Electrochemical surface treatment device and electrochemical surface treatment process

Abstract

The present invention discloses an electrochemical surface treatment device and an electrochemical surface treatment process, the electrochemical surface treatment device comprises an insulating container, a power supply and an electrode, a surface treatment module comprising a surface treatment unit is arranged in the insulating container, the surface treatment unit comprises a working liquid layer and a protective liquid layer stacked from top to bottom, the thickness of the working liquid layer is less than the height of the area to be surface treated on the workpiece, and the thickness of the working liquid layer and the protective liquid layer is greater than or equal to the height of the area to be surface treated on the workpiece; the positive electrode of the power supply is used to connect with the workpiece, and the electrode is connected to the working liquid layer and the negative electrode of the power supply respectively. The electrochemical surface treatment device of the present invention can be used for surface treatments such as electrolytic polishing, electroplating, and surface passivation of the workpiece, the surface treatment is uniform, and the surface of the workpiece is flat after treatment; its surface treatment rate is adjustable and flexible; and the amount of working liquid used is small, the cost is low, the structure is simple, it is easy to operate, and it is safe and reliable.

Description

Technical Field

[0001] The invention relates to a surface treatment technology, in particular to an electrochemical surface treatment device and an electrochemical surface treatment process. Background Art

[0002] The polishing of the mold is very important for improving the surface quality of the mold. The polishing processes of glass molds mainly include abrasive jet polishing and magnetorheological polishing. Abrasive jet polishing mainly uses the micro-cutting effect of SiC abrasive particles on the surface of the workpiece to remove the surface material of the workpiece. The abrasive jet has a high polishing efficiency, but the abrasive particles in the abrasive jet are easy to scratch the surface. At the same time, because there is a large mechanical force between the abrasive and the surface, there is a large hardened layer on the polished surface, which damages the surface quality. Magnetorheological polishing mainly uses the flexible "small grinding head" with viscoplastic behavior formed by the rheology of magnetorheological polishing fluid in a gradient magnetic field to have a rapid relative movement with the workpiece, so that the surface of the workpiece is subjected to a large shear force, thereby removing the surface material of the workpiece. The surface damage after magnetorheological polishing is very small and the surface quality is high, but the polishing efficiency is relatively low. In addition, the cost of magnetorheological polishing fluid is high, so the processing cost of this method is relatively high. Electrochemical polishing can obtain a surface with no subsurface damage layer and high finish, which is a promising mold polishing method. Electrochemical polishing mainly uses the selective dissolution of the workpiece surface as the anode of the electrolytic cell to achieve the effect of increasing surface brightness and smoothing the surface. The traditional electrochemical polishing process is to completely immerse the workpiece to be polished in the electrolyte and use an inert electrode in contact with it as the anode. During the polishing process, the workpiece material is dissolved and removed, while the inert electrode in contact with it does not react and only plays a conductive role; the other inert electrode acts alone as the cathode.

[0003] For electrochemical polishing, firstly, since the removal efficiency of different areas of the material surface in electrochemical polishing is mainly affected by the potential distribution, the area with high potential has high current density and high material dissolution rate, so the material removal rate in this area is high. In traditional electrochemical polishing, the entire mold is immersed in the electrolyte and in contact with the inert electrode as the anode. At this time, the area on the mold surface close to the inert electrode has high potential, high current density, and high material removal rate. On the contrary, the area far from the inert electrode has low material removal rate. When the material removal rates of different areas of the workpiece are inconsistent during the polishing process, the workpiece after polishing will have dimensional errors. Secondly, the surface potential of the workpiece will affect the formation of the mucus layer on the surface of the workpiece during the polishing process. When the surface potential distribution is uneven, it will lead to differences in the thickness, stability, formation and dissolution rate of the mucus layer in different areas. The surface of the area where the mucus layer is stably formed and dissolved will become smooth, while the surface of the area where the mucus layer is not stably formed and dissolved will become rough, which makes it difficult for traditional electrochemical polishing to obtain a completely smooth workpiece surface. Furthermore, because conventional electrochemical polishing involves completely immersing the workpiece to be processed in an electrolyte, a large amount of electrolyte is required to immerse the workpiece when a large area of ​​the workpiece needs to be polished, which makes it more expensive. Therefore, conventional electrochemical polishing processes are generally difficult to use for polishing large-area molds with three-dimensional structures. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an electrochemical surface treatment device and an electrochemical surface treatment process.

