Pulse electrochemical etching method for nickel-based superalloy core plate micro-channel

Abstract

The invention discloses a pulse electrochemical etching method for a nickel-based high-temperature alloy core plate micro-channel, and belongs to the technical field of metal microstructure manufacturing and surface processing. According to the method, the pattern windowing of the anti-corrosion layer is adopted to limit the forming area, pulse electrochemical selective dissolution is implemented under the conditions of flat plate opposite arrangement and slit flowing liquid supply, the electrolyte is compounded through a sulfuric acid system to improve the conductivity and wetting bubble removal capacity, and the lateral dissolution tendency is weakened in cooperation with the lateral corrosion inhibiting additive; meanwhile, efficient removal and morphology correction are taken into consideration through segmented excitation of rough etching and fine etching of asymmetric bipolar pulses, so that the micro-channel machining efficiency, stability and section rectangularity are synchronously improved under the condition that electrolyte is not replaced; and stable amplification of the process of the core boards with different sizes can be realized through parameterized control of the current density and the flow per unit area, so that the problems that the lateral erosion tendency is large, the section rectangularity is difficult to guarantee, the dissolution stability is insufficient, the efficiency and the morphology are difficult to consider and the like in the existing processing method are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of metal microstructure manufacturing and surface processing technology, and relates to a pulsed electrochemical etching method for microchannels of nickel-based high-temperature alloy core plates. In particular, it relates to a method for forming nickel-based high-temperature alloy microchannels for printed circuit heat exchanger (PCHE) core plates, specifically a processing method that forms windowed patterns by mask exposure and development and combines pulsed electrochemical etching. Background Technology

[0002] Printed circuit heat exchangers (PCHEs) are widely used in high-temperature gas-cooled reactors, supercritical CO2 cycles, aerospace, and high-end energy equipment due to their advantages such as large heat exchange area per unit volume, high temperature and high pressure resistance, and compact structure. One of the key manufacturing steps of PCHEs is the processing and forming of the core plate microchannels. Common microchannel cross-sections tend to be rectangular, the groove width is usually in the sub-millimeter to millimeter range, and the depth can reach about 1 mm. High requirements are placed on the perpendicularity of the sidewalls, side erosion, and surface morphology.

[0003] In existing technologies, microchannels in nickel-based superalloy core plates are often processed using methods such as chemical etching or chemical milling. However, chemical etching typically exhibits isotropic dissolution characteristics, easily leading to significant lateral dissolution. This results in a decrease in the rectangularity of the microchannel cross-section and an increase in the taper of the sidewalls, thereby affecting the diffusion bonding area and the flow consistency within the heat exchanger. Simultaneously, passivation films or corrosion product films easily form on the surface of nickel-based superalloys, and the dissolution rate fluctuates significantly during chemical etching, making it difficult to balance processing efficiency and morphology control. Furthermore, simply using DC electrochemical dissolution may also cause processing instability or morphology defects due to bubble coverage, product film accumulation, and uneven local current density.

[0004] Therefore, there is an urgent need for an electrochemical etching process suitable for nickel-based superalloy PCHE core plates that can ensure high removal efficiency, suppress side etching and improve cross-sectional rectangularity through electrical parameter control, and has a simple process chain that is easy to implement in engineering. Summary of the Invention

[0005] The present invention aims to provide an electrochemical etching method for microchannels of nickel-based high-temperature alloy core plates, in order to solve the problems of large lateral etching tendency, difficulty in ensuring cross-sectional rectangularity, insufficient dissolution stability, and difficulty in balancing efficiency and morphology in existing processing methods.

[0006] To solve the above-mentioned technical problems or achieve the purpose of this invention, the technical solution of this invention is as follows:

[0007] An electrochemical etching method for microchannels in a nickel-based superalloy core plate includes the following steps:

[0008] S1: Pretreatment: The surface of the nickel-based high-temperature alloy core plate is pretreated by successively undergoing alkaline washing, degreasing, acid washing, ultrapure water washing and drying.

[0009] S2: Glue application: Apply anti-corrosion ink to the surface of the core board and dry it until it sets;

[0010] S3: Mask design: Design the mask, draw the mask pattern, and then print out the film negative to obtain the film mask;

[0011] S4: Exposure: Place the film negative on the surface of the core board resist ink and align it, then place it in a UV exposure machine for exposure;

[0012] S5: Development: The exposed core board is placed in an alkaline developing solution for development, which dissolves the resist ink layer in the unexposed areas and retains the resist ink layer in the exposed areas, forming a microchannel pattern window area.

[0013] S6: Pulse Electrochemical Etching: The core board that has undergone development and windowing treatment is used as the anode and is parallelly clamped with a stable cathode plate in an acidic electrolyte. An asymmetric bipolar pulse power supply is applied under the condition of circulating acidic electrolyte to selectively anoly dissolve and shape the windowed area. The etching process is divided into a rough etching section and a fine etching section. The rough etching section is used to improve the removal efficiency per unit area to obtain 75%~95% of the target depth. The fine etching section suppresses side etching and improves the cross-sectional rectangularity by increasing the pulse frequency and shortening the positive pulse width.

[0014] S7: Demolding: After etching, the core board is immersed in alkaline demolding solution to remove the resist layer, then pickled to neutralize the residual alkaline substances, thoroughly cleaned with ultrapure water, and finally dried.

[0015] S8: Inspection: Use a two-dimensional measuring instrument or contour / microscopic measurement method to inspect the appearance and microchannel dimensions of the core board after film removal. After passing the inspection, package, store or ship.

[0016] Preferably, in step S2, the anti-corrosion ink film layer is attached to the core board, the film layer thickness is 40μm~60μm, the thickness uniformity is -5%~5%, and the film layer adhesion force is ≥25N / cm.

[0017] Preferably, the ultraviolet exposure energy in step S4 is 100 mJ / cm². 2 ~200mJ / cm 2 The exposure time is 40s~50s.

[0018] Preferably, in step S5, the developing temperature is 40℃~45℃ and the developing time is 3min~10min.

[0019] Preferably, in step S6, the coarse etching section and the fine etching section use the same acidic electrolyte; the acidic electrolyte is a sulfuric acid-based compound conductive electrolyte, comprising: 5.0wt%~30.0wt% sulfuric acid, preferably 10.0wt%~25.0wt%, to provide an acidic environment and enhance the anodic dissolution and removal capacity; and 2.0wt%~12.0wt% conductive salt, preferably 4.0wt%~8.0wt%, to improve the electrolyte conductivity and stabilize the current distribution. Sodium sulfate and / or sodium nitrate; an additive for wetting, defoaming, and inhibiting lateral corrosion at a concentration of 0.05 g / L to 10 g / L, wherein the additive is selected from one or more of benzotriazole, 2-mercaptobenzimidazole, polyethylene glycol, polyvinylpyrrolidone, and sodium dodecyl sulfate; a complexing agent for complexing metal ions and inhibiting secondary deposition at a concentration of 2 g / L to 3 g / L, wherein the complexing agent is selected from one or more of sodium citrate, sodium tartrate, disodium ethylenediaminetetraacetate, and sodium gluconate; and ultrapure water as the solvent.

