High-precision chemical mechanical polishing processing method

Abstract

The invention relates to the technical field of polishing machining, in particular to a high-precision chemical mechanical polishing machining method. The problem that in the prior art, low surface roughness and high polishing efficiency are difficult to achieve at the same time through chemical mechanical polishing is solved. Through a step-by-step polishing process, primary mechanical polishing, pre-polishing, secondary mechanical polishing and fine polishing are sequentially carried out, a pre-polishing solution and a fine polishing solution are prepared from silicon dioxide abrasive particles with different particle sizes and an additive, the formula of the polishing solution is optimized, and the pH value of the fine polishing solution is adjusted; the groove depth of the pre-polishing pad and the fine polishing pad is controlled, and the polishing efficiency is improved in cooperation with the fine polishing pad loaded with silicon dioxide. According to the method, the surface roughness is effectively reduced to nanoscale, the polishing efficiency is improved, the production cost is reduced, and the method has important significance in the metal processing industry.

Description

Technical Field

[0001] The invention relates to the technical field of polishing processing, in particular to a high-precision chemical mechanical polishing processing method. Background Art

[0002] With its excellent properties such as high hardness, high wear resistance and good heat resistance, cemented carbide is widely used in many fields such as machinery manufacturing, electronics, aerospace, etc. As various industries continue to improve the quality and performance requirements of cemented carbide products, the requirements for its processing accuracy and surface quality are also becoming increasingly stringent. High-quality surfaces can not only improve the wear resistance, corrosion resistance and fatigue resistance of cemented carbide products, but also improve the aesthetics and assembly accuracy of the products. However, existing processing technologies face many challenges in meeting these requirements.

[0003] In traditional polishing methods, whether it is single mechanical polishing, chemical polishing or a combination of the two, it is difficult to reduce the surface roughness of cemented carbide to a level that meets high-precision requirements. During mechanical polishing, the particle size of the abrasive tool and the polishing process parameters limit the removal effect of surface microscopic defects. Even if fine-grained abrasive tools are used, it is easy to leave tiny scratches on the surface, resulting in high surface roughness. During chemical polishing, the uniformity of the chemical reaction is difficult to accurately control, and localized excessive or insufficient corrosion is prone to occur, making the surface microscopic morphology unsatisfactory and unable to achieve nano-level surface roughness control.

[0004] In order to reduce the surface roughness, it is often necessary to increase the polishing time or perform multiple polishing, which leads to a significant reduction in polishing efficiency. In mechanical polishing, a finer-grained abrasive tool is required for long-term polishing. From rough grinding to fine grinding, the entire process takes a long time. Although chemical polishing can speed up the material removal rate to a certain extent, it has limited effect on improving surface quality, the overall polishing cycle is long, and the low polishing efficiency seriously 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, the existing technology cannot take into account both low surface roughness and high polishing efficiency, making it difficult for the existing technology 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 the present invention is to provide a high-precision chemical mechanical polishing method. The present invention sequentially performs primary mechanical polishing, pre-polishing, secondary mechanical polishing and fine polishing through a step-by-step polishing process, and reduces the surface roughness after polishing by controlling the number of sandpapers during the two mechanical polishing processes; prepares pre-polishing liquid and fine polishing liquid using silica abrasive particles of different particle sizes and additives, optimizes the formula of the polishing liquid, and adjusts the pH value of the fine polishing liquid; controls the groove depth of the pre-polishing pad and the fine polishing pad, and cooperates with the silica-loaded fine polishing pad to improve the polishing efficiency. The method effectively reduces the surface roughness to the nanometer level, improves the polishing efficiency, and reduces the production cost, which is of great significance to the metal processing industry.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a high-precision chemical mechanical polishing method, which comprises the following steps:

[0010] S1 mechanically polishes the material to be polished by sandpaper to obtain a treated polishing material;

[0011] S2 immerses the treated polishing material into a pre-polishing liquid and polishes it using a pre-polishing pad to obtain a pre-polishing material;

[0012] S3 performs secondary mechanical polishing on the pre-polished material using sandpaper to obtain a reprocessed polished material;

[0013] S4: immersing the reprocessed polishing material in a fine polishing liquid, and polishing with a fine polishing pad to obtain a fine polishing material;

[0014] S5: washing the fine polishing material with ethanol and rinsing with deionized water to obtain a polishing material;

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

[0016] The fine polishing liquid includes silica abrasive, sodium lauryl sulfate, phosphate buffer and other additives;

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

[0018] The modified polyurethane comprises polyurethane raw materials, silica powder, epoxy resin and additives.

