A polishing liquid for metal surface treatment and a preparation process thereof

Abstract

This invention discloses a polishing slurry for metal surface treatment and its preparation process, relating to the field of metal polishing agent technology. The polishing slurry raw material composition includes hexagonal flake α-alumina, nano-cerium oxide, hydroxyethylidene diphosphonic acid, potassium sodium tartrate, urea peroxide, boron nitride nanosheets, polyethylene glycol, sodium tetraborate, and deionized water. The preparation process includes two-dimensional lubricant pre-dispersion, composite abrasive slurry preparation, accelerator-oxidant mixed solution preparation, and mixing and filtration steps. This invention constructs a catalytic oxidation system using nano-cerium oxide and urea peroxide, uses hydroxyethylidene diphosphonic acid and potassium sodium tartrate as a complexing agent, and uses boron nitride nanosheets as an auxiliary lubricating component. Under weakly alkaline conditions, it achieves highly efficient polishing of titanium alloys, aluminum alloys, and dissimilar metal materials, exhibiting high removal rate, good surface smoothness, balanced removal rate of dissimilar metals, and excellent storage stability.

Description

Technical Field

[0001] This invention relates to the field of metal polishing agent technology, specifically to a polishing liquid for metal surface treatment and its preparation process. Background Technology

[0002] With the rapid development of consumer electronics, aerospace, and medical devices, titanium alloys, aluminum alloys, and dissimilar metal materials are widely used due to their excellent mechanical properties and functional characteristics. These applications place extremely high demands on the surface quality of the metals, typically requiring a mirror-like finish with nanoscale surface roughness and no scratches or corrosion defects.

[0003] Chemical mechanical polishing (CMP) is currently the primary method for achieving global planarization of metallic materials. Existing metal polishing slurries can be mainly classified into acidic polishing slurries, oxidizing polishing slurries, and neutral emulsion polishing slurries. Acidic polishing slurries typically use a strong acid system combined with an oxidizing agent to achieve chemical corrosion of the metal surface, but they suffer from severe corrosion of the polishing machine and difficulty in waste liquid treatment. Oxidizing polishing slurries often use liquid oxidizing agents such as hydrogen peroxide, but they are prone to decomposition during storage and use, leading to concentration fluctuations. Furthermore, they exhibit varying selectivity in oxidizing different metal components in titanium alloys, such as aluminum and vanadium, easily resulting in surface defects such as orange peel and pitting. While neutral emulsion polishing slurries reduce corrosion to the machine, they contain water-insoluble oily waxes, increasing the difficulty of subsequent cleaning processes, and they easily generate large amounts of foam during recycling, affecting normal production.

[0004] To address the aforementioned issues, several patent documents have proposed improvement solutions. For example, patent document CN116590711B discloses a polishing slurry for chemical mechanical polishing of palladium and copper, using nanodiamond as an abrasive to remove the inert metal palladium. However, this solution relies entirely on the ultra-hard properties of diamond for mechanical removal without adding an oxidizing agent, resulting in a low material removal rate. Furthermore, the extremely high hardness of diamond abrasives makes it prone to embedding into the metal surface when polishing softer copper materials, causing subsurface damage and affecting device performance.

[0005] Patent document CN114525512A discloses a recyclable titanium alloy mirror polishing slurry that uses reducing acids (such as phosphorous acid or hypophosphite) as reaction promoters. Hydrogen atoms diffuse into the titanium lattice to generate hydrides, thereby destroying the surface oxide film. However, this method may pose a risk of hydrogen embrittlement, as hydrogen atoms may diffuse into the titanium alloy matrix, leading to a reduction in workpiece fatigue life. This presents a safety hazard for applications with extremely high reliability requirements, such as aerospace or medical devices.

[0006] Patent document CN115198276B discloses a polishing slurry for treating titanium alloys, which uses a titanate coupling agent to modify alumina abrasives and adds strong oxidants such as persulfate and organic co-oxidants. However, this solution has chemical compatibility issues between components: the titanate coupling agent is easily hydrolyzed and degraded in aqueous systems; persulfate, as a strong oxidant, coexists with organic polymers in the system, which can easily trigger unintended oxidative degradation reactions, leading to component failure and system aging; at the same time, the micron-sized alumina abrasives require extremely strict control over particle size distribution when pursuing nanoscale surface roughness.