[0020] Preferably, the electrode spacing between the anode core plate and the cathode plate in step S6 is 0.5mm to 1.6mm, and more preferably 0.5mm to 1.6mm.

[0021] Preferably, in step S6, the acidic electrolyte flows in a circulating manner to form a narrow slit between the electrodes, and the electrolyte flow rate per unit effective etching area is 0.005 L / (min·cm). 2 0.3 L / (min·cm) 2 The preferred concentration is 0.01 L / (min·cm). 2 )~0.05L / (min·cm 2 Furthermore, the average flow velocity within the slit is 0.1 m / s to 5 m / s, preferably 0.8 m / s to 2 m / s.

[0022] Preferably, the roughing stage in step S6 employs asymmetric bipolar pulses for anodic dissolution, satisfying the asymmetric condition of strong forward pulses and weak reverse pulses: forward peak voltage U + The voltage range is 12V~18V, with a reverse peak voltage U. - The voltage range is 1.2V to 3.0V, and U + >U - Pulse frequency The pulse width is 0.8kHz to 1.0kHz; the positive pulse width t on+ The pulse duration is 350μs~600μs, and the reverse pulse width is t. on- The duration is 40μs~60μs and t on+ >t on- The average current density j per unit effective etching area in the rough etching section avg 10A / cm 2 ~25A / cm 2 .

[0023] Preferably, in step S6, the fine etching section is performed under the same electrolyte conditions as the rough etching section, using asymmetric bipolar pulses for shaping and etching, satisfying the asymmetric condition of strong positive pulse and weak reverse pulse: positive peak voltage U ' + The voltage range is 6V~9V, with a reverse peak voltage U. ' + The voltage range is 0.8V to 2.0V, and U ' + >U ' - Pulse frequency 10kHz~18kHz; positive pulse width t ' on+ The pulse width is 10μs~20μs, and the reverse pulse width is t. ' on- The duration is 5μs~10μs and t ' on+ >t ' on- The average current density j per unit effective etching area in the fine etching section ' avg 3A / cm 2 ~12A / cm 2 .

[0024] Preferably, the above steps are controlled by parameters such as current density per unit area and electrolyte flow rate per unit area, thereby achieving stable scale-up of the microchannel etching process for core boards of different sizes.

[0025] The electrochemical etching is carried out in an acidic compound electrolyte composed of sulfuric acid, sodium sulfate, and sodium nitrate, with the potential addition of additives such as benzotriazole, 2-mercaptobenzimidazole, polyethylene glycol, polyvinylpyrrolidone, and sodium dodecyl sulfate, as well as complexing agents. Sulfuric acid provides a stable acidic environment, allowing the nickel-based superalloy to undergo sustained dissolution under anodic conditions. Sodium sulfate and sodium nitrate, as conductive salts, increase the solution conductivity and reduce the inter-electrode ohmic voltage drop, resulting in a more uniform current distribution in the windowed area, thereby reducing localized over-etching and morphological fluctuations. Polyethylene glycol, polyvinylpyrrolidone, and sodium dodecyl sulfate improve wetting and defoaming, reducing the adhesion and shielding effects of bubbles in slits and sidewalls, and promoting the timely removal of reaction products. Benzotriazole and 2-mercaptobenzimidazole form a weak adsorption inhibition layer on the metal surface, inhibiting lateral dissolution in mass-limited areas such as sidewalls. Complexing agents are used to complex metal ions and stabilize the solution system, reducing secondary deposition and interfacial fluctuations, thereby improving etching precision and surface quality. All of the above components are aqueous systems, and additives that do not swell in the resist ink layer are selected to ensure that the resist layer maintains the integrity of the pattern in an acidic environment.

[0026] After being exposed by a mask and developed to form a windowed pattern, the core plate serves as the anode, which is clamped parallel to the acid-resistant conductive plate cathode. The electrolyte flows in a circulating manner, forming a slit between the electrodes and continuously renewing itself. This slit flow rapidly removes metal ions, bubbles, and heat generated during dissolution, weakening concentration polarization and local shielding effects, thus stabilizing the composition and mass transfer conditions in the electrochemical reaction zone and ensuring the consistency of the microchannel along its length. During etching, an asymmetric bipolar pulse excitation is applied. The positive pulse acts as the main excitation, driving anodic dissolution in the windowed area to remove material. The reverse pulse acts as an auxiliary excitation, periodically conditioning the interface state and weakening the interference of the product film and bubbles on the current, thereby improving processing stability and reducing the tendency for lateral etching. Under the same electrolyte conditions, etching is divided into a coarse etching section and a fine etching section. The coarse etching section focuses on higher removal efficiency to quickly obtain the main depth, while the fine etching section, by changing the pulse modulation method, makes the dissolution more localized and uniform, strengthening longitudinal shaping, suppressing lateral dissolution, and improving the sidewall morphology and cross-sectional rectangularity. By combining electrolyte formulation with pulse excitation for coordinated control, this invention achieves a balance between efficiency and morphology without replacing the electrolyte, and can achieve stable scale-up processing of core boards of different sizes by controlling the current density and flow rate per unit area.

[0027] Compared with existing technologies, this invention uses a patterned window to define the forming area of ​​the resist layer, and performs pulsed electrochemical selective dissolution under the conditions of flat plate opposition and slit flow liquid supply. It improves conductivity and wetting and defoaming capabilities by using a sulfuric acid system compounded electrolyte, and reduces the tendency of lateral dissolution by using additives to inhibit lateral corrosion. At the same time, it uses asymmetric bipolar pulses to stimulate coarse and fine etching in stages, achieving both efficient removal and morphology correction. Thus, it achieves simultaneous improvement in microchannel processing efficiency, stability and cross-sectional rectangularity without changing the electrolyte. Furthermore, it can achieve stable scale-up of core board processes of different sizes through parameterized control of current density and flow rate per unit area. Overall, it is superior to existing technologies in terms of processing accuracy, efficiency and process applicability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process flow for the microchannel pulse electrochemical etching method for nickel-based high-temperature alloy core plates of the present invention.

[0029] Figure 2 A schematic diagram of the experimental setup for the pulsed electrochemical etching method of the present invention is shown; wherein: 1 is the liquid inlet pipe, 2 is the acidic stirring device, 3 is the nickel-based high-temperature alloy core plate, 4 is the inert conductive cathode, 5 is the liquid outlet pipe, 6 is the temperature control device, 7 is the asymmetric bipolar pulse power supply, and 8 is the electrolytic cell.

