Diamond grinding wheel for high-hardness and brittle material and its preparation method

Abstract

The application relates to a diamond grinding wheel for high-hardness and high-brittle material, which is mainly prepared from the following components in parts by volume: Sb-Cu-Sn pre-alloy powder 20-50 parts, CaSnF6 negative expansion powder 5-15 parts, polyaryl sulfone resin powder 10-40 parts, Ta4HfC5 nano-carbide particles 5-20 parts and diamond abrasive 10-30 parts. The diamond grinding wheel has high sharpness, good self-sharpening property and long service life, and has high machining efficiency and surface quality when high-hardness and high-brittle material is machined.

Description

Technical Field

[0001] This invention belongs to the field of superhard abrasive grinding wheel technology, specifically relating to a diamond grinding wheel for grinding high-hardness and brittle materials and its preparation method. Background Technology

[0002] With the rapid development of 5G communications, national defense, and aerospace, the application areas of the semiconductor industry have expanded significantly. Chips are constantly evolving towards miniaturization, high capacity, and high stability, and second-generation semiconductors, represented by silicon, can no longer meet the demands of future development. New-generation wide-bandgap semiconductor materials such as silicon carbide, gallium nitride, aluminum nitride, gallium oxide, and diamond possess higher breakdown voltages, better thermal conductivity, and stronger radiation resistance, and are widely used in high-power, high-frequency, and high-temperature applications, representing an emerging and future direction for the semiconductor industry.

[0003] Compared to silicon, next-generation semiconductor materials such as silicon carbide are harder and more brittle. During processing, the surface quality of the workpiece is unstable, easily resulting in fragmentation. Furthermore, the requirements for grinding performance indicators such as warpage, roughness, and processing efficiency are further increased, significantly increasing the processing difficulty compared to silicon, thus hindering the development and application of next-generation semiconductor materials like silicon carbide. Currently, grinding silicon carbide and other next-generation semiconductor materials with diamond wheels is the only option. However, existing ceramic-bonded diamond wheels have high sintering temperatures, leading to surface carbonization and affecting wheel lifespan. Resin-bonded diamond wheels have low strength, high grinding wear, low load-bearing capacity, and are prone to surface cracking. Traditional metal-bonded wheels have high strength, good shape retention, and high thermal conductivity, but poor self-sharpening properties, making them prone to burning and cracking when grinding hard and brittle materials.

[0004] Chinese invention patent application CN115415944 discloses a silicon carbide wafer thinning metal-bonded grinding wheel. The metal bond is composed of the following raw materials by weight percentage: 60-85% copper-tin alloy powder, 10-20% titanium powder, 5-20% carbon powder, and 0.5-3% nano-silicon carbide. This patent improves the binding performance and strength of the binder for diamond by adding titanium powder, carbon powder, and nano-silicon carbide to the copper-tin alloy powder. The carbon powder and nano-silicon carbide enhance the self-sharpening property of the diamond. However, the grinding wheel sintering temperature is 800-820℃, which easily causes diamond carbonization, resulting in low production efficiency. Chinese invention patent CN106041760B discloses a self-sharpening diamond grinding wheel and its preparation method. However, the synthesis of its abrasive blocks requires high temperature and pressure, resulting in high production costs, neither of which can meet the grinding requirements of next-generation semiconductor materials such as silicon carbide.

[0005] Therefore, how to scientifically select diamond bond systems and fillers to obtain diamond grinding wheels with high processing efficiency, long service life, and continuous self-sharpening without dressing is a problem that the industry urgently needs to solve. Summary of the Invention

[0006] To address the problems mentioned above, the present invention aims to provide a diamond grinding wheel for grinding high-hardness and brittle materials. This diamond grinding wheel is highly sharp, has good self-sharpening properties, and a long service life, and exhibits high processing efficiency and surface quality when grinding high-hardness and brittle materials.

