CBN resin superhard grinding wheel and preparation process thereof

Abstract

The cBN resin superhard grinding wheel is prepared from the following raw materials in percentage by mass: 30 to 45 percent of cBN grinding material, 1 to 3 percent of nano yttrium oxide, 2 to 3 percent of nano zirconium oxide, 2 to 4 percent of coupling agent, 1 to 3 percent of silicon dioxide compound and the balance of phenolic resin. The phenolic resin matrix is jointly modified by the nano yttrium oxide, the nano zirconium oxide and the specific silicon dioxide compound, and the prepared grinding wheel has good wear resistance, hardness and temperature resistance.

Description

Technical Field

[0001] This application relates to the field of grinding wheel production and preparation, and in particular to a cBN resin superhard grinding wheel and its preparation process. Background Technology

[0002] Cubic boron nitride (cBN) resin superhard grinding wheels are key tools for machining hardened steel, high-temperature alloys, and other difficult-to-grind materials. However, in the typical long-cycle, heavy-load, dry or high-speed grinding conditions of aerospace, precision molds, and other fields, the inherent defects of the resin bond are significantly amplified.

[0003] In existing technologies, resins such as phenolic resins and polyimide resins have limited glass transition temperatures and thermal decomposition temperatures. Under sustained high grinding temperatures (often exceeding 300°C), they are prone to softening and thermal degradation, leading to a sharp decrease in the holding force of cBN abrasive grains. On the other hand, the flexible components introduced into traditional grinding wheels to balance toughness are prone to microcracks and plastic deformation under heavy impact. The combination of these two factors results in abnormal abrasive grain shedding, premature breakage of the bonding bridge, and coexistence of "passivation" and clogging on the working surface. This not only leads to a rapid decline in material removal rate and a vicious cycle of increasing grinding force and temperature, but also manifests as uncontrollable and drastic fluctuations in the wear ratio (G ratio) throughout the entire service life. Consequently, machining accuracy and surface quality deteriorate, severely shortening the actual service life of the grinding wheel and increasing the unit cost.

[0004] Existing technologies improve certain properties by simply modifying resins or adding fillers, but this often results in a trade-off and makes it difficult to achieve a synergistic improvement in high-temperature strength, toughness, and wear resistance. Summary of the Invention

[0005] In order to improve the problems of grinding performance degradation and wear ratio fluctuation caused by grinding wheels under high temperature and heavy load, this application provides a cBN resin superhard grinding wheel and its preparation process.

[0006] Firstly, this application provides a cBN resin superhard grinding wheel, which adopts the following technical solution: A cBN resin superhard grinding wheel is prepared by means of the following raw materials by mass percentage: 30-45% cBN abrasive, 1-3% nano yttrium oxide, 2-3% nano zirconium oxide, 2-4% coupling agent, 1-3% silica composite, and the balance being phenolic resin.

[0007] By adopting the above technical solution, nano-yttrium oxide, nano-zirconia, silica composite, and cBN abrasive are introduced into phenolic resin to construct a multi-component, multi-scale synergistically reinforced superhard grinding wheel. The addition of nanoparticles and the modification of the phenolic resin binder through coupling reaction improves its strength and temperature resistance. Nano-yttrium oxide and zirconia, as inorganic reinforcing phases, effectively improve the high-temperature strength and rigidity of the resin matrix; while the silica composite provides both interface modification and toughening functions. The synergistic effect of these three components optimizes the abrasive grain concentration, thereby fundamentally improving the stability of grinding operations, enhancing the quality of the cBN resin superhard grinding wheel, and extending its service life.

[0008] Preferably, the cBN abrasive has a particle size of 40-60 mesh.

[0009] By adopting the above technical solution, the particle size of cubic boron nitride is preferably within the above range, which has moderate strength and size, can ensure a sufficient number of cutting edges to achieve efficient grinding, and forms a good mechanical meshing and chemical bonding interface with the binder system, improving the heat dissipation of the system and having good stability.

[0010] Preferably, the silica composite raw materials include silane-modified nano silica and 1-vinyl-3-octylimidazolium tetrafluoroborate.

[0011] By adopting the above technical solution, silane-modified nano-silica provides a high specific surface area and reactive sites. 1-Vinyl-3-octylimidazolium tetrafluoroborate, as a polymeric ionic liquid, is introduced through chemical grafting. The surface of the prepared nano-silica has silane functional groups that react with phenolic resin and long chains of ionic liquid with dispersing and toughening effects, thereby further improving the dispersibility of nanofillers in the resin system and strengthening the interfacial bonding strength.