[0019] Preferably, the mesh number of the sandpaper in one polishing process is 100-200 mesh; the mesh number of the sandpaper in one polishing process is 500-800 mesh; and the material to be polished is selected from tungsten-cobalt alloy.

[0020] Preferably, the preparation of the pre-polishing liquid comprises the following steps:

[0021] Deionized water was added into the reaction kettle, and silicon dioxide abrasive particles with an average particle size of 50-80 nm were added under stirring conditions, the rotation speed was maintained at 500 rpm, and the mixture was stirred for 40 minutes to obtain a dispersion; 30% hydrogen peroxide solution was slowly added into the dispersion, the rotation speed was maintained at 20 minutes, ethylenediamine disuccinic acid was slowly added, and the mixture was stirred for 40 minutes. The mixture was evenly mixed to obtain a pre-polishing solution.

[0022] Preferably, the mass concentration of silicon dioxide abrasive 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 fine polishing liquid comprises the following steps:

[0024] Deionized water was added to the reaction kettle, and silicon dioxide abrasive particles with an average particle size of 20-30 nm were added under stirring conditions, the rotation speed was maintained at 500 rpm, and the mixture was stirred for 40 minutes to obtain a dispersion; sodium dodecyl sulfate was slowly added to the dispersion, and the mixture was stirred for 20 minutes; other additives were added in sequence, and the mixture was stirred for 20 minutes, and a phosphate buffer was added to adjust the pH value to 6-8, and the mixture was evenly mixed to obtain a fine polishing solution;

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

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

[0027] 100 parts of silica powder and auxiliary agents are added to a mixer in sequence, stirred at 100 rpm for 10 minutes, and mixed evenly to obtain a mixed system; 30 parts of epoxy resin are added to the mixed system, and stirred at 300 rpm for 30 minutes to obtain a slurry; the polyurethane raw material is sandblasted, quartz sand with a particle size of 0.5 mm is selected, the sandblasting pressure is controlled at 0.5 MPa, and the treatment is carried out for 10 minutes to obtain a treated polyurethane; the treated polyurethane is completely immersed in the slurry by dipping, soaked for 10 minutes, and then placed in an oven for curing, pre-cured at 80°C for 1 hour, then heated to 140°C, and cured for 3 hours to obtain a modified polyurethane; the modified polyurethane is molded with reference to the pre-polishing pad, and the demolding process obtains a fine polishing pad; wherein 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 auxiliary agents include 10 parts of polyvinyl alcohol, 5 parts of terminal carboxyl nitrile rubber and 5 parts of antioxidant 1010.

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

[0029] The aluminum alloy mold is heated to 80°C in a hot air circulation oven and preheated for 2 hours to obtain a treated mold; a silicone release agent is evenly sprayed on the surface of the treated mold, and the spraying thickness is controlled at 0.1 mm to obtain a filled mold; the polyurethane raw material is slowly poured into the groove cavity of the filling mold, and vacuum-assisted filling is performed, and the pressure is controlled to be -0.08 MPa to make the filling uniform, and maintained at 2 MPa for 10 minutes, and then added to a hot press, cured at 100°C for 2 hours, and demolded to obtain a pre-polished pad; wherein the groove depth of the pre-polished pad is 0.5-0.8 mm, the groove width is 1.2 mm, and the groove spacing is 5 mm.

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

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

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention adopts a step-by-step polishing method, uses a polishing liquid and a polishing pad in combination, and uses abrasives of different particle sizes in combination to gradually repair the surface of the alloy, so that the atomic arrangement on the surface of the cemented carbide is more orderly, and the nano-level surface roughness control is achieved. At the same time, by adjusting the abrasive particle size and the groove depth of the polishing pad at different polishing stages, the surface of the polished cemented carbide is uniformly improved, and different polishing liquids and polishing pads are used in coordination, thereby reducing the surface roughness and facilitating the subsequent processing and use of the cemented carbide.

[0034] 2. The present invention achieves different effects on abrasive particles and polishing liquid at different polishing stages through the coordination of mechanical and chemical polishing. Pre-polishing quickly removes a large amount of excess, and fine-controls fine polishing to avoid excessive or insufficient removal and reduce alloy loss. By using a step-by-step polishing processing method, pre-polishing liquid and fine polishing liquid are used in coordination, and the composition and ratio of different polishing liquids are optimized to reasonably control the material removal rate.