[0005] The technical solution adopted by the present invention is:

[0006] A first aspect of the present invention provides an electrochemical surface treatment device, comprising:

[0007] An insulating container, wherein a surface treatment module is provided in the insulating container, wherein the surface treatment module comprises a first surface treatment unit, wherein the first surface treatment unit comprises a first working liquid layer and a first protective liquid layer stacked from top to bottom, wherein the first working liquid layer is composed of a first working liquid, and the first protective liquid layer is composed of a first protective liquid; the thickness of the first working liquid layer is less than the height of the area to be surface treated on the workpiece, and the sum of the thickness of the first working liquid layer and the first protective liquid layer is greater than or equal to the height of the area to be surface treated on the workpiece;

[0008] A power source, the power source having a positive electrode and a negative electrode; the positive electrode is used to connect to the workpiece;

[0009] Electrodes are connected to the first working liquid layer and the negative electrode of the power supply respectively.

[0010] According to some embodiments of the present invention, the first working liquid and the first protective liquid are immiscible, and the density of the first working liquid is less than the density of the first protective liquid;

[0011] Alternatively, the first surface treatment unit also includes a first separation layer composed of a first separation liquid, the first separation layer is arranged between the first working liquid layer and the first protective liquid layer, the first separation liquid is immiscible with the first working liquid and the first protective liquid respectively, the density of the first working liquid is less than the density of the first separation liquid, and the density of the first separation liquid is less than the density of the first protective liquid.

[0012] According to some embodiments of the present invention, the thickness of the first protective liquid layer is greater than or equal to the height of the area to be surface processed on the workpiece.

[0013] According to some embodiments of the present invention, the first surface treatment unit is used to perform a first surface treatment on the workpiece, and the first surface treatment is any one of electrolytic polishing, electroplating, and surface passivation.

[0014] According to some embodiments of the present invention, the first surface treatment is electrolytic polishing, the first working fluid is an electrolyte, and the electrolyte is selected from at least one of potassium hydroxide solution, sodium hydroxide solution, sodium tartrate solution, and potassium tartrate solution; the first protective liquid is nonafluorobutyl methyl ether, carbon tetrachloride or trichloroethane.

[0015] According to some embodiments of the present invention, the surface treatment module also includes a second surface treatment unit stacked with the first surface treatment unit, the second surface treatment unit includes a second working liquid layer and a second protective liquid layer stacked from top to bottom, the second working liquid layer is composed of a second working liquid, and the second protective liquid layer is composed of a second protective liquid.

[0016] According to some embodiments of the present invention, the second surface treatment unit is used to perform a second surface treatment on the workpiece, and the second surface treatment is any one of electrolytic polishing, electroplating, and surface passivation.

[0017] According to some embodiments of the present invention, the electrochemical surface treatment device further comprises a driving component for driving the workpiece to move along the Z-axis direction, or along at least one of the X-axis direction and the Y-axis direction and the Z-axis direction.

[0018] According to some embodiments of the present invention, the electrochemical surface treatment device further comprises an ammeter and / or a voltmeter, the ammeter is connected in series with the power supply, and the voltmeter is connected in parallel with the power supply.

[0019] A second aspect of the present invention provides an electrochemical surface treatment process, comprising the following steps:

[0020] S1, injecting a first protective liquid and a first working liquid into an insulating container in sequence, wherein the first protective liquid and the first working liquid are immiscible, and the density of the first working liquid is less than the density of the first protective liquid, and standing until the solution is stratified, thereby forming a first surface treatment unit including a first working liquid layer and a first protective liquid layer stacked from top to bottom in the insulating container;

[0021] Alternatively, a first protective liquid and a first separating liquid are sequentially injected into the insulating container, wherein the first protective liquid and the first separating liquid are immiscible, and the density of the first separating liquid is less than the density of the first protective liquid, and after standing until the solution is stratified, a first working liquid is slowly injected into the insulating container, wherein the first working liquid and the first separating liquid are immiscible, and the density of the first working liquid is less than the density of the first separating liquid, and after standing until the solution is stratified, a first surface treatment unit including a first working liquid layer, a first separating layer, and a first protective liquid layer stacked from top to bottom is formed in the insulating container;

[0022] S2, connecting an electrode to the negative electrode of a power source, and inserting the electrode into the first working liquid layer;

[0023] S3, connecting the workpiece to the positive electrode of the power supply, and then inserting the workpiece into the first working liquid layer with the electrode between them, and starting the power supply when the workpiece contacts the first working liquid layer;

[0024] S4. Control the workpiece to move along the Z-axis direction according to the surface treatment requirements of the workpiece, or to move along the Z-axis direction and at least one of the X-axis direction and the Y-axis direction; until the surface treatment of the area to be surface treated on the workpiece is completed, and then turn off the power supply.