[0007] The present invention also provides a method for preparing the diamond grinding wheel for grinding the above-mentioned high hardness and brittle materials.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A diamond grinding wheel for grinding high-hardness and brittle materials, by volume, is mainly composed of the following components: 20-50 parts of Sb-Cu-Sn pre-alloy powder, 5-15 parts of CaSnF6 negative expansion powder, 10-40 parts of polyarylsulfone resin powder, 5-20 parts of Ta4HfC5 nano carbide particles, and 10-30 parts of diamond abrasive.

[0010] Specifically, the CaSnF6 negative expansion powder has a particle size of 2~8μm and a coefficient of thermal expansion of -15.78×10⁻⁶. -6 / ℃.

[0011] Furthermore, the Ta4HfC5 nanocarbide particles have a particle size of 200~600nm.

[0012] This invention adds antimony to a traditional copper-tin alloy. The resulting Sb-Cu-Sn alloy system, upon sintering, simultaneously generates a brittle Cu-Sn phase and acicular Sb-Cu intermetallic compounds. The binder exhibits high sharpness and good self-sharpening properties. The acicular Sb-Cu intermetallic compounds fracture during grinding, forming spalling pits, which improves the chip removal capacity of the diamond grinding wheel, reduces grinding heat on the workpiece surface, and results in high surface quality when grinding high-hardness and brittle materials. The polyarylsulfone is a heat-resistant resin. Introducing it into the Sb-Cu-Sn ternary alloy binder system allows the diamond grinding wheel to combine the shape retention of a metal binder with the soft elasticity of a resin binder, resulting in low load and high surface quality during grinding. The negative expansion powder CaSnF6 has a coefficient of thermal expansion of -15.78 × 10⁻⁶. -6At / ℃, this invention introduces CaSnF6 negative expansion powder into the binder to significantly reduce the binder's coefficient of thermal expansion. The resulting diamond superhard grinding wheel exhibits high cutting edge output, good self-sharpening properties, and high surface quality during continuous grinding of high-hardness and brittle materials. The nano-carbide is Ta4HfC5 ceramic particles, which act as self-lubricants during grinding, helping to reduce the coefficient of friction and improve the surface quality of the ground material.

[0013] Specifically, the diamond grinding wheel substrate is an aluminum substrate, with several elliptical grinding wheel grooves distributed on the end face of the substrate, and drainage grooves evenly distributed between the grinding wheel grooves. More preferably, approximately 24 elliptical grinding wheel grooves can be distributed on the end face of the substrate, with approximately 12 drainage grooves evenly distributed between the grinding wheel grooves, equivalent to two elliptical grinding wheel grooves forming a group, and one drainage groove evenly distributed between two groups (see [reference]). Figure 1 This matrix structure promotes the full flow of coolant in the abrasive layer and on the workpiece surface, which is beneficial for improving workpiece surface quality and grinding wheel life.

[0014] This invention provides a method for preparing a diamond grinding wheel for grinding high-hardness and brittle materials, comprising the following steps:

[0015] S1. Weigh out Sb-Cu-Sn pre-alloyed powder and CaSnF6 negative expansion powder according to the formula, mix and sieve, and then perform high-energy ball milling through a horizontal planetary ball mill to obtain the pre-formulated powder.

[0016] S2. Weigh out polysulfone resin powder and Ta4HfC5 nano carbide particles according to the formula, add binder and mix evenly, then press into blocks. Crush the obtained cold-pressed blocks through a crusher and grinder to obtain mixed powder.

[0017] S3. Weigh the pre-made powder and mixed powder, mix them evenly with the granulator, sieve them, add diamond abrasive, and then mix and dry them thoroughly in a three-dimensional mixer to obtain the molding material; the ball-to-powder ratio is 1:5, the rotation speed is 10~30 rpm, and the time is 5~20 hours.

[0018] S4. The molding material is put into a graphite mold and hot-pressed and sintered by a hot-pressing sintering machine to obtain a grinding wheel block;

[0019] S5. After heat treatment, the obtained grinding wheel block is cut into an elliptical end face by an electrical discharge machining (EDM) machine. The end face of the grinding wheel block is then bonded to the elliptical grinding wheel groove of the substrate to obtain a diamond grinding wheel for grinding high-hardness and brittle materials.