[0012] Preferably, the silane-modified nano-silica is prepared by the following method: Nano-silica was mixed with anhydrous ethanol to obtain a silica dispersion. KH-570 was hydrolyzed and added to the silica dispersion and mixed evenly. The system was then adjusted to acidity and heated to react. After the reaction, the mixture was washed, filtered, and dried to obtain modified nano-silica.

[0013] By adopting the above technical solution, KH-570 is used to perform surface grafting modification on nano-silica, introducing unsaturated double bonds and long-chain alkyl groups on the surface of silica, which improves the dispersion stability of nano-silica in the system and provides active sites for subsequent ionic liquid grafting reactions, thereby further improving the overall stability of the system.

[0014] Preferably, the silica composite is prepared by the following method: Modified nano-silica was mixed and dispersed with ethanol to obtain a modified nano-silica dispersion. 1-Vinyl-3-octylimidazolium tetrafluoroborate was added to the modified nano-silica dispersion and stirred. Then an initiator was added to continue the reaction. After the reaction, the mixture was centrifuged and washed. The precipitate was freeze-dried to obtain the silica complex.

[0015] By adopting the above technical solution, 1-vinyl-3-octylimidazolium tetrafluoroborate was bonded to the surface of modified nano-silica through free radical graft copolymerization, which improved the stability of the prepared grinding wheel at high temperature interface and enhanced the overall wear resistance of the system.

[0016] Preferably, the mass ratio of the nano-silica to KH-570 is 1:(0.65-0.75).

[0017] By adopting the above technical solution, the mass ratio between nano-silica and silane coupling agent is preferably within the above range, so that the surface of nano-silica has a sufficient density of KH-570 coating, so as to achieve effective organic modification of the surface, and reduce the phenomenon of excessive silane coupling agent self-polymerization weakening the interfacial bonding strength, so that the prepared modified nano-silica has good stability.

[0018] Preferably, the mass ratio between the silane-modified nano-silica and 1-vinyl-3-octylimidazolium tetrafluoroborate is 1:(0.7-0.8).

[0019] By adopting the above technical solution, the mass ratio between silane-modified nano-silica and 1-vinyl-3-octylimidazolium tetrafluoroborate is preferably within the above range, which balances the relationship between grafting rate and graft chain length. An ionic liquid polymer structure with appropriate density and length is formed on the surface of nano-silica, which improves dispersibility, toughens and resists high temperature, and also reduces the agglomeration phenomenon that may be caused by excessive grafting layer thickness, further improving the overall stability of the system.

[0020] Secondly, this application provides a method for preparing cBN resin superhard grinding wheels, using the following technical solution: A method for preparing a cBN resin superhard grinding wheel includes the following steps: (1) Prepare nano-yttrium oxide, nano-zirconia, silica composite and cBN abrasive; (2) The above raw materials are poured into an ethanol solution for washing and ultrasonic dispersion treatment to obtain nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and cBN dispersion. (3) Add the nano-yttrium oxide powder, nano-zirconia powder, silica composite powder and coupling agent from step (2) to an ethanol solution to obtain a mixture; (4) The cBN dispersion was extracted into granules by centrifugal sedimentation and sieving. (5) Clean and dry the granular material to obtain cBN-treated abrasive; (6) The mixture obtained in step (3) is stirred at high speed and mixed by ultrasonic vibration to obtain ultrasonically treated material; (7) Phenolic resin is added to the ultrasonically treated material obtained in step (6), and the material is heated to perform heat modification to obtain a binder; (8) Mix the binder obtained in step (7) with the cBN-treated abrasive obtained in step (5) and form it by hot pressing process to obtain the shaped material; (9) The molding material obtained in step (8) is bonded to prepare a grinding wheel, and then post-processed to obtain a cBN resin superhard grinding wheel.

[0021] By adopting the above technical solution, the process removes surface impurities and reduces the agglomeration of various components by independently ultrasonically cleaning and pre-dispersing the raw materials. The nano-reinforcing phase and coupling agent are pre-mixed and modified, and then compounded with phenolic resin, so that the functional filler is evenly distributed and firmly bonded in the binder, which further improves the stability and hardness of the prepared grinding wheel.