[0007] Patent document CN120682724B discloses a polishing composition for fine polishing of aluminum alloy surfaces, using a compound of perfluoropolyether, coconut oil alkanolamide, and sodium dodecylbenzenesulfonate as a surfactant, and copovidone and ammonium persulfate as corrosion inhibitors. However, in this scheme, the strong oxidant ammonium persulfate and the organic polymer copovidone are premixed, and an oxidative degradation reaction may occur between the two, leading to the failure of the corrosion inhibitor component; at the same time, the presence of a high concentration of electrolyte poses a challenge to the colloidal stability of silica sol, easily causing abrasive agglomeration and sedimentation.

[0008] In summary, the existing technology still faces the following technical challenges: first, how to ensure a high removal rate while avoiding damage to the metal substrate (including the risk of hydrogen embrittlement and subsurface damage); second, how to achieve stable coexistence of oxidants and organic components to prevent system aging and failure; and third, how to achieve simultaneous removal of different metal components (such as aluminum and vanadium in titanium alloys, or palladium-copper heterometals) to avoid step defects caused by selective corrosion. Therefore, developing a polishing slurry that combines high-efficiency removal, low damage, long lifespan, and applicability to various metal materials is of significant practical importance. Summary of the Invention

[0009] The purpose of this invention is to provide a polishing slurry for metal surface treatment and its preparation process. By constructing a multi-component synergistic system of rare earth catalytic oxidation, organophosphonic acid complexation and two-dimensional material-assisted lubrication, a high-efficiency, low-damage polishing slurry suitable for various metal substrates (including titanium alloys, aluminum alloys and palladium-copper alloys) is prepared, so as to solve the problems in the background art that single abrasives are prone to causing subsurface damage, strong oxidants and organic components have poor compatibility, and the polishing rate selectivity of heterogeneous metal materials is large.

[0010] In a first aspect, the present invention provides a polishing liquid for metal surface treatment, comprising the following raw materials in parts by weight: 5-15 parts of hexagonal plate-shaped α-alumina; 0.5-3 parts of nano-cerium oxide; 2-8 parts of hydroxyethylidene diphosphonic acid; 1-5 parts of potassium sodium tartrate; 3-10 parts of urea peroxide; 0.1-1 part of boron nitride nanosheets; 1-4 parts of polyethylene glycol; 0.5-2 parts of sodium tetraborate; 60-85 parts deionized water.

[0011] As a preferred embodiment of the present invention, the boron nitride nanosheets have a diameter of 100-500 nm and a thickness of 1-5 nm, and are a few-layer structure with fewer than 10 layers.

[0012] As a preferred embodiment of the present invention, the mass ratio of nano-cerium oxide, hydroxyethylidene diphosphonic acid and potassium sodium tartrate is (0.5-3):(2-8):2.

[0013] As a preferred embodiment of the present invention, the mass ratio of hydroxyethylidene diphosphonic acid to potassium sodium tartrate is adjusted according to the type of metal to be processed, depending on the different metal materials. For titanium alloy materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (2.5-4):1; For aluminum alloy materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1-1.5):1; For heterometallic materials containing palladium and copper, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1.2-2):1.

[0014] As a further preferred technical solution of the present invention, when the polishing liquid is applicable to multiple metal materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1.5-2.5):1.

[0015] As a preferred embodiment of the present invention, the nano-cerium oxide has a particle size of 30-80 nm, is cubic in phase, and has a purity greater than 99.9%.

[0016] As a preferred embodiment of the present invention, the hexagonal plate-like α-alumina has a particle size of 0.8-1.5 μm, a diameter-to-thickness ratio greater than 20:1, and a purity greater than 99.8%.

[0017] As a preferred embodiment of the present invention, the urea peroxide is in the form of a crystalline powder with an active oxygen content of not less than 16%.

[0018] As a preferred embodiment of the present invention, the pH value of the polishing solution is maintained at 7.5-8.5 using sodium tetraborate.