[0020] Specifically, in step S1, the Sb-Cu-Sn pre-alloyed powder, by volume, mainly consists of the following components: 10-40 parts copper-tin alloy powder, 10-25 parts copper powder, 3-15 parts tin powder, and 5-12 parts antimony powder. After mixing and sieving, the powder is placed in a zirconia ball mill jar at a ball-to-powder ratio of 15:1, and an appropriate amount of anhydrous ethanol is added as the milling medium. High-energy ball milling is performed using a horizontal planetary ball mill under argon protection to obtain the pre-prepared powder. The milling speed is 100-220 rpm, and the time is 5-30 hours. During ball milling, the alloy powder undergoes continuous cold welding and crushing, which helps to refine the alloy powder, improve the uniformity of the binder structure, and reduce the sintering time of the alloy powder.

[0021] Furthermore, the copper-tin alloy powder is preferably CuSn45 alloy powder with a particle size of 5~12μm.

[0022] Specifically, in step S2 of the present invention, the binder includes one or more of polyvinyl alcohol, polymethyl methacrylate, propylene glycol, and glacial acetic acid; in step S3, the granulating agent is composed of paraffin wax and binder KC-1700P mixed in a volume ratio of 2:1.

[0023] Furthermore, in step S4 of the present invention, the hot pressing sintering process is as follows: the temperature is increased from room temperature to 340±20℃ at a heating rate of 25~35℃ / min, and held for 2~5 min; then the temperature is increased to 370±20℃ at a heating rate of 15~20℃ / min, and held for 2~5 min, with a pressure of 2~3MPa; then the temperature is increased to 380~450℃ at a heating rate of 5~10℃ / min, and held for 8~25 min, with a pressure of 5~10MPa.

[0024] Furthermore, in step S5 of the present invention, the heat treatment process of the sintered grinding wheel block is as follows: the temperature is raised to 280~330℃ at a heating rate of 30±5℃ / min, held for 12~24h, and then cooled to room temperature at a cooling rate of 15±5℃ / min.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1) This invention selects the Sb-Cu-Sn alloy system as the binder. The brittle Cu-Sn phase and acicular Sb-Cu intermetallic compound in the microstructure are beneficial to improving the sharpness and self-sharpening of the diamond grinding wheel. The acicular Sb-Cu intermetallic compound breaks during the grinding process to form spalling pits, which increases the edge height of the abrasive, improves the chip carrying and chip removal capacity of the diamond grinding wheel, reduces the grinding heat on the workpiece surface, and results in high surface quality when grinding high hard and brittle materials.

[0027] 2) The present invention introduces high-temperature resistant and high-strength polyarylsulfone resin into the binder, which is beneficial to improve the binder's holding force on diamond and increase the load resistance of the grinding wheel. At the same time, it takes into account the soft elasticity of the resin, which can improve the surface quality of the workpiece being ground.

[0028] 3) The present invention introduces CaSnF6 negative expansion powder into the binder, which on the one hand can significantly reduce the thermal expansion coefficient of the binder, reduce the residual stress at the interface between the binder and diamond particles, improve the binding force of the binder on the diamond, and increase the diamond tip height. On the other hand, the difference in thermal expansion coefficient between the negative expansion material and the Sb-Cu-Sn alloy will generate high shrinkage stress at their interface. During the grinding process, the binder tends to fracture brittlely. The resulting diamond superhard grinding wheel has high tip height, good self-sharpening properties and high surface quality when continuously grinding high hard and brittle materials.

[0029] 4) The present invention introduces nano-carbide Ta4HfC5 ceramic particles into the binder, which plays a self-lubricating role in the grinding process, which helps to reduce the friction coefficient and improve the grinding surface quality.

