A rare earth polishing solution for additive manufacturing of AlSi10Mg micro-pipe and a preparation method and application thereof

Abstract

This invention discloses a rare earth polishing slurry for multiphase jet chemical mechanical polishing of microchannels in AlSi10Mg additive manufacturing, its preparation method, and its application. The polishing slurry consists of 800-mesh SiO2 abrasive particles, H2O2 oxidant, CeCl3·7H2O rare earth corrosion inhibitor, Na2CO3 pH adjuster, and deionized water. The mass fraction of SiO2 abrasive particles is 15%-25%, the mass fraction of H2O2 is 1-3%, the concentration of CeCl3·7H2O is 2-4 mM, and the pH value of the polishing slurry is 8-10. Experiments have shown that under the boundary selection conditions of the polishing slurry parameters, the surface roughness Sa after polishing can reach 0.312 μm and 0.298 μm, respectively, with only slight defects on the surface, significantly better than the comparative examples; while under optimized conditions, Sa is as low as 0.257 μm, resulting in a smooth and flat surface. This polishing slurry, through Ce... 3+ / Ce 4+ The selective and strong adsorption of the α-Al phase achieves synergistic and uniform removal of the Al matrix and the eutectic Si phase, and the components are environmentally friendly. This invention can achieve high removal rates and low roughness across a wide parameter window, and is particularly suitable for multiphase jet polishing of micro-channels with large aspect ratios, showing broad prospects for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing slurry technology, specifically to a rare earth polishing slurry for AlSi10Mg additive manufacturing of microchannels, its preparation method, and its application. Background Technology

[0002] AlSi10Mg alloy, with its excellent specific strength, thermal conductivity, and machinability, has become an ideal material for high-performance heat pipes / heat dissipation components in aerospace, electronic heat dissipation, and new energy vehicles. Additive manufacturing (AM), especially laser powder bed melting (LPBF) technology, can produce microchannels with complex internal flow paths (typically with an inner diameter of less than 1 mm and an aspect ratio greater than 100), which is difficult to achieve with traditional processing methods.

[0003] However, the inner wall of AlSi10Mg microchannels formed by LPBF has inherent surface defects, including adhered semi-molten powder, oxide scale, molten pool ripples, and step effects, resulting in a surface roughness (Sa) typically as high as 4-8 μm, which severely affects heat transfer efficiency and fluid transport capacity. Due to the small diameter and large depth-to-diameter ratio of the tubes, traditional methods such as mechanical polishing and abrasive flow machining are difficult to access or cannot achieve uniform polishing along the entire length.

[0004] Chemical mechanical polishing (CMP) is an effective technique for achieving global surface planarization. However, it faces a key challenge when used on AlSi10Mg alloys: this alloy consists of an α-Al matrix with significantly different chemical reactivity and an electrochemically inert eutectic Si phase. In conventional alkaline polishing solutions, the α-Al phase is easily over-corroded, forming corrosion pits, while the Si phase is difficult to remove effectively, leading to the problem of "selective corrosion" and ultimately poor surface quality that fails to meet application requirements.

[0005] In recent years, the use of rare earth cerium salts as corrosion inhibitors for aluminum alloy surface treatment has been studied. However, there are no reports on their application in the CMP process of AlSi10Mg alloys, specifically addressing the challenge of synergistic removal of α-Al and Si phases. Therefore, developing a green and environmentally friendly polishing fluid that can balance the removal rates of both phases and achieve ultra-smooth inner wall polishing has significant industrial value. Summary of the Invention

[0006] The present invention aims to provide a rare earth chemical mechanical polishing slurry for polishing the inner surface of AlSi10Mg micro-channels in additive manufacturing and its preparation method, so as to solve the technical problems of excessive corrosion or residual protrusions caused by the mismatch between the removal rates of Al matrix and Si phase, as well as the uneven surface quality of the pipe with large length-to-diameter ratio throughout the entire length.

