A method for precision polishing of 3D printing with shape electrode based additive manufacturing metal micro internal runner
By using electrochemical polishing with 3D-printed conformal electrodes, the problems of uneven polishing and microcracks on the inner surface of additively manufactured metal microchannels were solved. This method achieves efficient and precise polishing of the inner and outer surfaces of the microchannels, significantly reducing roughness and improving the performance and stability of the channel components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2023-12-27
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies cannot effectively solve the problems of uneven polishing and microcracks on the inner surface of metal microchannels in additive manufacturing, resulting in high roughness and affecting the performance and stability of the channel components.
Electrochemical conformal polishing is performed using conformal electrodes fabricated based on 3D printing. After initial polishing by surrounding the outer surface with a titanium mesh, the 3D-printed conformal electrodes are replaced for precision polishing within the flow channel. Combined with a peristaltic pump-driven polishing solution and ultrasonic cleaning, efficient polishing of both inner and outer surfaces is achieved.
It significantly reduced the roughness of the inner and outer surfaces of the micro-channel, with the outer surface roughness reduced to Ra≤1.6μm and the inner surface roughness reduced to Ra≤0.6μm, thereby improving the quality uniformity and stability of the channel components.
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Figure CN117773248B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a polishing method for additive manufacturing of metal micro-internal channels. Background Technology
[0002] Flow channel structures are a primary structural type for transferring mass or energy. With increasing demands for lightweighting, mass transfer, and energy exchange efficiency, their structural designs are becoming increasingly complex, making it difficult for traditional processes to meet design requirements. Additive manufacturing technology can be used to solve the manufacturing challenges of complex flow channel structures. Currently, additive manufacturing has made significant progress in materials, processes, and stability; however, the precision finishing technology for internal surfaces remains unresolved, especially for complex micro-flow channels with diameters less than 1 mm. The internal surface is even rougher, with Ra ≥ 15 μm, hindering the smooth flow of fluid and affecting the overall performance and stability of the flow channel components. The polishing technology for micro-flow channels has not been fully resolved and has become a critical technological bottleneck requiring breakthrough. Regarding the problem of rough internal surfaces in additively fabricated micro-flow channels, domestic and international scholars have studied the applicability of current mainstream finishing processes. Machining is mainly used for polishing external surfaces, while abrasive flow and electrochemical polishing can be used for finishing internal flow channels. However, for some complex, small-diameter internal flow channel structures, these methods are not suitable and easily lead to defects such as uneven polishing and microcracks.
[0003] Polishing the inner surface of microchannels has always been a challenging problem in the polishing field, placing even more stringent requirements on the design and manufacturing of polishing electrodes. Conventional flat plate electrodes can no longer meet the requirements for providing rapid and stable transport of electrons, ions, electrolytes, and reaction-evolved gases, thus limiting polishing efficiency and uniformity. Therefore, there is an urgent need to develop special electrodes for polishing inner channels, combining structural design and 3D printing to fabricate specially shaped, high-performance electrodes to achieve conformal precision polishing of microchannels. Summary of the Invention
[0004] The present invention aims to solve the technical problems that the current additive manufacturing process for smoothing the inner surface of metal microchannels is prone to defects such as uneven polishing and microcracks, and provides a conformal precision polishing method for additive manufacturing metal microchannels based on 3D printed conformal electrodes.
[0005] The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes of the present invention is carried out according to the following steps:
[0006] 1. Connect the additively manufactured metal microchannel to the anode of the electrochemical workstation, and connect the titanium mesh to the cathode of the electrochemical workstation; then place the additively manufactured metal microchannel and titanium mesh into an electrolytic cell containing polishing solution, with the titanium mesh arranged in a ring around the periphery of the additively manufactured metal microchannel; start the electrochemical workstation, measure the electrochemical polarization curve of the metal microchannel, and obtain the voltage value corresponding to the limiting current plateau;
[0007] The inner surface of the additively manufactured metal microchannel has a bifurcated and continuously variable cross-section structural feature.