[0030] 5) The diamond grinding wheel for grinding high-hardness and brittle materials of the present invention has several elliptical grinding wheel grooves distributed on the end face of the substrate. Compared with the existing grinding wheel layer segmented cutting structure, there is less continuous contact surface during grinding, which effectively reduces grinding resistance, improves chip removal capacity and cooling efficiency. The drainage grooves evenly distributed between the grinding wheel grooves promote the full flow of coolant in the abrasive layer and the workpiece surface, which is beneficial to improving the workpiece surface quality and grinding wheel service life. When using the diamond grinding wheel for grinding high-hardness and brittle materials of the present invention to thin 4-inch silicon carbide wafers and gallium nitride wafers, the TTV of the ground surface is within 2.0μm and 2.4μm, respectively, and no dressing is required, resulting in high grinding surface quality. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the substrate used in the diamond grinding wheel for grinding high-hardness and brittle materials according to the present invention;

[0032] Among them: 1. Elliptical grinding wheel groove; 2. Drainage groove;

[0033] Figure 2 This is a schematic diagram of the diamond grinding wheel for grinding high-hardness and brittle materials according to the present invention;

[0034] Among them: 3. Elliptical grinding wheel block; 4. Aluminum substrate. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, all raw materials used in the following embodiments are common commercially available products that can be directly purchased in the art, or can be prepared using conventional methods in the art. Room temperature refers to 25±5℃.

[0037] For example, CaSnF6 negative expansion powder can be prepared according to the literature (Gao, Qilong, et al. A new isotropicnegative thermal expansion material of CaSnF6 with facile and low-cost synthesis. Nano Research (2022): 1-9.); Ta4HfC5 nanocarbide particles can be prepared according to the literature (Preparation and characterization of ultrahigh‐temperature ternary ceramics Ta4HfC5. Journal of the American Ceramic Society 99.10 (2016): 3198-3201.).

[0038] Polyarylsulfone resin powder (PPSU200) was purchased from Dongguan Peichen New Materials Co., Ltd., and binder (KC-1700P) was purchased from Fujian United New Materials Technology Co., Ltd. The copper-tin alloy powder used was CuSn45 alloy powder with a particle size of 5~12μm, purchased from Hebei Yuechao Wear-Resistant Materials Co., Ltd.

[0039] In the embodiments, the diamond grinding wheel substrates used are all aluminum substrates, with 24 elliptical grinding wheel grooves distributed on the end face of the substrate, and 12 drainage grooves evenly distributed between the grinding wheel grooves (see...). Figure 1 This matrix structure promotes the full flow of coolant in the abrasive layer and on the workpiece surface, which is beneficial for improving workpiece surface quality and grinding wheel life.

[0040] Example 1:

[0041] In this embodiment, a diamond grinding wheel for grinding high-hardness and brittle materials is composed of the following components by volume: 49 parts of Sb-Cu-Sn pre-alloy powder, 5 parts of CaSnF6 negative expansion powder, 15 parts of polyarylsulfone resin powder, 6 parts of Ta4HfC5 nano carbide particles, and 25 parts of diamond abrasive.

[0042] The specific preparation method of the diamond grinding wheel for grinding the above-mentioned high-hardness and brittle materials is as follows:

[0043] S1. According to the formula ratio, weigh 49 parts of Sb-Cu-Sn pre-alloyed powder (by volume, it consists of 21 parts of copper-tin alloy powder, 15 parts of copper powder, 5 parts of tin powder, and 8 parts of antimony powder) and 5 parts of CaSnF6 negative expansion powder, mix them, pass them through a 200-mesh sieve, and put them into a zirconia ball mill jar at a ball-to-material ratio of 15:1. Add an appropriate amount of anhydrous ethanol as the ball milling medium, and perform high-energy ball milling in a horizontal planetary ball mill under argon protection to obtain the pre-made powder. The ball milling speed is 200 rpm and the time is 12 hours.