[0025] The beneficial effects of the embodiments of the present invention are:

[0026] An embodiment of the present invention provides an electrochemical surface treatment device, in which an insulating container of the electrochemical surface treatment device is provided with a surface treatment module including a first surface treatment unit, the first surface treatment unit including a first working liquid layer and a first protective liquid layer stacked from top to bottom, and the thickness of the first working liquid layer is less than the height of the area to be surface treated on the workpiece. The above electrical surface treatment device can be applied to surface treatments such as electrolytic polishing, electroplating, and surface passivation of the workpiece. When in use, the workpiece to be processed can be connected to the positive electrode of the power supply, and then the workpiece can be inserted into the first working liquid layer, and the power supply can be started when the workpiece contacts the first working liquid layer to form a circuit; then the workpiece can be controlled to move along the Z-axis direction, or along at least one of the X-axis direction and the Y-axis direction and the Z-axis direction according to the surface treatment requirements of the workpiece, and the electrochemical surface treatment can be performed. Among them, since the first surface treatment unit includes a first working liquid layer and a first protective liquid layer stacked from top to bottom to form a layered solution electrochemical surface treatment, the potential difference on the reaction surface can be reduced, the surface treatment uniformity is high, the surface of the workpiece is flat after treatment, and the structural size changes of different areas on the surface are small. Moreover, through the setting of the above-mentioned first surface treatment unit, the electrochemical polishing device can realize the regulation of different surface treatment rates by changing parameters such as the concentration of the first working liquid, the thickness of the first working liquid layer, and the movement rate of the workpiece, and has strong flexibility; in addition, the electrochemical surface treatment device can reduce the amount of the first working liquid and reduce costs. It has a simple structure and is easy for users to operate. It uses a smaller electrolytic current to perform surface polishing, which is safer and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of an electrochemical surface treatment device according to an embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of the principle of material removal from the sample surface during the electrochemical polishing process of a microfluidic tungsten mold using an electrochemical surface treatment device according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the structure of the workpiece to be polished;

[0030] Figure 4 yes Figure 3 Sectional view along section AA;

[0031] Figure 5 is the SEM image of three sites on the workpiece surface before polishing;

[0032] Figure 6 It is a SEM image of three sites on the surface of a workpiece after the workpiece is subjected to layered solution dynamic electrochemical polishing by the electrochemical surface treatment device according to an embodiment of the present invention;

[0033] Figure 7It is the profile changes of three locations on the workpiece surface during the polishing process of the workpiece using the traditional electrochemical polishing method;

[0034] Figure 8 The present invention is a schematic diagram of the contour changes of three sites on the workpiece surface during the layered solution dynamic electrochemical polishing process of the workpiece using the electrochemical surface treatment device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0036] In the description of the embodiments of the present invention, if the description of the orientation is involved, the orientation or position relationship indicated by "upper", "lower", "front", "back", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. If "multiple" is involved, it means more than two. If "greater than", "less than", or "exceeds" is involved, it should be understood as not including the number itself. If "above", "below", or "within" is involved, it should be understood as including the number itself. If "first" or "second" is involved, it should be understood as being used to distinguish technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0037] See also Figure 1 , Figure 1 is a schematic structural diagram of an electrochemical surface treatment device according to an embodiment of the present invention, Figure 1 FIG. 4 is a schematic diagram showing the connection between the electrochemical surface treatment device and the workpiece 40 in the use state, and the workpiece 40 is not a component of the electrochemical surface treatment device itself. Figure 1As shown, the electrochemical surface treatment device includes an insulating container 10, a power source 20 and an electrode 30. A surface treatment module is provided in the insulating container 10, and the surface treatment module includes a first surface treatment unit, and the first surface treatment unit includes a first working liquid layer 11 and a first protective liquid layer 12 stacked from top to bottom, the first working liquid layer 11 is composed of a first working liquid, and the first protective liquid layer 12 is composed of a first protective liquid; the thickness of the first working liquid layer 11 is less than the height of the area to be surface treated on the workpiece 40, and the sum of the thickness of the first working liquid layer 11 and the first protective liquid layer 12 is greater than or equal to the height of the area to be surface treated on the workpiece 40; the power source 20 has a positive electrode and a negative electrode, and the positive electrode of the power source 20 is used to connect to the workpiece 40; the electrode 30 is connected to the first working liquid layer 11 and the negative electrode of the power source 20 respectively. Among them, the height of the area to be surface treated on the workpiece 40 is the height of the area on the workpiece 40 that needs to be surface treated in the corresponding surface treatment unit along the direction perpendicular to the first working liquid layer 11.

[0038] The insulating container 10 is generally an insulating container with an opening facing upward. In order to facilitate observation of the movement of the workpiece 40 in the insulating container 10, a transparent insulating container is generally used, and its shape can be set to regular shapes such as a cuboid, a cube, a cylinder, an elliptical cylinder, or other irregular shapes. For the convenience of assembly and preparation, a glass beaker can be directly used.

