A high-precision chemical mechanical polishing method

Abstract

This invention relates to the field of polishing technology, specifically a high-precision chemical mechanical polishing (CMP) method. This invention overcomes the problem in existing CMP techniques of simultaneously achieving low surface roughness and high polishing efficiency. The invention employs a step-by-step polishing process, sequentially performing primary mechanical polishing, pre-polishing, secondary mechanical polishing, and fine polishing. Pre-polishing and fine polishing solutions are prepared using silica abrasives of different particle sizes and additives. The polishing solution formulation is optimized, and the pH value of the fine polishing solution is adjusted. The groove depth of the pre-polishing and fine polishing pads is controlled, synergistically improving polishing efficiency with the silica-loaded fine polishing pad. This method effectively reduces surface roughness to the nanometer level, improves polishing efficiency, and reduces production costs, making it of significant importance to the metal processing industry.

Description

Technical Field

[0001] This invention relates to the field of polishing technology, specifically a high-precision chemical mechanical polishing method. Background Technology

[0002] Cemented carbide, with its superior properties such as high hardness, high wear resistance, and good heat resistance, is widely used in many fields, including machinery manufacturing, electronics, and aerospace. As industries continuously raise their requirements for the quality and performance of cemented carbide products, the demands for their machining accuracy and surface quality are also becoming increasingly stringent. High-quality surfaces not only improve the wear resistance, corrosion resistance, and fatigue resistance of cemented carbide products, but also enhance their aesthetics and assembly precision. However, existing machining technologies face numerous challenges in meeting these demands.

[0003] Traditional polishing methods, whether mechanical polishing alone, chemical polishing, or a combination of both, struggle to reduce the surface roughness of cemented carbide to meet high-precision requirements. In mechanical polishing, the abrasive grain size and polishing process parameters limit the removal of microscopic surface defects. Even with fine-grained abrasives, tiny scratches can easily remain on the surface, resulting in high surface roughness. In chemical polishing, the uniformity of the chemical reaction is difficult to control precisely, easily leading to localized over- or under-corrosion, resulting in unsatisfactory surface morphology and an inability to achieve nanoscale surface roughness control.

[0004] To reduce surface roughness, polishing time often needs to be increased or multiple polishing processes are required, which leads to a significant decrease in polishing efficiency. In mechanical polishing, finer-grit abrasives are needed for extended grinding, from coarse to fine grinding, and the entire process is time-consuming. Although chemical polishing can accelerate material removal to some extent, its effect on improving surface quality is limited, and the overall polishing cycle is long. The low polishing efficiency severely restricts the production capacity and economic benefits of enterprises.

[0005] In summary, due to the contradictory effects of different polishing methods and parameters on surface roughness and polishing efficiency, existing technologies cannot simultaneously achieve both low surface roughness and high polishing efficiency, making it difficult for them to meet the high-efficiency and high-precision requirements of modern industry for cemented carbide processing.

[0006] Therefore, a high-precision chemical mechanical polishing method is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a high-precision chemical mechanical polishing (CMP) method. This invention employs a step-by-step polishing process, sequentially performing primary mechanical polishing, pre-polishing, secondary mechanical polishing, and fine polishing. By controlling the grit size of the abrasive paper during the two mechanical polishing processes, the surface roughness after polishing is reduced. Pre-polishing and fine polishing solutions are prepared using silica abrasive particles of different sizes and additives; the polishing solution formula is optimized, and the pH value of the fine polishing solution is adjusted. The groove depth of the pre-polishing and fine polishing pads is controlled, and the silica-loaded fine polishing pads synergistically improve polishing efficiency. This method effectively reduces surface roughness to the nanometer level, improves polishing efficiency, and reduces production costs, which is of great significance to the metal processing industry.

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

[0009] This invention provides a high-precision chemical mechanical polishing (CMP) method, which includes the following steps:

[0010] S1 involves mechanically polishing the material to be polished once with sandpaper to obtain the treated polishing material;

[0011] S2 involves immersing the polishing material in a pre-polishing liquid and polishing it using a pre-polishing pad to obtain the pre-polishing material.

[0012] S3 uses sandpaper to perform secondary mechanical polishing on the pre-polished material to obtain the reprocessed polishing material;

[0013] S4 involves immersing the reprocessing polishing material in a fine polishing liquid and polishing it using a fine polishing pad to obtain a fine polishing material.

[0014] S5 cleans the fine polishing material with ethanol and rinses it with deionized water to obtain the polishing material;

[0015] The pre-polishing solution includes silica abrasive particles, 30% hydrogen peroxide solution, and ethylenediamine disuccinic acid;

[0016] The polishing solution includes silica abrasive particles, sodium dodecyl sulfate, phosphate buffer, and other additives;

[0017] The fine polishing pad is prepared by filling an aluminum alloy mold with modified polyurethane;

[0018] Modified polyurethane includes polyurethane raw materials, silica powder, epoxy resin, and additives.

[0019] Preferably, the sandpaper grit is 100-200 grit in one polishing process; or 500-800 grit in one polishing process; and the polishing material is selected from tungsten-cobalt alloy.