[0022] Preferably, step (4) of the centrifugal sedimentation sieving method specifically includes the following steps: (4-1) Add the cBN dispersion to the aqueous alcohol mixture of ethanol and deionized water, and distribute it evenly into centrifuge bottles; (4-2) Centrifuge the centrifuge bottles separately to allow large particles of impurities to settle, and filter out the upper mixture for later use. (4-3) Divide the filtered upper mixture into centrifuge bottles and centrifuge them separately to allow particles within the target particle size range to settle, filter out the upper mixture of overly fine particles, and obtain the bottom particles, which are the granular material.

[0023] By adopting the above technical solution, the centrifuge bottle is evenly divided and the mechanism is stable to ensure the centrifugation effect. The two centrifugation operations under different conditions first remove impurity particles with high density or excessive particle size from the raw material, and then accurately separate and collect the abrasive within the target particle size range, narrowing the original particle size distribution and obtaining abrasive with better particle size consistency. Compared with traditional vibrating sieving, it can more effectively remove ultrafine powder and near-shaped impurities, and obtain abrasive with concentrated particle size and clean surface, so that the prepared grinding wheel has a uniform structure and good wear resistance.

[0024] Preferably, in step (4-1), the volume ratio of ethanol to deionized water in the water-ethanol mixture is (1.5-2):1.

[0025] By adopting the above technical solution, and preferably having the volume ratio of ethanol to deionized water in the aqueous alcohol solution within the above range, the prepared aqueous alcohol solution has good density, viscosity and surface tension, which can fully wet and disperse cubic boron nitride abrasive, reduce system flocculation, and precisely control the sedimentation of abrasive particles by adjusting the solvent polarity, thereby obtaining abrasive with a finer target particle size.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. A multi-component synergistic reinforcement system was constructed by modifying the phenolic resin matrix with nano-yttrium oxide, nano-zirconia and a specific silica composite. This system significantly improved the strength, rigidity and holding force of the binder at high temperature and cBN abrasive particles, effectively suppressed the performance degradation and wear ratio fluctuation during heavy-duty grinding, and thus greatly extended the service life of the grinding wheel. 2. An optimized centrifugal sedimentation sieving process was adopted for cBN abrasive, and its particle size was controlled within 40-60 mesh. This resulted in high-purity, narrowly distributed target abrasive grains, ensuring the high uniformity and stability of the grinding wheel working layer structure, improving the stability and efficiency of the grinding process, and reducing the fluctuation of service performance caused by abrasive grain differences. 3. The introduction of nano-silica composite modified by ionic liquid grafting significantly improves the dispersibility and interfacial bonding strength of nanofillers in resin. The nano-silica composite has excellent toughening and high-temperature stability effects, further enhancing the overall impact resistance and heat resistance of the grinding wheel. Detailed Implementation

[0027] The present application will be further described in detail below with reference to the embodiments: Raw material description: All raw materials in the examples are commercially available; the hot pressing process was carried out at a pressing temperature of 160℃, a pressure of 15MPa, and a holding time of 30min. The coupling agent was KH-550 (CAS No.: 919-30-2), the particle size of nano-zirconia was 20-40nm, the particle size of nano-yttrium oxide was 30-50nm, and the silica composite obtained was selected with a particle size of 50-80nm. The nano-silica particles used had a particle size of 15-25nm.

[0028] Example 1 Preparation of modified nano-silica: 15.15g of nano-silica was mixed with 700g of anhydrous ethanol and stirred at 25℃ for 30min to obtain a silica dispersion. 9.85g of KH-570 (CAS No.: 2530-85-0) was mixed with 20g of deionized water and stirred to hydrolyze KH-570. The mixture was cooled to 25℃ and then added to the silica dispersion. The mixture was stirred thoroughly until homogeneous. Glacial acetic acid was added to adjust the pH of the system to 2. The temperature was raised to 70℃ and refluxed for 3h. After the reaction was completed, the mixture was washed with anhydrous ethanol and filtered to obtain a filter cake. The filter cake was dried in a vacuum drying oven at 70℃ for 8h to obtain modified nano-silica.

[0029] Preparation of silica composites: 11.76 g of modified nano-silica was mixed with 600 g of anhydrous ethanol and stirred at 25 °C for 30 min to obtain a modified nano-silica dispersion. 8.24 g of 1-vinyl-3-octylimidazolium tetrafluoroborate (CAS No.: 1823137-12-7) was added to the modified nano-silica dispersion and stirred at 25 °C for 30 min. Then, 0.48 g of initiator azobisisobutyronitrile (CAS No.: 78-67-1) was added, and nitrogen gas was continuously introduced. The reaction was carried out at 75 °C for 18 h. After the reaction was completed, the mixture was centrifuged at 10000 rpm for 8 min to remove the supernatant. Anhydrous ethanol was added and the mixture was centrifuged repeatedly to remove excess raw materials and azobisisobutyronitrile, resulting in a precipitate. The precipitate was placed in a freeze dryer and freeze-dried at -4 °C for 72 h to obtain the silica composite.

