Method for preparing superhard micro-powder and metal ceramic binder solid-phase sintered grinding wheel

Abstract

The present application belongs to the technical field of solid phase sintering, and relates to a preparation method of a superhard micro-powder and metal ceramic binder solid phase sintered grinding wheel. The preparation method comprises the following steps: weighing each component according to the following raw material composition: 60-80 parts of diamond micro-powder, 30-35 parts of metal ceramic binder, 5-10 parts of hollow filler, 3-5 parts of resin adhesive, and 10-15 parts of dispersing agent; first, the resin adhesive and the dispersing agent are uniformly mixed to obtain a glue solution; then, the diamond micro-powder, the metal ceramic binder and the hollow filler are uniformly mixed, and the glue solution is added in batches to obtain a mixture; after the mixture is cold-pressed and formed, it is dried, high-temperature sintered and cooled to obtain the grinding wheel product. In the present application, hollow fillers with different particle sizes are selected as pore-forming agents. In the grinding wheel, the diamond micro-powder and the metal ceramic binder are tightly packed, and the hollow fillers with different sizes are dispersed in the grinding wheel. The hollow fillers with different sizes are beneficial to improving the packing density of the diamond micro-powder and the metal ceramic binder.

Description

Technical Field

[0001] This invention belongs to the field of solid-state sintering technology, and more specifically, relates to a method for preparing a grinding wheel by solid-state sintering of ultrahard micro powder and metal-ceramic binder. Background Technology

[0002] Compared to ordinary abrasives, diamond abrasives offer superior grinding performance and a longer lifespan, making them widely used for precision machining of various difficult-to-machine hard and brittle materials. Diamond abrasives can be categorized into three types based on their binder: metal, resin, and cermet. Among these, diamond abrasives prepared with ceramic binders offer advantages such as lower grinding force, lower grinding temperature, and adjustable porosity.

[0003] Porosity plays a crucial role in diamond abrasives prepared with cermet binders. During grinding, the pores in the grinding wheel can carry grinding fluid to the grinding zone, reducing heat accumulation during grinding. In addition, the presence of pores also helps with chip removal, prevents wheel clogging, and improves grinding efficiency.

[0004] Pores in grinding wheels prepared by solid-state sintering using ceramics as a binder are generally generated in two ways. One is through the natural formation of pores during sintering due to the stacking of abrasive particles and the binder; controlling the number, size, and distribution of pores generated in this process is quite difficult. The other method involves adding a pore-forming agent during the grinding wheel manufacturing process, thereby artificially controlling the number, size, and distribution of pores. Based on the pore-forming mechanism, pore-forming agents can be classified into post-sintering dissolution type, heating carbonization or decomposition type, and hollow microsphere type.

[0005] However, regardless of the type of pore-forming agent added, it is currently observed that the pore-forming process can easily cause defects in the physical structure of the grinding wheel, thereby reducing the strength of the grinding wheel. In particular, it can easily lead to a decrease in the hardness of the grinding wheel, resulting in significant detachment of the bonding agent or abrasive during grinding, which affects the service life of the grinding wheel. Summary of the Invention

[0006] In the existing grinding wheel manufacturing process, the simple addition of commonly used pore-forming agents can easily lead to a decrease in the overall strength of the grinding wheel, especially its hardness, which in turn causes significant detachment of the binder or abrasive during grinding, affecting the service life of the grinding wheel. This invention provides a method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a grinding wheel by solid-phase sintering of ultrahard micro powder with a metal-ceramic binder, the specific preparation steps of which include:

[0009] Weigh each component according to the following raw material composition: 60-80 parts diamond micro powder (i.e., superhard micro powder), 30-35 parts metal ceramic binder, 5-10 parts hollow filler, 3-5 parts resin binder, and 10-15 parts dispersant.