[0020] Preferably, the preparation of the pre-polishing solution includes the following steps:

[0021] Deionized water was added to the reactor, and silica abrasive particles with an average particle size of 50-80 nm were added under stirring. The stirring speed was maintained at 500 rpm for 40 min to obtain a dispersion. 30% hydrogen peroxide solution was slowly added to the dispersion, and the stirring speed was maintained at 20 min for 20 min. Ethylenediamine disuccinic acid was slowly added and stirred for 40 min to obtain a pre-polishing solution.

[0022] Preferably, the mass concentration of silica abrasive particles is 8%-12%; the mass concentration of hydrogen peroxide is 3%-6%; and the mass concentration of ethylenediamine disuccinic acid is 0.5%-1.5%.

[0023] Preferably, the preparation of the polishing solution includes the following steps:

[0024] Deionized water was added to the reactor, and silica abrasive particles with an average particle size of 20-30 nm were added under stirring. The stirring speed was maintained at 500 rpm for 40 min to obtain a dispersion. Sodium dodecyl sulfate was slowly added to the dispersion and stirred for 20 min. Other additives were added in sequence and stirred for 20 min. Then, phosphate buffer was added to adjust the pH value to 6-8. The mixture was mixed evenly to obtain a fine polishing solution.

[0025] Other additives include cobalt ethylenediaminetetraacetic acid complex, benzotriazole, polyvinyl alcohol, and ethylenediamine disuccinate.

[0026] Preferably, the preparation of the polishing pad includes the following steps:

[0027] 100 parts of silica powder and additives were added sequentially to a mixer and stirred at 100 rpm for 10 minutes to obtain a uniform mixture. 30 parts of epoxy resin were added to the mixture and stirred at 300 rpm for 30 minutes to obtain a slurry. The polyurethane raw material was sandblasted using 0.5 mm quartz sand at a pressure of 0.5 MPa for 10 minutes to obtain treated polyurethane. The treated polyurethane was dip-coated into the slurry for 10 minutes, then placed in an oven for curing. Pre-curing was performed at 80°C for 1 hour, followed by curing at 140°C for 3 hours to obtain modified polyurethane. The modified polyurethane was molded and demolded according to the pre-polishing pad process to obtain a fine polishing pad. The groove depth of the fine polishing pad was 0.2-0.5 mm, the groove width was 1.2 mm, and the groove spacing was 5 mm. The additives included 10 parts of polyvinyl alcohol, 5 parts of carboxyl-terminated nitrile rubber, and 5 parts of antioxidant 1010.

[0028] Preferably, the preparation of the pre-polishing pad includes the following steps:

[0029] The aluminum alloy mold was heated to 80℃ using a hot air circulating oven and preheated for 2 hours to obtain a treated mold. An organosilicon release agent was uniformly sprayed onto the surface of the treated mold, with the spray thickness controlled at 0.1mm, to obtain a filled mold. Polyurethane raw material was slowly poured into the groove cavity of the filled mold, and vacuum-assisted filling was performed, controlling the pressure at -0.08MPa to ensure uniform filling. The filling was maintained at 2MPa for 10 minutes, then placed in a hot press and cured at 100℃ for 2 hours. Demolding yielded a pre-polished pad. The groove depth of the pre-polished pad was 0.5-0.8mm, the groove width was 1.2mm, and the groove spacing was 5mm.

[0030] Preferably, the primary polishing pressure is 0.2-0.4 MPa; the secondary polishing pressure is 0.4-0.6 MPa; the primary polishing speed is 150-250 r / min; and the secondary polishing speed is 80-150 r / min.

[0031] Preferably, the pre-polishing parameters are: pre-polishing liquid temperature of 30-40℃, polishing pressure of 8Kpa, polishing liquid flow rate of 50ml / min, and polishing disc rotation speed of 80-120r / min; the fine polishing parameters are: fine polishing liquid temperature of 20-25℃, polishing pressure of 8Kpa, polishing liquid flow rate of 50ml / min, and polishing disc rotation speed of 40-60r / min.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention employs a step-by-step polishing method, utilizing polishing slurry and polishing pads in combination, and abrasives of different particle sizes to gradually repair the surface of the cemented carbide. This results in a more ordered atomic arrangement on the surface of the cemented carbide, achieving nanoscale surface roughness control. Simultaneously, by adjusting the abrasive particle size and polishing pad groove depth at different polishing stages, the homogenization of the polished cemented carbide surface is improved. The synergistic use of different polishing slurries and polishing pads reduces surface roughness, facilitating subsequent processing and use of the cemented carbide.

[0034] 2. This invention achieves different effects on abrasive grains and polishing fluids at different polishing stages through the synergy of mechanical and chemical polishing. Pre-polishing quickly removes a large amount of excess material, while fine polishing provides precise control to avoid over- or under-removal and reduce alloy loss. By using a step-by-step polishing process, pre-polishing fluid and fine polishing fluid are used in synergy, and the composition and ratio of different polishing fluids are optimized to reasonably control the material removal rate.