[0030] Preparation of cBN resin superhard grinding wheels: (1) Prepare raw materials according to the following mass percentages: 30% cBN abrasive, 1% nano yttrium oxide, 2% nano zirconium oxide, 1% silica composite, 2% coupling agent, and the remainder is phenolic resin; (2) The cBN abrasive, nano yttrium oxide, nano zirconium oxide and silica composite were respectively poured into ethanol solution for cleaning. The mass ratio of raw materials to ethanol was 1:5. The materials were dispersed by ultrasonic treatment for 25 min to obtain nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and cBN dispersion respectively. (3) Add the nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and coupling agent from step (2) to an ethanol solution, and mix the powder and ethanol in a mass ratio of 1:3 to obtain a mixture; (4) The cBN abrasive was extracted by centrifugal sedimentation and sieving: (4-1) Add cBN dispersion to an aqueous alcohol mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol mixture is 1.5:1, and divide it into 6 centrifuge bottles, with the weight difference between each centrifuge bottle being less than 0.1g; (4-2) Centrifuge the centrifuge bottles separately at a speed of 3000 r / min for 30 s to allow large particles of impurities to settle and filter out the supernatant solution for later use. (4-3) Divide the filtered upper mixture into 6 centrifuge bottles again and centrifuge at 4500 r / min for 60 s to allow particles in the 40-60 mesh size range to settle. Filter out the upper mixture of overly fine particles to obtain the bottom particles, which are the granular material. (5) The obtained granules were washed three times with deionized water and then dried at 60°C for 8 hours to obtain cBN-treated abrasive. (6) Stir the mixture obtained in step (3) at a speed of 800 rpm and mix it by ultrasonic vibration for 15 min to obtain ultrasonically treated material; (7) Phenolic resin (CAS No.: 9003-35-4) was added to the ultrasonically treated material obtained in step (6), and the mixture was heated at 50°C for 25 minutes to obtain a binder. (8) The binder obtained in step (7) is mixed with the cBN-treated abrasive obtained in step (5), and the mixture is formed by hot pressing to obtain the shaped material. (9) The molding material obtained in step (8) is bonded to form a grinding wheel, and then post-processed to obtain a cBN resin superhard grinding wheel.

[0031] Example 2 Preparation of modified nano-silica: 14.29 g of nano-silica was mixed with 700 g of anhydrous ethanol and stirred at 25 °C for 30 min to obtain a silica dispersion. 10.71 g of KH-570 was mixed with 20 g of deionized water and stirred to hydrolyze KH-570. The mixture was then cooled to 25 °C and added to the silica dispersion. The mixture was stirred thoroughly until homogeneous. Glacial acetic acid was added to adjust the pH of the system to 2. The temperature was raised to 70 °C and refluxed for 3 h. After the reaction was completed, the mixture was washed with anhydrous ethanol and filtered to obtain a filter cake. The filter cake was dried in a vacuum drying oven at 70 °C for 8 h to obtain modified nano-silica.

[0032] Preparation of silica composites: 11.11 g of modified nano-silica was mixed with 600 g of anhydrous ethanol and stirred at 25 °C for 30 min to obtain a modified nano-silica dispersion. 8.89 g of 1-vinyl-3-octylimidazolium tetrafluoroborate was added to the modified nano-silica dispersion and stirred at 25 °C for 30 min. Then, 0.48 g of the initiator azobisisobutyronitrile was added, and nitrogen gas was continuously introduced. The reaction was carried out at 75 °C for 18 h. After the reaction was completed, the mixture was centrifuged at 10000 rpm for 8 min to remove the supernatant. Anhydrous ethanol was added and the mixture was centrifuged repeatedly to remove excess raw materials and azobisisobutyronitrile, resulting in a precipitate. The precipitate was placed in a freeze dryer and freeze-dried at -4 °C for 72 h to obtain the silica composite.