[0035] 3. The present invention uses a step-by-step polishing process, utilizes the synergistic effect of primary mechanical polishing and secondary mechanical polishing, optimizes parameters and processes, utilizes primary mechanical polishing to quickly remove excess, and utilizes small-particle abrasives for efficient and fine processing in secondary mechanical polishing, while removing residual abrasives in the pre-polishing process, thereby shortening the polishing time as a whole, improving polishing efficiency, and reducing production costs.

[0036] 4. The present invention adopts a step-by-step polishing process, utilizes the synergistic effect of pre-polishing and fine polishing, adjusts the parameters of the polishing liquid and the polishing pad during the pre-polishing and fine polishing processes, utilizes silicon dioxide to be combined with the fine polishing pad, and adopts a microporous structure inside the polishing pad to achieve a self-dressing function. A small amount of abrasive is added to the fine polishing liquid to reduce the amount of abrasive and avoid abrasive residue during the fine polishing process. At the same time, the fine polishing pad can be reused after dressing and will not pollute the environment. The synergistic effect improves the polishing efficiency, reduces the production cost, and improves the production benefit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a flow chart of the high-precision chemical mechanical polishing method of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0039] See also Figure 1 The present 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] 100 parts of deionized water were added to a reaction kettle, and 10 parts of silicon dioxide abrasive particles with an average particle size of 60 nm were added under stirring conditions, the rotation speed was maintained at 500 rpm, and the mixture was stirred for 40 minutes to obtain a dispersion; 5 parts of a 30% hydrogen peroxide solution were slowly added to the dispersion, the rotation speed was maintained at 20 minutes, and 1 part of ethylenediamine disuccinic acid was slowly added, and the mixture was stirred for 40 minutes. The mixture was evenly mixed to obtain a pre-polishing solution;

[0042] The aluminum alloy mold was heated to 80°C in a hot air circulation oven and preheated for 2 hours to obtain a treated mold; a silicone release agent was evenly sprayed on the surface of the treated mold, and the spraying thickness was controlled to be 0.1 mm to obtain a filled mold; the polyurethane raw material was slowly poured into the groove cavity of the filling mold, and vacuum-assisted filling was performed to control the pressure to -0.08 MPa to ensure uniform filling. After the mold was closed, it was maintained at 2 MPa for 10 minutes, and then added to a hot press, and secondary cured at 100°C for 2 hours, and demolded to obtain a pre-polished pad. The groove depth of the pre-polished pad was 0.5 mm, the groove width was 1.2 mm, and the groove spacing was 5 mm.

[0043] 1000 parts of deionized water were added to a reaction kettle, 30 parts of silicon dioxide abrasive particles with an average particle size of 20 nm were added under stirring, the rotation speed was maintained at 500 rpm, and the mixture was stirred for 40 minutes to obtain a dispersion; 3 parts of sodium dodecyl sulfate were slowly added to the dispersion, the rotation speed was maintained at 20 minutes to increase the dispersibility of silicon dioxide, 2 parts of ethylenediaminetetraacetic acid cobalt (II) complex, 1 part of benzotriazole, 5 parts of polyvinyl alcohol, and 3 parts of ethylenediamine disuccinate were added in sequence, and after each component was added, the mixture was stirred for 20 minutes to fully mix the components, and then the pH value was adjusted to 7, and the mixture was mixed to obtain a fine polishing solution;

[0044] 100 parts of silica powder, 10 parts of polyvinyl alcohol, 5 parts of terminal carboxyl nitrile rubber and 5 parts of antioxidant 1010 were added to a mixer in sequence, stirred at 100 rpm for 10 minutes, and mixed evenly to obtain a mixed system; 30 parts of epoxy resin were added to the mixed system, and stirred at 300 rpm for 30 minutes to obtain a slurry; the polyurethane raw material was sandblasted, quartz sand with a particle size of 0.5 mm was selected, the sandblasting pressure was controlled at 0.5 MPa, and the treated polyurethane was treated for 10 minutes; the treated polyurethane was completely immersed in the slurry by dipping, soaked for 10 minutes, and then put into an oven for curing, pre-cured at 80°C for 1 hour, then heated to 140°C, and cured for 3 hours to obtain a modified polyurethane; the modified polyurethane was molded according to the pre-polishing pad, and the demolding process obtained a fine polishing pad; the groove depth of the fine polishing pad is 0.3 mm, the groove width is 1.2 mm, and the groove spacing is 5 mm.