[0008] The surface roughness Ra of the inner surface of the additively manufactured metal microchannel is ≥15μm;
[0009] 2. Polishing of the additively manufactured metal microchannels is performed by applying a constant voltage 10% to 50% higher than the voltage value corresponding to the limiting current platform through an electrochemical workstation. The temperature of the polishing solution is 30℃ to 70℃, the polishing time is 10 min to 40 min, and the polishing solution is stirred by a peristaltic pump with a flow rate of 100 mL / min to 500 mL / min.
[0010] 3. Replace the titanium mesh in step 2 with a conformal electrode prepared by 3D printing. The size of the three-dimensional model of the conformal electrode is proportionally reduced to 70% to 90% of the size of the three-dimensional model of the inner surface of the additively manufactured metal microchannel. The conformal electrode is placed inside the additively manufactured metal microchannel and the axis of the conformal electrode is coincident with the axis of the additively manufactured metal microchannel. Apply a constant voltage of 50% to 80% higher than the voltage value corresponding to the limiting current platform obtained in step 1 to the additively manufactured metal microchannel component after polishing in step 2 using an electrochemical workstation for conformal polishing. The polishing solution is stirred by a peristaltic pump.
[0011] Fourth, the additively manufactured metal microchannel component polished in step three is placed in deionized water for ultrasonic cleaning for 30 to 40 minutes. Then, it is placed in a drying oven and heated at 60 to 80 degrees Celsius for 0.5 to 1 hour to obtain additively manufactured metal microchannels with excellent internal and external surface quality.
[0012] The polishing solution used in steps two and three does not need to be replaced; the polishing solution used in step one can be used instead.
[0013] This invention focuses on additively manufactured metal microchannels and employs 3D-printed conformal electrodes for electrochemical conformal polishing. In step one, a titanium mesh is first arranged in a ring around the periphery of the additively manufactured metal microchannel as a counter electrode. In step two, overvoltage electrochemical polishing is performed at a voltage 10%–50% higher than the limiting current plateau voltage, which can quickly remove protrusions on the outer surface of the microchannel. The overvoltage polishing based on the titanium mesh improves the uniformity of the channel's outer surface, reducing the surface roughness to Ra≤1.6μm. However, the polishing effect on the inner surface of the microchannel is not significant, with a post-polishing inner surface roughness Ra≥5μm. In step three... The titanium mesh electrode was replaced with a 3D-printed conformal electrode, which was then placed inside the additively manufactured metal microchannel and aligned with the channel's axis (this can be achieved by separately limiting and fixing the channel and the conformal electrode's exterior). A small gap was maintained between the conformal electrode and the inner surface of the channel. Then, an overvoltage electrochemical polishing based on the 3D-printed conformal electrode was performed using a voltage 50%–80% higher than the polishing voltage in step one. This resulted in excellent inner and outer surface quality. Compared to the outer surface polished in step two, the roughness was reduced to Ra≤0.6μm, and compared to the inner surface polished in step two, the roughness was reduced to Ra≤0.6μm.
[0014] The polishing method of the present invention is simple and reduces the cycle and cost of surface treatment of the inner and outer surfaces of the metal microchannels in additive manufacturing. Moreover, the roughness of the inner and outer surfaces of the microchannels after polishing is reduced to less than 4% of the initial roughness. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of the additively manufactured metal microchannel in step one of Experiment 1;
[0016] Figure 2 This is a schematic diagram of the conformal electrode material prepared by 3D printing in step three of Experiment 1;
[0017] Figure 3 This is a schematic diagram of placing the 3D-printed conformal electrode material prepared in step three of Experiment 1 inside the additively manufactured metal microchannels.
[0018] Figure 4 A scanning electron microscope image of the morphology of the inner surface of the additively manufactured microchannels in Experiment 1 when no operation was performed;
[0019] Figure 5 This is a scanning electron microscope image of the morphology of the inner surface of the additively manufactured microchannel after polishing in Experiment 1.
[0020] Figure 6 These are scanning electron microscope images of the morphology of the inner surface of the additively manufactured microchannels after polishing in Experiment 2. Detailed Implementation
[0021] Specific Implementation Method 1: This implementation method is a precision polishing method for additive manufacturing of metal micro-internal channels based on 3D printed conformal electrodes, specifically carried out according to the following steps:
[0022] 1. Connect the additively manufactured metal microchannel to the anode of the electrochemical workstation, and connect the titanium mesh to the cathode of the electrochemical workstation; then place the additively manufactured metal microchannel and titanium mesh into an electrolytic cell containing polishing solution, with the titanium mesh arranged in a ring around the periphery of the additively manufactured metal microchannel; start the electrochemical workstation, measure the electrochemical polarization curve of the metal microchannel, and obtain the voltage value corresponding to the limiting current plateau;
[0023] The inner surface of the additively manufactured metal microchannel has a bifurcated and continuously variable cross-section structural feature.