[0033] Preparation of cBN resin superhard grinding wheels: (1) Prepare raw materials according to the following mass percentages: cBN abrasive 45%, nano yttrium oxide 3%, nano zirconium oxide 3%, silica composite 3%, coupling agent 4%, and the remainder is phenolic resin; (2) The cBN abrasive, nano yttrium oxide, nano zirconium oxide and silica composite were respectively poured into ethanol solution for cleaning. The mass ratio of raw materials to ethanol was 1:5. The materials were dispersed by ultrasonic treatment for 25 min to obtain nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and cBN dispersion respectively. (3) Add the nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and coupling agent from step (2) to an ethanol solution, and mix the powder and ethanol in a mass ratio of 1:3 to obtain a mixture; (4) The cBN abrasive was extracted by centrifugal sedimentation and sieving: (4-1) Add cBN dispersion to an aqueous alcohol mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol mixture is 2:1, and divide it into 7 centrifuge bottles, with the weight difference between each centrifuge bottle being less than 0.1g. (4-2) Centrifuge the centrifuge bottles separately at a speed of 3000 r / min for 30 s to allow large particles of impurities to settle and filter out the supernatant solution for later use. (4-3) Divide the filtered upper mixture into 7 centrifuge bottles again and centrifuge at 4500 r / min for 60 s to allow particles in the 40-60 mesh size range to settle. Filter out the upper mixture of overly fine particles to obtain the bottom particles, which are the granular material. (5) The obtained granules were washed three times with deionized water and then dried at 60°C for 8 hours to obtain cBN-treated abrasive. (6) Stir the mixture obtained in step (3) at a speed of 800 rpm and mix it by ultrasonic vibration for 15 min to obtain ultrasonically treated material; (7) Phenolic resin is added to the ultrasonically treated material obtained in step (6), and the mixture is heated at 60°C for 25 minutes to obtain a binder. (8) The binder obtained in step (7) is mixed with the cBN-treated abrasive obtained in step (5), and the mixture is formed by hot pressing to obtain the shaped material. (9) The molding material obtained in step (8) is bonded to form a grinding wheel, and then post-processed to obtain a cBN resin superhard grinding wheel.

[0034] Example 3 Preparation of modified nano-silica: 14.71 g of nano-silica was mixed with 700 g of anhydrous ethanol and stirred at 25 °C for 30 min to obtain a silica dispersion. 10.29 g of KH-570 was mixed with 20 g of deionized water and stirred to hydrolyze KH-570. The mixture was then cooled to 25 °C and added to the silica dispersion. The mixture was stirred thoroughly until homogeneous. Glacial acetic acid was added to adjust the pH of the system to 2.5. The temperature was raised to 70 °C and refluxed for 3 h. After the reaction was completed, the mixture was washed with anhydrous ethanol and filtered to obtain a filter cake. The filter cake was dried in a vacuum drying oven at 70 °C for 8 h to obtain modified nano-silica.

[0035] Preparation of silica composites: 11.43 g of modified nano-silica was mixed with 600 g of anhydrous ethanol and stirred at 25 °C for 30 min to obtain a modified nano-silica dispersion. 8.57 g of 1-vinyl-3-octylimidazolium tetrafluoroborate was added to the modified nano-silica dispersion and stirred at 25 °C for 30 min. Then, 0.48 g of the initiator azobisisobutyronitrile was added, and nitrogen gas was continuously introduced. The reaction was carried out at 75 °C for 18 h. After the reaction was completed, the mixture was centrifuged at 10000 rpm for 8 min to remove the supernatant. Anhydrous ethanol was added and the mixture was centrifuged repeatedly to remove excess raw materials and azobisisobutyronitrile, resulting in a precipitate. The precipitate was placed in a freeze dryer and freeze-dried at -4 °C for 72 h to obtain the silica composite.