[0030] Figure 3 The pulse control parameters for the rough etching section and the fine etching section in Example 1 are shown; where (a) is the waveform of the rough etching section and (b) is the waveform of the fine etching section. Detailed Implementation

[0031] This invention provides a pulsed electrochemical etching method for microchannels in a nickel-based high-temperature alloy core plate, the process flow of which is as follows: Figure 1 As shown, the process includes, in sequence, core board pretreatment, resist ink coating and shaping, microchannel mask design and plate making, ultraviolet exposure, development to form the windowed area, pulsed electrochemical etching, demolding and cleaning, and dimensional inspection and quality judgment. The pulsed electrochemical etching step employs a combination of coarse and fine etching stages. First, the windowed area is rapidly removed and shaped, then the sidewalls are reshaped to suppress side etching, thereby achieving efficient microchannel forming and high-precision control.

[0032] The experimental setup for the pulsed electrochemical etching method of this invention is as follows: Figure 2 As shown, the device includes an electrolytic cell 8, an asymmetric bipolar pulse power supply 7, and a flow and temperature control system. The flow and temperature control system includes an inlet pipe 1, an outlet pipe 5, an acidic stirring device 2, and a temperature control device 6. A nickel-based high-temperature alloy core plate 3 serves as the anode, and an inert conductive material serves as the inert conductive cathode 4. These two are arranged in parallel opposite positions and are both immersed in a sulfuric acid-based composite H2SO4-Na2SO4 / NaNO3 conductive electrolyte. The electrolyte circulates through the inlet pipe 1 and the outlet pipe 5 to ensure timely removal of reaction products and stable renewal of interfacial conditions. The acidic stirring device 2 stirs the electrolyte, promoting the timely removal of reaction products and bubbles from the electrode surface, thus improving mass transfer efficiency and processing stability. Simultaneously, the temperature control device 6 maintains temperature stability during the electrolysis process. The asymmetric bipolar pulse power supply 7 applies an asymmetric bipolar pulse signal to the anode and the inert conductive cathode 4, causing the windowed area to undergo rapid removal and sidewall shaping in sequence under the conditions of coarse etching and fine etching, thereby realizing the selective anodic dissolution and shaping of the microchannel.

[0033] This invention discloses an electrochemical etching method for nickel-based high-temperature alloy microchannels for PCHE core plates of printed circuit heat exchangers. The method defines the forming area by patterning windows in the resist layer, applies an asymmetric bipolar pulse power supply under the conditions of flat plate opposition and electrolyte slit flow, and performs selective anodic dissolution forming on the windowed area. The etching process is divided into a coarse etching section and a fine etching section to balance removal efficiency and morphology correction, thereby improving the rectangularity of the microchannel cross-section, reducing the tendency of lateral etching, and improving processing consistency and stability.

[0034] The concentrated sulfuric acid used in the following examples has a mass fraction of 98 wt%, with the molecular formula H₂SO₄. It is a colorless or slightly yellow oily liquid at room temperature and is highly corrosive. Sodium sulfate has the molecular formula Na₂SO₄. It is a white crystalline powder or powder at room temperature and is readily soluble in water. Sodium nitrate has the molecular formula NaNO₃. It is a colorless or white crystalline solid at room temperature and is readily soluble in water. Benzotriazole has the molecular formula C₆H₅N₃. It is a white to pale yellow crystalline powder at room temperature, which dissolves in water to form a clear solution. 2-Mercaptobenzimidazole has the molecular formula C₇H₆N₂S. It is a white or pale yellow crystalline powder at room temperature. Polyethylene glycol is HO-(CH₂CH₂O). n -H (PEG, a colorless to pale yellow viscous liquid or waxy solid at room temperature, varying with molecular weight), is highly water-soluble; the molecular formula of polyvinylpyrrolidone is (C6H9NO). n It is a white to pale yellow powder or granules at room temperature and is highly water-soluble; sodium dodecyl sulfate has the molecular formula C2. 12 H 25 SO4Na, a white granular or powdered substance at room temperature, is readily soluble in water and acts as a surfactant to improve wetting and promote bubble desorption. The complexing agent can be disodium ethylenediaminetetraacetate (EDTA-2Na) and / or citric acid (C6H8O7) and its salts, all of which are commercially available water-soluble reagents. In each embodiment, the acidic electrolyte is prepared by diluting the above-mentioned concentrated sulfuric acid according to the specified ratio, and then compounded with sodium sulfate, sodium nitrate, and additives to form a sulfuric acid-based compound electrolyte, used for electrochemical selective dissolution and shaping without causing swelling or loss of adhesion of the resist ink layer. The typical composition range of the nickel-based high-temperature alloy core plate base material is as follows: nickel (Ni) 50%~60%, chromium (Cr) 20%~23%, cobalt (Co) 10%~15%, molybdenum (Mo) 8%~10%, aluminum (Al) 1.0%~1.5%, iron (Fe) 4.0%~5.0%, titanium (Ti) 0.2%~1.0%, carbon (C) 0.1%~0.2%, silicon (Si) 0.2%~0.5%, and manganese (Mn) 0.5%~1.0%. The base material is forged and then processed into a plate using a composite rolling process, with a final plate thickness of approximately 2 mm.

[0035] This invention uses a flat plate electrode made of a conductive material that exhibits electrochemical stability in acidic electrolytes as the cathode. The cathode maintains electrochemical inertness under acidic electrolyte and asymmetric bipolar pulse conditions, exhibiting no significant dissolution or participation in the reaction during electrode reactions, thereby providing a stable current circuit. Cathode materials used in this invention include graphite plates, titanium plates, titanium-based coated electrodes, or stainless steel plates. The following embodiments use a titanium plate as an example for specific illustration.

[0036] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0037] Example 1:

[0038] This embodiment provides a pulsed electrochemical etching method for microchannels in a nickel-based high-temperature alloy core plate, including the following steps:

[0039] S1: Pretreatment. The surface of the nickel-based high-temperature alloy core plate undergoes pretreatment in sequence, including alkaline washing, electrolytic degreasing, acid washing, ultrapure water washing, and drying, to remove various impurities, oil stains, and oxide layers from the core plate surface.

[0040] S2: Coating. The resist ink is coated onto the core board surface using a roller coating method and then dried for setting. The drying temperature is 55℃, and the drying time is 40 minutes. After setting, the ink film thickness is 50μm, the thickness uniformity is -5%~5%, and the film adhesion is ≥25N / cm. The resist ink is a commercially available conventional electrochemical etching resist ink, which needs to form a stable resist mask after exposure and development, and remain intact without significant swelling or peeling under subsequent acidic electrolyte and pulsed electrochemical etching conditions.

[0041] S3: Mask Design. The microchannel mask pattern was drawn using CAD and output as a film to obtain the film mask. The microchannel diameter was set to 0.5mm, the groove width to 1mm, and the diameter compensation value to +0.05mm. The mask pattern was inspected and found to be free of broken lines, burrs, and obvious jagged edges.

[0042] S4: Exposure. The film is attached to the surface of the resist ink and aligned before UV exposure. UV exposure energy: 150 mJ / cm². 2 Exposure time: 40 seconds.

[0043] S5: Development. The exposed core board is placed in an alkaline developer to develop and form windowed areas. The developer used is 20g / L sodium carbonate, the development temperature is 45℃, and the development time is 3min. After development, it is thoroughly rinsed with ultrapure water and dried.