[0007] To achieve the above-mentioned technical effects, the present invention provides a rare earth polishing slurry for AlSi10Mg additive manufacturing of micro-channels, characterized in that it comprises abrasive particles, oxidant, pH adjuster, rare earth corrosion inhibitor and deionized water; The abrasive particles are SiO2, and their mass is 15%-25% of the total mass of the polishing slurry. The oxidant is H2O2, and its mass is 1%-3% of the total mass of the polishing solution; The rare earth corrosion inhibitor is CeCl3·7H2O, and its concentration in the polishing solution is 2-4 mM. The pH adjuster is Na2CO3, used to adjust the pH value of the polishing solution to 8-10.

[0008] In this scheme, the concentration of the rare earth corrosion inhibitor CeCl3·7H2O in the polishing solution is 2-4 mM. Within this concentration range, Ce... 3+ It can effectively catalyze the decomposition of H2O2 to produce active oxygen (·OH), accelerating surface oxidation; simultaneously, the Ce(OH)3 generated by hydrolysis and the CeO2 generated by oxidation form a composite protective layer on the Al surface, inhibiting excessive corrosion. Too low a concentration results in insufficient corrosion inhibition, while too high a concentration leads to excessive corrosion. - The increased erosion actually damages the passivation film.

[0009] Furthermore, the SiO2 abrasive particles are 800 mesh, and their mass is 15% of the total mass of the polishing slurry; the mass of the H2O2 is 1% of the total mass of the polishing slurry; the concentration of the CeCl3·7H2O is 2 mM; and the pH value of the polishing slurry is 8.

[0010] Furthermore, the SiO2 abrasive particles are 800 mesh, and their mass is 25% of the total mass of the polishing slurry; the mass of the H2O2 is 3% of the total mass of the polishing slurry; the concentration of the CeCl3·7H2O is 4 mM; and the pH value of the polishing slurry is 10.

[0011] In this scheme, the particle size of the SiO2 abrasive is 800 mesh (about 15-20 μm). This particle size range can maintain stable suspension and conveying performance in micro-channels, while providing sufficient mechanical removal capacity to eliminate molten pool waviness.

[0012] Furthermore, the inner diameter of the microchannel is 0.1-1 mm, and the length-to-diameter ratio is greater than 100.

[0013] This invention also provides a method for preparing a rare earth polishing slurry for AlSi10Mg additive manufacturing of microchannels, characterized by comprising the following steps: S1: Add the SiO2 abrasive particles of the formula amount to deionized water, stir and mix to fully disperse them, prevent the abrasive particles from agglomerating and settling, and obtain an abrasive particle dispersion; S2: Add the prescribed amounts of H2O2 and CeCl3·7H2O sequentially to the abrasive dispersion, and continue stirring and mixing to obtain a mixed solution; S3: Slowly add Na2CO3 to the mixture, adjust the pH to 8-10, and stir evenly to obtain the rare earth polishing solution.

[0014] This preparation method ensures that the polishing slurry maintains stable suspension properties and chemical activity during multiphase jet polishing.

[0015] Furthermore, the stirring time in S1 is 0.5-2 h, and the stirring time in S2 is 0.25-1 h.

[0016] This invention also provides a method for polishing the inner surface of AlSi10Mg additively manufactured microchannels with the aforementioned rare earth polishing slurry, characterized by comprising the following steps: S1: Connect the microchannel to the nozzle of the multiphase jet polishing device; S2: Using the high-speed airflow generated by compressed air, the rare earth polishing liquid is drawn into the nozzle and atomized into micron-sized droplets to form a solid-liquid-gas multiphase jet; S3: The multiphase jet is continuously injected into the inner cavity of the micro-channel to perform chemical mechanical polishing on the inner wall of the channel; During the polishing process, the rare earth polishing fluid is continuously stirred to maintain its uniformity. After polishing is completed, the microchannels are cleaned and dried.

[0017] Furthermore, the pressure of the compressed air is 0.5-0.8 MPa, and the polishing time is 20-40 min.

[0018] Furthermore, the micron-sized droplets have a particle size of 10-100 μm, and the polishing fluid is recycled and reused.

[0019] The present invention also provides the application of the rare earth polishing fluid in the chemical mechanical polishing of the inner surface of AlSi10Mg microchannels in additive manufacturing.