[0036] Preparation of cBN resin superhard grinding wheels: (1) Prepare raw materials according to the following mass percentages: cBN abrasive 37%, nano yttrium oxide 2%, nano zirconium oxide 2.5%, silica composite 2%, coupling agent 3%, and the balance is phenolic resin; (2) The cBN abrasive, nano yttrium oxide, nano zirconium oxide and silica composite were respectively poured into ethanol solution for cleaning. The mass ratio of raw materials to ethanol was 1:5. The materials were dispersed by ultrasonic treatment for 25 min to obtain nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and cBN dispersion respectively. (3) Add the nano yttrium oxide powder, nano zirconium oxide powder, silica composite powder and coupling agent from step (2) to an ethanol solution, and mix the powder and ethanol in a mass ratio of 1:3 to obtain a mixture; (4) The cBN abrasive was extracted by centrifugal sedimentation and sieving: (4-1) Add cBN dispersion to an aqueous alcohol mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol mixture is 1.75:1, and divide it into 8 centrifuge bottles, with the weight difference between each centrifuge bottle being less than 0.1g; (4-2) Centrifuge the centrifuge bottles separately at a speed of 3000 r / min for 30 s to allow large particles of impurities to settle and filter out the supernatant solution for later use. (4-3) Divide the filtered upper mixture into 8 centrifuge bottles again and centrifuge at 4500 r / min for 60 s to allow particles in the 40-60 mesh size range to settle. Filter out the upper mixture of overly fine particles to obtain the bottom particles, which are the granular material. (5) The obtained granules were washed three times with deionized water and then dried at 60°C for 8 hours to obtain cBN-treated abrasive. (6) Stir the mixture obtained in step (3) at a speed of 800 rpm and mix it by ultrasonic vibration for 15 min to obtain ultrasonically treated material; (7) Phenolic resin is added to the ultrasonically treated material obtained in step (6), and the material is heated at 65°C for 25 minutes to obtain a binder. (8) The binder obtained in step (7) is mixed with the cBN-treated abrasive obtained in step (5), and the mixture is formed by hot pressing to obtain the shaped material. (9) The molding material obtained in step (8) is bonded to form a grinding wheel, and then post-processed to obtain a cBN resin superhard grinding wheel.

[0037] Example 4 Example 4 is based on Example 3. In Example 4, when preparing silane-modified nano silica, 16.67g of nano silica and 8.33g of KH-570 were used.

[0038] Example 5 Example 5 is based on Example 3. In Example 5, when preparing silane-modified nano silica, 13.16g of nano silica and 11.84g of KH-570 were used.

[0039] Example 6 Example 6 is based on Example 3. In Example 6, when preparing the silica composite material, 12.5g of silane-modified nano silica and 7.5g of 1-vinyl-3-octylimidazolium tetrafluoroborate were used.

[0040] Example 7 Example 7 is based on Example 3. In Example 7, when preparing the silica composite material, 10.53g of silane-modified nano silica and 9.47g of 1-vinyl-3-octylimidazolium tetrafluoroborate were used.

[0041] Example 8 Example 8 is based on Example 3. In Example 8, when preparing the silica composite material, the silane-modified nano silica is replaced with ordinary nano silica.

[0042] Example 9 Example 9 is based on Example 3. In Example 9, when preparing cBN resin superhard grinding wheel, the volume ratio of ethanol to deionized water in the water-alcohol mixture in step (4-1) is 1.2:1.

[0043] Example 10 Example 10 is based on Example 3. In Example 10, when preparing cBN resin superhard grinding wheel, the volume ratio of ethanol to deionized water in the water-alcohol mixture in step (4-1) is 2.5:1.

[0044] Example 11 Example 11 is based on Example 3. In Example 11, when preparing cBN resin superhard grinding wheels, the particle size of the granules obtained in step (4-3) is 30-60 mesh.

[0045] Example 12 Example 12 is based on Example 3. In Example 12, when preparing cBN resin superhard grinding wheels, the particle size of the granules obtained in step (4-3) is 40-70 mesh.

[0046] Example 13 Example 13 is based on Example 3. In step (4-1) of Example 13, all the cBN dispersion and water-alcohol mixture are placed in the same centrifuge bottle and centrifuged.

[0047] Example 14 Example 14 is based on Example 3. In step (4-3) of Example 14, the upper mixture is centrifuged in the same centrifuge bottle.

[0048] Comparative Example 1 Comparative Example 1 is based on Example 3, except that the silica composite is replaced with an equal amount of ordinary nano silica.

[0049] Comparative Example 2 Comparative Example 2 is based on Example 3, but without the addition of silica composite and with an equal amount of phenolic resin.

[0050] Comparative Example 3 Comparative Example 3 is based on Example 3, but without the addition of nano-yttrium oxide; instead, an equal amount of phenolic resin is used to make up the difference.

[0051] Comparative Example 4 Comparative Example 4 is based on Example 3, but without the addition of nano-zirconia; instead, an equal amount of phenolic resin is used to make up the difference.

[0052] Performance testing The following performance tests were performed on the samples of Examples 1-14 and Comparative Examples 1-4: (1) Hardness Using GB / T 230.3-2022 as the testing reference, the hardness of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were recorded in Table 1.