[0044] S6: Pulse Electrochemical Etching. The developed and windowed core board serves as the anode, and a conductive material plate with electrochemical stability in the acidic electrolyte serves as the cathode, both mounted in parallel. An asymmetric bipolar pulsed power supply is applied under circulating acidic electrolyte conditions to selectively anolyze and shape the windowed area. The electrode spacing between the anode and cathode is 1.0 mm. The acidic electrolyte circulation creates a narrow slit flow between the electrodes, with an electrolyte flow rate of 0.015 L / (min·cm) per unit effective etching area. 2 The average flow velocity inside the slit is 0.8 m / s.

[0045] In step S6, the coarse etching section and the fine etching section use the same acidic electrolyte. The acidic electrolyte is a sulfuric acid-based composite conductive electrolyte, with ultrapure water as the solvent. The sulfuric acid is prepared using concentrated sulfuric acid with a mass fraction of 98 wt%, resulting in a sulfuric acid mass fraction of 15.0 wt% in the electrolyte. The conductive salt is used to improve the conductivity of the electrolyte and help stabilize the current distribution; the total mass fraction of the conductive salt is 8.0 wt%, of which sodium sulfate and sodium nitrate account for 4.0 wt%. The additive is used for wetting, defoaming, and inhibiting lateral corrosion. In this embodiment, the total amount of additive is 2.7 g / L, specifically: benzotriazole 1.0 g / L, 2-mercaptobenzimidazole 0.5 g / L, polyethylene glycol 0.5 g / L, polyvinylpyrrolidone 0.5 g / L, and sodium dodecyl sulfate 0.2 g / L. The complexing agent is used to complex metal ions and help inhibit secondary deposition; sodium citrate is selected as the complexing agent, and its dosage is 2.0 g / L.

[0046] The etching process is divided into a rough etching stage and a fine etching stage, and the switching control is performed under the same electrolyte conditions (e.g.) Figure 3 (As shown). The rough-cut section employs asymmetric bipolar pulse anodic dissolution, with a positive peak voltage U. + The reverse peak voltage is 14V. - The voltage is 1.5V; the pulse frequency f is 1.0kHz; the positive pulse width t is 1.5V. on+ The pulse width is 500 μs, and the reverse pulse width is t. on- The current density per unit effective etching area in the rough etching section is 50 μs; j is 50 μs. avg 15A / cm 2 After the rough etching stage reaches approximately 85% of the target depth, the fine etching stage begins. The fine etching stage employs asymmetric bipolar pulse etching for shaping, with a positive peak voltage U... ' + It is 7V, and the reverse peak voltage U ' - 1.0V; pulse frequency 15kHz; positive pulse width t ' on+ The pulse width is 15 μs, and the reverse pulse width is t. ' on-The average current density j per unit effective etching area in the fine etching section is 5 μs. ' avg 5A / cm 2 .

[0047] S7: Demolding. After etching, the core board is immersed in an alkaline release solution to remove the resist layer. The release solution is an 8 wt% sodium hydroxide aqueous solution at 70°C for 30 minutes. After demolding, it is rinsed with ultrapure water and then acid-washed with a 5 wt% sulfuric acid aqueous solution for 60 seconds to neutralize residual alkaline substances. Finally, it is thoroughly rinsed with ultrapure water and dried.

[0048] S8: Inspection. A 2D measuring instrument and profilometer are used to inspect the appearance and microchannel dimensions of the core board after film removal. Inspection results show that the average etching rate per unit depth in the coarse etching section is approximately 0.026 mm / s, the average etching rate per unit depth in the fine etching section is approximately 0.009 mm / s, and the overall average etching rate is 0.02 mm / s. The microchannel etching depth is 1.00 mm; the microchannel diameter is 0.50 mm, and the groove width is 1.00 mm; the single-sided lateral etching depth is ≤30 μm. After passing inspection, the core board is packaged, stored, or shipped.

[0049] This embodiment employs a moderate electrolyte strength and slit circulation renewal capability to maintain a relatively balanced anodic dissolution and product discharge. Simultaneously, through segmented pulse control of the coarse and fine etching sections, the main depth is obtained quickly first, and then lateral expansion and edge over-etching are suppressed, thereby achieving a good balance between efficiency and sidewall quality.

[0050] Example 2:

[0051] S1: Pretreatment. The surface of the nickel-based high-temperature alloy core plate is pretreated by successively undergoing alkaline washing, degreasing, acid washing, ultrapure water washing, and drying to remove impurities, oil stains, and oxide layers from the core plate surface.

[0052] S2: Coating. The resist ink is coated onto the core board surface using a roller coating method and then dried for setting. The drying temperature is 55℃, and the drying time is 40 minutes. After setting, the ink film thickness is 50μm, the thickness uniformity is -5%~5%, and the film adhesion is ≥25N / cm. The resist ink is a commercially available conventional electrochemical etching resist ink, which only needs to form a stable resist mask after exposure and development, and remain intact without significant swelling or peeling under subsequent acidic electrolyte and pulsed electrochemical etching conditions.

[0053] S3: Mask Design. The microchannel mask pattern was drawn using CAD and output as a film to obtain the film mask. The microchannel diameter was set to 0.5mm, the groove width to 1mm, and the diameter compensation value to +0.05mm. The mask pattern was inspected and found to be free of broken lines, burrs, and obvious jagged edges.

[0054] S4: Exposure. The film is attached to the surface of the resist ink and aligned before UV exposure. UV exposure energy: 180 mJ / cm². 2 Exposure time: 45 seconds.

[0055] S5: Development. The exposed core board is placed in an alkaline developer to develop and form windowed areas. The developer used is 20g / L sodium carbonate, the development temperature is 45℃, and the development time is 3min. After development, it is thoroughly rinsed with ultrapure water and dried.

[0056] S6: Pulse Electrochemical Etching. The developed and windowed core board serves as the anode, and a conductive material plate with electrochemical stability in the acidic electrolyte serves as the cathode, both mounted in parallel. An asymmetric bipolar pulsed power supply is applied under circulating acidic electrolyte conditions to selectively anolyze and shape the windowed area. The electrode spacing between the anode and cathode is 0.5 mm. The acidic electrolyte circulation creates a narrow slit flow between the electrodes, with an electrolyte flow rate of 0.005 L / (min·cm) per unit effective etching area. 2 The average flow velocity inside the slit is 2.0 m / s.