[0045] Polishing method of tungsten cobalt alloy:

[0046] A mechanical polishing device was used, 150-mesh sandpaper was used, the rotation speed was maintained at 200 rpm, and the polishing pressure was 0.3 MPa to polish the surface of the tungsten-cobalt alloy once for 20 minutes to obtain a treated tungsten-cobalt alloy;

[0047] The treated tungsten-cobalt alloy is immersed in a pre-polishing liquid, and the tungsten-cobalt alloy is polished with a pre-polishing pad, the pre-polishing liquid temperature is 40° C., the polishing pressure is 8 KPa, the polishing liquid flow rate is 50 ml / min, the polishing disc speed is 100 r / min, and the polishing time is 40 min to obtain a pre-tungsten-cobalt alloy;

[0048] A mechanical polishing device was used, 600-mesh sandpaper was used, the rotation speed was maintained at 100 rpm, and the polishing pressure was 0.5 MPa to perform secondary polishing on the surface of the pre-tungsten-cobalt alloy for 10 minutes to obtain a reprocessed tungsten-cobalt alloy;

[0049] The reprocessed tungsten-cobalt alloy was immersed in the fine polishing liquid and polished with the fine polishing pad. The fine polishing liquid temperature was 20°C, the polishing pressure was 8Kpa, the polishing liquid flow rate was 50ml / min, the polishing disk speed was 50r / min, the polishing time was 20min, and the polished tungsten-cobalt alloy was obtained by washing with ethanol and rinsing with deionized water.

[0050] Examples 2-8 refer to the preparation methods and parameter conditions of Example 1, with the differences shown in Table 1.

[0051] Table 1 Parameter changes of Examples 1-8

[0052]

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

[0054] Comparative Example 2 refers to Example 1, but does not use the step-by-step polishing method, and only uses a combination of pre-polishing and fine polishing.

[0055] Comparative Example 3 refers to Example 1, but does not use the step-by-step polishing method, but only uses mechanical polishing.

[0056] Comparative Example 4 refers to Example 1, except that the mesh size of the sandpaper used in the two mechanical polishings is the same, both of which are 50 mesh.

[0057] Comparative Example 5 refers to Example 1, except that the mesh size of the sandpaper used in the two mechanical polishings is the same, both of which are 1000 mesh.

[0058] Comparative Example 6 refers to Example 1, except that the average particle size of silicon dioxide in the polishing liquid during pre-polishing and fine polishing is the same, both 10 nm.

[0059] Comparative Example 7 refers to Example 1, except that the average particle size of silica in the polishing liquid during pre-polishing and fine polishing is the same, both 100 nm.

[0060] Comparative Example 8 refers to Example 1, except that the depth of the grooves in the polishing pad during pre-polishing and fine polishing is the same, both 0.1 mm.

[0061] Comparative Example 9 refers to Example 1, except that the depth of the groove in the polishing pad during pre-polishing and fine polishing is the same, both 1.2 mm.