[0039] The electrochemical surface treatment device of this embodiment is specifically an electrochemical polishing device for electrochemical polishing of a workpiece 40. The first surface treatment unit is composed of a layered solution formed by mixing an immiscible first working liquid (i.e., an electrolyte) and a first protective liquid, and the density of the first working liquid is less than the density of the first protective liquid, so that the first working liquid layer 11 (i.e., the first electrolyte layer) is in the upper layer, and the first protective liquid layer 12 is in the lower layer, that is, the first working liquid layer 11 and the first protective liquid layer 12 are stacked from top to bottom. The electrolyte can be selected from at least one of potassium hydroxide solution, sodium hydroxide solution, sodium tartrate solution, and potassium tartrate solution. The first protective liquid is chemically inert to the workpiece to be processed, that is, it does not react chemically with the workpiece, and nonafluorobutyl methyl ether can be specifically used. In this embodiment, the electrolyte is a 0.5% NaOH solution, and the first protective liquid is nonafluorobutyl methyl ether.

[0040] The first working liquid layer 11 and the first protective liquid layer 12 in the first surface treatment unit can be layered by natural layering. Of course, the first partitioning liquid can also be used to force the layering between the first working liquid and the first protective liquid. When the density difference between the first working liquid and the first protective liquid is large, and there is no reaction or mutual solubility between the two, the solutions can be layered naturally; and when there is a chemical reaction or mutual solubility between the first working liquid and the first protective liquid, for example, a polymer film (liquid film layer) can be used for forced layering, and the first partitioning liquid is also chemically inert to the workpiece to be processed, that is, it does not chemically react with the workpiece. Therefore, in some embodiments, the first surface treatment unit may also include a first partitioning layer composed of a first partitioning liquid, the first partitioning layer is arranged between the first working liquid layer 11 and the first protective liquid layer 12, the first partitioning liquid of the first partitioning layer is respectively immiscible with the first working liquid of the first working liquid layer 11 and the first protective liquid of the first protective liquid layer 12, the density of the first working liquid is less than the density of the first partitioning liquid, and the density of the first partitioning liquid is less than the density of the first protective liquid.

[0041] In order to improve the uniformity of the surface treatment, the thickness of the first protective liquid layer 12 of the first surface treatment unit in the insulating container 10 can be designed to be greater than or equal to the height of the area to be surface treated on the workpiece 40. When in use, the area to be surface treated on the workpiece 40 can completely pass through the first working liquid layer 11, thereby improving the uniformity of the surface treatment.

[0042] In this embodiment, the electrode 30 is a platinum electrode, and the platinum electrode is immersed in the first working liquid layer 11. In order to facilitate assembly and connection, the platinum electrode is specifically connected to the negative electrode of the power supply 20 through a conductive connector 31. The conductive connector 31 used is specifically a copper rod wrapped with an insulating material (such as insulating plastic). In order to prevent the copper rod from contacting and reacting with the electrolyte, it is necessary to wrap the insulating material on its outside. In other embodiments, the electrode 30 can also be partially immersed in the electrolyte layer, and the efficiency of the electrochemical surface treatment can be controlled by changing the size of the immersion area.

[0043] In order to facilitate the control of the movement of the workpiece 40, the electrochemical surface treatment device of this embodiment also includes a driving component 50, which is used to drive the workpiece 40 to move along the Z-axis direction, or, to move along at least one of the X-axis direction and the Y-axis direction and the Z-axis direction. The driving component 50 can use a manipulator, specifically a three-axis manipulator or other manipulators, and the specific type of the manipulator can be selected according to the movement required to be achieved by the workpiece. Through the above driving method of the driving component 50, the relative movement between the workpiece 40 and the electrode 30 is controlled to change the surface treatment rate. For example, when the electrochemical surface treatment device of this embodiment is used for electrolytic polishing, by driving the workpiece 40 to move downward along the Z-axis direction, similar to constant current density, polishing with a constant material removal rate is performed; if the workpiece 40 is driven to move along the Z-axis direction while increasing the movement in the horizontal X-axis direction and / or Y-axis direction, it is a variable current density, and polishing with a variable material removal rate is performed. When the workpiece 40 moves horizontally toward the electrode 30 (cathode), the current density is large and the material removal rate is high; when the workpiece 40 moves horizontally away from the electrode 30, the current density is small and the material removal rate is low. In the above control process, polishing with a variable material removal rate can be considered for polishing workpieces with a gradual structure (such as a cone), and shaping can be performed while polishing. In addition, the above movement process along the Z-axis direction, or along at least one of the X-axis direction and the Y-axis direction and the Z-axis direction, can also involve rotational movement, specifically by connecting a drive motor for driving the workpiece 40 to rotate at the output end of the manipulator.