[0010] First, mix the resin adhesive and dispersant evenly to obtain the adhesive solution;

[0011] After the diamond micro powder, metal ceramic binder and hollow filler are mixed evenly, they are added to the adhesive in batches to obtain the mixture.

[0012] After the mixture is cold-pressed into shape, dried, sintered at high temperature, and cooled, the grinding wheel product is obtained.

[0013] The hollow packing is composed of the following gradations of hollow packing with different particle sizes: 10-15 parts of packing with a D50 of 100-120μm, 10-15 parts of packing with a D50 of 180-200μm, and 3-5 parts of packing with a D50 of 220-300μm.

[0014] The above technical solution uses hollow fillers of different particle sizes as pore-forming agents during the preparation process. Since the raw materials in the grinding wheel are densely packed with diamond powder and metal-ceramic binder, while the hollow fillers of different sizes are dispersed in it, the hollow fillers of different sizes are beneficial to improving the packing density of diamond powder and metal-ceramic binder during the process. In addition, during the sintering process, the internal gas can diffuse and permeate more easily to the outside, thereby avoiding the decrease in the strength or hardness of the grinding wheel due to the gas generated during the sintering process remaining inside the grinding wheel.

[0015] Furthermore, in the actual gradation process, the inventors have found that the particle size difference between different sizes of particles, as well as the amount added, will significantly affect the compactness of the packing and the ease of gas diffusion. This is because if the particle size difference between the fillers is too large and there are too many small particles, during the actual mixing process, due to the higher surface energy of the small particles, they will compete for and consume more metal-ceramic binder and diamond micro powder. The amount of metal-ceramic binder and diamond micro powder surrounding the large particles will be significantly less than that surrounding the small particles. This will exacerbate the difference in the distribution of diamond micro powder and metal-ceramic binder around the large and small particles, causing uneven stress in different parts of the grinding wheel. Moreover, during gas diffusion, it is easy to block near the large particles, thereby aggravating the physical defects or poor performance around the large particles and further leading to a decline in the performance of the grinding wheel.

[0016] Furthermore, the hollow filler is hollow alumina; the surface of the hollow alumina is coated with nano-titanium dioxide; the coating amount of the nano-titanium dioxide is 5-10% of the mass of the hollow alumina.

[0017] Furthermore, the hollow alumina is ellipsoidal hollow alumina.

[0018] Furthermore, by employing ellipsoidal hollow alumina, different alumina particles can be randomly oriented when dispersed within the grinding wheel system, thereby achieving overall reinforcement of the grinding wheel in different spatial directions and further improving the strength and hardness of the grinding wheel.

[0019] Furthermore, the metal-ceramic binder comprises the following raw materials in parts by weight: 40-50 parts silicon dioxide, 10-12 parts zinc oxide, 5-10 parts sodium oxide, 8-12 parts potassium oxide, and 2-4 parts titanium dioxide.

[0020] Furthermore, the D50 of the metal-ceramic binder is 0.2-0.6 μm.

[0021] Furthermore, the resin adhesive is PVDF, and the dispersant is N-methylpyrrolidone.

[0022] Furthermore, the diamond micro powder is selected from diamond micro powder with a D50 of 2-5μm.

[0023] Furthermore, the batch addition of the adhesive includes:

[0024] After mixing the diamond micro powder, metal-ceramic binder, and hollow filler evenly, add half of the adhesive solution and continue stirring and mixing. Then add the remaining half of the adhesive solution and continue stirring and mixing until evenly mixed.