[0053] (2) Wear resistance Using GB / T 33144-2016 as the testing reference, the wear resistance of the samples was tested. Each sample was tested 3 times, the wear ratio was recorded, the average value was taken, and the test results were filled in Table 1.

[0054] (3) Temperature resistance The sample was kept at a set high temperature (300℃) for 10 minutes, and then quickly removed and immersed in circulating cooling water at 25℃ for 3 minutes. The above process is one cycle. The number of cycles in which the sample cracked was observed. Each sample was tested 3 times, and the average value was taken. The test results were filled in Table 1.

[0055] Table 1 Performance test results of Examples 1-14 and Comparative Examples 1-4 The hardness of Examples 1-3 is 93.0 or higher, indicating that the resin superhard grinding wheel prepared in this application has good hardness; the wear ratio of Examples 1-3 is 535 or higher, indicating that the resin superhard grinding wheel prepared in this application has good wear resistance; the number of cracking cycles of Examples 1-3 is 22 or higher, indicating that the resin superhard grinding wheel prepared in this application has good temperature resistance.

[0056] In Examples 4 and 5, the mass ratio between nano-silica and KH-570 is not within the range specified in this application. When the content of KH-570 is too low, the surface modification of nano-silica is incomplete, hydroxyl groups remain and agglomerate, and there are insufficient grafting sites. When the content of KH-570 is too high, the excess KH-570 self-agglomerates and forms a loose polymer layer on the particle surface, which becomes a weak point under stress.

[0057] In Examples 6 and 7, the mass ratio between silane-modified nano-silica and 1-vinyl-3-octylimidazolium tetrafluoroborate is not within the range specified in this application. When 1-vinyl-3-octylimidazolium tetrafluoroborate is insufficient, the grafting is inadequate, and the lubrication and toughening effect is difficult to fully exert. When 1-vinyl-3-octylimidazolium tetrafluoroborate is excessive, the long chain of the system will cause particle agglomeration, and the excessively thick flexible layer will reduce the modulus of the composite itself.

[0058] In Example 8, when preparing the silica composite material, the nano-silica was not modified with silane. The nano-silica had poor dispersibility and poor compatibility with phenolic resin, resulting in agglomeration and stress defects. Furthermore, it was difficult to form a stable interfacial bond with 1-vinyl-3-octylimidazole tetrafluoroborate, leading to a decline in performance.

[0059] In Examples 9 and 10, the volume ratio of ethanol to deionized water in step (4-1) is not within the range specified in this application. When there is too little ethanol, the water-ethanol mixture has strong polarity and insufficient wettability for cBN, resulting in flocculation and agglomeration. During centrifugation, some target particle size particles settle with impurities, causing the final particle size to be outside the expected particle size range and performance to decline. When there is too much ethanol, the density of the water-ethanol mixture is too low, and it cannot effectively settle the target particle size particles, leaving some overly fine particles and affecting the stability of the system.

[0060] In Examples 11 and 12, the target particle size values ​​of the granules are not within the range defined in this application. When the lower limit of the particle size of the granules drops to 30 mesh, coarse particles are introduced, and the cutting force is too large during grinding, which causes local stress concentration in the binder, reduces processing stability, and affects product quality. When the upper limit of the particle size of the granules rises to 70 mesh, fine particles are introduced, and a large amount of heat is generated during grinding, which accelerates the thermal degradation of the resin binder and affects wear resistance.

[0061] In Examples 13 and 14, the centrifugal sedimentation sieving method did not perform uniform centrifugation in all cases. When the cBN dispersion was centrifuged using only one centrifuge bottle, the material distribution was uneven during centrifugation, and some large particles of impurities did not settle completely. The remaining impurities formed stress defects inside the grinding wheel. When the upper mixture was centrifuged using only one centrifuge bottle, the material thickness inside the bottle was too large during centrifugation, and the target particle size abrasive particles could not settle sufficiently. Some of them were filtered out along with the fine particles in the upper layer, resulting in a decrease in the interfacial bonding strength between the obtained granules and the binder, and a decrease in product quality.

[0062] Comparative Example 1 replaced the silica composite with ordinary nano silica. The untreated nano silica agglomerated and had poor interfacial bonding with the resin system.

[0063] Comparative Example 2 did not add silica composite, thus lacking interface modification and toughening effects, making it difficult to support cBN abrasive particles and reducing the stability of the interface structure.

[0064] Comparative Example 3, without the addition of nano-yttrium oxide, could not provide excellent high-temperature stability and dispersion enhancement, and the synergistic effect of the nanocomposite was destroyed.