[0044] In order to facilitate monitoring of the current size of the current loop and the voltage across the insulating container 10 during the surface treatment process, the electrochemical surface treatment device of this embodiment may further include an ammeter 60 and a voltmeter 70. The ammeter 60 is connected in series with the power supply 20, and the voltmeter 70 is connected in parallel with the power supply 20, so that the current size passing through the main loop during the surface treatment process is measured by the ammeter 60, and the voltage value applied to the two ends of the insulating container 10 during the surface treatment process is measured by the voltmeter 70. Of course, in other embodiments, the setting of the ammeter 60 and the voltmeter 70 may be cancelled, or the ammeter 60 or the voltmeter 70 may be set separately.

[0045] The first surface treatment unit in the surface treatment module of the electrochemical surface treatment device of this embodiment is used for performing the first surface treatment on the workpiece, wherein the first surface treatment is specifically electrolytic polishing, and the first working liquid is an electrolyte. In other embodiments, the electrochemical surface treatment device can also be designed based on similar principles for other first surface treatments such as electroplating and surface passivation, and the working liquid of the first working liquid layer 11 and the first protective liquid of the first protective liquid layer 12 can be selected according to the surface treatment requirements.

[0046] In addition, in the present embodiment, the surface treatment module in the insulating container 10 includes a surface treatment unit for performing a first surface treatment on the workpiece. In other embodiments, the surface treatment module can also be designed to include a plurality of surface treatment units according to the requirements of the surface treatment. The surface treatment units are stacked and arranged to achieve surface treatment of different areas on the workpiece 40.

[0047] For example, in some embodiments, based on Figure 1 The electrochemical surface treatment device shown in the figure, the surface treatment module in the insulating container 10 thereof may also include a second surface treatment unit stacked with the first surface treatment unit, the second surface treatment unit includes a second working liquid layer and a second protective liquid layer stacked from top to bottom, the second working liquid layer is composed of a second working liquid, the second protective liquid layer is composed of a second protective liquid, the second working liquid layer can be used to perform a second surface treatment on the workpiece, and the second surface treatment can be any one of electrolytic polishing, electroplating and surface passivation.

[0048] Similar to the first surface treatment unit, in the second surface treatment unit, the second working liquid layer and the second protective liquid layer can be formed by adopting immiscible second working liquid and second protective liquid, and the density of the second working liquid is less than the density of the second protective liquid; or, the second surface treatment unit is designed to also include a second separation layer composed of a second separation liquid, the second separation layer is arranged between the second working liquid layer and the second protective liquid layer, the second separation liquid is immiscible with the second working liquid and the second protective liquid, respectively, the density of the second working liquid is less than the density of the second separation liquid, and the density of the second separation liquid is less than the density of the second protective liquid.

[0049] The number of surface treatment units in the surface treatment module of the electrochemical surface treatment device is specifically designed according to the surface treatment requirements of the workpiece 40. The surface treatment units can be designed to include a working liquid layer and a protective liquid layer stacked from top to bottom, and each surface treatment unit is stacked. The thickness of each working liquid layer is generally less than the height of the area to be surface treated on the workpiece; and for the protective liquid layer, except for the bottommost protective liquid layer, other protective liquid layers can be set to mainly isolate two adjacent working liquid layers, and the bottommost protective liquid layer can be set to mainly protect the area to be surface treated of the workpiece from participating in the reaction. Therefore, the thickness of the bottommost protective liquid layer is generally required to be greater than the height of the area to be surface treated on the workpiece.

[0050] When in use, each surface treatment unit in the surface treatment module can be designed as a different processing procedure. When the workpiece moves downward, the first surface treatment unit and the second surface treatment unit can be used as the first processing procedure and the second processing procedure, respectively, and so on. For example, when the first surface treatment unit is a unit with an electrolysis function and the second surface treatment unit is a unit with a surface passivation function, when the workpiece passes through the first surface treatment unit and the second surface treatment unit in sequence, it is equivalent to first electrolyzing the surface of the workpiece to dissolve some impurities on the surface, and then passivating the surface of the workpiece to obtain a single uniform and dense oxide layer.

[0051] The above electrochemical surface treatment device can be used for surface treatment of workpieces such as electrolytic polishing, electroplating, and surface passivation. The specific operation can be performed according to the following steps:

[0052] S1. Use any of the above electrochemical surface treatment devices to connect the workpiece to the positive electrode of the power supply;

[0053] S2, inserting the workpiece connected to the positive electrode of the power supply into the first working liquid layer, and starting the power supply when the workpiece contacts the first working liquid layer;

[0054] S3. Control the workpiece to move along the Z-axis direction according to the surface treatment requirements of the workpiece, or move along the Z-axis direction and at least one of the X-axis direction and the Y-axis direction; until the surface treatment of the first area to be surface treated on the workpiece is completed, and then turn off the power supply.