[0020] The technical solution of this invention addresses the challenge of polishing the inner surface of micro-channels (inner diameter 0.1-1 mm, length-to-diameter ratio > 100) manufactured by AlSi10Mg additive manufacturing. This solution employs multiphase jet polishing technology, which uses the siphon principle to draw rare earth polishing fluid into the nozzle at high speed. The fluid is then atomized into micron-sized droplets containing abrasive particles by the atomization structure. The droplets are then delivered into the inside of the channel using 0.7 MPa compressed air, achieving efficient polishing through solid-liquid-gas multiphase flow.

[0021] AlSi10Mg alloy consists of an α-Al matrix and a eutectic Si phase. The two phases have significantly different chemical reactivity, making synergistic removal difficult with traditional polishing slurries. This solution innovatively employs rare-earth cerium salt CeCl3·7H2O as a corrosion inhibitor, utilizing Ce... 3+ / Ce 4+ The selective adsorption characteristics on the Al surface were confirmed by molecular dynamics simulations. The adsorption energies of CeO2 and Ce(OH)3 on the Al surface are significantly higher than those on the Si surface. This allows for the preferential formation of a Ce(OH)3 / CeO2 composite protective layer on the Al matrix surface, preventing excessive corrosion of Al while maintaining the removal activity of the Si phase, thus achieving uniform polishing along the entire length of the microchannel.

[0022] In a weakly alkaline environment, H2O2 has a moderate oxidizing effect on Al and Si, forming a removable oxide layer on the surface without causing excessive corrosion; Na2CO3 acts as a pH buffer to maintain the stability of the polishing slurry; 800-mesh SiO2 abrasive grains provide suitable mechanical removal capabilities in multiphase flow, effectively eliminating molten pool waviness, and the moderate particle size will not cause blockage in micro-channels.

[0023] Ce 3+ Catalyzing the decomposition of H2O2 to generate active oxygen improves oxidation efficiency; CeO2 and Al2O3 form Al-O-Ce bonds to enhance film stability, achieving chemical-mechanical synergistic polishing, and finally obtaining an ultra-smooth inner surface with a roughness of less than 0.3 μm.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: I. This invention constructs a rare earth CMP polishing slurry system for AlSi10Mg additive manufacturing of micro-channels. In the prior art, CeCl3·7H2O is not used as a corrosion inhibitor specifically for AlSi10Mg alloy CMP polishing slurries. Through the synergistic combination of four components, namely SiO2 abrasive particles, H2O2 oxidant, Na2CO3 alkaline environment, and CeCl3·7H2O rare earth corrosion inhibitor, the selective corrosion problem of mismatch between the removal rate of Al matrix and Si phase under this specific scenario is solved.

[0025] Second, this invention, for the first time through quantitative calculations, reveals that the adsorption energies (-35.473 kcal / mol and -8.047 kcal / mol) of CeO2 and Ce(OH)3 generated in the polishing slurry on the α-Al main exposed surface Al(200) are 72.4% and 51.7% higher, respectively, than those on the Si main exposed surface Si(111). Based on the above mechanism, it was found that utilizing Ce... 3+ / Ce 4+ Under alkaline conditions, it preferentially adsorbs onto the Al surface to form a dense protective layer, thereby inhibiting excessive Al corrosion while maintaining effective removal of the Si phase.

[0026] 3. After polishing the inner wall of the additively manufactured AlSi10Mg microchannel for 30 min using the formulation of this invention, the surface quality was significantly improved compared with comparative examples 1-4 (which had obvious corrosion pits or molten pool ripples). The optimal Sa was as low as 0.257 μm, and the Sa was also better than all comparative examples under the boundary conditions of the polishing slurry preparation parameters.

[0027] Fourth, the polishing fluid of the present invention does not contain heavy metals such as chromium and lead, nor strong acids and alkalis, and meets the requirements of green manufacturing; its component design is highly compatible with multiphase jet process, and can achieve uniform polishing throughout the entire length of micro-channels with an aspect ratio >100. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic cross-sectional view of the AlSi10Mg microchannel in an embodiment of the present invention, showing its internal microgroove structure.