[0057] In step S6, the coarse etching section and the fine etching section use the same acidic electrolyte. The acidic electrolyte is a sulfuric acid-based composite conductive electrolyte, with ultrapure water as the solvent. The sulfuric acid is prepared using concentrated sulfuric acid with a mass fraction of 98 wt%, resulting in a sulfuric acid mass fraction of 30.0 wt% in the electrolyte. The conductive salt is used to improve the conductivity of the electrolyte and help stabilize the current distribution; the total mass fraction of the conductive salt is 6.0 wt%, of which sodium sulfate accounts for 4.0 wt% and sodium nitrate accounts for 2.0 wt%. The additive is used for wetting, defoaming, and inhibiting lateral corrosion. In this embodiment, the total amount of additive is 2.7 g / L, specifically: benzotriazole 1.0 g / L, 2-mercaptobenzimidazole 0.5 g / L, polyethylene glycol 0.5 g / L, polyvinylpyrrolidone 0.5 g / L, and sodium dodecyl sulfate 0.2 g / L. The complexing agent is used to complex metal ions and help inhibit secondary deposition; the complexing agent is sodium citrate, and its dosage is 2.0 g / L.

[0058] The etching process is divided into a rough etching stage and a fine etching stage, and the switching between them is controlled under the same electrolyte conditions. The rough etching stage uses asymmetric bipolar pulses for anodic dissolution, with a positive peak voltage U. + It is 18V, and the reverse peak voltage U - The voltage is 3V; the pulse frequency f is 1.0kHz; the positive pulse width t is 3V. on+ The pulse width is 600 μs, and the reverse pulse width is t. on- The average current density (j) per unit effective etching area in the rough etching section is 60 μs. avg 25A / cm 2After the rough etching stage reaches approximately 95% of the target depth, the fine etching stage begins. The fine etching stage employs asymmetric bipolar pulse etching for shaping and reshaping, with a positive peak voltage U... ' + The reverse peak voltage is 9V, U. ' - 2V; pulse frequency 10kHz; positive pulse width t ' on+ The pulse width is 20 μs, and the reverse pulse width is t. ' on- The average current density j per unit effective etching area in the fine etching section is 10 μs. ' avg 10A / cm 2 .

[0059] S7: Demolding. After etching, the core board is immersed in an alkaline release solution to remove the resist layer. The release solution is an 8 wt% sodium hydroxide aqueous solution at 70°C for 30 minutes. After demolding, it is rinsed with ultrapure water and then acid-washed with a 5 wt% sulfuric acid aqueous solution for 60 seconds to neutralize residual alkaline substances. Finally, it is thoroughly rinsed with ultrapure water and dried.

[0060] S8: Inspection. A 2D measuring instrument and profilometer were used to inspect the appearance and microchannel dimensions of the core board after film removal. The inspection revealed that the average etching rate per unit depth in the coarse etching section was approximately 0.049 mm / s, the average etching rate per unit depth in the fine etching section was approximately 0.054 mm / s, and the overall average etching rate was 0.05 mm / s. The microchannel etching depth was 1.00 mm; the microchannel diameter was 0.50 mm, and the groove width was 1.00 mm; the single-sided etching depth was ≤80 μm. After passing inspection, the core board was packaged, stored, or shipped.

[0061] This embodiment improves the conductivity and mass transfer capabilities of the electrolyte and enhances the interelectrode electric field and slit flow renewal, resulting in more concentrated effective dissolution in the windowed area. Compared to Example 1, the amount of material removed per unit time is significantly increased; however, under stronger electric field and higher mass transfer conditions, the current concentration effect at the window edge is more significant, and the tendency for lateral dissolution is correspondingly enhanced, thus increasing the risk of lateral corrosion.

[0062] Example 3:

[0063] S1: Pretreatment. The surface of the nickel-based high-temperature alloy core plate is pretreated by successively performing alkaline washing, electrolytic degreasing, acid washing, ultrapure water washing, and drying to remove oil, oxide film, and adsorbed impurities from the core plate surface, ensuring a clean and uniform surface.

[0064] S2: Coating. The resist ink is coated onto the core board surface using a roller coating method and then dried for setting. The drying temperature is 55℃, and the drying time is 40 minutes. After setting, the ink film thickness is 50μm, the thickness uniformity is -5%~5%, and the film adhesion is ≥25N / cm. The resist ink is a commercially available conventional electrochemical etching resist ink, which only needs to form a stable resist mask after exposure and development, and remain intact without significant swelling or peeling under subsequent acidic electrolyte and pulsed electrochemical etching conditions.

[0065] S3: Mask Design. The microchannel mask pattern was drawn using CAD software and output as a film to obtain the film mask. The microchannel diameter was set to 0.5mm, the groove width to 1.0mm, and the diameter compensation value to +0.05mm. The mask pattern was inspected and found to be free of broken lines, burrs, and obvious jagged edges.

[0066] S4: Exposure. The film is attached to the surface of the resist ink and aligned before UV exposure. UV exposure energy: 160 mJ / cm². 2 Exposure time is 50 seconds to improve the curing degree and corrosion resistance stability of the anti-corrosion pattern boundary.

[0067] S5: Development. The exposed core board is placed in an alkaline developer to form windowed areas. The developer used is 20 g / L sodium carbonate, the development temperature is 40℃, and the development time is 10 min. After development, it is thoroughly rinsed with ultrapure water and dried.

[0068] S6: Pulse Electrochemical Etching. The developed, windowed core board is used as the anode, and a conductive material plate with electrochemical stability in the acidic electrolyte is used as the cathode, both mounted in parallel. An asymmetric bipolar pulsed power supply is applied under circulating acidic electrolyte conditions to selectively anolyze and shape the windowed area. The electrode spacing between the anode and cathode is 1.6 mm. The acidic electrolyte circulation creates a narrow slit flow between the electrodes, with an electrolyte flow rate of 0.3 L / (min·cm) per unit effective etching area. 2 The average flow velocity inside the slit is 0.5 m / s.

[0069] In step S6, the coarse etching section and the fine etching section use the same acidic electrolyte. The acidic electrolyte is a sulfuric acid-based composite conductive electrolyte, with ultrapure water as the solvent. The sulfuric acid is prepared using concentrated sulfuric acid with a mass fraction of 98 wt%, resulting in a sulfuric acid mass fraction of 5.0 wt% in the electrolyte. The conductive salt is used to improve the conductivity of the electrolyte and help stabilize the current distribution; the total mass fraction of the conductive salt is 4.0 wt%, of which sodium sulfate and sodium nitrate account for 2.0 wt%. The additive is used for wetting, defoaming, and inhibiting lateral corrosion. In this embodiment, the total amount of additive is 4.8 g / L, specifically: benzotriazole 1.5 g / L, 2-mercaptobenzimidazole 1.0 g / L, polyethylene glycol 1.0 g / L, polyvinylpyrrolidone 1.0 g / L, and sodium dodecyl sulfate 0.3 g / L. The complexing agent is used to complex metal ions and help inhibit secondary deposition; sodium citrate is selected as the complexing agent, and its dosage is 3.0 g / L.