[0055] The above electrochemical surface treatment device is used for surface treatment such as electrolytic polishing, electroplating, and surface passivation of the workpiece surface. Since the first surface treatment unit includes a first working liquid layer and a first protective liquid layer stacked from top to bottom to form a layered solution electrochemical surface treatment, the potential difference on the reaction surface can be reduced, the surface treatment uniformity is high, the surface of the workpiece is flat after treatment, and the structural size changes in different areas on the surface are small. In addition, through the setting of the above surface treatment unit, the electrochemical polishing device can achieve the regulation of different surface treatment rates by changing parameters such as the concentration of the first working liquid, the thickness of the first working liquid layer, and the movement rate of the workpiece; in addition, the electrochemical surface treatment device can reduce the amount of working liquid (such as electrolyte) used, reduce costs, and has a simple structure, is easy for users to operate, and can reduce the driving voltage and current, which is safe and reliable.

[0056] Accordingly, the present invention also provides an electrochemical surface treatment process, which comprises the following steps:

[0057] S1, injecting a first protective liquid and a first working liquid into an insulating container in sequence, wherein the first protective liquid and the first working liquid are immiscible, and the density of the first working liquid is less than the density of the first protective liquid, and standing until the solution is stratified, thereby forming a first surface treatment unit including a first working liquid layer and a first protective liquid layer stacked from top to bottom in the insulating container;

[0058] Alternatively, a first protective liquid and a first separating liquid are sequentially injected into the insulating container, the first protective liquid and the first separating liquid are immiscible, and the density of the first separating liquid is less than the density of the first protective liquid, and after standing until the solution is separated into layers, a first working liquid is slowly injected into the insulating container, the first working liquid and the first separating liquid are also immiscible, and the density of the first working liquid is less than the density of the first separating liquid, and the solution is allowed to stand until the solution is separated, thereby forming a first surface treatment unit including a first working liquid layer, a first separating layer, and a first protective liquid layer stacked from top to bottom in the insulating container;

[0059] S2, connect an electrode to the negative electrode of the power supply, and insert the electrode into the first working liquid layer;

[0060] S3, connecting the workpiece to the positive electrode of the power supply, and then inserting the workpiece into the first working liquid layer with the electrode spaced apart, and starting the power supply when the workpiece contacts the first working liquid layer; specifically, generally inserting the workpiece into the first working liquid layer with the electrode spaced apart and parallel to the electrode;

[0061] S4. Control the workpiece to move along the Z-axis direction according to the surface treatment requirements of the workpiece, or move along the Z-axis direction and at least one of the X-axis direction and the Y-axis direction; until the surface treatment of the first area to be surface treated on the workpiece is completed, and then turn off the power.

[0062] Schematic diagram of the material removal principle of the sample surface during electrochemical polishing Figure 2 As shown, Figure 2 The middle slime layer is a thin layer formed on the workpiece surface after the electrochemical polishing reaction occurs. Figure 2 As shown, the electrochemical polishing reaction uses the difference in dissolution rate between the raised area and the flat area on the surface to achieve surface smoothness.

[0063] Specifically, the microfluidic tungsten mold is electrochemically polished according to a process similar to the above, and the specific process includes:

[0064] 1) Wash a 900 mL glass beaker with deionized water and dry it, then place it on a horizontal table as an electrolytic cell;

[0065] 2) Pour 800 mL of nonafluorobutyl methyl ether into the electrolytic cell; prepare a NaOH solution with a mass fraction of 0.5%, and pour the NaOH solution into the electrolytic cell containing nonafluorobutyl methyl ether. Since the two solutions are immiscible and have a large density difference, the NaOH solution with a smaller density floats on the nonafluorobutyl methyl ether, and the thickness of the NaOH solution is 10 mm by controlling the volume of the poured NaOH solution; after the layered solution is prepared, let it stand for 10 minutes to allow the two solutions to be fully layered, and the upper NaOH solution is the electrolyte layer (i.e., the working liquid layer); the lower nonafluorobutyl methyl ether is the protective liquid layer;

[0066] 3) Place the workpiece (microfluidic tungsten mold, such as Figure 3 and Figure 4 The upper end of the workpiece is connected to the positive pole of the power supply and connected to the drive assembly by clamping, and the connected workpiece is suspended vertically above the electrolyte layer. The platinum electrode (as the cathode) is immersed in the electrolyte layer, and the other end is connected to the negative pole of the power supply through a copper rod wrapped in insulating plastic.