[0019] A second aspect of the present invention provides a process for preparing a polishing slurry for metal surface treatment, comprising the following steps: S1. Weigh out the boron nitride nanosheets and polyethylene glycol according to the formula, add 10-15% of deionized water according to the total formula, and use ultrasonic dispersion treatment for 20-40 min, controlling the temperature of the dispersion to not exceed 40℃, to obtain a two-dimensional lubricant pre-dispersion of boron nitride nanosheets. S2. Add the remaining deionized water in the formula to the stirred reactor. Under stirring conditions of 100-200 r / min, slowly add hexagonal sheet α-alumina and nano-cerium oxide in sequence and stir for 10-20 min. Then add the boron nitride nanosheet two-dimensional lubricant pre-dispersion liquid prepared in step S1 and continue stirring for 15-30 min to obtain the composite abrasive slurry. S3. In another container, add a small amount of deionized water and heat to 30-35℃. Then, add hydroxyethylidene diphosphonic acid, potassium sodium tartrate, and sodium tetraborate in sequence and stir until completely dissolved to obtain a clear solution. After the solution cools to room temperature, slowly add urea peroxide and stir until completely dissolved to obtain a mixed solution of accelerator and oxidant. S4. Add the accelerator-oxidant mixed solution prepared in step S3 to the composite abrasive slurry prepared in step S2 while stirring at a speed of 100-150 r / min. After the addition is complete, increase the stirring speed to 250-300 r / min and continue stirring for 30-50 min. Let it stand to defoam and then filter it through a filter screen to obtain the polishing liquid for metal surface treatment.

[0020] It should be noted that the hexagonal lamellar α-alumina in the polishing slurry serves as the primary abrasive. Its lamellar structure generates directional micro-cutting during polishing, primarily responsible for the removal of the bulk material. Nano-cerium oxide in the polishing slurry is further processed via Ce... 3 + / Ce 4+The redox cycle catalyzes the decomposition of urea peroxide to produce hydrogen peroxide, generating highly reactive oxygen species. These reactive oxygen species can efficiently oxidize metal surfaces, forming a uniform oxide layer, creating conditions for subsequent mechanical removal. Hydroxyethylidene diphosphonic acid (HEDDI) and potassium sodium tartrate are used as composite complexing agents. HEDDI exhibits strong complexing ability for high-valence metal ions such as titanium and iron ions, while potassium sodium tartrate shows good complexing effect for variable-valence metal ions such as copper, aluminum, and vanadium oxide ions. The combined use of these two agents can promptly complex and dissolve the oxidized metal ions from the surface into the solution phase, preventing hydrolysis and redeposition. Simultaneously, HEDDI molecules can form a chemical adsorption film on the fresh metal surface through phosphonate groups, providing passivation protection. Boron nitride nanosheets, with their layered structure and low coefficient of friction, fill the space between abrasive particles and the workpiece surface during polishing, converting some sliding friction into rolling friction, thus providing auxiliary lubrication and reducing frictional heat. Polyethylene glycol acts as a dispersant to assist in the uniform dispersion of boron nitride nanosheets and simultaneously adjusts the rheological properties of the polishing fluid. Sodium tetraborate acts as a pH buffer, maintaining the polishing slurry in a weakly alkaline range. This ensures the dispersion stability of the silicon-aluminum abrasive while preventing excessive corrosion of the metal matrix by strong alkalinity. Urea peroxide is introduced in solid crystalline form, slowly decomposing in water to release hydrogen peroxide, providing a stable and long-lasting oxidant source and avoiding concentration fluctuations caused by the rapid decomposition of liquid hydrogen peroxide. When this polishing slurry is applied, under polishing pressure, the abrasive particles contact the workpiece surface, and the chemical components act simultaneously on the surface. Multiple processes—oxidation, complexation, mechanical removal, and lubrication protection—cooperate synergistically, achieving efficient material removal and the formation of a smooth surface. For titanium alloys, aluminum alloys, and dissimilar metals containing palladium and copper, this system can adjust the removal rate of different metals by adjusting the complexing agent ratio, avoiding step effects or selective corrosion caused by differences in electrochemical properties, resulting in a polished surface with good smoothness and uniformity.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a catalytic oxidation system constructed by nano-cerium oxide and urea peroxide to catalyze the generation of highly active oxygen species under weakly alkaline conditions, thereby achieving uniform oxidation of the metal surface and avoiding the risk of overall corrosion of the substrate by strong acids and bases. At the same time, the slow decomposition characteristics of solid urea peroxide ensure the long-term stability of the oxidation process and overcome the limitations of liquid oxidant concentration fluctuation and poor storage stability.