[0030] Figure 2 This is a schematic diagram of the multiphase jet chemical mechanical polishing apparatus used in an embodiment of the present invention.

[0031] Figure 3 The images show (a) a white light interferometer surface morphology image and roughness measurement results of the inner wall of the micro-channel after polishing in Embodiment 1 of the present invention, and (b) a scanning electron microscope (SEM) surface morphology image.

[0032] Figure 4 The images show (a) a white light interferometer surface morphology image and roughness measurement results of the inner wall of the micro-channel after polishing in Embodiment 2 of the present invention, and (b) a SEM surface morphology image.

[0033] Figure 5 The images show (a) a white light interferometer surface morphology image and roughness measurement results of the inner wall of the micro-channel after polishing in Embodiment 3 of the present invention, and (b) a SEM surface morphology image.

[0034] Figure 6 The images show (a) a white light interferometer surface morphology image and roughness measurement results of the inner wall of the polished micro-channel in Comparative Example 1 of this invention, and (b) a SEM surface morphology image.

[0035] Figure 7The images shown are (a) white light interferometer surface morphology and roughness measurement results of the inner wall of the polished micro-channel in Comparative Example 2 of this invention, and (b) SEM surface morphology.

[0036] Figure 8 The images shown are (a) white light interferometer surface morphology and roughness measurement results of the inner wall of the polished micro-channel in Comparative Example 3 of this invention, and (b) SEM surface morphology.

[0037] Figure 9 The images shown are (a) white light interferometer surface morphology and roughness measurement results of the inner wall of the polished micro-channel in Comparative Example 4 of this invention, and (b) SEM surface morphology.

[0038] In the attached image: Figure 1 , Figure 2 For illustrative purposes only; where 1, switch; 2, compressed air storage tank; 3, air pipeline; 4, pressure gauge; 5, nozzle; 6, polishing fluid pipeline; 7, connector; 8, micro-pipeline; 9, return fluid box; 10, polishing fluid container; 11, stirrer.

[0039] Figure 3-8 In the image, (a) is a white light interferometer image with the color bar on the right indicating the height, and (b) is a SEM image with a scale bar of 10 μm. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0041] Preparation example: (1) Polishing object All embodiments and comparative examples used AlSi10Mg heat pipes as the polishing object, and the inner wall of the heat pipe had the following characteristics: Figure 1 The microgroove structure shown has a groove width (core width) of less than 1 mm and an aspect ratio of greater than 100.

[0042] (2) Preparation of polishing slurry SiO2 abrasive particles (800 mesh) were added to deionized water and stirred at 600 rpm for 1 hour to ensure thorough dispersion. Then, 30% H2O2 solution (calculated based on the target purity H2O2 mass fraction) and CeCl3·7H2O were added sequentially, and stirring was continued for 30 minutes. Finally, the pH was adjusted to the target value using Na2CO3. The specific formulations of each embodiment and comparative example are shown in Table 1.

[0043] Table 1. Composition of polishing fluid in each embodiment and comparative example.

[0044] Example 1 This embodiment provides a rare earth polishing slurry for AlSi10Mg microchannels, comprising: 800-mesh SiO2 abrasive grains, with a mass fraction of 15% of the total mass of the polishing slurry; 1% pure H2O2 (corresponding to 3.33 wt% of a 30% H2O2 solution); 2 mM CeCl3·7H2O; and the remainder being deionized water; with the pH adjusted to 8 using Na2CO3. After preparing the polishing slurry according to the above method, the inner wall of the AlSi10Mg heat pipe is polished for 30 minutes using a multiphase jet polishing process.