[0067] 4) Set the output voltage and limit current of the power supply. The current during the polishing process is less than the limit current value, which plays a role in protecting the current loop; control the workpiece to move downward at a uniform speed of 40μm / s through the drive component; start the power supply for electrochemical polishing reaction when the workpiece contacts the electrolyte layer, and turn off the power supply to stop the electrochemical polishing reaction when the workpiece completely passes through the upper electrolyte layer (the downward movement distance is 56mm). At this time, the workpiece will stop after continuing to move a short distance.

[0068] 5) When the power is turned off and the workpiece stops moving, take out the workpiece, ultrasonically clean it with alcohol for 5 minutes, rinse it with deionized water for 1 minute, and then blow it dry with nitrogen.

[0069] 6) Since one dynamic polishing did not completely remove the surface defects of the workpiece, polishing was performed 10 times according to the above similar operations to obtain a smooth surface.

[0070] In order to investigate the polishing effect, the contour change and morphology change of the workpiece surface were studied respectively. The contour change measurement was used to understand the change of characteristic dimensions (height H and width X of the cross section) and whether the contour changes of different parts are uniform; and the morphology change measurement was used to understand whether the surface defects of the workpiece surface are effectively removed after polishing.

[0071] Among them, for the study of the morphological changes of the workpiece, a scanning electron microscope was used to observe the three sites a, b, and c on the surface of the workpiece before and after polishing (such as Figure 3 The morphology was measured and the results were shown in Figure 5 and Figure 6 As shown, Figure 5(a), (b), and (c) are SEM images of the workpiece surface at sites a, b, and c before polishing, respectively. (a-1), (b-1), and (c-1) are the enlarged images of (a), (b), and (c), respectively. Figure 6 (a), (b), and (c) are SEM images of three sites a, b, and c on the workpiece surface after polishing, respectively. (a-1), (b-1), and (c-1) are enlarged images of the corresponding (a), (b), and (c), respectively.

[0072] Depend on Figure 5 It can be seen that the surface defects of the workpiece before polishing are due to the surface defects introduced by the initial machining; Figure 6 It can be seen that after the above 10 times of layered solution dynamic electrochemical polishing, the defects on the workpiece surface were effectively removed, the surface became smooth and obvious grain boundaries could be seen.

[0073] For the profile change of the workpiece surface, a surface profiler was used to measure the three positions a, b, and c of the workpiece surface before polishing and after polishing 3, 6, and 10 times (e.g. Figure 3 In addition, in order to compare the role of the above electrochemical polishing method in optimizing the uniformity of material removal, the traditional electrochemical polishing method (filling the above electrolyte in the electrolytic cell for immersion electrolytic polishing) was also used to perform 10 polishings according to the corresponding time, and the same method was used to measure the changes in the contour curves of three locations on the workpiece surface before polishing and after polishing 3 times, 6 times, and 10 times respectively. Through the above experiments, the contour changes of the workpiece surface using layered solution dynamic electrochemical polishing and traditional electrochemical polishing were compared and analyzed, and the results are shown in the figure below. Figure 7 and Figure 8 As shown, Figure 7 (a), (b), and (c) are the contour changes of the workpiece surface at three locations a, b, and c using the traditional electrochemical polishing process. Figure 8 (a), (b), and (c) are the contour changes of the workpiece surface at three locations a, b, and c during the dynamic electrochemical polishing process using a layered solution. Figure 7 and Figure 8 ΔHm represents the height change, and ΔWm represents the half-height width change.

[0074] Depend on Figure 7 It can be seen that the maximum change in the height of the characteristic structure during traditional electrochemical polishing is 15.9μm, the minimum change is 7.7μm, and the difference between the two is 8.2μm. The maximum change in width is 85.9μm, the minimum change is 62.4μm, and the difference between the two is 23.5μm. This shows that the material removal amount at different sites in traditional electrochemical polishing is quite different, and the polishing uniformity is not good.

[0075] Depend on Figure 8 It can be seen that the maximum change in the height of the characteristic structure during the above layered solution dynamic electrochemical polishing process is 4.9μm, and the minimum change is 4.3μm, and the difference between the two is within 1μm. The maximum change in width is 81.5μm, and the minimum change is 73.0μm. The difference between the two is 8.5μm, which is less than 10μm. It can be seen that the layered solution dynamic electrochemical polishing method used in this application has greatly improved the uniformity of material removal compared to traditional electrochemical polishing.

[0076] From the above, by using the above layered solution dynamic electrochemical polishing method to polish the workpiece, a smooth surface can be obtained, and the material removal rate in different areas is basically the same; through the above polishing treatment, the size change difference in different areas of the workpiece surface is reduced to within 10μm, and the surface roughness Sa is reduced from 200nm before polishing to 5nm.