[0065] Comparative Example 4 did not contain nano-zirconia, thus losing the phase transformation toughening phase, resulting in a decrease in the resin matrix's resistance to crack propagation, as well as reduced hardness and wear resistance.

[0066] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A cBN resin-bonded superabrasive grinding wheel characterized by: The raw materials are prepared according to the mass percentage, including: cBN abrasive 30-45%, nano yttrium oxide 1-3%, nano zirconium oxide 2-3%, coupling agent 2-4%, silica compound 1-3%, and the rest is phenolic resin.

2. A cBN resin-bonded superabrasive grinding wheel according to claim 1, characterised in that: The particle size of the cBN abrasive is 40-60 mesh.

3. A cBN resin-bonded superabrasive grinding wheel according to claim 1, characterized in that: The raw materials of the silica compound include silane modified nano silica and 1-vinyl-3-octyl imidazole tetrafluoroborate.

4. A cBN resin-bonded superabrasive grinding wheel according to claim 3, characterised in that: The silane modified nano silica is prepared by the following method: The nano silica is mixed with anhydrous ethanol to obtain a silica dispersion liquid, and then the hydrolyzed KH-570 is added to the silica dispersion liquid and mixed uniformly, and then the system is adjusted to be acidic, and then the reaction is carried out by heating, and after the reaction, the product is washed, filtered and dried to obtain the modified nano silica.

5. A cBN resin-bonded superabrasive grinding wheel according to claim 4, characterised in that: The silica compound is prepared by the following method: The modified nano silica is mixed and dispersed with ethanol to obtain a modified nano silica dispersion liquid, and then 1-vinyl-3-octyl imidazole tetrafluoroborate is added to the modified nano silica dispersion liquid and stirred, and then an initiator is added for further reaction, and after the reaction, the product is centrifuged and washed, and then the precipitate is freeze-dried to obtain the silica compound.

6. A cBN resin-bonded superabrasive grinding wheel according to claim 4, characterised in that: The mass ratio between the nano silica and KH-570 is 1:(0.65-0.75).

7. A cBN resin-bonded superabrasive grinding wheel according to claim 5, characterised in that: The mass ratio between the silane modified nano silica and 1-vinyl-3-octyl imidazole tetrafluoroborate is 1:(0.7-0.8).

8. A method of making a cBN resin superabrasive wheel according to any one of claims 1 to 7, characterised in that: The method comprises the following steps: (1) preparing nano yttrium oxide, nano zirconium oxide, silica compound and cBN abrasive; (2) washing the above raw materials in ethanol solution and performing ultrasonic dispersion treatment to obtain nano yttrium oxide powder, nano zirconium oxide powder, silica compound powder and cBN dispersion; (3) adding the nano yttrium oxide powder, nano zirconium oxide powder and silica compound powder in step (2) to ethanol solution to obtain a mixture; (4) extracting the granular material from the cBN dispersion by centrifugal sedimentation and screening method; (5) washing and drying the granular material to obtain cBN treated abrasive; (6) stirring the mixture obtained in step (3) at high speed and mixing by ultrasonic vibration to obtain an ultrasonic treated material; (7) adding phenolic resin to the ultrasonic treated material obtained in step (6) and heating to modify to obtain a binder; (8) mixing the binder obtained in step (7) with the cBN treated abrasive obtained in step (5) and forming by hot pressing process to obtain a formed material; (9) preparing a grinding wheel by bonding process for the formed material obtained in step (8), and then performing post-processing to obtain a cBN resin superhard grinding wheel.

9. A method of making a cBN resin-bonded superabrasive grinding wheel according to claim 8, characterised in that: In step (4), the centrifugal sedimentation and screening method comprises the following steps: (4-1) adding the cBN dispersion to a water-alcohol mixed solution of ethanol and deionized water and dividing it into centrifuge bottles; (4-2) centrifuging the centrifuge bottles respectively, and the large particle impurities are settled, and the upper mixed liquid is filtered out for use. (4-3) The filtered upper mixed solution is equally divided into centrifugal bottles, and centrifugal operation is respectively performed to make the particles in the target particle size range to be settled, and the upper fine particle mixed solution is filtered to obtain the bottom particles, i.e. the granular material.

10. A method of making a cBN resin-bonded superabrasive grinding wheel according to claim 9, characterised in that: In the step (4-1), the volume ratio of ethanol to deionized water in the water-alcohol mixed solution is (1.5-2):1.

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