[0062] Experimental Example 1 Surface Roughness Test

[0063] A surface roughness measuring instrument is selected, and its sensor is equipped with a diamond stylus. The stylus is aimed at the surface of the tungsten-cobalt alloy workpiece, and scanned at a certain speed and stroke. The stylus moves up and down with the microscopic undulations of the surface. The sensor converts the displacement signal into an electrical signal. After amplification, filtering, and other processing, the instrument directly displays the surface roughness parameter value. The polished tungsten-cobalt alloys prepared in Examples 1-8 and Comparative Examples 1-9 are tested for surface roughness. Eight measurement points are evenly selected on the surface of the workpiece, and then the average value is 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 test 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] It can be seen from the results in Table 2 that by adjusting the mesh number of sandpaper in mechanical polishing, the average particle size of silicon dioxide in the polishing liquid, and the groove depth in the polishing pad during the polishing process, the improvement effect on the surface roughness of the tungsten-cobalt alloy can be significantly improved; in Comparative Examples 1-3, the processing method of step-by-step polishing is not adopted, and the surface roughness of the tungsten-cobalt alloy obtained after polishing is high, and the surface uniformity is reduced, which is not conducive to the subsequent processing and use of the tungsten-cobalt alloy. Step-by-step polishing can significantly reduce the surface roughness. Combined with Comparative Examples 4-5, relatively large abrasive particles are used during mechanical polishing to perform preliminary processing on the cemented carbide surface, which can quickly remove large protrusions, burrs, knife marks and other defects on the alloy surface caused by the previous processing. In the process of chemical pre-polishing, The oxide layer generated by chemical reaction can be removed, the surface is subjected to preliminary microscopic flattening treatment, the smaller protrusions and unevenness remaining after mechanical polishing are removed, and the surface roughness is further reduced; after mechanical polishing with small-particle sandpaper, the surface microscopic protrusions are ground to make the surface smoother, further reducing the surface microscopic height difference; finally, in the fine polishing process, the synergistic effect of chemical reaction and tiny abrasive particles can adjust and remove the surface at the atomic scale, making the surface atomic arrangement more orderly and flat, and realizing nanoscale surface roughness control, further reducing the surface roughness, and improving the uniformity of the alloy surface; for the simultaneous treatment of the silicon dioxide particle size in Comparative Examples 6-7, the surface roughness is The surface roughness of the hard alloy surface is obviously increased. During pre-polishing, a finer-sized silica is used, but its cutting ability is insufficient, and it is difficult to quickly remove the larger protrusions and unevenness left on the surface of the cemented carbide due to the previous processing, resulting in poor surface roughness reduction effect; using a larger-sized abrasive, although the cutting force is enhanced, it is easy to produce deeper scratches and larger pits on the surface, resulting in uneven roughness distribution; in the fine-polishing stage, abrasives with too fine a particle size can be used to finely process the surface, but due to its limited removal ability, some deeper micro scratches and defects cannot be effectively repaired, which also leads to poor surface micro flatness, while abrasives with larger particle sizes cannot accurately remove the micro protrusions on the surface, and will leave tiny unevenness on the surface, making it difficult to achieve nano-polishing. The surface roughness requirement of the meter level is metre-level; in comparative examples 8-9, the groove depth of the polishing pad is processed simultaneously, but compared with examples 1-8, the surface roughness is significantly increased, because in the pre-polishing stage, the polishing pad with deeper grooves can quickly remove impurities on the alloy surface, and can also preliminarily improve the surface flatness, laying the foundation for the subsequent fine polishing. If the groove depth is not matched, the surface will leave more large scratches and unevenness, increasing the difficulty of subsequent fine polishing; in the fine polishing stage, the polishing pad with shallower grooves can make the abrasive particles act evenly, effectively remove microscopic protrusions, and reduce the surface roughness. If the groove depth is too large, the small-size abrasive particles cannot evenly cover the workpiece surface, which easily causes uneven surface micromorphology and uneven surface roughness;In summary, by adopting the step-by-step polishing method and adjusting the abrasive particle size and the groove depth of the polishing pad at different polishing stages, the surface uniformity of the polished cemented carbide is improved. By using different polishing liquids and polishing pads in a coordinated manner through step-by-step processing, the surface roughness is reduced, which facilitates the subsequent processing and use of 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 changes of Examples 9-15

[0069]

[0070]

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

[0072] Comparative Example 2 refers to Example 1, but does not use the step-by-step polishing method, and only uses a combination of pre-polishing and fine polishing.

[0073] Comparative Example 3 refers to Example 1, but does not use the step-by-step polishing method, but only uses mechanical polishing.

[0074] Comparative Example 10 refers to Example 9, the pre-polishing liquid and the fine polishing liquid are of the same type and amount, and the pre-polishing liquid is used for polishing.

[0075] Comparative Example 11 refers to Example 9, except that no phosphate buffer is added to the polishing liquid to adjust the pH.

[0076] Comparative Example 12 refers to Example 9, and the pH value of the fine polishing liquid is 5.

[0077] Comparative Example 13 refers to Example 9, and the pH value of the fine polishing liquid is 9.

[0078] Comparative Example 14 refers to Example 9, and the concentration of silicon dioxide in the fine polishing liquid is the same as that in the pre-polishing liquid.

[0079] Comparative Example 15 refers to Example 9, except that no silica abrasive is added to the fine polishing liquid, and chemical mechanical polishing is performed using the silica in the fine polishing pad.

[0080] Experimental Example 2 Material Removal Rate Test

[0081] Before polishing, use a high-precision electronic balance to accurately weigh the initial mass of the cemented carbide workpiece. After polishing, weigh the workpiece mass again. According to the mass difference, combined with the density of the workpiece material, the material removal volume is calculated by the formula, and then the material removal volume is divided by the polishing time to obtain the material removal rate; the tungsten-cobalt alloys of Examples 9-15, Comparative Examples 1-3, and Comparative Examples 10-15 before and after polishing are tested for material removal rate, and the material removal rates after pre-polishing and fine polishing are tested respectively, and the test results are shown in Table 4.