[0035] 3. This invention utilizes a step-by-step polishing process, taking advantage of the synergistic effect of primary and secondary mechanical polishing, to optimize parameters and processes. Primary mechanical polishing quickly removes excess material, while secondary mechanical polishing uses small-particle abrasives for efficient and precise processing, while also removing residual abrasives from the pre-polishing process. Overall, this shortens polishing time, improves polishing efficiency, and reduces production costs.

[0036] 4. This invention utilizes a step-by-step polishing process, taking advantage of the synergistic effect of pre-polishing and fine polishing. The parameters of the polishing slurry and polishing pad are adjusted during the pre-polishing and fine polishing processes. Silica is incorporated into the fine polishing pad, which employs a microporous structure to achieve self-repairing functionality. A small amount of abrasive is added to the fine polishing slurry to reduce abrasive usage and avoid abrasive residue during the fine polishing process. Furthermore, the fine polishing pad can be reused after repair and will not pollute the environment. The synergistic effect improves polishing efficiency, reduces production costs, and increases production benefits. Attached Figure Description

[0037] Figure 1 This is a flowchart of the high-precision chemical mechanical polishing method of the present invention. Detailed Implementation

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Please see Figure 1 This invention provides a high-precision chemical mechanical polishing method. Figure 1 The flowchart of the high-precision chemical mechanical polishing method of the present invention is as follows:

[0040] Example 1

[0041] Add 100 parts of deionized water to a reaction vessel, add 10 parts of silica abrasive particles with an average particle size of 60 nm under stirring, maintain a speed of 500 rpm, and stir for 40 min to obtain a dispersion; slowly add 5 parts of 30% hydrogen peroxide solution to the dispersion, maintain a speed of stirring for 20 min, slowly add 1 part of ethylenediamine disuccinic acid, stir for 40 min, and mix evenly to obtain a pre-polishing solution;

[0042] The aluminum alloy mold was heated to 80℃ using a hot air circulating oven and preheated for 2 hours to obtain a treated mold. A silicone release agent was evenly sprayed onto the surface of the treated mold, with the spray thickness controlled at 0.1mm, to obtain a filled mold. Polyurethane raw material was slowly poured into the groove cavity of the filled mold, and vacuum-assisted filling was performed, controlling the pressure at -0.08MPa to ensure uniform filling. After mold closing, the pressure was maintained at 2MPa for 10 minutes, and then the mold was placed in a hot press for secondary curing at 100℃ for 2 hours. Demolding yielded a pre-polished pad with a groove depth of 0.5mm, a groove width of 1.2mm, and a groove spacing of 5mm.

[0043] Add 1000 parts of deionized water to a reaction vessel, and add 30 parts of silica abrasive particles with an average particle size of 20 nm under stirring. Maintain a speed of 500 rpm and stir for 40 min to obtain a dispersion. Slowly add 3 parts of sodium dodecyl sulfate to the dispersion and stir for 20 min to increase the dispersibility of silica. Then add 2 parts of ethylenediaminetetraacetic acid cobalt(II) complex, 1 part of benzotriazole, 5 parts of polyvinyl alcohol, and 3 parts of ethylenediamine disuccinate in sequence. After each addition of a component, stir for 20 min to ensure that the components are fully mixed. Then add the components to adjust the pH value to 7 and mix evenly to obtain a fine polishing solution.

[0044] 100 parts silica powder, 10 parts polyvinyl alcohol, 5 parts carboxyl-terminated nitrile butadiene rubber, and 5 parts antioxidant 1010 were added sequentially to a mixer and stirred at 100 rpm for 10 minutes to obtain a homogeneous mixture. 30 parts epoxy resin were added to the mixture and stirred at 300 rpm for 30 minutes to obtain a slurry. The polyurethane raw material was sandblasted using 0.5 mm quartz sand at a pressure of 0.5 MPa for 10 minutes to obtain treated polyurethane. The treated polyurethane was dip-coated into the slurry for 10 minutes, then placed in an oven for curing at 80°C for 1 hour, followed by curing at 140°C for 3 hours to obtain modified polyurethane. The modified polyurethane was then molded and demolded according to the pre-polishing pad process to obtain a fine polishing pad. The groove depth of the fine polishing pad was 0.3 mm, the groove width was 1.2 mm, and the groove spacing was 5 mm.

[0045] Polishing methods for tungsten-cobalt alloys:

[0046] The tungsten-cobalt alloy surface was polished for 20 minutes using mechanical polishing equipment, 150-grit sandpaper, at a speed of 200 rpm and a polishing pressure of 0.3 MPa to obtain the treated tungsten-cobalt alloy.

[0047] The tungsten-cobalt alloy was immersed in a pre-polishing solution and polished using a pre-polishing pad. The temperature of the pre-polishing solution was 40℃, the polishing pressure was 8Kpa, the flow rate of the polishing solution was 50ml / min, the rotation speed of the polishing pad was 100r / min, and the polishing time was 40min to obtain the pre-tungsten-cobalt alloy.

[0048] Using mechanical polishing equipment, 600-grit sandpaper, a rotation speed of 100 rpm, and a polishing pressure of 0.5 MPa, the surface of the pre-tungsten cobalt alloy was polished twice for 10 minutes to obtain the reprocessed tungsten cobalt alloy.