[0022] (2) In this invention, hydroxyethylidene diphosphonic acid and potassium sodium tartrate are combined as complexing agents. The former has a strong complexing ability for high-valence metal ions, while the latter has an excellent complexing effect on variable-valence metal ions. The synergistic effect of the two can dissolve and remove oxidation products from the surface in time, preventing hydrolysis and redeposition. At the same time, hydroxyethylidene diphosphonic acid can form a chemical adsorption film on the fresh surface, which also has a passivation protection function, simplifying the formulation system.

[0023] (3) The present invention introduces boron nitride nanosheets as an auxiliary lubricating component. Its layered structure forms a rolling lubrication effect between the abrasive and the workpiece interface, effectively reducing the risk of frictional heat and mechanical scratches. Combined with the directional micro-cutting effect of hexagonal α-alumina, it significantly improves the smoothness of the polished surface while ensuring the material removal efficiency.

[0024] (4) By adjusting the ratio of composite complexing agent, the present invention can balance the removal rate of different metal components in titanium alloy, aluminum alloy and palladium copper alloy, effectively suppress the step effect or selective corrosion caused by differences in electrochemical properties, and broaden the applicability of polishing liquid to different metal materials. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0026] A polishing liquid for metal surface treatment comprises the following raw materials in parts by weight: 10 parts of hexagonal plate-shaped α-alumina; 1.8 parts of nano-cerium oxide; 5 parts of hydroxyethylidene diphosphonic acid; 3 parts of potassium sodium tartrate; 6.5 parts of urea peroxide; 0.55 parts of boron nitride nanosheets; 2.5 parts polyethylene glycol; 1.2 parts sodium tetraborate; 75 parts of deionized water.

[0027] The preparation process of a polishing slurry for metal surface treatment is as follows: S1. Weigh 0.55 parts of boron nitride nanosheets and 2.5 parts of polyethylene glycol, add 11 parts of deionized water (accounting for 15% of the total formula), and use ultrasonic dispersion treatment for 30 min (power 300W, ultrasonic 3s interval 2s), control the temperature of the dispersion to not exceed 40℃, and obtain a two-dimensional lubricant pre-dispersion of boron nitride nanosheets. S2. Add the remaining 64 parts of deionized water to the stirred reactor. Under stirring at 150 r / min, slowly add 10 parts of hexagonal sheet α-alumina and 1.8 parts of nano-cerium oxide in sequence and stir for 15 min. Then add the boron nitride nanosheet pre-dispersion liquid prepared in step S1 and continue stirring for 20 min to obtain the composite abrasive slurry. S3. In another container, add 5 parts of deionized water and heat to 32°C. Then, add 5 parts of hydroxyethylidene diphosphonic acid, 3 parts of potassium sodium tartrate, and 1.2 parts of sodium tetraborate in sequence. Stir until completely dissolved to obtain a clear solution. After the solution cools to room temperature, slowly add 6.5 parts of urea peroxide and stir until completely dissolved to obtain a mixed solution of accelerator and oxidant. S4. The accelerator-oxidant mixed solution prepared in step S3 is slowly added to the composite abrasive slurry prepared in step S2 while stirring at 120 r / min. After the addition is complete, the stirring speed is increased to 280 r / min, and stirring is continued for 40 min. After standing to defoam for 60 min, the slurry is filtered through a 300-mesh stainless steel filter and a 5 μm polypropylene filter to obtain a polishing solution for metal surface treatment. The pH value of the polishing solution was measured to be 8.1. Example

[0028] A polishing liquid for metal surface treatment comprises the following raw materials in parts by weight: Five parts of hexagonal plate-shaped α-alumina; 0.5 parts of nano-cerium oxide; 2 parts of hydroxyethylidene diphosphonic acid; 1 part of potassium sodium tartrate; 3 parts of carbamate peroxide; 0.1 parts of boron nitride nanosheets; 1 part polyethylene glycol; 0.5 parts of sodium tetraborate; 60 parts of deionized water.

[0029] The preparation process is the same as in Example 1.

[0030] The pH value of the polishing solution was measured to be 7.6. Example

[0031] A polishing liquid for metal surface treatment comprises the following raw materials in parts by weight: 15 parts of hexagonal plate-shaped α-alumina; 3 parts of nano-cerium oxide; 8 parts of hydroxyethylidene diphosphonic acid; 5 parts of potassium sodium tartrate; 10 parts of urea peroxide; One part of boron nitride nanosheets; 4 parts polyethylene glycol; Two parts of sodium tetraborate; 85 parts of deionized water.

[0032] The preparation process is the same as in Example 1.