[0025] The above-mentioned technical solution further coats the hollow alumina particles with a small amount of nano-titanium dioxide. This can improve the surface roughness of the hollow alumina particles, thereby enhancing the bonding strength between the hollow alumina particles and the grinding wheel body. In addition, during the actual grinding process, when titanium dioxide exists on its surface as a heterogeneous nucleus, it can cause the surface of the hollow alumina particles to gradually break, avoiding large-area instantaneous breakage of the particles that would cause large particles to peel off from the grinding wheel, thus affecting the grinding effect. Detailed Implementation

[0026] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0027] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0028] Example 1

[0029] This invention provides a method for preparing a grinding wheel by solid-state sintering of ultrahard micro powder and a metal-ceramic binder, specifically a method for preparing a grinding wheel by solid-state sintering, comprising the following steps:

[0030] Hollow filler gradation: By weight, take 10 parts of hollow filler with a D50 of 100 μm, 10 parts of hollow filler with a D50 of 180 μm, and 3 parts of hollow filler with a D50 of 220 μm; wherein, the hollow filler is hollow alumina with a surface coated with nano-titanium dioxide, and the coating amount of the nano-titanium dioxide is 5% of the mass of the hollow alumina; and the hollow alumina is ellipsoidal hollow alumina; the average wall thickness of the hollow alumina is 10 μm;

[0031] Weighing of raw materials: By weight, take 60 parts diamond micro powder (i.e., superhard micro powder), 30 parts metal ceramic binder, 5 parts hollow filler, 3 parts resin binder, and 10 parts dispersant.

[0032] The diamond micro powder is selected from diamond micro powder with a D50 of 2μm.

[0033] Wherein, the resin binder is PVDF, and the dispersant is N-methylpyrrolidone;

[0034] The metal-ceramic binder comprises the following raw materials in parts by weight: 40 parts silicon dioxide, 10 parts zinc oxide, 5 parts sodium oxide, 8 parts potassium oxide, and 2 parts titanium dioxide; and the D50 of the metal-ceramic binder is 0.2 μm.

[0035] First, mix the resin adhesive and dispersant evenly to obtain the adhesive solution;

[0036] Diamond micro powder, metal-ceramic binder, and hollow filler are poured into a mixer and continuously stirred at 600 rpm for 30 minutes. The adhesive solution is then divided into two equal parts. Half of the adhesive solution is added to the mixer and stirred continuously at 600 rpm for 30 minutes. The remaining half of the adhesive solution is then added and stirred continuously at 600 rpm for 30 minutes to obtain the mixture.

[0037] After the mixture is cold-pressed into shape, it is dried at 70℃ for 8 hours, then sintered at 680℃ for 60 minutes. After cooling to room temperature in the furnace, the material is discharged to obtain the grinding wheel product.

[0038] The above technical solution uses hollow fillers of different particle sizes as pore-forming agents during the preparation process. Since the raw materials in the grinding wheel are densely packed with diamond powder and metal-ceramic binder, while the hollow fillers of different sizes are dispersed in it, the hollow fillers of different sizes are beneficial to improving the packing density of diamond powder and metal-ceramic binder during the process. In addition, during the sintering process, the internal gas can diffuse and permeate more easily to the outside, thereby avoiding the decrease in the strength or hardness of the grinding wheel due to the gas generated during the sintering process remaining inside the grinding wheel.

[0039] Furthermore, in the actual gradation process, the inventors have found that the particle size difference between different sizes of particles, as well as the amount added, will significantly affect the compactness of the packing and the ease of gas diffusion. This is because if the particle size difference between the fillers is too large and there are too many small particles, during the actual mixing process, due to the higher surface energy of the small particles, they will compete for and consume more metal-ceramic binder and diamond micro powder. The amount of metal-ceramic binder and diamond micro powder surrounding the large particles will be significantly less than that surrounding the small particles. This will exacerbate the difference in the distribution of diamond micro powder and metal-ceramic binder around the large and small particles, causing uneven stress in different parts of the grinding wheel. Moreover, during gas diffusion, it is easy to block near the large particles, thereby aggravating the physical defects or poor performance around the large particles and further leading to a decline in the performance of the grinding wheel.