[0044] S2. Weigh 15 parts of polyarylsulfone resin powder and 6 parts of Ta4HfC5 nano carbide particles according to the formula, add 0.7 parts of binder, grind and mix evenly, and then cold press into Φ15×8 blocks by a powder tablet press. Crush the blocks by a pulverizer and grinder to obtain mixed powder. The binder is obtained by uniformly mixing polyvinyl alcohol, polymethyl methacrylate and glacial acetic acid in a volume ratio of 2:3:1.

[0045] S3. Weigh 54 parts of pre-made powder, 21 parts of mixed powder, and 1.5 parts of granulator. Mix them evenly and pass them through a 200-mesh sieve. Add 25 parts of diamond abrasive and mix thoroughly in a three-dimensional mixer. Dry at 250°C for 2 hours to obtain the molding material. The ball-to-powder ratio is 1:5, the rotation speed is 20 rpm, and the time is 10 hours. The granulator is obtained by mixing paraffin wax and binder KC1700P in a volume ratio of 2:1.

[0046] S4. After the molding material is put into the graphite mold, it is hot-pressed and sintered by a hot-pressing sintering machine to obtain the grinding wheel block. The hot-pressing sintering process is as follows: the temperature is raised from room temperature to 340℃ at a heating rate of 30℃ / min and held for 2min; then the temperature is raised to 370℃ at a heating rate of 15℃ / min and held for 2min at a pressure of 2MPa; then the temperature is raised to 430℃ at a heating rate of 8℃ / min and held for 12min at a pressure of 8MPa.

[0047] S5. Heat-treat the sintered grinding wheel block (heat treatment process: heat to 310℃ at a heating rate of 30℃ / min, hold for 15h, and then cool down to room temperature at a cooling rate of 15℃ / min). After heat treatment, form the grinding wheel block with an elliptical end face by an electric spark cutting machine. Bond the end face of the grinding wheel block to the elliptical grinding wheel groove of the aluminum substrate to obtain a diamond grinding wheel for grinding high hardness and brittle materials.

[0048] Example 2:

[0049] In this embodiment, a diamond grinding wheel for grinding high-hardness and brittle materials is composed of the following components by volume: 45 parts of Sb-Cu-Sn pre-alloy powder, 10 parts of CaSnF6 negative expansion powder, 14 parts of polyarylsulfone resin powder, 6 parts of Ta4HfC5 nano carbide particles, and 25 parts of diamond abrasive.

[0050] The specific preparation method of the diamond grinding wheel for grinding the above-mentioned high-hardness and brittle materials is as follows:

[0051] S1. According to the formula ratio, weigh 45 parts of Sb-Cu-Sn pre-alloyed powder (by volume, it consists of 21 parts of copper-tin alloy powder, 13 parts of copper powder, 4 parts of tin powder, and 7 parts of antimony powder) and 10 parts of CaSnF6 negative expansion powder, mix them, pass them through a 200-mesh sieve, and put them into a zirconia ball mill jar at a ball-to-material ratio of 15:1. Add an appropriate amount of anhydrous ethanol as the ball milling medium, and perform high-energy ball milling in a horizontal planetary ball mill under argon protection to obtain the pre-made powder. The ball milling speed is 200 rpm and the time is 12 hours.

[0052] S2. Weigh 14 parts of polyarylsulfone resin powder and 6 parts of Ta4HfC5 nano carbide particles according to the formula, add 0.7 parts of binder, grind and mix evenly, then cold press into Φ15×8 blocks using a powder tablet press, and crush by a pulverizer to obtain mixed powder; the binder is obtained by uniformly mixing polyvinyl alcohol, polymethyl methacrylate and glacial acetic acid in a volume ratio of 2:3:1.

[0053] S3. Weigh 55 parts of pre-made powder, 20 parts of mixed powder, and 1.5 parts of granulator. Mix them evenly and pass them through a 200-mesh sieve. Add 25 parts of diamond abrasive and mix them thoroughly in a three-dimensional mixer. Dry the mixture at 250°C for 2 hours to obtain the molding material. The ball-to-powder ratio is 1:5, the rotation speed is 20 rpm, and the time is 10 hours. The granulator is obtained by mixing paraffin wax and binder KC1700P in a volume ratio of 2:1.