[0024] The surface roughness Ra of the inner surface of the additively manufactured metal microchannel is ≥15μm;
[0025] 2. Polishing of the additively manufactured metal microchannels is performed by applying a constant voltage 10% to 50% higher than the voltage value corresponding to the limiting current platform through an electrochemical workstation. The temperature of the polishing solution is 30℃ to 70℃, the polishing time is 10 min to 40 min, and the polishing solution is stirred by a peristaltic pump with a flow rate of 100 mL / min to 500 mL / min.
[0026] 3. Replace the titanium mesh in step 2 with a conformal electrode prepared by 3D printing. The size of the three-dimensional model of the conformal electrode is proportionally reduced to 70% to 90% of the size of the three-dimensional model of the inner surface of the additively manufactured metal microchannel. The conformal electrode is placed inside the additively manufactured metal microchannel and the axis of the conformal electrode is coincident with the axis of the additively manufactured metal microchannel. Apply a constant voltage of 50% to 80% higher than the voltage value corresponding to the limiting current platform obtained in step 1 to the additively manufactured metal microchannel component after polishing in step 2 using an electrochemical workstation for conformal polishing. The polishing solution is stirred by a peristaltic pump.
[0027] Fourth, the additively manufactured metal microchannel component polished in step three is placed in deionized water for ultrasonic cleaning for 30 to 40 minutes. Then, it is placed in a drying oven and heated at 60 to 80 degrees Celsius for 0.5 to 1 hour to obtain additively manufactured metal microchannels with excellent internal and external surface quality.
[0028] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the additively manufactured metal microchannel component described in step one is made of TC4 titanium alloy, and the corresponding polishing solution is composed of the following volume fractions: 50%–65% perchloric acid, 10%–20% glacial acetic acid, and the remainder is water. Everything else is the same as in Specific Implementation Method One.
[0029] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the material of the additively manufactured metal microchannel component described in step one is 316L stainless steel, and the corresponding polishing solution is composed of the following volume fractions: 30%–50% sulfuric acid, 10%–20% phosphoric acid, and the remainder is water. Everything else is the same as in Specific Implementation Method One or Two.
[0030] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the material of the additively manufactured metal microchannel component described in step one is IN718 nickel-based high-temperature alloy, and the corresponding polishing solution is composed of: 25%–50% sulfuric acid, 15%–25% phosphoric acid, and the remainder is water, by volume. Everything else is the same as in Specific Implementation Methods One to Three.
[0031] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the titanium mesh mentioned in step one is prepared by a titanium wire weaving method, and the diameter of the titanium wire is 50μm to 200μm. Everything else is the same as in Specific Implementation Methods One to Four.
[0032] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the conformal electrode prepared by 3D printing in step three is made of TC4 titanium alloy with a density ≥99% and high conductivity. Everything else is the same as in Specific Implementation Method Five.
[0033] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the conformal electrode prepared by 3D printing in step three is made of IN718 nickel-based high-temperature alloy. A layer of Ni nanowires is then electrochemically deposited on the surface of the conformal electrode, increasing its specific surface area and improving polishing efficiency. Everything else is the same as in Specific Implementation Method Six.
[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the polishing time in step three is 30 to 80 minutes. Everything else is the same as in Specific Implementation Method Seven.
[0035] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the temperature of the polishing solution in step three is 50℃~80℃. Everything else is the same as in Specific Implementation Method Eight.
[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the flow rate of the peristaltic pump in step three is 400 mL / min to 800 mL / min. Everything else is the same as in Specific Implementation Method Nine.