[0082] Table 4 Material removal rate test of Examples 9-15, Comparative Examples 1-3, Comparative Examples 10-15

[0083]

[0084]

[0085] From the results in Table 4, it can be seen that in Comparative Examples 1-3, the material removal rate of the polished tungsten-cobalt alloy obtained by polishing the tungsten-cobalt alloy without using the step-by-step polishing method is increased, the loss of the alloy material is increased, and the surface roughness is increased, and the overall polishing efficiency of the alloy is reduced; in the mechanical polishing stage, silicon dioxide with different particle sizes is selected as abrasive, and the mechanical grinding effect is enhanced through the synergistic effect of the front and rear large and small particle sizes; at the same time, in the chemical polishing stage, the efficient oxidant and complexing agent in the polishing liquid formula promote the chemical reaction and control the overall material removal rate; in Comparative Examples 10 and 14, the same polishing liquid ratio is used in the pre-polishing stage and the fine polishing stage, which cannot take into account the requirements for abrasive cutting ability and precision at different stages, and all adopt When using coarse-grained abrasives, although the cutting force is strong in the fine polishing stage, it is difficult to accurately remove microscopic protrusions and it is easy to cause surface damage, which cannot meet the high-precision requirements. At the same time, the high removal efficiency further increases the loss of alloy, which is not conducive to industrial use; if fine-grained abrasives are used, in the pre-polishing stage, the cutting ability is insufficient, it is difficult to quickly remove a large amount of processing allowance, prolong the processing time, and reduce the material removal rate; at the same time, sodium dodecyl sulfate is added to the fine polishing liquid to enhance the abrasive dispersion and the affinity of the polishing liquid to the workpiece surface. It can be seen from Example 15 that the reduction in the affinity of the polishing liquid with the polishing pad and the workpiece will further affect the material removal rate, resulting in an increase in the material removal rate in the fine polishing stage; if the same polishing liquid is used, it is impossible to accurately match the different stages. The need for additives: in the pre-polishing stage, the addition of sodium dodecyl sulfate will cause excessive dispersion, resulting in 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 abrasives are easy to agglomerate and cannot act evenly on the workpiece surface, reducing effective cutting sites and excessively reducing the material removal rate; in Examples 11-13, the pH value of the fine polishing liquid is not adjusted, which has a significant impact on the material removal rate and surface roughness of the alloy polishing. The acidity of the solution is enhanced, which inhibits the activity of the high-efficiency catalyst, slows down the chemical reaction rate, and further affects the material removal efficiency. At the same time, the strong acid environment may also cause excessive corrosion on the cemented carbide surface and uneven dissolution, which not only reduces the material removal rate, but also further reduces the material removal rate. step affects the surface roughness; the increase in the alkalinity of the solution will change the performance of sodium dodecyl sulfate, reduce its ability to disperse the abrasive particles and its affinity to the workpiece surface, cause the abrasive particles to agglomerate, and fail to act evenly on the workpiece surface, reduce the effective cutting sites, and reduce the material removal rate. In addition, the alkaline environment will react with certain components in the cemented carbide to form a passivation film that is difficult to remove on the surface, hindering the material removal process and reducing the material removal efficiency; in summary, by using the step-by-step polishing method, coordinating the use of pre-polishing liquid and fine polishing liquid, and optimizing the composition and ratio of different polishing liquids, the material removal rate can be reasonably controlled. If the material removal rate is too high, it may cause excessive damage to the surface, increasing the difficulty of subsequent fine polishing;If it is too low, the previous processing traces cannot be effectively removed, which will also affect the polishing efficiency and reduce production costs. ;

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

[0087] Table 5 Parameter changes of 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, and the differences are shown in Table 6.

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

[0091]

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

[0093] Comparative Example 2 refers to Example 1, but does not use the step-by-step polishing method, and only uses a combination of pre-polishing and fine polishing.

[0094] Comparative Example 3 refers to Example 1, but does not use the step-by-step polishing method, but only uses mechanical polishing.

[0095] Comparative Example 16 refers to Example 1. During the preparation of the fine polishing pad, the polyurethane raw material is not sandblasted.

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

[0097] Comparative Example 18 refers to Example 1, and the fine polishing pad refers to the preparation steps of the pre-polishing pad without being modified with 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 of the secondary polishing are used during the primary polishing and secondary polishing processes.