[0049] The reprocessed tungsten-cobalt alloy was immersed in a fine polishing solution and polished using a fine polishing pad. The temperature of the fine polishing solution was 20℃, the polishing pressure was 8Kpa, the flow rate of the polishing solution was 50ml / min, the rotation speed of the polishing pad was 50r / min, and the polishing time was 20min. The polished tungsten-cobalt alloy was obtained by cleaning with ethanol and rinsing with deionized water.

[0050] Examples 2-8 follow the same preparation method and parameter conditions as Example 1, with differences shown in Table 1.

[0051] Table 1. Parameter variations in Examples 1-8

[0052]

[0053] Comparative Example 1 refers to Example 1, but does not use a step-by-step polishing process; it only uses a combination of mechanical polishing and fine polishing.

[0054] Comparative Example 2 follows the same process as Example 1, but does not use a step-by-step polishing method; instead, it uses a combination of pre-polishing and fine polishing.

[0055] Comparative Example 3 refers to Example 1, but does not use a step-by-step polishing process; it only uses mechanical polishing.

[0056] Comparative Example 4 is the same as Example 1, except that the sandpaper used for both mechanical polishing processes is the same, which is 50 grit.

[0057] Comparative Example 5 is the same as Example 1, except that the grit of the sandpaper used for both mechanical polishing processes is the same, which is 1000 grit.

[0058] Comparative Example 6 is the same as Example 1, except that the average particle size of the silicon dioxide in the polishing solution is the same in both the pre-polishing and fine polishing processes, which is 10 nm.

[0059] Comparative Example 7 is the same as Example 1, except that the average particle size of the silicon dioxide in the polishing solution is the same in both the pre-polishing and fine polishing processes, which is 100 nm.

[0060] Comparative Example 8 is the same as Example 1, except that the depth of the groove in the polishing pad is the same during both the pre-polishing and fine polishing processes, which is 0.1 mm.

[0061] Comparative Example 9 is the same as Example 1, except that the depth of the grooves in the polishing pad is the same during both the pre-polishing and fine polishing processes, which is 1.2 mm.

[0062] Experiment Example 1: Surface Roughness Test

[0063] A surface roughness measuring instrument was selected, equipped with a diamond stylus. The stylus was aimed at the surface of the tungsten-cobalt alloy workpiece and scanned at a certain speed and stroke. The stylus moved up and down following the microscopic undulations of the surface. The sensor converted the displacement signal into an electrical signal, which, after amplification and filtering, was directly displayed by the instrument as the surface roughness parameter value. The polished tungsten-cobalt alloys prepared in Examples 1-8 and Comparative Examples 1-9 were subjected to surface roughness testing. Eight measurement points were evenly selected on the workpiece surface, and the average value was taken as the surface roughness result of the polished tungsten-cobalt alloy. The test results are shown in Table 2.

[0064] Table 2 Surface roughness tests of Examples 1-8 and Comparative Examples 1-9

[0065] Example Surface roughness / μm Roughness deviation / μm Example 1 0.08 0.01 Example 2 0.1 0.01 Example 3 0.09 0.01 Example 4 0.08 0.01 Example 5 0.12 0.02 Example 6 0.08 0.01 Example 7 0.09 0.01 Example 8 0.08 0.01 Comparative Example 1 0.3 0.05 Comparative Example 2 0.2 0.03 Comparative Example 3 0.5 0.05 Comparative Example 4 0.3 0.04 Comparative Example 5 0.2 0.04 Comparative Example 6 0.2 0.03 Comparative Example 7 0.3 0.04 Comparative Example 8 0.2 0.03 Comparative Example 9 0.4 0.06