[0070] The etching process is divided into a rough etching stage and a fine etching stage, and the switching between them is controlled under the same electrolyte conditions. The rough etching stage uses asymmetric bipolar pulses for anodic dissolution, with a positive peak voltage U. + 12V, reverse peak voltage U - The voltage is 1.2V; the pulse frequency f is 0.8kHz; the positive pulse width t is 1.2V. on+ The pulse width is 350 μs, and the reverse pulse width is t. on- The average current density per unit effective etching area in the rough etching section is 40 μs; avg 10A / cm 2 After the rough etching stage reaches approximately 75% of the target depth, the fine etching stage begins. The fine etching stage employs asymmetric bipolar pulse etching for shaping, with a positive peak voltage U... ' + The reverse peak voltage is 6V. ' - 0.8V; pulse frequency 18kHz; positive pulse width t ' on+ The pulse width is 10 μs, and the reverse pulse width is t. ' on- The average current density j per unit effective etching area in the fine etching section is 5 μs. ' avg 3A / cm 2 .

[0071] S7: Demolding. After etching, the core board is immersed in an alkaline release solution to remove the resist layer. The release solution is an 8 wt% sodium hydroxide aqueous solution at 70°C for 30 minutes. After demolding, it is rinsed with ultrapure water and then acid-washed with a 5 wt% sulfuric acid aqueous solution for 60 seconds to neutralize residual alkaline substances. Finally, it is thoroughly rinsed with ultrapure water and dried.

[0072] S8: Inspection. A 2D measuring instrument and profilometer were used to inspect the appearance and microchannel dimensions of the core board after film removal. The inspection revealed that the average etching rate per unit depth in the coarse etching section was approximately 0.0079 mm / s, the average etching rate per unit depth in the fine etching section was approximately 0.0024 mm / s, and the overall average etching rate was approximately 0.005 mm / s. The microchannel etching depth was 1.00 mm; the microchannel diameter was 0.50 mm, and the groove width was 1.00 mm; the single-sided etching depth was ≤15 μm. After passing inspection, the core board was packaged, stored, or shipped.

[0073] This embodiment reduces the reactivity of the electrolyte and weakens mass transfer and electric field strength, making the dissolution process gentler and edge over-etching easier to suppress; combined with a more shape-correcting pulse strategy, straighter sidewalls and lower lateral etch can be obtained, but the material removal efficiency decreases accordingly.

[0074] Comparative Example 1:

[0075] S1: Pretreatment. The surface of the nickel-based high-temperature alloy core plate undergoes pretreatment in sequence, including alkaline washing, electrolytic degreasing, acid washing, ultrapure water washing, and drying, to remove various impurities, oil stains, and oxide layers from the core plate surface.

[0076] S2: Coating. The resist ink is coated onto the core board surface using a roller coating method and then dried for setting. The drying temperature is 55℃, and the drying time is 40 minutes. After setting, the ink film thickness is 50μm, the thickness uniformity is -5%~5%, and the film adhesion is ≥25N / cm. The resist ink is a commercially available conventional electrochemical etching resist ink, which only needs to form a stable resist mask after exposure and development, and remain intact without significant swelling or peeling under subsequent acidic electrolyte and pulsed electrochemical etching conditions.

[0077] S3: Mask Design. The microchannel mask pattern was drawn using CAD and output as a film to obtain the film mask. The microchannel diameter was set to 0.5mm, the groove width to 1mm, and the diameter compensation value to +0.05mm. The mask pattern was inspected and found to be free of broken lines, burrs, and obvious jagged edges.

[0078] S4: Exposure. The film is attached to the surface of the resist ink and aligned before UV exposure. UV exposure energy: 150 mJ / cm². 2 Exposure time: 40 seconds.

[0079] S5: Development. The exposed core board is placed in an alkaline developer to develop and form windowed areas. The developer used is 20g / L sodium carbonate, the development temperature is 45℃, and the development time is 3min. After development, it is thoroughly rinsed with ultrapure water and dried.

[0080] S6: Electrochemical Etching. The developed and windowed core board serves as the anode, and a conductive material plate with electrochemical stability in the acidic electrolyte serves as the cathode. They are mounted in parallel, with an electrode spacing of 1.0 mm. The acidic electrolyte circulates through a narrow slit between the electrodes, with an electrolyte flow rate of 0.015 L / (min·cm) per unit effective etching area. 2 The average flow velocity inside the slit is 0.8 m / s.

[0081] The acidic electrolyte is a sulfuric acid-based composite conductive electrolyte, with ultrapure water as the solvent. The sulfuric acid is prepared using 98 wt% concentrated sulfuric acid, resulting in a sulfuric acid content of 15.0 wt% in the electrolyte. The conductive salt is used to improve the electrolyte conductivity and help stabilize the current distribution; the total mass fraction of the conductive salt is 8.0 wt%, including 4.0 wt% sodium sulfate and 4.0 wt% sodium nitrate. The additives are used for wetting, defoaming, and inhibiting lateral corrosion. In this embodiment, the total amount of additives is 2.7 g / L, specifically: 1.0 g / L benzotriazole, 0.5 g / L 2-mercaptobenzimidazole, 0.5 g / L polyethylene glycol, 0.5 g / L polyvinylpyrrolidone, and 0.2 g / L sodium dodecyl sulfate. The complexing agent is used to complex metal ions and help inhibit secondary deposition; sodium citrate is selected as the complexing agent, and its dosage is 2.0 g / L.

[0082] Compared with Example 1, this comparative example does not use asymmetric bipolar pulse and coarse etching stage and fine etching stage switching control in the etching stage. Instead, it uses a single electronic control method to perform anodic dissolution and shaping of the window area until the target depth is reached.

[0083] Specifically, the single electrical control method is unipolar pulse constant parameter control: only a positive anodic dissolution pulse is applied throughout the entire etching process, without applying a reverse voltage pulse, and there is no segmented switching between coarse and fine etching stages. The single electrical control parameter is set as follows: positive pulse voltage U + 14V, no reverse pulse; frequency f is 1.0kHz; forward conduction time t on+ The turn-off time is 500 μs. off The duration is 500 μs with a duty cycle of 50%; the average current density per unit effective etch area is calculated based on the average current density over one cycle of the positive pulse. avg ≈15A / cm 2 Etching continues under the aforementioned fixed electrical control parameters until the microchannel depth reaches the target depth.

[0084] S7: Demolding. The demolding solution is an 8 wt% sodium hydroxide aqueous solution, at a temperature of 70°C for 30 minutes. After demolding, rinse with ultrapure water, then acid wash with a 5 wt% sulfuric acid aqueous solution for 60 seconds to neutralize residual alkaline substances. Finally, rinse thoroughly with ultrapure water and dry.

[0085] S8: Inspection. A 2D measuring instrument and a profilometer were used to inspect the appearance and microchannel dimensions of the core board after the film was removed. The inspection showed that the average etching rate of the overall etching process was 0.030 mm / s, the microchannel etching depth was 1.00 mm, the microchannel diameter was 0.56 mm, the groove width was 1.08 mm, and the single-sided etching depth was ≤150 μm.