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

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

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

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

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

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

[0106] Experimental Example 3 Polishing Efficiency Measurement

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

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

[0109]

[0110]

[0111] From the results in Table 7, it can be seen that in Comparative Examples 1-3, the processing method of step-by-step polishing is not adopted. Compared with Example 16, under the same polishing time, the surface roughness of the tungsten-cobalt alloy obtained after polishing is high, the surface uniformity is reduced, and the surface roughness cannot be reduced by extending the polishing time, which further illustrates that the synergistic effect of step-by-step polishing can significantly reduce the surface roughness and improve the polishing efficiency. From the results of Comparative Examples 16-18, it can be seen that in the preparation process of the fine polishing pad, the surface activity of the polyurethane raw material is improved by sandblasting, and the introduction of polar groups is conducive to the further combination of the silica abrasive and the polishing pad polyurethane. At the same time, the secondary curing process can improve the bonding ability and avoid the abrasive from falling off due to friction and wear during the fine polishing process. At the same time, silica abrasives are combined in the polishing pad, and a microporous structure is used inside the polishing pad to achieve a self-dressing function, thereby reducing the content of silica abrasives in the polishing liquid, and reducing the influence of abrasives during fine polishing, which leads to an increase in the surface roughness of the alloy and reduces the polishing efficiency. At the same time, the polishing pad can be reused after dressing, thereby reducing production costs. Comparative Examples 19-20 use the same mechanical polishing parameters, and the polishing efficiency of the alloy is extended. In the first mechanical polishing process, a higher polishing pressure and rotation speed can be used to quickly remove larger protrusions and processing allowances on the surface of the cemented carbide, laying the foundation for subsequent fine processing and greatly shortening the time for removing a large amount of material. During the second mechanical polishing, a small-particle abrasive is used under lower pressure and rotation speed conditions. The polishing liquid abrasives remaining after the previous step are cut and removed, and at the same time, the tiny defects and high-precision requirements are finely processed to prepare for the subsequent fine polishing process, reducing unnecessary repeated processing time and improving the 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 effect on the polishing efficiency. During the pre-polishing process, the appropriate temperature increases the plasticity of the alloy material, which is beneficial to the removal of the material by the abrasive, improves the polishing efficiency, enables the pre-polishing liquid to better play a lubricating and cooling role, reduces the friction between the abrasive tool and the workpiece, and the cutting effect of the abrasive tool is fully exerted at a suitable rotation speed, which can effectively remove most of the excess on the alloy surface, providing a good foundation for fine polishing; During the fine polishing process, the alloy surface has a certain plasticity, which is convenient for the abrasive to remove fine materials, ensuring the precise trimming of the surface microstructure by the abrasive tool. The abrasive tool can not only accurately remove surface micro defects, but also maintain a certain material removal speed, so that the fine polishing process is carried out efficiently and stably, and the fine polishing efficiency is improved; From the results of comparative examples 25-26, it can be seen that adjusting the groove structure of the polishing pad will have a significant adverse effect on the polishing efficiency. A large amount of material needs to be removed in the pre-polishing stage. The deeper grooves can better accommodate the polishing liquid and abrasive chips. At the same time, sufficient polishing liquid supply can ensure the continuous chemical reaction and mechanical action, prevent the abrasive chips from scratching the processed surface for the second time, keep the polishing process smooth, and improve the polishing efficiency;In addition, the deeper grooves can make the contact between the polishing pad and the workpiece surface more elastic and cushioning. During the polishing process, this elastic contact can enable the abrasive to better play a cutting role, which is conducive to removing the larger protrusions and unevenness left on the cemented carbide surface due to the previous processing, speeding up the material removal speed and improving the pre-polishing efficiency; the purpose of fine polishing is to achieve nano-level surface roughness control, which requires more delicate material removal. The shallower grooves can make the polishing pad more closely and evenly contact with the workpiece surface, ensuring that the abrasive acts more evenly and stably on the workpiece surface, which is conducive to accurately removing surface micro-protrusions and reducing surface Roughness, improve the efficiency and quality of fine polishing, and at the same time, the shallow grooves can reduce the flow and disturbance of the polishing liquid during the polishing process, so that the chemical reagents and abrasives in the polishing liquid can act more stably on the workpiece surface, avoiding the residue of abrasives in the fine polishing liquid, resulting in uneven distribution of abrasives, thereby improving the efficiency of fine polishing; In summary, by controlling the polishing pressure and polishing speed during the first mechanical polishing and the second mechanical polishing process, adjusting the parameters of the polishing liquid and the polishing pad during the pre-polishing and fine polishing process, the polishing efficiency is improved under synergistic effect, and the production cost is reduced while improving the production efficiency. ;