[0066] As shown in Table 2, adjusting the grit size of the sandpaper, the average particle size of silica in the polishing slurry, and the groove depth in the polishing pad during the polishing process can significantly improve the surface roughness of the tungsten-cobalt alloy. In Comparative Examples 1-3, the lack of step-by-step polishing resulted in high surface roughness and reduced surface uniformity of the tungsten-cobalt alloy, which is detrimental to subsequent processing and use. Step-by-step polishing significantly reduces surface roughness. Combined with Comparative Examples 4-5, the use of relatively large abrasive grains in the mechanical polishing process for preliminary processing of the cemented carbide surface can quickly remove large protrusions, burrs, and tool marks caused by previous processing. During chemical pre-polishing, [the surface roughness can be further improved]. The process removes the oxide layer generated by chemical reactions, performs preliminary micro-smoothing of the surface, removes small protrusions and unevenness remaining after mechanical polishing, and further reduces surface roughness. Mechanical grinding with small-particle sandpaper further grinds away microscopic protrusions, making the surface smoother and reducing surface micro-height differences. Finally, during fine polishing, the synergistic effect of chemical reactions and micro-abrasive particles allows for surface adjustment and removal at the atomic scale, resulting in a more ordered and smoother atomic arrangement. This enables nanoscale surface roughness control, further reducing surface roughness and improving alloy surface uniformity. Comparative Examples 6-7, with their simultaneous treatment of silica particle size, show a significant reduction in surface roughness compared to Examples 1-8. The surface roughness reduction is significantly affected by several factors. During pre-polishing, using finer silica grains results in insufficient cutting power, making it difficult to quickly remove larger protrusions and unevenness left on the carbide surface from previous processing, leading to poor surface roughness reduction. While using larger abrasive grains increases cutting force, it easily creates deeper scratches and larger pits, resulting in uneven surface roughness distribution. In the fine polishing stage, using excessively fine abrasive grains, although capable of fine surface treatment, has limited removal capacity and cannot effectively repair some deep micro-scratches and defects, also leading to poor surface micro-smoothness. Larger abrasive grains, on the other hand, cannot precisely remove micro-protrusions, leaving tiny unevenness on the surface, making it difficult to achieve nano-scale smoothness. Meter-level surface roughness requirements; in Comparative Examples 8-9, the groove depth of the polishing pad was processed synchronously. However, compared with Examples 1-8, the surface roughness was significantly increased. In the pre-polishing stage, the polishing pad with deeper grooves can quickly remove impurities from the alloy surface and also initially improve the surface flatness, laying the foundation for subsequent fine polishing. If the groove depth is mismatched, more large scratches and unevenness will be left on the surface, increasing the difficulty of subsequent fine polishing. In the fine polishing stage, the polishing pad with shallower grooves can make the abrasive grains act evenly, effectively removing micro protrusions and reducing surface roughness. If the groove depth is too large, the action of small-diameter abrasive grains cannot evenly cover the workpiece surface, which can easily cause uneven surface micromorphology and result in uneven surface roughness.In summary, by employing a step-by-step polishing method and adjusting the abrasive particle size and polishing pad groove depth at different polishing stages, the surface homogenization of the polished cemented carbide is improved. Furthermore, by using different polishing fluids and pads in combination during step-by-step processing, surface roughness is reduced, facilitating subsequent machining and use of the cemented carbide.

[0067] Example 9 is the same as Example 1; Examples 10-15 refer to the preparation method and parameter conditions of Example 1, and the differences are shown in Table 3.

[0068] Table 3. Parameter variations in Examples 9-15

[0069]

[0070]

[0071] Comparative Example 1 refers to Example 1, but does not use a step-by-step polishing process; it only uses a combination of mechanical polishing and fine polishing.

[0072] Comparative Example 2 follows the same process as Example 1, but does not use a step-by-step polishing method; instead, it uses a combination of pre-polishing and fine polishing.

[0073] Comparative Example 3 refers to Example 1, but does not use a step-by-step polishing process; it only uses mechanical polishing.

[0074] Comparative Example 10 refers to Example 9, with the same type and amount of pre-polishing liquid and fine polishing liquid, and polishing is performed using the pre-polishing liquid.

[0075] Comparative Example 11 refers to Example 9, but without adding phosphate buffer to adjust the pH in the polishing solution.

[0076] Comparative Example 12 refers to Example 9, with the pH value of the polishing solution being 5.

[0077] Comparative Example 13 refers to Example 9, with the pH value of the polishing solution being 9.

[0078] Comparative Example 14 refers to Example 9, with the same silica concentration in the fine polishing solution as in the pre-polishing solution.

[0079] Comparative Example 15 refers to Example 9, but without adding silica abrasive to the polishing solution, chemical mechanical polishing is performed using silica in the polishing pad.

[0080] Experiment Example 2: Material Removal Rate Test

[0081] Before polishing, the initial mass of the cemented carbide workpiece was accurately weighed using a high-precision electronic balance. After polishing, the workpiece mass was weighed again. Based on the mass difference and the density of the workpiece material, the material removal volume was calculated using a formula. The material removal rate was then obtained by dividing the material removal volume by the polishing time. The material removal rates of the tungsten-cobalt alloys before and after polishing in Examples 9-15, Comparative Examples 1-3, and Comparative Examples 10-15 were tested. The material removal rates after pre-polishing and fine polishing were tested respectively, and the test results are shown in Table 4.

[0082] Table 4. Material removal rate tests for Examples 9-15, Comparative Examples 1-3, and Comparative Examples 10-15

[0083]

[0084]