[0037] The invention was verified using the following experiments:
[0038] Experiment 1: This experiment demonstrates a method for precision polishing of metal micro-channels using 3D-printed conformal electrodes in additive manufacturing. The method is carried out as follows:
[0039] 1. Connect the additively manufactured metal microchannel to the anode of the electrochemical workstation, and connect the titanium mesh to the cathode of the electrochemical workstation; then place the additively manufactured metal microchannel and titanium mesh into an electrolytic cell containing polishing solution, with the titanium mesh arranged in a ring around the periphery of the additively manufactured metal microchannel; start the electrochemical workstation, measure the electrochemical polarization curve of the metal microchannel, and obtain the voltage value corresponding to the limiting current plateau;
[0040] The additively manufactured metal microchannel component is made of IN718 nickel-based high-temperature alloy, and the polishing solution is composed of the following by volume: 30% sulfuric acid, 20% phosphoric acid, and the remainder is water.
[0041] The surface roughness Ra of the inner surface of the additively manufactured metal microchannel is ≥15μm;
[0042] The titanium mesh is prepared by a titanium wire weaving method, and the diameter of the titanium wire is 100 μm;
[0043] 2. Polishing of the additively manufactured metal microchannels was performed by applying a constant voltage 10% higher than the voltage value corresponding to the limiting current platform through an electrochemical workstation. The temperature of the polishing solution was 40℃, the polishing time was 30min, and the polishing solution was stirred by a peristaltic pump with a flow rate of 300mL / min.
[0044] 3. Replace the titanium mesh in step 2 with a conformal electrode prepared by 3D printing. The size of the three-dimensional model of the conformal electrode is proportionally reduced to 70% to 90% of the size of the three-dimensional model of the inner surface of the additively manufactured metal microchannel. The conformal electrode is placed inside the additively manufactured metal microchannel and the axis of the conformal electrode coincides with the axis of the additively manufactured metal microchannel. Apply a constant voltage 60% higher than the voltage value corresponding to the limiting current platform obtained in step 1 to the additively manufactured metal microchannel component polished in step 2 using an electrochemical workstation for conformal polishing. The polishing time is 50 min. The polishing solution is stirred by a peristaltic pump with a flow rate of 500 mL / min.
[0045] The conformal electrode material prepared by 3D printing is TC4 titanium alloy;
[0046] Fourth, the additively manufactured metal microchannel component polished in step three is placed in deionized water for ultrasonic cleaning for 30 minutes, and then placed in a drying oven and heated at 70°C for 1 hour to obtain additively manufactured metal microchannels with excellent internal and external surface quality.
[0047] The surface roughness of the inner and outer surfaces of the additively manufactured IN718 microchannels obtained by polishing in Experiment 1 was Ra≤0.6μm.
[0048] Experiment 2: The difference between this experiment and Experiment 1 is that the conformal electrode prepared by 3D printing in step 3 is made of IN718 nickel-based high-temperature alloy, and a layer of Ni nanowires is electrochemically deposited on the surface of the conformal electrode. Everything else is the same as Experiment 1.
[0049] The surface roughness of the inner and outer surfaces of the additively manufactured IN718 microchannels obtained in Experiment 2 is Ra≤0.5μm.
[0050] Figure 1 This is a schematic diagram of the metal microchannel fabricated by additive manufacturing in step one of Experiment 1. As can be seen from the figure, the microchannel has a complex structure with complex features such as bifurcation and continuous variable cross-section.
[0051] Figure 2 This is a schematic diagram of the conformal electrode material prepared by 3D printing in step three of Experiment 1.
[0052] Figure 3 This is a schematic diagram of placing the 3D-printed conformal electrode material prepared in step three of Experiment 1 inside the additively manufactured metal microchannel. 1 is the conformal electrode, and 2 is the micro-additively manufactured metal microchannel. As can be seen from the figure, the conformal electrode and the flow channel are completely matched in terms of direction and shape. The conformal electrode is placed inside the flow channel along the axis of the flow channel, and a small gap is always maintained between it and the inner surface of the flow channel.
[0053] Figure 4 The image shows a scanning electron microscope (SEM) image of the morphology of the inner surface of the additively manufactured microchannel without any operation in Experiment 1. The image shows that the inner surface of the channel is uneven, with obvious steps and randomly distributed adhering particle protrusions, resulting in a rough surface.
[0054] Figure 5 The image shows a scanning electron microscope (SEM) image of the morphology of the inner surface of the additively manufactured microchannel after polishing in Experiment 1. It can be seen that the steps, protrusions and adhered particles on the inner surface have been removed, and the surface roughness has been reduced to Ra of 0.6 μm.