[0033] The pH value of the polishing solution was measured to be 8.4.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that boron nitride nanosheets were not added, but were replaced with an equal mass of hexagonal sheet-like α-alumina (i.e., the amount of hexagonal sheet-like α-alumina was adjusted to 10.55 parts).

[0035] The remaining components and preparation process are consistent with those in Example 1.

[0036] Comparative Example 2 The difference between this comparative example and Example 1 is that hydroxyethylidene diphosphonic acid was not added; instead, an equal mass of potassium sodium tartrate was added.

[0037] The remaining components and preparation process are consistent with those in Example 1.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that potassium sodium tartrate was not added; instead, an equal mass of hydroxyethylidene diphosphonic acid was added.

[0039] The remaining components and preparation process are consistent with those in Example 1.

[0040] Comparative Example 4 The difference between this comparative example and Example 1 is that urea peroxide was not added; instead, an equal mass of nano-cerium oxide was added.

[0041] The remaining components and preparation process are consistent with those in Example 1.

[0042] Comparative Example 5 The difference between this comparative example and Example 1 is that urea peroxide was not added; instead, an equal mass of hydrogen peroxide was added (based on the equivalent of 6.5 parts of urea peroxide to hydrogen peroxide, the active oxygen content of urea peroxide is 16.5%, which is equivalent to approximately 3.6 parts of hydrogen peroxide, and approximately 12 parts of 30% concentration hydrogen peroxide was used). To maintain consistent timing of oxidant addition, in step S3, hydrogen peroxide was mixed with the solution prepared in step S3 containing hydroxyethylidene diphosphonic acid, potassium sodium tartrate, and sodium tetraborate.

[0043] The remaining components and preparation process are consistent with those in Example 1.

[0044] Comparative Example 6 The difference between this comparative example and Example 1 is that nano-cerium oxide was not added; instead, an equal mass of urea peroxide was added.

[0045] test: I. Polishing Performance Test (Surface Roughness and Material Removal Rate) A polishing test platform was used to test TC4 titanium alloy specimens (20mm × 20mm) of uniform specifications. Polishing parameters were: polishing pressure 2 psi, polishing disc rotation speed 70 rpm, polishing fluid flow rate 3 mL / min, and polishing time 30 min. Surface roughness Ra before and after polishing was measured using a 3D confocal microscope, and the material removal rate was calculated using a precision balance weighing method (gravimetric method, accuracy 0.01 mg). Each sample was tested three times, and the average value was taken.

[0046] II. Selectivity Test for Foreign Metal Removal Rate Patterned wafer fabrication technology was used to prepare heterogeneous metal test patterns with alternating palladium (Pd) and copper (Cu) films on the same substrate, with a film thickness of 1 μm. Polishing was performed using the polishing solutions from the examples and comparative examples, with the same polishing parameters. A profilometer was used to measure the changes in Pd and Cu film thicknesses before and after polishing, and the removal rates of both were calculated. The selectivity ratio was calculated as the Pd removal rate / Cu removal rate; a ratio closer to 1 indicates more uniform heterogeneous metal removal.

[0047] III. Evaluation of Surface Scratches The surface of the polished TC4 titanium alloy specimen was observed using a metallographic microscope (magnification 100×). Ten fields of view were randomly selected, and the number of micro-scratches with a length greater than 10μm within each field of view was counted. The average scratch density per square centimeter was calculated.

[0048] IV. Polishing slurry storage stability test Following the dispersion stability test method in GB / T 5559-2010, the polishing solution was placed in a transparent glass reagent bottle and stored at a constant temperature of 25℃ for 30 days. The sedimentation at the bottom of the bottle was observed. If there was no obvious stratification or sedimentation, it was considered stable; if there was slight stratification that could be recovered by shaking, it was considered slight sedimentation; and if there was obvious irreversible sedimentation, it was considered sedimentation. The pH change of the polishing solution before and after storage was also measured.

[0049] V. Evaluation of Metal Corrosion Inhibition Effect (Electrochemical Testing) A three-electrode electrochemical workstation was used, with TC4 titanium alloy as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum electrode as the auxiliary electrode. After immersion in the polishing solutions of the examples and comparative examples for 30 min, the potentiodynamic polarization curves were measured, with a scan range of -0.5 V to +0.5 V (relative to open circuit potential) and a scan rate of 1 mV / s. The corrosion current density (Icorr) was calculated using the Tafel extrapolation method; a lower corrosion current density indicates a better corrosion inhibition effect on the metal substrate.