[0085] Table 4 shows that in Comparative Examples 1-3, polishing the tungsten-cobalt alloy without using a step-by-step polishing method resulted in a higher material removal rate, increased alloy material loss, and increased surface roughness, leading to a decrease in the overall polishing efficiency. In the mechanical polishing stage, using silica with different particle sizes as abrasives enhanced the mechanical grinding effect through the synergistic effect of the different particle sizes. Simultaneously, in the chemical polishing stage, the highly efficient oxidizing and complexing agents in the polishing slurry formula promoted the chemical reaction and controlled the overall material removal rate. In Comparative Examples 10 and 14, the same polishing slurry ratio was used in the pre-polishing and fine polishing stages, which could not simultaneously meet the different requirements for abrasive cutting ability and precision at each stage. While coarse-grained abrasives offer strong cutting force in the fine polishing stage, they struggle to precisely remove microscopic protrusions and easily cause surface damage, failing to meet high-precision requirements. Furthermore, the higher removal efficiency further increases alloy loss, hindering industrial application. Conversely, using fine-grained abrasives in the pre-polishing stage results in insufficient cutting power, making it difficult to quickly remove large machining allowances, extending processing time, and reducing material removal rate. Adding sodium dodecyl sulfate to the fine polishing slurry enhances abrasive dispersion and the affinity between the slurry and the workpiece surface. Comparative Example 15 shows that reduced affinity between the slurry, polishing pad, and workpiece further impacts material removal rate, leading to an increase in material removal rate during the fine polishing stage. Using the same polishing slurry cannot precisely match different stages. Regarding the need for additives, in the pre-polishing stage, adding sodium dodecyl sulfate can cause excessive dispersion, leading to unstable abrasive cutting force and affecting material removal. If no additives are added or the amount added is inappropriate, in the fine polishing stage, the abrasive particles tend to agglomerate, failing to act uniformly on the workpiece surface, reducing effective cutting points, and excessively lowering the material removal rate. In Comparative Examples 11-13, the lack of pH adjustment in the fine polishing solution significantly affected both the material removal rate and surface roughness of the alloy polishing. Increased solution acidity inhibited the activity of the high-efficiency catalyst, slowing down the chemical reaction rate and further affecting the material removal efficiency. Simultaneously, the strong acid environment may also lead to excessive corrosion of the cemented carbide surface, resulting in uneven dissolution, which not only reduces the material removal rate but also... The alkalinity of the solution affects surface roughness; it alters the properties of sodium dodecyl sulfate, reducing its ability to disperse abrasive particles and its affinity for the workpiece surface, leading to abrasive particle aggregation and uneven application to the workpiece surface. This reduces effective cutting points and material removal rate. Furthermore, the alkaline environment can cause side reactions with certain components in the cemented carbide, forming a difficult-to-remove passivation film on the surface, hindering the material removal process and reducing efficiency. In conclusion, by using a step-by-step polishing method, combining pre-polishing and fine polishing solutions, and optimizing the composition and ratio of different polishing solutions, the material removal rate can be effectively controlled. Excessive material removal rate may cause excessive surface damage, increasing the difficulty of subsequent fine polishing.If the temperature is too low, it will not be able to effectively remove traces of previous processing, which will also affect polishing efficiency and reduce production costs.

[0086] Example 16 is the same as Example 1. Examples 17-21 refer to the preparation method and parameter conditions of Example 16. The differences are shown in Table 5.

[0087] Table 5 Parameter changes in Examples 16-21

[0088]

[0089] Example 22 is the same as Example 1. Examples 23-27 refer to the preparation method and parameter conditions of Example 22. The differences are shown in Table 6.

[0090] Table 6 Parameter changes in Examples 22-27

[0091]

[0092] Comparative Example 1 refers to Example 1, but does not use a step-by-step polishing process; it only uses a combination of mechanical polishing and fine polishing.

[0093] Comparative Example 2 follows the same process as Example 1, but does not use a step-by-step polishing method; instead, it uses a combination of pre-polishing and fine polishing.

[0094] Comparative Example 3 refers to Example 1, but does not use a step-by-step polishing process; it only uses mechanical polishing.

[0095] Comparative Example 16 refers to Example 1, in which the polyurethane raw material is not subjected to sandblasting treatment during the preparation of the fine polishing pad.

[0096] Comparative Example 17 refers to Example 1. In the preparation of the fine polishing pad, the modified polyurethane is not subjected to a secondary curing treatment.

[0097] Comparative Example 18 follows the same procedure as Example 1, with the fine polishing pad prepared according to the same steps as the pre-polishing pad, without modification by silica abrasive.

[0098] Comparative Example 19 refers to Example 16, and the polishing parameters of the first polishing are used in the first polishing and second polishing processes.

[0099] Comparative Example 20 refers to Example 16, and the polishing parameters for the second polishing are used in the first and second polishing processes.

[0100] Comparative Example 21 refers to Example 22, during the pre-polishing and fine polishing processes, the temperature of the polishing liquid used for pre-polishing is as follows.

[0101] Comparative Example 22 refers to Example 22, during the pre-polishing and fine polishing processes, the temperature of the polishing liquid used for fine polishing is as follows.

[0102] Comparative Example 23 refers to Example 22. During the pre-polishing and fine polishing processes, the polishing disc speed used for pre-polishing is adjusted.

[0103] Comparative Example 24 refers to Example 22, during the pre-polishing and fine polishing processes, the polishing disc speed used for fine polishing is adjusted.

[0104] Comparative Example 25 refers to Example 22, except that the depth of the groove in the polishing pad is the same during both the pre-polishing and fine polishing processes, which is 0.3 mm.

[0105] Comparative Example 26 refers to Example 22, except that the depth of the groove in the polishing pad is the same during both the pre-polishing and fine polishing processes, which is 0.8 mm.

