silicon wafer after fine grinding using the grinding wheel prepared in Experimental Example 1 of this invention. Detailed Implementation

[0017] The present invention will be further illustrated by specific embodiments below.

[0018] Experimental Example 1 Weigh 7% of the binder and pour it into a beaker containing a certain amount of pure water. Heat the beaker to 80-90℃ and stir magnetically until dissolved to obtain a 2wt% binder solution. Pour the binder solution into a mixing tank containing 54% of 8000-mesh diamond abrasive, 26% of ceramic binder, 2% of dispersant, and ball milling stones at a ball-to-material ratio of 2:1. Mix the mixture in a three-dimensional mixer for 5 hours to obtain a mixture. Add 2% of thickener to the mixture and then vacuum-mix it at high speed in a planetary vacuum degassing machine for 5 minutes to improve the stability of the structure. Then pour the mixture into a beaker, add 3% of initiator and 6% of foaming agent, and stir magnetically at room temperature for 32 minutes to chemically foam the mixture on the basis of a stable structure, forming a porous scaffold. After being poured into a mold and frozen at -40°C for 2 hours, the material was vacuum dried at 10°C for 16 hours. After demolding, the material was kept in a muffle furnace at 750°C for 4 hours. Finally, porous ceramic diamond grinding wheel teeth with a porosity of 75% and a pore size of 20~200μm were obtained.

[0019] Experimental Example 2 Take 7% of the binder and pour it into a beaker containing a certain amount of pure water. Heat it to 80~90℃ and stir it magnetically to dissolve it, thus obtaining a 2wt% binder solution. Pour the binder solution into a mixing tank containing 30% of 8000-mesh diamond abrasive, 47% of ceramic binder, 2% of dispersant, and ball milling stones with a ball-to-material ratio of 2:1. Mix the mixture in a three-dimensional mixer for 4 hours to obtain a mixture. Add 4% of thickener to the mixture and then vacuum mix it at high speed in a planetary vacuum degassing machine for 5 minutes to improve the stability of the structure. Then pour it into a beaker, add 5% of initiator and 10% of foaming agent, and stir it magnetically at room temperature for 30 minutes to chemically foam the structure and form a porous scaffold. The mixture was poured into a mold and placed in an 80°C water bath for 30 minutes. Then it was frozen at -30°C for 3 hours and vacuum dried at 17°C for 15 hours. After demolding, it was kept in a muffle furnace at 600°C for 3 hours. Finally, porous ceramic diamond grinding wheel teeth with a porosity of 43% and a pore size of 250~1000μm were obtained.

[0020] Experimental Example 3 Take 8% of the binder and pour it into a beaker containing a certain amount of pure water. Heat it to 80~90℃ and stir it magnetically to dissolve it, thus obtaining a 2wt% binder solution. Pour the binder solution into a mixing tank containing 50% of 30,000-mesh diamond abrasive, 23% of ceramic binder, 3% of dispersant, and ball milling stones with a ball-to-material ratio of 2:1. Mix it in a three-dimensional mixer for 5 hours to obtain a mixture. Add 1% of thickener to the mixture and then vacuum mix it at high speed in a planetary vacuum degassing machine for 5 minutes to improve the stability of the structure. Then pour it into a beaker, add 3% of initiator and 6% of foaming agent, and stir it magnetically at room temperature for 35 minutes to chemically foam the structure and form a porous scaffold. After being poured into a mold and frozen at -30°C for 3 hours, the material was vacuum dried at 17°C for 18 hours. After demolding, the material was kept in a muffle furnace at 810°C for 3 hours. Finally, porous ceramic diamond grinding wheel teeth with a porosity of 76% and a pore size of 20~120μm were obtained.

[0021] Comparative Example 1 Weigh 7% of the binder and pour it into a beaker containing a certain amount of pure water. Heat to 80-90℃ and stir magnetically until dissolved to obtain a 2wt% binder solution. Pour the binder solution into a mixing tank containing 54% 8000-mesh diamond abrasive, 26% ceramic binder, 2% dispersant, and ball-to-material ratio 2:1 grinding stones. Mix in a three-dimensional mixer for 5 hours to obtain a mixture. Add 2% thickener to the mixture and pour it into a beaker. Add 3% initiator and 6% foaming agent, and stir magnetically at room temperature for 32 minutes. Pour into a mold and freeze at -40℃ for 2 hours, then vacuum dry at 10℃ for 16 hours. After demolding, keep warm in a muffle furnace at 750ºC for 4 hours to obtain a structure with few pores and uneven structure.