[0045] Before polishing, the inner wall of the microchannel was flushed for 30 seconds with a 20 wt% SiO2 suspension (2000 mesh), followed by ultrasonic cleaning for 5 minutes to remove loose powder and slag from the inner wall. The polishing apparatus is as follows: Figure 2 As shown, the system consists of an air compressor, a drying filter pressure regulator, a siphon nozzle, a connector, a return liquid box, a polishing fluid container, and a stirrer. The working air pressure is limited to 0.7 MPa by the pressure regulator. A micro-channel is connected to the siphon nozzle via a connector whose inner diameter is the same as the inner diameter of the channel to prevent pressure loss. The air compressor provides compressed air, which is then regulated and introduced into the nozzle. Under the action of siphon and high-speed airflow, the polishing fluid is drawn in and atomized, forming a solid-liquid-gas multiphase jet that is continuously sprayed into the inner cavity of the channel. During the polishing process, the stirrer in the polishing fluid container continuously operates to prevent abrasive particle sedimentation. The sprayed polishing fluid is recovered and recycled through the return liquid box. After polishing, the channel is removed, ultrasonically cleaned in deionized water for 5 minutes, dried with high-pressure air, and then surface quality is inspected.

[0046] The polishing results are shown in Table 2. The surface morphology after polishing is as follows: Figure 3 As shown.

[0047] Example 2 This embodiment provides a rare earth polishing slurry for AlSi10Mg microchannels, comprising: 800-mesh SiO2 abrasive grains, with a mass fraction of 25% of the total mass of the polishing slurry; 3% pure H2O2 (corresponding to 10 wt% of a 30% H2O2 solution); a CeCl3·7H2O concentration of 4 mM; and the remainder being deionized water; with the pH adjusted to 10 using Na2CO3. After preparing the polishing slurry using the same method, the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0048] The polishing results are shown in Table 2. The surface morphology after polishing is as follows: Figure 4 As shown.

[0049] Example 3 This embodiment provides a rare earth polishing slurry for AlSi10Mg microchannels, comprising: 800-mesh SiO2 abrasive grains, with a mass fraction of 20% of the total mass of the polishing slurry; 2% pure H2O2 (corresponding to 6.67 wt% of a 30% H2O2 solution); 3 mM CeCl3·7H2O; and the remainder being deionized water; with the pH adjusted to 9 using Na2CO3. After preparing the polishing slurry using the same method, the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0050] The polishing results are shown in Table 2. The surface morphology after polishing is as follows: Figure 5 As shown.

[0051] Comparative Example 1 This comparative example provides a polishing slurry with the following composition: 800-mesh SiO2 abrasive grains, accounting for 20% of the total mass of the polishing slurry; free of H2O2 and CeCl3·7H2O; the balance being deionized water; no Na2CO3 added; and a pH of approximately 7. The same method is followed (skipping H2O). 2、 After preparing the polishing solution (by adding Ce salt and Na2CO3), the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0052] The polishing results are shown in Table 2. The surface morphology after polishing is as follows: Figure 6 As shown in the figure. This comparative example is used to verify that effective chemical-mechanical synergistic polishing cannot be achieved when only SiO2 abrasive particles are present.

[0053] Comparative Example 2 This comparative example provides a polishing slurry with the following composition: 800-mesh SiO2 abrasive grains, with a mass fraction of 20% of the total mass of the polishing slurry; 2% pure H2O2 by mass; free of CeCl3·7H2O; the balance being deionized water; no Na2CO3 added; and a pH of approximately 7. After preparing the polishing slurry using the same method (skipping the Ce salt and Na2CO3 addition steps), the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0054] The polishing results are shown in Table 2. This comparative example forms a comprehensive comparison with Example 3 regarding "the presence or absence of Ce salt and pH adjustment only," demonstrating that simply adding H2O2 cannot achieve good surface quality under conditions of no rare earth corrosion inhibitors and no pH adjustment.

[0055] Comparative Example 3 This comparative example provides a polishing slurry with the following composition: 800-mesh SiO2 abrasive grains, with a mass fraction of 20% of the total mass of the polishing slurry; 2% pure H2O2 by mass; free of CeCl3·7H2O; the balance being deionized water; and pH adjusted to 9 with Na2CO3. After preparing the polishing slurry using the same method (skipping the Ce salt addition step), the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0056] The polishing results are shown in Table 2. This comparative example, compared with Example 3, forms a single-variable comparison of "with or without Ce salt only," demonstrating that under optimal pH conditions, the Al matrix can still undergo excessive corrosion even without Ce salt.