[0054] S4. After the molding material is put into the graphite mold, it is hot-pressed and sintered by a hot-pressing sintering machine to obtain the grinding wheel block. The hot-pressing sintering process is as follows: the temperature is raised from room temperature to 340℃ at a heating rate of 30℃ / min and held for 2min; then the temperature is raised to 370℃ at a heating rate of 15℃ / min and held for 2min at a pressure of 2MPa; then the temperature is raised to 430℃ at a heating rate of 8℃ / min and held for 12min at a pressure of 8MPa.

[0055] S5. Heat-treat the sintered grinding wheel block (heat treatment process: heat to 310℃ at a heating rate of 30℃ / min, hold for 15h, and then cool down to room temperature at a cooling rate of 15℃ / min). After heat treatment, form the grinding wheel block with an elliptical end face by an electric spark cutting machine. Bond the end face of the grinding wheel block to the elliptical grinding wheel groove of the base material to obtain a diamond grinding wheel for grinding high hardness and brittle materials.

[0056] Example 3:

[0057] In this embodiment, a diamond grinding wheel for grinding high-hardness and brittle materials is composed of the following components: by volume, 42 parts of Sb-Cu-Sn pre-alloy powder, 15 parts of CaSnF6 negative expansion powder, 13 parts of polyarylsulfone resin powder, 5 parts of Ta4HfC5 nano carbide particles, and 25 parts of diamond abrasive.

[0058] The specific preparation method of the diamond grinding wheel for grinding the above-mentioned high-hardness and brittle materials is as follows:

[0059] S1. According to the formula ratio, weigh 42 parts of Sb-Cu-Sn pre-alloyed powder (by volume, it consists of 19 parts of copper-tin alloy powder, 12 parts of copper powder, 4 parts of tin powder, and 7 parts of antimony powder) and 15 parts of CaSnF6 negative expansion powder, mix them, pass them through a 200-mesh sieve, and put them into a zirconia ball mill jar at a ball-to-material ratio of 15:1. Add an appropriate amount of anhydrous ethanol as the ball milling medium, and perform high-energy ball milling in a horizontal planetary ball mill under argon protection to obtain the pre-made powder. The ball milling speed is 200 rpm and the time is 12 hours.

[0060] S2. Weigh 13 parts of polyarylsulfone resin powder and 5 parts of Ta4HfC5 nano carbide particles according to the formula, add 0.7 parts of binder, grind and mix evenly, then cold press into Φ15×8 blocks using a powder tablet press, and crush by a pulverizer to obtain mixed powder; the binder is obtained by uniformly mixing polyvinyl alcohol, polymethyl methacrylate and glacial acetic acid in a volume ratio of 2:3:1.

[0061] S3. Weigh 57 parts of pre-made powder, 18 parts of mixed powder, and 1.5 parts of granulator. Mix them evenly and pass them through a 200-mesh sieve. Add 25 parts of diamond abrasive and mix them thoroughly in a three-dimensional mixer. Dry the mixture at 250°C for 2 hours to obtain the molding material. The ball-to-powder ratio is 1:5, the rotation speed is 20 rpm, and the time is 10 hours. The granulator is obtained by mixing paraffin wax and binder KC1700P in a volume ratio of 2:1.

[0062] S4. After the molding material is put into the graphite mold, it is hot-pressed and sintered by a hot-pressing sintering machine to obtain the grinding wheel block. The hot-pressing sintering process is as follows: the temperature is raised from room temperature to 340℃ at a heating rate of 30℃ / min and held for 2min; then the temperature is raised to 370℃ at a heating rate of 15℃ / min and held for 2min at a pressure of 2MPa; then the temperature is raised to 430℃ at a heating rate of 8℃ / min and held for 12min at a pressure of 8MPa.