[0112] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention 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 comprises the following steps: S1 mechanically polishes the material to be polished by sandpaper to obtain a treated polishing material; S2: immersing the treated polishing material in a pre-polishing liquid, and polishing with a pre-polishing pad to obtain a pre-polishing material; S3: performing secondary mechanical polishing on the pre-polished material using sandpaper to obtain a reprocessed polished material; S4 immersing the reprocessed polishing material in a fine polishing liquid, and polishing with a fine polishing pad to obtain a fine polishing material; S5: washing the fine polishing material with ethanol and rinsing with deionized water to obtain a polishing material; The pre-polishing liquid comprises silicon dioxide abrasive grains, 30% hydrogen peroxide solution and ethylenediamine disuccinic acid; The fine polishing liquid comprises silicon dioxide abrasive grains, sodium lauryl sulfate, phosphate buffer and other additives; The fine polishing pad is prepared by filling modified polyurethane into an aluminum alloy mold; The modified polyurethane comprises polyurethane raw materials, silicon dioxide powder, epoxy resin and additives.

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

3. A high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the pre-polishing liquid comprises the following steps: Deionized water was added into the reaction kettle, and the silicon dioxide abrasive with an average particle size of 50-80 nm was added under stirring, the rotation speed was maintained at 500 rpm, and the mixture was stirred for 40 minutes to obtain a dispersion; the 30% hydrogen peroxide solution was slowly added into the dispersion, the rotation speed was maintained at 20 minutes, and the ethylenediamine disuccinic acid was slowly added, stirred for 40 minutes, and the mixture was evenly mixed to obtain the pre-polishing solution.

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

5. A high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the fine polishing liquid comprises the following steps: Deionized water is added to a reaction kettle, and silicon dioxide abrasive particles with an average particle size of 20-30 nm are added under stirring conditions, the rotation speed is maintained at 500 rpm, and the mixture is stirred for 40 minutes to obtain a dispersion; sodium dodecyl sulfate is slowly added to the dispersion, and the mixture is stirred for 20 minutes; the other additives are added in sequence, and the mixture is stirred for 20 minutes, and the phosphate buffer is added to adjust the pH value to 6-8, and the mixture is uniformly mixed to obtain the fine polishing liquid; The other auxiliary agents include ethylenediaminetetraacetic acid cobalt complex, benzotriazole, polyvinyl alcohol and ethylenediamine disuccinate.

6. A high-precision chemical mechanical polishing method according to claim 1, characterized in that: The preparation of the fine polishing pad comprises the following steps: 100 parts of the silicon dioxide powder and the auxiliary agent are added to a stirrer in sequence, stirred at 100 rpm for 10 minutes, and mixed evenly to obtain a mixed system; 30 parts of the epoxy resin are added to the mixed system, and stirred at 300 rpm for 30 minutes to obtain a slurry; the polyurethane raw material is sandblasted, quartz sand with a particle size of 0.5 mm is selected, the sandblasting pressure is controlled at 0.5 MPa, and the treatment is carried out for 10 minutes to obtain a treated polyurethane; the treated polyurethane is completely immersed in the slurry by dipping, soaked for 10 minutes, and then put into an oven for curing, pre-cured at 80° C. for 1 hour, then heated to 140° C., and cured for 3 hours to obtain the modified polyurethane; the modified polyurethane is molded according to the pre-polishing pad, and the demolding process obtains the fine polishing pad; wherein 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 auxiliary agent includes 10 parts of polyvinyl alcohol, 5 parts of terminal carboxyl nitrile rubber and 5 parts of antioxidant 1010.

7. A high-precision chemical mechanical polishing method according to claim 6, characterized in that: The preparation of the pre-polishing pad comprises the following steps: The aluminum alloy mold is heated to 80° C. in a hot air circulation oven and preheated for 2 hours to obtain a treated mold; an organic silicone release agent is evenly sprayed on the surface of the treated mold, and the spraying thickness is controlled to be 0.1 mm to obtain a filled mold; the polyurethane raw material is slowly poured into the groove cavity of the filled mold, and vacuum-assisted filling is performed, and the pressure is controlled to be -0.08 MPa, and maintained at 2 MPa for 10 minutes, and then added to a hot press, cured at 100° C. for 2 hours, and demolded to obtain the pre-polishing pad; The groove depth of the pre-polishing pad is 0.5-0.8 mm, the groove width is 1.2 mm, and the groove spacing is 5 mm.

8. A high-precision chemical mechanical polishing method according to claim 1, characterized in that: The first polishing pressure is 0.2-0.4MPa; the second polishing pressure is 0.4-0.6MPa; the first polishing rotation speed is 150-250r / min; the second polishing rotation speed is 80-150r / min.

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

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