[0057] Comparative Example 4 This comparative example provides a polishing slurry with the following composition: 800-mesh SiO2 abrasive grains, with a mass fraction of 20% of the total mass of the polishing slurry; 2% pure H2O2 by mass; a CeCl3·7H2O concentration of 5 mM; and the balance being deionized water; the pH is adjusted to 9 with Na2CO3. After preparing the polishing slurry using the same method, the inner wall of the AlSi10Mg heat pipe was polished for 30 minutes using the same polishing process as in Example 1.

[0058] The polishing results are shown in Table 2. This comparative example, compared with Example 3, forms a single variable comparison of "Ce salt concentration" to demonstrate that when the CeCl3·7H2O concentration exceeds the range of this invention (2-4 mM), excess Cl... - This can lead to increased surface corrosion and a reversal of the corrosion inhibition effect.

[0059] Test methods, polishing test results and analysis: (1) Test method: Surface roughness (Sa): Measured using a Bruker Contour X-200 white light interferometer, with a measurement area of ​​165 × 138 μm. 2 The data is processed by convolutional high-pass filtering to eliminate the influence of surface curvature.

[0060] Surface morphology: Observed using a FEI NOVA NanoSEM 450 scanning electron microscope.

[0061] Material Removal Rate (MRR): The average mass loss per minute (mg / min) is calculated by measuring the mass difference of the fitting before and after polishing using a high-precision balance and dividing it by the polishing time (30 min).

[0062] Molecular dynamics simulations: Using density functional theory-based software, the adsorption energies of CeO2 and Ce(OH)3 molecules on Al(200) and Si(111) crystal planes were calculated. The adsorption energy E0 adsorption =Etotal -(E surface +E molecule ).

[0063] (2) Polishing test results: The polishing results (material removal rate MRR, surface roughness Sa, and surface quality) of Examples 1-3 and Comparative Examples 1-5 are shown in Table 2, and the corresponding surface morphology photographs are shown in Table 2. Figures 3 to 9 .

[0064] Table 2 Polishing results of each embodiment and comparative example

[0065] (3) Results Analysis Table 2 summarizes the polishing results (MRR, Sa, and surface quality) of each embodiment and comparative example. Corresponding surface morphology photographs are shown below. Figures 3 to 9 The results showed that low surface roughness and high material removal rate could be achieved within the component range defined in this invention. Example 3 (SiO2 20%, H2O 22%, CeCl3·7H2O 3 mM, pH 9) achieved the best surface quality: MRR of 3.66 mg / min, Sa as low as 0.257 μm, and SEM observation showed a smooth and flat surface with almost no defects. Figure 5 ).

[0066] It should be particularly noted that Examples 1 and 2 are located at the lower limit (15% SiO2, 1% H2O, 2 mM CeCl3·7H2O, pH 8) and upper limit (25% SiO2, 3% H2O, 4 mM CeCl3·7H2O, pH 10) of the scope defined by this invention, respectively. Even under these boundary conditions, this invention still exhibits excellent polishing performance. Example 1 (lower limit boundary): MRR was 2.85 mg / min, Sa was 0.312 μm, and only slight molten pool ripples were present on the surface, significantly better than all comparative examples (the Sa of comparative examples 1-3 was all between 0.33-0.34 μm, accompanied by numerous ripples or corrosion pits). This demonstrates that at the lowest abrasive, lowest oxidant, lowest corrosion inhibitor, and alkaline lower limit (pH=8), Ce 3+ / Ce 4+ The selective adsorption of the material can still effectively inhibit the corrosion of the Al matrix, achieving an industrially acceptable smooth surface.

[0067] Example 2 (Upper Limit): MRR reached 4.12 mg / min, while Sa remained at an excellent level of 0.298 μm. Only very slight corrosion traces were observed on the surface, with no pits or obvious ripples. This indicates that the corrosion inhibition mechanism remained stable under conditions of high abrasiveness, high oxidant, high corrosion inhibitor, and strong alkalinity (pH 10), without the problems observed in Comparative Example 4 due to Ce. 3+ Excessively high (5 mM) Cl - The erosion problem was solved, and the highest material removal efficiency was achieved.