[0086] In this comparative example, while maintaining the same electrolyte composition and inter-electrode slit circulation conditions as in Example 1, the comparative example did not employ asymmetric bipolar pulses or segmented switching control between coarse and fine etching stages during the etching phase; instead, it used only unipolar pulses with constant parameters for continuous etching. Due to the lack of periodic conditioning of the interface state by the reverse pulse, bubble coverage and reaction product films were difficult to eliminate in a timely manner, the current density in the window edge region was more likely to remain concentrated, and lateral dissolution in the sidewall mass transfer-restricted region accumulated over a long period. This resulted in significantly larger diameter and groove widths, a significant increase in lateral etching on one side (≤150 μm), a decrease in the rectangularity of the microchannel cross-section, and poorer dimensional controllability. In contrast, this application employs asymmetric bipolar pulses combined with switching control between coarse and fine etching stages. This achieves higher longitudinal removal efficiency in the coarse etching stage, and in the fine etching stage, by increasing the pulse modulation frequency, shortening the forward pulse width, and introducing reverse pulse conditioning, it suppresses edge over-etching and lateral dissolution, thereby reducing the tendency for lateral etching and improving the rectangularity and dimensional consistency of the microchannel cross-section.

[0087] Comparative Example 2:

[0088] S1: Pretreatment. The surface of the nickel-based high-temperature alloy core plate undergoes pretreatment in sequence, including alkaline washing, electrolytic degreasing, acid washing, ultrapure water washing, and drying, to remove various impurities, oil stains, and oxide layers from the core plate surface.

[0089] S2: Coating. The resist ink is coated onto the core board surface using a roller coating method and then dried for setting. The drying temperature is 55℃, and the drying time is 40 minutes. After setting, the ink film thickness is 50μm, the thickness uniformity is -5%~5%, and the film adhesion is ≥25N / cm. The resist ink is a commercially available conventional electrochemical etching resist ink, which only needs to form a stable resist mask after exposure and development, and remain intact without significant swelling or peeling under subsequent acidic electrolyte and pulsed electrochemical etching conditions.

[0090] S3: Mask Design. The microchannel mask pattern was drawn using CAD and output as a film to obtain the film mask. The microchannel diameter was set to 0.5mm, the groove width to 1mm, and the diameter compensation value to +0.05mm. The mask pattern was inspected and found to be free of broken lines, burrs, and obvious jagged edges.

[0091] S4: Exposure. The film is attached to the surface of the resist ink and aligned before UV exposure. UV exposure energy: 150 mJ / cm². 2 Exposure time: 40 seconds.

[0092] S5: Development. The exposed core board is placed in an alkaline developer to develop and form windowed areas. The developer used is 20g / L sodium carbonate, the development temperature is 45℃, and the development time is 3min. After development, it is thoroughly rinsed with ultrapure water and dried.

[0093] S6: Electrochemical etching. The core board after development and windowing is used as the anode, and a conductive material plate with electrochemical stability in acidic electrolyte is used as the cathode. They are clamped in parallel with a spacing of 1.0 mm.

[0094] The acidic electrolyte is a sulfuric acid-based composite conductive electrolyte, with ultrapure water as the solvent. The sulfuric acid is prepared using 98 wt% concentrated sulfuric acid, resulting in a sulfuric acid content of 15.0 wt% in the electrolyte. The conductive salt is used to improve the electrolyte conductivity and help stabilize the current distribution; the total mass fraction of the conductive salt is 8.0 wt%, including 4.0 wt% sodium sulfate and 4.0 wt% sodium nitrate. The additives are used for wetting, defoaming, and inhibiting lateral corrosion; the total amount of additives is 2.7 g / L, specifically: 1.0 g / L benzotriazole, 0.5 g / L 2-mercaptobenzimidazole, 0.5 g / L polyethylene glycol, 0.5 g / L polyvinylpyrrolidone, and 0.2 g / L sodium dodecyl sulfate. The complexing agent is used to complex metal ions and help inhibit secondary deposition; sodium citrate is selected as the complexing agent, and its dosage is 2.0 g / L.

[0095] The difference from the embodiments is that, in this comparative example, no electrolyte circulation is used during the etching process; the electrolyte remains stationary and only undergoes natural convection, without forming a slit for circulation between the electrodes; the electrolyte flow rate per unit effective etching area is 0 L / (min·cm). 2 The average flow velocity inside the slit is approximately 0 m / s.

[0096] To eliminate the influence of electronic control factors, the electronic control strategy in this comparative example is the same as that in Example 1: the etching process is divided into a rough etching stage and a fine etching stage, and switching control is performed under the same electrolyte conditions. In the rough etching stage, asymmetric bipolar pulses are used for anodic dissolution, with a positive peak voltage U... + The reverse peak voltage is 14V. - The voltage is 1.5V; the pulse frequency f is 1.0kHz; the positive pulse width t is 1.5V. on+ The pulse width is 500 μs, and the reverse pulse width is t. on- The current density per unit effective etching area in the rough etching section is 50 μs; j is 50 μs. avg 15A / cm 2After the rough etching stage reaches approximately 85% of the target depth, the fine etching stage begins. The fine etching stage employs asymmetric bipolar pulse etching for shaping, with a positive peak voltage U... ' + It is 7V, and the reverse peak voltage U ' + 1.0V; pulse frequency 15kHz; positive pulse width t ' on+ The pulse width is 15 μs, and the reverse pulse width is t. ' on- The average current density j per unit effective etching area in the fine etching section is 5 μs. ' avg 5A / cm 2 Etching continues under the aforementioned electronic control parameters until the microchannel depth reaches the target depth.

[0097] S7: Demolding. The demolding solution is an 8 wt% sodium hydroxide aqueous solution, at a temperature of 70°C for 30 minutes. After demolding, rinse with ultrapure water, then acid wash with a 5 wt% sulfuric acid aqueous solution for 60 seconds to neutralize residual alkaline substances. Finally, rinse thoroughly with ultrapure water and dry.

[0098] S8: Inspection. A 2D measuring instrument and a profilometer were used to inspect the appearance and microchannel dimensions of the core board after film removal. The inspection showed that the average etching rate of the overall etching process was 0.016 mm / s, the microchannel etching depth was 1.00 mm, the microchannel diameter was 0.54 mm, the groove width was 1.06 mm, and the single-sided etching depth was ≤120 μm.

[0099] Because this comparative example did not employ electrolyte circulation and thus did not create a slit flow between the electrodes, the dissolved products and bubbles were difficult to remove in time. This led to increased concentration polarization and local current density fluctuations between the electrodes, making the lateral dissolution more likely to occur at the window edge region, resulting in larger diameter and groove widths and a significant increase in lateral corrosion. In contrast, this invention continuously updates the interfacial mass transfer conditions through electrolyte circulation and the creation of a slit flow between the electrodes. This effectively suppresses lateral dissolution while ensuring removal efficiency, thereby improving the rectangularity of the microchannel cross-section and reducing the tendency for lateral corrosion. As can be seen from the results in Table 1, under the premise of consistent target main dimensions, the differences in each operating condition essentially stem from the different spatiotemporal distributions of mass transfer conditions and electrochemical dissolution, thus forming an "efficiency-lateral corrosion" trade-off.