[0106] Experimental Example 3: Polishing Efficiency Measurement

[0107] Before polishing the tungsten-cobalt alloy, the equipment was adjusted to its optimal state. Then, the exact time of starting polishing was recorded. The end time was recorded when the surface roughness of the tungsten-cobalt alloy reached 0.08-0.12 μm in Examples 16-27, Comparative Examples 1-3, and Comparative Examples 16-26 was achieved. The total polishing time was obtained by calculating the difference between the start and end times. The test results are shown in Table 7.

[0108] Table 7 Polishing efficiency determination of Examples 16-27, Comparative Examples 1-3, and Comparative Examples 16-26

[0109]

[0110]

[0111] As shown in Table 7, in Comparative Examples 1-3, the non-step polishing method resulted in a higher surface roughness and decreased surface uniformity of the tungsten-cobalt alloy after polishing compared to Example 16, even with the same polishing time. Furthermore, extending the polishing time did not reduce the surface roughness, further demonstrating that the synergistic effect of step polishing can significantly reduce surface roughness and improve polishing efficiency. The results of Comparative Examples 16-18 show that during the preparation of the fine polishing pad, sandblasting enhances the surface activity of the polyurethane raw material. The introduction of polar groups facilitates further bonding between the silica abrasive and the polyurethane of the polishing pad. Simultaneously, the secondary curing process improves the bonding ability and prevents the abrasive from detaching due to friction and wear during fine polishing. Simultaneously, silica abrasives are incorporated into the polishing pad, which employs a microporous structure to achieve self-cleaning functionality. This reduces the silica abrasive content in the polishing slurry, minimizing the impact of abrasives during fine polishing and reducing the increase in alloy surface roughness and polishing efficiency. Furthermore, the polishing pad can be reused after cleaning, lowering production costs. Comparative Examples 19-20, using the same mechanical polishing parameters, showed extended alloy polishing efficiency. In the first mechanical polishing process, higher polishing pressure and speed quickly removed larger protrusions and machining allowances from the cemented carbide surface, laying the foundation for subsequent fine machining and significantly shortening the time required to remove large amounts of material. During the second mechanical polishing, smaller abrasive particles were used under lower pressure and speed conditions. The abrasive residue from the polishing slurry after the previous steps is removed by cutting, while minor defects and high-precision requirements are finely processed to prepare for the subsequent fine polishing process, reducing unnecessary reprocessing time and improving overall polishing efficiency. The results of Comparative Examples 21-24 show that changing the parameters in the pre-polishing and fine polishing processes has a significant impact on polishing efficiency. In the pre-polishing process, a suitable temperature increases the plasticity of the alloy material, which is conducive to the removal of material by the abrasive and improves polishing efficiency. The pre-polishing slurry can better play its lubricating and cooling role, reducing friction between the abrasive and the workpiece. At a suitable rotation speed, the cutting action of the abrasive is fully utilized, which can effectively remove most of the excess material on the alloy surface, providing a good foundation for fine polishing. During the fine polishing process, the alloy surface possesses a certain degree of plasticity, facilitating the abrasive's precise material removal and ensuring accurate trimming of the surface microstructure by the abrasive tool. The abrasive tool can accurately remove surface micro-defects while maintaining a certain material removal rate, enabling the fine polishing process to proceed efficiently and stably, thus improving polishing efficiency. Comparative examples 25-26 show that adjusting the groove structure of the polishing pad has a significant adverse impact on polishing efficiency. The pre-polishing stage requires the removal of a large amount of material, and deeper grooves can better accommodate polishing fluid and abrasive debris. At the same time, a sufficient supply of polishing fluid can ensure the continuous chemical reaction and mechanical action, prevent secondary scratches on the processed surface by abrasive debris, maintain a smooth polishing process, and improve polishing efficiency.Furthermore, deeper grooves allow for more elastic and cushioned contact between the polishing pad and the workpiece surface. During polishing, this elastic contact enables the abrasive grains to better exert their cutting action, which is beneficial for removing larger protrusions and unevenness left on the surface of cemented carbide due to previous processing, accelerating material removal speed, and improving pre-polishing efficiency. Fine polishing aims to achieve nanoscale surface roughness control, requiring more precise material removal. Shallower grooves allow for closer and more uniform contact between the polishing pad and the workpiece surface, ensuring more uniform and stable action of the abrasive grains on the workpiece surface. This is beneficial for accurately removing microscopic protrusions on the surface and reducing surface roughness. Roughness improves the efficiency and quality of fine polishing. Shallower grooves reduce the flow and disturbance of the polishing slurry during polishing, allowing the chemical reagents and abrasive grains in the slurry to act more stably on the workpiece surface. This avoids abrasive residue in the fine polishing slurry, which can lead to uneven abrasive grain distribution, thus improving fine polishing efficiency. In summary, by separately controlling the polishing pressure and polishing speed during primary and secondary mechanical polishing, and adjusting the parameters of the polishing slurry and polishing pad during pre-polishing and fine polishing, polishing efficiency is improved through synergistic effects, reducing production costs while increasing production efficiency.