[0050] VI. Summary of Results Table 1

[0051] VII. Discussion of Results As shown in Table 1, the polishing slurries for metal surface treatment prepared in Examples 1-3 of this invention exhibit excellent comprehensive performance. Regarding polishing effect, the surface roughness of the titanium alloys treated in Examples 1-3 is all below 1.5 nm, and the material removal rate is maintained between 248-312 nm / min, demonstrating a good balance between polishing efficiency and surface quality. In terms of heterogeneous metal processing capability, the Pd / Cu removal selectivity ratios in Examples 1-3 are all within the range of 0.95-1.03, close to the ideal value of 1.0, indicating that the polishing slurry can achieve simultaneous removal of different metal components and effectively suppress the step effect. Regarding surface integrity, the scratch density in Examples 1-3 is all below 2 scratches / cm². 2 The results were superior to those of the comparative examples. Storage stability tests showed that Examples 1-3 maintained a uniform dispersion state after 30 days of standing, and electrochemical tests indicated that the corrosion current density of Examples 1-3 remained at 0.4 μA / cm². 2 The left and right sides demonstrate a good corrosion inhibition effect.

[0052] The synergistic effect of the complexing agents can be analyzed from the test results of Comparative Example 2 and Comparative Example 3.

[0053] In Comparative Example 2, when potassium sodium tartrate was used alone as a complexing agent, the Pd / Cu removal selectivity ratio was 1.42, far deviating from the ideal value of 1.0, and the surface roughness increased to 2.45 nm. In Comparative Example 3, when hydroxyethylidene diphosphonic acid (HEDDI) was used alone as a complexing agent, the Pd / Cu removal selectivity ratio was 1.38, and the surface roughness was 2.38 nm. Both alone were difficult to effectively balance the removal rates of palladium and copper, leading to a step effect between the dissimilar metals. In contrast, in Example 1, after combining the two, the selectivity ratio was optimized to 0.98, and the surface roughness decreased to 1.12 nm, indicating that HEDDI and potassium sodium tartrate have a superior synergistic effect in complexing metal ions of different valence states. HEDDI exhibits strong complexing ability for high-valence titanium and iron ions, while potassium sodium tartrate has excellent complexing effect for variable-valence copper and aluminum ions. The combined use of the two can cover a wider range of metal ions, achieving simultaneous removal of dissimilar metals.

[0054] The synergistic effect of the catalytic oxidation system can be systematically analyzed from the test results of Comparative Examples 4, 5, and 6.

[0055] In Comparative Example 4, when no urea peroxide was added and only the amount of nano-cerium oxide was increased, the material removal rate dropped to 156 nm / min due to the lack of oxidant source, indicating that nano-cerium oxide particles alone cannot effectively oxidize the metal surface.

[0056] In Comparative Example 5, when hydrogen peroxide was used instead of urea peroxide, the removal rate increased to 241 nm / min, which was better than Comparative Examples 4 and 6, but still lower than Example 1; the surface roughness was 2.41 nm, and the scratch density was 3.7 scratches / cm. 2 The Pd / Cu removal selectivity ratio was 1.09, which was inferior to that of Example 1. This indicates that although the presence of nano-cerium oxide provides some catalytic effect, liquid hydrogen peroxide is prone to decomposition during storage and use, leading to concentration fluctuations and failing to achieve stable and slow release of hydrogen peroxide like solid urea peroxide. The rapid decomposition of hydrogen peroxide causes a decrease in the effective concentration of the oxidant and results in uneven local oxidation reaction intensity, affecting the stability of the polishing process and the uniformity of surface quality. Comparative Example 5 showed slight precipitation after 30 days of storage, further confirming the negative impact of liquid hydrogen peroxide on system stability—its decomposition products or the side reactions they trigger may disrupt the colloidal balance of the polishing solution.

[0057] In Comparative Example 6, without the addition of nano-cerium oxide and only by increasing the amount of urea peroxide, the removal rate was slightly improved to 172 nm / min, but still far lower than that of Example 1, and the surface roughness increased to 2.63 nm. This indicates that in the absence of nano-cerium oxide catalysis, the decomposition efficiency of hydrogen peroxide generated by the decomposition of urea peroxide is low, and it cannot be efficiently converted into hydroxyl radicals with strong oxidizing power, resulting in insufficient oxidation efficiency.