[0100] Table 1. Comparison of key parameters and performance results of microchannel electrochemical etching under different working conditions;

[0101] ;

[0102] Example 1 employs a moderate electrolyte strength and flow renewal capacity to maintain a relative balance between anodic dissolution and product removal. A segmented pulse process of "coarse etching – fine etching" achieves efficient removal first, followed by suppression of lateral spread, thus balancing efficiency and sidewall quality. Example 2 improves the electrolyte's conductivity and mass transfer capacity, and enhances the interelectrode electric field and slit renewal, concentrating effective dissolution in the open area and increasing the removal rate per unit time. However, the stronger local electric field and edge current concentration effect increase the tendency for lateral dissolution, thus raising the risk of lateral corrosion. Example 3 reduces electrolyte reactivity and weakens mass transfer and electric field strength, resulting in a gentler dissolution process and suppression of edge over-etching. Combined with a more "shape-correcting" pulse strategy, straighter sidewalls and lower lateral corrosion are achieved, but efficiency is correspondingly reduced. Comparative Example 1, despite having similar electrolyte composition and slit flow conditions, still exhibited lateral etching and dimensional deviations. The main reason was the lack of asymmetric bipolar pulse and coarse-fine etching stage switching control during the etching process. This resulted in the dissolution driving force at the window edge remaining at a high level for an extended period, making it difficult to suppress edge current concentration and lateral dissolution in a timely manner. Consequently, the consistency and dimensional controllability of the microchannel formation were reduced. Comparative Example 2, while maintaining the same electro-control strategy as Example 1, did not employ electrolyte circulation and thus failed to create slit flow between the electrodes. Dissolution products and bubbles were difficult to remove from the electrode interface in a timely manner, leading to deteriorated mass transfer conditions and increased concentration polarization. This made lateral dissolution more likely to occur at the window edge, resulting in increased diameter and groove width, and a significant increase in lateral etching.

[0103] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A pulsed electrochemical etching method for microchannels in a nickel-based high-temperature alloy core plate, characterized in that, Includes the following steps: S1： Pretreatment: The surface of the nickel-based high-temperature alloy core plate is pretreated by successively undergoing alkaline washing, degreasing, acid washing, ultrapure water washing and drying; S2: Glue application: Apply anti-corrosion ink to the surface of the core board and dry it until it sets; S3: Mask design: Design the mask, draw the mask pattern, and then print out the film negative to obtain the film mask; S4: Exposure: Place the film negative on the surface of the core board resist ink and align it, then place it in a UV exposure machine for exposure; S5: Development: The exposed core board is placed in an alkaline developing solution for development, which dissolves the resist ink layer in the unexposed areas and retains the resist ink layer in the exposed areas, forming a microchannel pattern window area. S6: Pulse electrochemical etching: The core board that has undergone development and windowing treatment is used as the anode and is parallelly clamped with a stable cathode plate in an acidic electrolyte. An asymmetric bipolar pulse power supply is applied under the condition of circulating acidic electrolyte to selectively anoly dissolve and shape the windowed area. The pulse electrochemical etching process includes a coarse etching section and a fine etching section. The electrolyte is circulated to form a slit flow between the electrodes. S7: Demolding: After etching, the core board is immersed in alkaline demolding solution to remove the resist layer, then pickled to neutralize the residual alkaline substances, thoroughly cleaned with ultrapure water, and finally dried. S8: Inspection: Use a two-dimensional measuring instrument or contour / microscopic measurement method to inspect the appearance and microchannel dimensions of the core board after film removal. After passing the inspection, package, store or ship.

2. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 1, characterized in that, In S6, the coarse etching section and the fine etching section use the same sulfuric acid system to prepare a conductive acidic electrolyte, including: sulfuric acid 5.0wt%~30.0wt%, conductive salt 2.0wt%~12.0wt%, additives 0.05g / L~10g / L, complexing agent 2g / L~3g / L; The conductive salt is sodium sulfate and / or sodium nitrate; the additives are selected from one or more of benzotriazole, 2-mercaptobenzimidazole, polyethylene glycol, polyvinylpyrrolidone and sodium dodecyl sulfate; the complexing agent is selected from one or more of sodium citrate, sodium tartrate, disodium ethylenediaminetetraacetate and sodium gluconate; and the solvent is ultrapure water.

3. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2, characterized in that, The sulfuric acid system is used to prepare a conductive acidic electrolyte, comprising: 10.0wt%~25.0wt% sulfuric acid and 4.0wt%~8.0wt% conductive salt.

4. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2, characterized in that, In S6, the electrode spacing between the anode and cathode is 0.5 mm to 1.6 mm, and the electrolyte flow rate per unit effective etching area is 0.005 L / (min·cm). 2 0.3 L / (min·cm) 2 The average flow velocity within the slit is 0.1 m / s to 5 m / s.

5. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 4, characterized in that, The electrolyte flow rate per unit effective etching area is 0.01 L / (min·cm). 2 )~0.05L / (min·cm 2 ).

6. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2 or 4, characterized in that, The rough-cut section employs asymmetric bipolar pulse anodic dissolution, satisfying the asymmetric condition of strong forward pulse and weak reverse pulse: forward peak voltage U + The voltage range is 12V~18V, with a reverse peak voltage U. - The voltage range is 1.2V to 3.0V, and U + >U - Pulse frequency The pulse width is 0.8kHz to 1.0kHz; the positive pulse width t on+ The pulse duration is 350μs~600μs, and the reverse pulse width is t. on- The duration is 40μs~60μs and t on+ >t on- The average current density j per unit effective etching area in the rough etching section avg 10A / cm 2 ~25A / cm 2 ; The rough etching section achieves 75% to 95% of the target etching depth.

7. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2 or 4, characterized in that, The fine etching section employs asymmetric bipolar pulse etching to achieve the desired shape, satisfying the asymmetric condition of strong forward pulse and weak reverse pulse: forward peak voltage U ' + The voltage range is 6V~9V, with a reverse peak voltage U. ' - The voltage range is 0.8V to 2.0V, and U ' + >U ' - Pulse frequency 10kHz~18kHz; positive pulse width t ' on+ The pulse width is 10μs~20μs, and the reverse pulse width is t. ' on- The duration is 5μs~10μs, and t ' on+ >t ' on- The average current density j per unit effective etching area in the fine etching section ' avg 3A / cm 2 ~12A / cm 2 .

8. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2 or 4, characterized in that, In S2, the anti-corrosion ink film layer is attached to the core board, with a film thickness of 40μm~60μm, a thickness uniformity of -5%~5%, and a film adhesion force ≥25N / cm.

9. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 2 or 4, characterized in that, In S4, the UV exposure energy is 100 mJ / cm². 2 ~200mJ / cm 2 The exposure time is 40s~50s.

10. The pulsed electrochemical etching method for microchannels of a nickel-based high-temperature alloy core plate according to claim 1, characterized in that, In S5, the developing temperature is 40℃~45℃, and the developing time is 3min~10min.

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