[0055] Figure 6 These are scanning electron microscope (SEM) images of the morphology of the inner surface of the additively manufactured microchannels after polishing in Experiment 2. It can be seen that the inner surface roughness is reduced to Ra of 0.5 μm, compared to... Figure 4It declined further.
Claims
1. A method for additive manufacturing of metal micro-internal channels based on 3D-printed conformal electrodes for precision polishing, characterized in that... The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes is carried out according to the following steps:
1. Connect the additively manufactured metal micro-channel to the anode of the electrochemical workstation and connect the titanium mesh to the cathode of the electrochemical workstation; then place the additively manufactured metal micro-channel and titanium mesh into an electrolytic cell containing polishing solution, with the titanium mesh arranged in a ring around the periphery of the additively manufactured metal micro-channel. Start the electrochemical workstation, measure the electrochemical polarization curve of the metal micro internal flow channel and obtain the voltage value corresponding to the limiting current plateau; The inner surface of the additively manufactured metal micro-internal flow channel has a bifurcated and continuously variable cross-section structural feature. The surface roughness Ra of the inner surface of the additively manufactured metal micro-internal flow channel is ≥15μm; 2. Polishing of the additively manufactured metal micro-internal flow channels is performed by applying a constant voltage 10% to 50% higher than the voltage value corresponding to the limiting current platform through an electrochemical workstation. The temperature of the polishing solution is 30℃ to 70℃, the polishing time is 10 min to 40 min, and the polishing solution is stirred by a peristaltic pump with a flow rate of 100 mL / min to 500 mL / min.
3. Replace the titanium mesh in step 2 with a conformal electrode prepared by 3D printing. The size of the three-dimensional model of the conformal electrode is proportionally reduced to 70%~90% of the size of the three-dimensional model of the inner surface of the additively manufactured metal micro-channel. The conformal electrode is placed inside the additively manufactured metal micro-channel and the axis of the conformal electrode coincides with the axis of the additively manufactured metal micro-channel. Apply a constant voltage of 50%~80% higher than the voltage value corresponding to the limiting current platform obtained in step 1 to the additively manufactured metal micro-channel after polishing in step 2 using an electrochemical workstation for conformal polishing. The polishing solution is stirred by a peristaltic pump. Fourth, the additively manufactured metal micro-internal flow channels polished in step three are placed in deionized water for ultrasonic cleaning for 30-40 minutes. Then, they are placed in a drying oven and heated at 60-80°C for 0.5-1 hour to obtain additively manufactured metal micro-internal flow channels with excellent internal and external surface quality.
2. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The additively manufactured metal micro-internal flow channel described in step one is made of TC4 titanium alloy, and the corresponding polishing solution is composed of the following volume fractions: 50%~65% perchloric acid, 10%~20% glacial acetic acid, and the remainder is water.
3. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The metal micro-internal flow channel manufactured in step one is made of 316L stainless steel, and the corresponding polishing solution is divided into the following components by volume: 30%~50% sulfuric acid, 10%~20% phosphoric acid, and the remainder is water.
4. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The metal micro-internal flow channel manufactured in step one is made of IN718 nickel-based high-temperature alloy, and the corresponding polishing solution is composed of the following by volume: 25%~50% sulfuric acid, 15%~25% phosphoric acid, and the remainder is water.
5. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The titanium mesh mentioned in step one is prepared by a titanium wire weaving method, and the diameter of the titanium wire is 50μm~200μm.
6. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The conformal electrode prepared by 3D printing in step three is made of TC4 titanium alloy with a density ≥99%.
7. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The conformal electrode prepared by 3D printing in step three is made of IN718 nickel-based high-temperature alloy, and a layer of Ni nanowires is electrochemically deposited on the surface of the conformal electrode.
8. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The polishing time in step three is 30 to 80 minutes.
9. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The temperature of the polishing solution in step three is 50℃~80℃.
10. The additive manufacturing method for conformal precision polishing of metal micro-internal channels based on 3D printed conformal electrodes according to claim 1, characterized in that... The flow rate of the peristaltic pump in step three is 400 mL / min to 800 mL / min.