[0040] The above-mentioned technical solution further coats the hollow alumina particles with a small amount of nano-titanium dioxide. This can improve the surface roughness of the hollow alumina particles, thereby enhancing the bonding strength between the hollow alumina particles and the grinding wheel body. In addition, during the actual grinding process, when titanium dioxide exists on its surface as a heterogeneous nucleus, it can cause the surface of the hollow alumina particles to gradually break, avoiding large-area instantaneous breakage of the particles that would cause large particles to peel off from the grinding wheel, thus affecting the grinding effect.

[0041] Example 2

[0042] Hollow filler gradation: By weight, take 12 parts of hollow filler with a D50 of 110 μm, 12 parts of hollow filler with a D50 of 190 μm, and 4 parts of hollow filler with a D50 of 260 μm; wherein, the hollow filler is hollow alumina with a surface coated with nano-titanium dioxide, and the coating amount of the nano-titanium dioxide is 8% of the mass of the hollow alumina; and the hollow alumina is ellipsoidal hollow alumina; the average wall thickness of the hollow alumina is 12 μm;

[0043] Weighing of raw materials: By weight, take 70 parts diamond micro powder, 32 parts metal ceramic binder, 8 parts hollow filler, 4 parts resin binder, and 12 parts dispersant in sequence.

[0044] The diamond micro powder is selected from diamond micro powder with a D50 of 3μm.

[0045] Wherein, the resin binder is PVDF, and the dispersant is N-methylpyrrolidone;

[0046] The metal-ceramic binder comprises the following raw materials in parts by weight: 45 parts silicon dioxide, 11 parts zinc oxide, 8 parts sodium oxide, 10 parts potassium oxide, and 3 parts titanium dioxide; and the D50 of the metal-ceramic binder is 0.4 μm.

[0047] First, mix the resin adhesive and dispersant evenly to obtain the adhesive solution;

[0048] Diamond micro powder, metal-ceramic binder and hollow filler are poured into a mixer and stirred continuously at 700 r / min for 50 min. The adhesive solution is then divided into two equal parts. Half of the adhesive solution is added to the mixer and stirred continuously at 700 r / min for 50 min. The remaining half of the adhesive solution is then added and stirred continuously at 700 r / min for 50 min to obtain the mixture.

[0049] After the mixture is cold-pressed into shape, it is dried at 75℃ for 9 hours, then sintered at 690℃ for 70 minutes. After cooling to room temperature in the furnace, the material is discharged to obtain the grinding wheel product.

[0050] The above-mentioned technical solution further coats the hollow alumina particles with a small amount of nano-titanium dioxide. This can improve the surface roughness of the hollow alumina particles, thereby enhancing the bonding strength between the hollow alumina particles and the grinding wheel body. In addition, during the actual grinding process, when titanium dioxide exists on its surface as a heterogeneous nucleus, it can cause the surface of the hollow alumina particles to gradually break, avoiding large-area instantaneous breakage of the particles that would cause large particles to peel off from the grinding wheel, thus affecting the grinding effect.

[0051] Example 3

[0052] Hollow filler gradation: By weight, take 15 parts of hollow filler with a D50 of 120μm, 15 parts of hollow filler with a D50 of 200μm, and 5 parts of hollow filler with a D50 of 300μm; wherein, the hollow filler is hollow alumina with a surface coated with nano-titanium dioxide, and the coating amount of the nano-titanium dioxide is 10% of the mass of the hollow alumina; and the hollow alumina is ellipsoidal hollow alumina; the average wall thickness of the hollow alumina is 15μm;

[0053] Weighing of raw materials: By weight, take 80 parts diamond micro powder, 35 parts metal ceramic binder, 10 parts hollow filler, 5 parts resin binder, and 15 parts dispersant in sequence.

[0054] The diamond micro powder is selected from diamond micro powder with a D50 of 5μm.

[0055] Wherein, the resin binder is PVDF, and the dispersant is N-methylpyrrolidone;

[0056] The metal-ceramic binder comprises the following raw materials in parts by weight: 50 parts silicon dioxide, 12 parts zinc oxide, 10 parts sodium oxide, 12 parts potassium oxide, and 4 parts titanium dioxide; and the D50 of the metal-ceramic binder is 0.6 μm.