[0022] Comparative Example 2 Take 8% of the binder and pour it into a beaker containing a certain amount of pure water. Heat it to 80~90℃ and stir it magnetically to dissolve it, thus obtaining a 2wt% binder solution. Pour the binder solution into a mixing tank containing 30% of 8000-mesh diamond abrasive, 40% of ceramic binder, 2% of dispersant, and ball milling stones with a ball-to-material ratio of 2:1. Mix the mixture in a three-dimensional mixer for 4 hours to obtain a mixture. Add 4% of thickener to the mixture and then vacuum mix it at high speed in a planetary vacuum degassing machine for 5 minutes to improve the stability of the structure. Then pour it into a beaker, add 5% of initiator and 10% of foaming agent, and stir it magnetically at room temperature for 30 minutes to chemically foam the structure and form a porous scaffold. The mixture was poured into a mold and placed in an 80°C water bath for 30 minutes. Then it was frozen at -30°C for 3 hours and vacuum dried at 17°C for 15 hours. After demolding, it was kept in a muffle furnace at 600°C for 3 hours. Finally, a porous ceramic diamond grinding wheel with a pore size of 250~2000μm and a mixed pore structure of circular and ice crystal-like vertical lines was obtained. However, the stability was poor and the service life was short. Comparative Example 3 Take 8% of the binder and pour it into a beaker containing a certain amount of pure water. Heat it to 80~90℃ and stir it magnetically to dissolve it, thus obtaining a 2wt% binder solution. Pour the binder solution into a mixing tank containing 45% of 30,000-mesh diamond abrasive, 23% of ceramic binder, 3% of dispersant, and ball milling stones with a ball-to-material ratio of 2:1. Mix it in a three-dimensional mixer for 5 hours to obtain a mixture. Add 1% of thickener to the mixture and then vacuum mix it at high speed in a planetary vacuum degassing machine for 5 minutes to improve the stability of the structure. Then pour it into a beaker, add 3% of initiator and 6% of foaming agent, and stir it magnetically at room temperature for 40 minutes to chemically foam on the basis of a stable structure to form a porous scaffold. After being poured into a mold and frozen at -30°C for 3 hours, the material was vacuum dried at 17°C for 18 hours. After demolding, the material was kept in a muffle furnace at 810°C for 3 hours. Finally, porous ceramic diamond grinding wheel teeth with a porosity of 61% and a pore size of 20~200μm were obtained.

[0023] like Figure 8 As shown, the porous ceramic diamond grinding wheel prepared in Experiment 1 was used to finely grind the silicon wafer. The grinding parameters were: grinding wheel speed 3000 rpm, table speed 100 rpm. The silicon wafer removal depth was 35 μm, the feed rate was 0.3 μm / s to remove 30 μm, and the feed rate was 0.2 μm / s to remove 5 μm.

[0024] As can be seen from the examples and comparative examples, comparative example 1 did not use planetary vacuum mixing compared to example 1. Without this step, the air bubbles in the slurry could not be effectively removed, resulting in uneven pores and poor structural stability during subsequent foaming. Comparative example 1 ultimately obtained fewer pores and uneven structure.

[0025] The amount of ceramic binder used in Comparative Example 2 was lower than that in Experimental Example 2, resulting in lower strength. In Comparative Example 3, the magnetic stirring time at room temperature was 40 minutes, compared to Example 3. Excessive stirring time may cause bubbles to merge, rupture, or the stability of the slurry to be compromised, affecting the regularity and porosity of the final pore structure. The porosity of Comparative Example 3 was 61%, lower than the 76% of the similar Example 3.

[0026] Example 2 uses a water bath step compared to Example 1, which can result in a larger range of pore sizes, making it suitable for rough grinding and heavy-duty grinding.

[0027] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, and materials used in the embodiments, based on the knowledge of those skilled in the art and the description of the present invention, any prior art methods, devices, and materials similar to or equivalent to those described, used, and materials in the embodiments of the present invention can be used to implement the present invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing porous ceramic diamond grinding wheel teeth, characterized in that: The preparation method includes the following steps: S1: Prepare the adhesive into an adhesive solution; S2: The binder solution is mixed with diamond abrasive, ceramic binder and dispersant to obtain a first mixture; S3: Vacuum mix the first mixture and the thickener to obtain the second mixture; S4: The second mixture is mixed with the initiator and foaming agent, and then frozen, dried and sintered to obtain the porous ceramic diamond grinding wheel teeth; The porous ceramic diamond grinding wheel teeth are made of the following raw materials by weight: 30%~54% diamond abrasive, 7%~8% binder, 2%~3% dispersant, 1%~4% thickener, 3%~5% initiator, 6%~10% foaming agent, and the balance being ceramic binder; the binder is polyvinyl alcohol, the dispersant is ammonium citrate, the thickener is methylcellulose, the initiator is ammonium persulfate, the foaming agent is ammonium dodecyl sulfate, and the ceramic binder is borosilicate low-melting-point glass powder; In step S3, the vacuum mixing is performed using a planetary vacuum degassing machine, and the vacuum mixing time is at least 5 minutes. In step S4, the mixing includes magnetic stirring, and the magnetic stirring time is 30-35 minutes. In step S4, the freezing and drying are carried out using a vacuum freeze dryer. The freezing time is 2-3 hours, the drying time is 15-18 hours, the freezing temperature is -40℃ to -30℃, and the drying temperature is 10℃ to 17℃. In step S4, the sintering includes holding at a temperature of 600~810℃ for 3~4 hours.

2. The preparation method according to claim 1, characterized in that, The diamond abrasive has a particle size of 8000~30000 mesh.

3. The preparation method according to claim 1, characterized in that, In step S2, the mixing includes ball milling, and the ball milling time is 4 to 5 hours.

4. The preparation method according to claim 1, characterized in that, In step S4, a water bath step is also included before freezing.

5. The preparation method according to claim 1, characterized in that, The porous ceramic diamond grinding wheel teeth have a porosity of 43-76% and a pore size of 20-1000 μm.

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