[0077] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An electrochemical surface treatment device, characterized in that: include: An insulating container, wherein a surface treatment module is provided in the insulating container, wherein the surface treatment module comprises a first surface treatment unit, wherein the first surface treatment unit comprises a first working liquid layer and a first protective liquid layer stacked from top to bottom, wherein the first working liquid layer is composed of a first working liquid, and the first protective liquid layer is composed of a first protective liquid; the thickness of the first working liquid layer is less than the height of the area to be surface treated on the workpiece, and the sum of the thickness of the first working liquid layer and the first protective liquid layer is greater than or equal to the height of the area to be surface treated on the workpiece; A power source, the power source having a positive electrode and a negative electrode; the positive electrode is used to connect to the workpiece; Electrodes, the electrodes are respectively connected to the first working liquid layer and the negative electrode of the power supply; The first surface treatment is electrolytic polishing, the first working liquid is an electrolyte, and the electrolyte is selected from at least one of potassium hydroxide solution, sodium hydroxide solution, sodium tartrate solution, and potassium tartrate solution; the first protective liquid is nonafluorobutyl methyl ether, carbon tetrachloride or trichloroethane; The electrochemical surface treatment device further comprises a driving assembly, wherein the driving assembly is used to drive the workpiece to move along the Z-axis direction, or along at least one of the X-axis direction and the Y-axis direction and the Z-axis direction; The first surface treatment unit is used to perform a first surface treatment on the workpiece, and the first surface treatment is electrolytic polishing.

2. The electrochemical surface treatment device according to claim 1, characterized in that: The first working liquid and the first protective liquid are immiscible, and the density of the first working liquid is less than the density of the first protective liquid; Alternatively, the first surface treatment unit also includes a first separation layer composed of a first separation liquid, the first separation layer is arranged between the first working liquid layer and the first protective liquid layer, the first separation liquid is immiscible with the first working liquid and the first protective liquid respectively, the density of the first working liquid is less than the density of the first separation liquid, and the density of the first separation liquid is less than the density of the first protective liquid.

3. The electrochemical surface treatment device according to claim 1, characterized in that: The thickness of the first protective liquid layer is greater than or equal to the height of the area to be surface treated on the workpiece.

4. The electrochemical surface treatment device according to claim 1, characterized in that: The surface treatment module also includes a second surface treatment unit stacked with the first surface treatment unit, the second surface treatment unit includes a second working liquid layer and a second protective liquid layer stacked from top to bottom, the second working liquid layer is composed of a second working liquid, and the second protective liquid layer is composed of a second protective liquid.

5. The electrochemical surface treatment device according to claim 4, characterized in that: The second surface treatment unit is used to perform a second surface treatment on the workpiece, and the second surface treatment is any one of electrolytic polishing, electroplating, and surface passivation.

6. The electrochemical surface treatment device according to any one of claims 1 to 5, characterized in that: The electrochemical surface treatment device further comprises an ammeter and / or a voltmeter, wherein the ammeter is connected in series with the power source, and the voltmeter is connected in parallel with the power source.

7. An electrochemical surface treatment process using the electrochemical surface treatment device according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, injecting a first protective liquid and a first working liquid into an insulating container in sequence, wherein the first protective liquid and the first working liquid are immiscible, and the density of the first working liquid is less than the density of the first protective liquid, and standing until the solution is stratified, thereby forming a first surface treatment unit including a first working liquid layer and a first protective liquid layer stacked from top to bottom in the insulating container; Alternatively, a first protective liquid and a first separating liquid are sequentially injected into the insulating container, wherein the first protective liquid and the first separating liquid are immiscible, and the density of the first separating liquid is less than the density of the first protective liquid, and after standing until the solution is stratified, a first working liquid is slowly injected into the insulating container, wherein the first working liquid and the first separating liquid are immiscible, and the density of the first working liquid is less than the density of the first separating liquid, and after standing until the solution is stratified, a first surface treatment unit including a first working liquid layer, a first separating layer, and a first protective liquid layer stacked from top to bottom is formed in the insulating container; S2, connecting an electrode to the negative electrode of a power source, and inserting the electrode into the first working liquid layer; S3, connecting the workpiece to the positive electrode of the power supply, and then inserting the workpiece into the first working liquid layer with the electrode between them, and starting the power supply when the workpiece contacts the first working liquid layer; S4. Control the workpiece to move along the Z-axis direction according to the surface treatment requirements of the workpiece, or to move along the Z-axis direction and at least one of the X-axis direction and the Y-axis direction; until the surface treatment of the area to be surface treated on the workpiece is completed, and then turn off the power supply.

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