[0058] In contrast, in Example 1, nano-cerium oxide and urea peroxide were used in combination. Urea peroxide slowly decomposed in solid crystalline form to release hydrogen peroxide, which continuously generated hydroxyl radicals under the catalytic action of nano-cerium oxide, achieving uniform oxidation of the metal surface and increasing the removal rate to 285 nm / min, thus improving surface quality. Comparisons 4, 5, and 6 with Examples 1-3 confirmed the synergistic effect of the catalytic oxidation system constructed by nano-cerium oxide and urea peroxide: nano-cerium oxide provides catalytic active sites, while urea peroxide provides a stable and persistent source of hydrogen peroxide; both are indispensable.

[0059] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the scope defined by the invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A polishing liquid for metal surface treatment, characterized by: Including the following parts by weight of raw materials: 5-15 parts of hexagonal plate-shaped α-alumina; 0.5-3 parts of nano-cerium oxide; 2-8 parts of hydroxyethylidene diphosphonic acid; 1-5 parts of potassium sodium tartrate; 3-10 parts of urea peroxide; 0.1-1 part of boron nitride nanosheets; 1-4 parts of polyethylene glycol; 0.5-2 parts of sodium tetraborate; 60-85 parts deionized water.

2. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The boron nitride nanosheets have a diameter of 100-500 nm and a thickness of 1-5 nm, and are a few-layer structure with fewer than 10 layers.

3. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The mass ratio of nano-cerium oxide, hydroxyethylidene diphosphonic acid, and potassium sodium tartrate is (0.5-3):(2-8):

2.

4. The polishing slurry for metal surface treatment according to claim 3, characterized in that: The mass ratio of hydroxyethylidene diphosphonic acid to potassium sodium tartrate is adjusted according to the type of metal to be processed, depending on the specific metal material being processed. For titanium alloy materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (2.5-4):1; For aluminum alloy materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1-1.5):1; For heterometallic materials containing palladium and copper, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1.2-2):

1.

5. The polishing slurry for metal surface treatment according to claim 3, characterized in that: When the polishing slurry is suitable for multiple metal materials, the mass ratio of the hydroxyethylidene diphosphonic acid to potassium sodium tartrate is (1.5-2.5):

1.

6. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The nano-cerium oxide has a particle size of 30-80 nm, is cubic in phase, and has a purity greater than 99.9%.

7. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The hexagonal plate-shaped α-alumina has a particle size of 0.8-1.5 μm, an aspect ratio greater than 20:1, and a purity greater than 99.8%.

8. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The urea peroxide is in crystalline powder form, with an active oxygen content of not less than 16%.

9. The polishing slurry for metal surface treatment according to claim 1, characterized in that: The pH of the polishing solution is maintained at 7.5-8.5 using sodium tetraborate.

10. A process for preparing a polishing slurry for metal surface treatment as described in any one of claims 1-9, characterized in that: The preparation steps include the following: S1. Weigh out the boron nitride nanosheets and polyethylene glycol according to the formula, add 10-15% of deionized water according to the total formula, and use ultrasonic dispersion treatment for 20-40 min, controlling the temperature of the dispersion to not exceed 40℃, to obtain a two-dimensional lubricant pre-dispersion of boron nitride nanosheets. S2. Add the remaining deionized water in the formula to the stirred reactor. Under the stirring condition of 100-200 r / min, add hexagonal sheet α-alumina and nano-cerium oxide in sequence and stir for 10-20 min. Then add the boron nitride nanosheet two-dimensional lubricant pre-dispersion liquid prepared in step S1 and continue stirring for 15-30 min to obtain composite abrasive slurry. S3. In another container, add deionized water and heat to 30-35℃. Then add hydroxyethylidene diphosphonic acid, potassium sodium tartrate, and sodium tetraborate in sequence and stir until completely dissolved to obtain a clear solution. After the solution cools to room temperature, add urea peroxide and stir until completely dissolved to obtain a mixed solution of accelerator and oxidant. S4. Add the accelerator-oxidant mixed solution prepared in step S3 to the composite abrasive slurry prepared in step S2 while stirring at a speed of 100-150 r / min. After the addition is complete, increase the stirring speed to 250-300 r / min and continue stirring for 30-50 min. Let it stand to defoam and then filter it through a filter screen to obtain the polishing liquid for metal surface treatment.

Images