[0057] First, mix the resin adhesive and dispersant evenly to obtain the adhesive solution;

[0058] Diamond micro powder, metal-ceramic binder, and hollow filler are poured into a mixer and continuously stirred at 800 rpm for 60 minutes. The adhesive solution is then divided into two equal parts. Half of the adhesive solution is added to the mixer and stirred continuously at 800 rpm for 60 minutes. The remaining half of the adhesive solution is then added and stirred continuously at 800 rpm for 60 minutes to obtain the mixture.

[0059] After the mixture is cold-pressed into shape, it is dried at 80℃ for 10 hours, then sintered at 700℃ for 80 minutes. After cooling to room temperature in the furnace, the material is discharged to obtain the grinding wheel product.

[0060] The above technical solution uses hollow fillers of different particle sizes as pore-forming agents during the preparation process. Since the raw materials in the grinding wheel are densely packed with diamond powder and metal-ceramic binder, while the hollow fillers of different sizes are dispersed in it, the hollow fillers of different sizes are beneficial to improving the packing density of diamond powder and metal-ceramic binder during the process. In addition, during the sintering process, the internal gas can diffuse and permeate more easily to the outside, thereby avoiding the decrease in the strength or hardness of the grinding wheel due to the gas generated during the sintering process remaining inside the grinding wheel.

[0061] Furthermore, in the actual gradation process, the inventors have found that the particle size difference between different sizes of particles, as well as the amount added, will significantly affect the compactness of the packing and the ease of gas diffusion. This is because if the particle size difference between the fillers is too large and there are too many small particles, during the actual mixing process, due to the higher surface energy of the small particles, they will compete for and consume more metal-ceramic binder and diamond micro powder. The amount of metal-ceramic binder and diamond micro powder surrounding the large particles will be significantly less than that surrounding the small particles. This will exacerbate the difference in the distribution of diamond micro powder and metal-ceramic binder around the large and small particles, causing uneven stress in different parts of the grinding wheel. Moreover, during gas diffusion, it is easy to block near the large particles, thereby aggravating the physical defects or poor performance around the large particles and further leading to a decline in the performance of the grinding wheel.

[0062] The above-mentioned technical solution further coats the hollow alumina particles with a small amount of nano-titanium dioxide. This can improve the surface roughness of the hollow alumina particles, thereby enhancing the bonding strength between the hollow alumina particles and the grinding wheel body. In addition, during the actual grinding process, when titanium dioxide exists on its surface as a heterogeneous nucleus, it can cause the surface of the hollow alumina particles to gradually break, avoiding large-area instantaneous breakage of the particles that would cause large particles to peel off from the grinding wheel, thus affecting the grinding effect.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 1 is that spherical hollow alumina of equal mass is used instead of ellipsoidal hollow alumina, while the other conditions remain unchanged.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 1 is that the hollow alumina surface is not coated with nano-titanium dioxide, while the other conditions remain unchanged.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 1 is that the hollow packing is composed of the following hollow packing particles of different sizes: 20 parts of packing with a D50 of 100 μm, 10 parts of packing with a D50 of 180 μm, and 3 parts of packing with a D50 of 220 μm; all other conditions remain unchanged.

[0069] Comparative Example 4

[0070] The difference between this comparative example and Example 1 is that the hollow packing is composed of the following hollow packing particles of different sizes: 10 parts of packing with a D50 of 100 μm, 10 parts of packing with a D50 of 180 μm, and 10 parts of packing with a D50 of 220 μm; all other conditions remain unchanged.