[0068] The successful verification of the above boundary conditions fully demonstrates the process robustness of the polishing fluid of the present invention within a wide parameter window, providing a reliable guarantee for adapting to different equipment and batches of materials in industrial production.

[0069] Meanwhile, the core inventiveness of this invention lies in revealing the conditional range of synergistic effects of the components in the polishing slurry, rather than simply providing a single optimal value. This can be clearly demonstrated through a comparison of the proportions and examples: Comparative Example 1 contained only SiO2 abrasive particles but no pH control. The polished inner wall could only remove loose surface material and could not eliminate the inherent molten pool ripples of additive manufacturing, resulting in poor surface quality.

[0070] Comparative Example 2: H2O2 was added but no pH adjustment or corrosion inhibitor was added. Although the MRR of the inner wall was slightly improved after polishing, the chemical action lacked directional guidance and the molten pool ripples were still obvious.

[0071] Comparative Example 3 adjusted the pH to 9 but did not use rare earth corrosion inhibitors. The chemimechanical synergy during the polishing process was improved, but the Al matrix on the inner wall was excessively corroded, forming obvious corrosion pits.

[0072] Comparative Example 4: The rare earth corrosion inhibitor concentration exceeded the range of this invention. The CeCl3·7H2O concentration was set to a high concentration of 5 mM. The excessively high CeCl3·7H2O concentration introduced excess Cl. - This leads to increased surface erosion, which in turn reduces quality.

[0073] The above results indicate that a balance between high MRR and low Sa can only be achieved when SiO2, H2O2, CeCl3·7H2O, and pH are synergistically within the range defined in this invention. In particular, the concentration of CeCl3·7H2O needs to be strictly controlled between 2-4 mM; too low a concentration cannot inhibit corrosion, while above this range, it will lead to corrosion due to Cl... - Side effects worsen the surface.

[0074] The setting of the upper and lower boundaries of the parameters in Examples 1 and 2 demonstrates the practicality of each parameter setting, avoiding the defect of "only effective at the optimal point and ineffective near the boundary". At the same time, the horizontal comparison with Comparative Examples 1-4 proves that only when all components fall within the closed interval defined by this invention can high removal rate and low roughness be obtained simultaneously, and boundary conditions are no exception.

[0075] (4) Mechanism Analysis To clarify Ce 3+ / Ce 4+ To investigate the selective corrosion inhibition mechanism of species during polishing, this study calculated the adsorption energies of CeO2 and Ce(OH)3 on the main constituent phases of AlSi10Mg alloy (typical crystal plane Al(200) of α-Al phase and typical crystal plane Si(111) of eutectic Si phase) using molecular dynamics simulation. The results are shown in Table 3.

[0076] Table 3 Adsorption energies of CeO2 and Ce(OH)3 on Al(200) and Si(111) surfaces

[0077] Based on the results in Table 3, the absolute value of the adsorption energy of CeO2 on the Al(200) surface is 72.42% higher than that on the Si(111) surface, and the absolute value of the adsorption energy of Ce(OH)3 on the Al surface is 51.67% higher than that on the Si surface. These results confirm that the adsorption energy of CeO2 in the polishing solution is higher than that on the Si surface. 3+ / Ce 4+ The species exhibits a significantly stronger adsorption affinity for the α-Al phase, preferentially and stably adsorbing onto the Al matrix surface to form a protective corrosion-inhibiting layer. However, its adsorption of the eutectic Si phase is weaker, allowing for selective removal of the Si phase by abrasive particles and oxidants. This "selective adsorption-differential removal" mechanism achieves synergistic and uniform polishing of the Al matrix and Si phase, avoiding localized over-etching or residual protrusions. This mechanism remains stable within the pH range of 8-10, and Ce... 3+ / Ce 4+ All species can effectively form protective films, providing theoretical support for the effectiveness of boundary conditions.