[0112] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision chemical mechanical polishing method, characterized in that: The high-precision chemical mechanical polishing method includes the following steps: S1 involves mechanically polishing the material to be polished once with sandpaper to obtain the treated polishing material; S2. The polishing material is immersed in a pre-polishing liquid and polished using a pre-polishing pad to obtain a pre-polishing material. S3 The pre-polishing material is mechanically polished a second time with sandpaper to obtain a reprocessed polishing material; S4. The reprocessed polishing material is immersed in the fine polishing liquid, and polished using a fine polishing pad to obtain the fine polishing material. S5 The fine polishing material is cleaned with ethanol and rinsed with deionized water to obtain the polishing material; The pre-polishing solution comprises silica abrasive particles, 30% hydrogen peroxide solution, and ethylenediamine disuccinic acid; The polishing solution includes silica abrasive particles, sodium dodecyl sulfate, phosphate buffer, and other additives. The polishing pad is prepared by filling an aluminum alloy mold with modified polyurethane. The modified polyurethane includes polyurethane raw materials, silica powder, epoxy resin, and additives; The preparation of the polishing pad includes the following steps: 100 parts of the silica powder and the additives are added sequentially to a mixer and stirred at 100 rpm for 10 minutes to obtain a uniform mixture; 30 parts of the epoxy resin are added to the mixture and stirred at 300 rpm for 30 minutes to obtain a slurry; the polyurethane raw material is sandblasted using 0.5 mm quartz sand at a pressure controlled at 0.5 MPa for 10 minutes to obtain treated polyurethane; the treated polyurethane is then dip-coated... The modified polyurethane is obtained by completely immersing the material in the slurry for 10 minutes, then curing it in an oven at 80°C for 1 hour, followed by curing at 140°C for 3 hours. The modified polyurethane is then molded according to the pre-polishing pad, and the fine polishing pad is obtained by demolding. The groove depth of the fine polishing pad is 0.2-0.5 mm, the groove width is 1.2 mm, and the groove spacing is 5 mm. The additives include 10 parts of polyvinyl alcohol, 5 parts of carboxyl-terminated nitrile butadiene rubber, and 5 parts of antioxidant 1010.

2. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The sandpaper used in the first mechanical polishing process is 100-200 mesh; the sandpaper used in the first mechanical polishing process is 500-800 mesh; the material to be polished is selected from tungsten-cobalt alloy.

3. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the pre-polishing liquid includes the following steps: Deionized water was added to the reaction vessel, and silica abrasive particles with an average particle size of 50-80 nm were added under stirring. The stirring speed was maintained at 500 rpm for 40 min to obtain a dispersion. The 30% hydrogen peroxide solution was slowly added to the dispersion, and the stirring speed was maintained at 20 min for 20 min. The ethylenediamine disuccinic acid was slowly added, and the stirring was maintained at 40 min for 40 min to obtain the pre-polishing solution.

4. The high-precision chemical mechanical polishing method according to claim 3, characterized in that: The silica abrasive particles have a mass concentration of 8%-12%; the hydrogen peroxide has a mass concentration of 3%-6%; and the ethylenediamine disuccinic acid has a mass concentration of 0.5%-1.5%.

5. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the polishing solution includes the following steps: Deionized water was added to a reaction vessel, and silica abrasive particles with an average particle size of 20-30 nm were added under stirring. The stirring speed was maintained at 500 rpm for 40 min to obtain a dispersion. Sodium dodecyl sulfate was slowly added to the dispersion and stirred for 20 min. Other additives were added in sequence and stirred for 20 min. Then, phosphate buffer was added to adjust the pH value to 6-8, and the mixture was stirred evenly to obtain the fine polishing solution. The other additives include cobalt ethylenediaminetetraacetic acid complex, benzotriazole, polyvinyl alcohol, and ethylenediamine disuccinate.

6. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the pre-polishing pad includes the following steps: The aluminum alloy mold was heated to 80°C using a hot air circulating oven and preheated for 2 hours to obtain a treated mold. An organosilicon release agent was uniformly sprayed onto the surface of the treated mold, with the spray thickness controlled at 0.1 mm, to obtain a filled mold. The polyurethane raw material was slowly poured into the groove cavity of the filled mold, and vacuum-assisted filling was performed, controlling the pressure at -0.08 MPa. The pressure was maintained at 2 MPa for 10 minutes, and then the mold was placed in a hot press and cured at 100°C for 2 hours. The mold was then demolded to obtain the pre-polished pad. The pre-polishing pad has a groove depth of 0.5-0.8 mm, a groove width of 1.2 mm, and a groove spacing of 5 mm.

7. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The primary mechanical polishing pressure is 0.2-0.4 MPa; the secondary mechanical polishing pressure is 0.4-0.6 MPa; the primary mechanical polishing speed is 150-250 r / min; and the secondary mechanical polishing speed is 80-150 r / min.

8. The high-precision chemical mechanical polishing method according to claim 1, characterized in that: The pre-polishing parameters are: pre-polishing liquid temperature 30-40℃, polishing pressure 8Kpa, polishing liquid flow rate 50ml / min, and polishing disc rotation speed 80-120r / min; the fine polishing parameters are: fine polishing liquid temperature 20-25℃, polishing pressure 8Kpa, polishing liquid flow rate 50ml / min, and polishing disc rotation speed 40-60r / min.

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