[0071] The performance of the grinding wheel products obtained in Examples 1-3 and Comparative Examples 1-4 was tested. The specific test methods and results are as follows:

[0072] Bending strength test: The products obtained from each embodiment and comparative example were placed on a QT-1166 universal testing machine and their bending strength was measured using the three-point bending method. The loading speed was 0.5 mm / min, and each measurement was performed 5 times to calculate the average value. The specific test results are shown in Table 1.

[0073] Hardness test: The hardness of the products obtained in each embodiment and comparative example was measured using an HR-150DT electric Rockwell hardness tester. The hardness standard was HRF, the initial load was 98N, and the final load was 588N. Five points were taken on the upper and lower surfaces of the grinding wheel, for a total of 10 points. The maximum and minimum hardness values ​​were removed and the average value was taken. The specific test results are shown in Table 1.

[0074] Grinding performance test: The grinding performance of the grinding wheel was tested using a DMG-6011V ultra-precision grinder. The workpiece was quartz glass with a diameter of 160mm. The grinding wheel speed was set to 3500r / min, and the feed rate was 1×10⁻⁶. -4 cm / s, feed depth 5×10 -3 cm, using deionized water as coolant, observe whether there is large-area detachment of the bonding agent on the surface of the grinding wheel during the grinding process, the specific phenomena are shown in Table 1;

[0075] Table 1: Product Performance Test Results

[0076] Example 1 92.1 108 No obvious shedding Example 2 92.2 110 No obvious shedding Example 3 92.4 112 No obvious shedding Comparative Example 1 89.9 106 A small amount of binder detached Comparative Example 2 90.2 105 A small amount of binder detached Comparative Example 3 82.3 96 Significant bond detachment Comparative Example 4 85.6 97 Significant bond detachment

[0077] As can be seen from the test results in Table 1, the product obtained by this invention has excellent mechanical properties and grinding performance.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a grinding wheel by solid-phase sintering of ultrahard micro powder with a metal-ceramic binder, characterized in that, The preparation method includes the following steps: Weigh each component according to the following raw material composition: 60-80 parts diamond micro powder, 30-35 parts metal ceramic binder, 5-10 parts hollow filler, 3-5 parts resin binder, and 10-15 parts dispersant. The hollow filler is hollow alumina; the hollow alumina is ellipsoidal hollow alumina; the surface of the hollow alumina is coated with nano-titanium dioxide; the coating amount of nano-titanium dioxide is 5-10% of the mass of the hollow alumina; First, mix the resin adhesive and dispersant evenly to obtain the adhesive solution; After the diamond micro powder, metal ceramic binder and hollow filler are mixed evenly, they are added to the adhesive in batches to obtain the mixture. After the mixture is cold-pressed into shape, dried, sintered at high temperature, and cooled, the grinding wheel product is obtained. The hollow packing is composed of the following gradations of hollow packing with different particle sizes: 10-15 parts of packing with a D50 of 100-120μm, 10-15 parts of packing with a D50 of 180-200μm, and 3-5 parts of packing with a D50 of 220-300μm.

2. The method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder according to claim 1, characterized in that, The metal-ceramic binder comprises the following raw materials in parts by weight: 40-50 parts silicon dioxide, 10-12 parts zinc oxide, 5-10 parts sodium oxide, 8-12 parts potassium oxide, and 2-4 parts titanium dioxide.

3. The method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder according to claim 2, characterized in that, The D50 of the metal-ceramic binder is 0.2-0.6 μm.

4. The method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder according to claim 1, characterized in that, The resin binder is PVDF, and the dispersant is N-methylpyrrolidone.

5. The method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder according to claim 1, characterized in that, The diamond micro powder used is diamond micro powder with a D50 of 2-5μm.

6. The method for preparing a grinding wheel by solid-phase sintering of superhard micro powder and metal-ceramic binder according to claim 1, characterized in that, The batch addition of adhesive includes: After mixing the diamond micro powder, metal-ceramic binder, and hollow filler evenly, add half of the adhesive solution and continue stirring. Then add the remaining half of the adhesive solution and continue stirring until evenly mixed.