[0063] S5. Heat-treat the sintered grinding wheel block (heat treatment process: heat to 310℃ at a heating rate of 30℃ / min, hold for 15h, and then cool down to room temperature at a cooling rate of 15℃ / min). After heat treatment, form the grinding wheel block with an elliptical end face by an electric spark cutting machine. Bond the end face of the grinding wheel block to the elliptical grinding wheel groove of the base material to obtain a diamond grinding wheel for grinding high hardness and brittle materials.

[0064] Comparative Example 1:

[0065] In this comparative example, a metal-bonded diamond grinding wheel is composed of the following components by volume: 45 parts copper-tin pre-alloyed powder, 8 parts tin powder, 5 parts titanium powder, 10 parts graphite, 7 parts cerium oxide, and 25 parts diamond abrasive.

[0066] The specific preparation method of the above-mentioned metal-bonded diamond grinding wheel is as follows:

[0067] S1. Weigh 45 parts copper-tin alloy powder, 8 parts tin powder, and 5 parts titanium powder by volume, mix them, pass them through a 200-mesh sieve, and put them into a zirconia ball mill jar at a ball-to-material ratio of 15:1. Add an appropriate amount of anhydrous ethanol as the ball milling medium, and perform high-energy ball milling in a horizontal planetary ball mill under argon protection to obtain pre-alloyed powder. The ball milling speed is 200 rpm and the time is 12 h. The copper-tin pre-alloyed powder is CuSn25.

[0068] S2. Weigh 10 parts graphite, 7 parts cerium oxide, and 25 parts diamond abrasive, mix them with the pre-alloyed powder in S1, and then mix them thoroughly in a three-dimensional mixer to obtain the molding material. The ball-to-material ratio is 1:5, the rotation speed is 20 rpm, and the time is 10 h.

[0069] S3. After the molding material is put into the graphite mold, it is hot-pressed and sintered by a hot-pressing sintering machine to obtain the grinding wheel block. The hot-pressing sintering process is as follows: the temperature is raised from room temperature to 460℃ at a heating rate of 30℃ / min and held for 2min; then the temperature is raised to 520℃ at a heating rate of 15℃ / min and held for 2min at a pressure of 2MPa; then the temperature is raised to 540℃ at a heating rate of 8℃ / min and held for 12min at a pressure of 8MPa.

[0070] S4. The sintered grinding wheel block is bonded to the substrate to obtain a metal-bonded diamond grinding wheel.

[0071] Application Trial

[0072] Tables 1 and 2 present the experimental results of the thinning of 200 silicon carbide and gallium nitride wafers using grinding wheels on a DISCO8640 thinning machine in Examples 1-3 and Comparative Example 1, respectively.

[0073] Table 1. Experimental results of grinding 4-inch silicon carbide wafers using grinding wheels in Examples 1-3 and Comparative Example 1.

[0074]

[0075] Table 2. Experimental results of grinding 4-inch gallium nitride wafers using a grinding wheel in Examples 1-3 and Comparative Example 1.

[0076]

[0077] As shown in Tables 1 and 2, the diamond grinding wheel for grinding high-hardness and brittle materials in this embodiment of the invention achieves a total thickness variation (TTV) of less than 2.0 μm on the grinding surface when thinning 4-inch silicon carbide wafers, requiring no dressing. Compared to the <5.2 μm of the metal-bonded diamond wheel in Comparative Example 1, this exhibits better self-sharpening properties and higher grinding surface quality. Furthermore, the diamond grinding wheel for grinding high-hardness and brittle materials in this invention also achieves better grinding surface quality when thinning 4-inch gallium nitride wafers, with a TTV of less than 2.4 μm requiring no dressing, which is superior to the <6.2 μm of Comparative Example 1.