[0078] In summary, this invention, by limiting the synergistic effect range of SiO2, H2O2, CeCl3·7H2O, and pH, has developed a green rare-earth chemical mechanical polishing slurry suitable for polishing the inner surface of micro-channels in AlSi10Mg additive manufacturing. Within the aforementioned range, the surface roughness after polishing can reach as low as 0.257 μm, resulting in a smooth and flat surface. The boundary conditions also exhibit excellent polishing performance, demonstrating the wide process window and industrial robustness of this invention. Outside this range (e.g., lack of corrosion inhibitors, improper concentration, or pH mismatch), equivalent surface quality cannot be obtained. Mechanistic studies show that CeCl3·7H2O… 3+ / Ce4+ The selective and strong adsorption of species to the α-Al phase is key to achieving uniform polishing. This polishing slurry is environmentally friendly and easy to prepare, making it particularly suitable for multiphase jet polishing of microchannels with large aspect ratios, and it shows significant promise for industrial applications.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rare earth polishing slurry for AlSi10Mg additive manufacturing of microchannels, characterized in that, Including abrasive particles, oxidants, pH adjusters, rare earth corrosion inhibitors, and deionized water; The abrasive particles are SiO2, and their mass is 15%-25% of the total mass of the polishing slurry. The oxidant is H2O2, and its mass is 1%-3% of the total mass of the polishing solution; The rare earth corrosion inhibitor is CeCl3·7H2O, and its concentration in the polishing solution is 2-4 mM. The pH adjuster is Na2CO3, used to adjust the pH value of the polishing solution to 8-10.

2. The rare earth polishing fluid according to claim 1, characterized in that, The SiO2 abrasive particles are 800 mesh, and their mass is 15% of the total mass of the polishing slurry. The mass of the H2O2 is 1% of the total mass of the polishing slurry. The concentration of the CeCl3·7H2O is 2 mM, and the pH value of the polishing slurry is 8.

3. The rare earth polishing fluid according to claim 1, characterized in that, The SiO2 abrasive particles are 800 mesh, and their mass is 25% of the total mass of the polishing slurry. The mass of the H2O2 is 3% of the total mass of the polishing slurry. The concentration of the CeCl3·7H2O is 4 mM, and the pH value of the polishing slurry is 10.

4. The rare earth polishing fluid according to any one of claims 1-3, characterized in that, The inner diameter of the micro-channel is 0.1-1 mm, and the length-to-diameter ratio is greater than 100.

5. A method for preparing a rare earth polishing slurry for AlSi10Mg additive manufacturing of microchannels according to claim 4, characterized in that, Includes the following steps: S1: Add the SiO2 abrasive particles of the formula amount to deionized water, stir and mix to fully disperse them, and obtain the abrasive dispersion; S2: Add the prescribed amounts of H2O2 and CeCl3·7H2O sequentially to the abrasive dispersion, and continue stirring and mixing to obtain a mixed solution; S3: Slowly add Na2CO3 to the mixture, adjust the pH to 8-10, and stir evenly to obtain the rare earth polishing solution.

6. The preparation method according to claim 5, characterized in that, The stirring time in S1 is 0.5-2 h, and the stirring time in S2 is 0.25-1 h.

7. A method for polishing the inner surface of AlSi10Mg additively manufactured microchannels using the rare earth polishing slurry of claim 4, characterized in that, Includes the following steps: S1: Connect the microchannel to the nozzle of the multiphase jet polishing device; S2: Using the high-speed airflow generated by compressed air, the rare earth polishing liquid is drawn into the nozzle and atomized into micron-sized droplets to form a solid-liquid-gas multiphase jet; S3: The multiphase jet is continuously injected into the inner cavity of the micro-channel to perform chemical mechanical polishing on the inner wall of the channel; During the polishing process, the rare earth polishing fluid is continuously stirred to maintain its uniformity. After polishing is completed, the microchannels are cleaned and dried.

8. The polishing method according to claim 7, characterized in that, The pressure of the compressed air is 0.5-0.8 MPa, and the polishing time is 20-40 min.

9. The polishing method according to claim 7, characterized in that, The micron-sized droplets have a particle size of 10-100 μm, and the polishing fluid is recycled and reused.

10. The application of the rare earth polishing slurry according to claim 4 in the chemical mechanical polishing of the inner surface of AlSi10Mg microchannels in additive manufacturing.

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