Claims

1. A diamond grinding wheel for grinding high-hardness and brittle materials, characterized in that, The high-hard-and-brittle material grinding diamond wheel is made of the following components by volume fraction: 20-50 parts of Sb-Cu-Sn pre-alloy powder, 5-15 parts of CaSnF6 negative expansion powder, 10-40 parts of polyaryl sulfone resin powder, 5-20 parts of Ta4HfC5 nano-carbide particles, and 10-30 parts of diamond abrasive. When the high-hard-and-brittle material grinding diamond is used to grind 4-inch silicon carbide wafers and gallium nitride wafers, the grinding surface TTV is within 2.0 μm and 2.4 μm respectively, and the grinding surface quality is high.

2. The diamond grinding wheel for high-hardness and brittle material according to claim 1, characterized in that, The CaSnF6 negative expansion powder has a particle size of 2-8 μm.

3. The diamond grinding wheel for high-hardness and brittle material according to claim 1, characterized in that, The Ta4HfC5 nano-carbide particles have a particle size of 200-600 nm.

4. The diamond grinding wheel for high-hardness and brittle material according to Claim 1, wherein The diamond wheel base is an aluminum base, and a plurality of oval wheel grooves are distributed at the end face of the base, and drainage grooves are uniformly distributed between the wheel grooves.

5. The method of claim 1 to 4, wherein the diamond grinding wheel for high-hardness brittle material is prepared by the steps of: The method comprises the following steps: ​ S1. Sb-Cu-Sn pre-alloy powder and CaSnF6 negative expansion powder are weighed according to the formula, mixed, sieved, and ball milled to obtain preformed powder; S2. Polyaryl sulfone resin powder and Ta4HfC5 nano-carbide particles are weighed according to the formula, mixed, and uniformly pressed into a block, and the obtained cold-pressed block is broken to obtain mixed powder; S3. The preformed powder and the mixed powder are uniformly mixed with a granulating agent, sieved, mixed with diamond abrasive, and dried to obtain molding material; S4. The molding material is hot-pressed and sintered to obtain a wheel block; S5. The obtained wheel block is heat treated to form an oval-shaped wheel block, and the wheel block end face is bonded to the oval wheel groove of the base to obtain a high-hard-and-brittle material grinding diamond wheel.

6. The method of claim 5, wherein the diamond wheel is prepared by the steps of: In step S1, the Sb-Cu-Sn pre-alloy powder mainly comprises the following components by volume fraction: 10-40 parts of copper-tin alloy powder, 10-25 parts of copper powder, 3-15 parts of tin powder, and 5-12 parts of antimony powder. ​ 7. The method of claim 6, wherein the diamond wheel is prepared by the steps of: The copper-tin alloy powder is CuSn45 alloy powder with a particle size of 5-12 μm. ​ 8. The method of claim 5, wherein the diamond wheel is prepared by the steps of: In step S2, the binder comprises one or more of polyvinyl alcohol, polymethyl methacrylate, propylene glycol, and glacial acetic acid; and in step S3, the granulating agent is composed of paraffin and binder KC-1700P in a volume ratio of 2:

1. ​ 9. The method of claim 5, wherein the diamond wheel is prepared by the steps of: In step S4, the hot-pressing and sintering process is as follows: the temperature is raised from room temperature to 340±20℃ at a rate of 25-35℃ / min, and then raised to 370±20℃ at a rate of 15-20℃ / min, and then raised to 380-450℃ at a rate of 5-10℃ / min, and the pressure is 2-3 MPa, and the temperature is maintained for 2-5 min; the temperature is maintained for 2-5 min, and the pressure is 2-3 MPa; and then the temperature is raised to 380-450℃ at a rate of 5-10℃ / min, and the pressure is 5-10 MPa, and the temperature is maintained for 8-25 min. ​ 10. The method of claim 5, wherein the diamond wheel is prepared by the steps of: In step S5, the heat treatment process of the sintered wheel block is as follows: the temperature is raised to 280-330℃ at a rate of 30±5℃ / min, and then the temperature is maintained for 12-24 h, and then the temperature is lowered to room temperature at a rate of 15±5℃ / min. ​

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