Method for etching micro-nano structure on surface of curved stainless steel

Abstract

The invention provides a method for etching a micro-nano structure on the surface of curved stainless steel. Comprising the following steps: 1, sandblasting a stainless steel substrate; step 2, preparing an etching solution; 3, preparing a cathode motor; step 4, etching the stainless steel substrate; and step 5, ultrasonic-assisted treatment. According to the method, a stable current path is formed through the self-electricity-generating chemical reaction of the stainless steel curved sheet and the carbon nano tube, oxidation dissolution of anode metal Fe, Cr and the like is accelerated, meanwhile, hydrogen ions on the surface of the cathode are efficiently reduced, and the etching kinetics is remarkably improved; besides, a traditional external power supply device is replaced by self-polarization potential generated by a primary battery effect, so that the process energy consumption is remarkably reduced, and the problem of etching uniformity caused by surface curvature difference of a curved surface component is effectively solved by adopting a collaborative etching scheme of a cathode profiling electrode and ultrasonic assistance; compared with a traditional etching system containing chromic acid or nitric acid, the method has the advantage that the pollution risk to the environment is remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel surface treatment, and in particular to a method for etching micro-nano structures on curved stainless steel surfaces. Background Art

[0002] Stainless steel is widely used in both industrial and consumer applications due to its excellent processability, high toughness, corrosion resistance, and excellent overall physical properties. However, while its outstanding corrosion resistance offers advantages, it also makes it difficult to achieve effective surface treatment with conventional chemical etchants. Etching solutions containing highly polluting chemicals such as chromic acid and nitric acid, commonly used in traditional processes, while effective in terms of etching efficiency, pose multiple environmental risks. Firstly, toxic gases emitted during the production process can cause atmospheric pollution, and secondly, non-compliant discharge of treated wastewater poses a serious threat to aquatic ecosystems. Furthermore, these chemical etching processes require complex post-processing purification of residual acidic and heavy metal components, significantly increasing production costs and hindering their effectiveness in meeting increasingly stringent environmental standards. Consequently, driven by the "dual carbon" strategic goals and the global concept of sustainable development, the development of new, environmentally friendly etching technologies that meet the demands of stainless steel processing while adhering to the principles of green chemistry has become a critical and pressing challenge in the field of surface engineering.

[0003] Curved stainless steel components often experience significant differences in etching solution flow rate and contact time across different curvature regions (e.g., concave and convex surfaces), leading to uneven etching depths and localized accumulation or loss of etching solution, impacting the etching effect. Furthermore, due to the varying shapes and sizes of components with varying curvatures, parameters such as etching time and temperature must be adjusted in real time to the curved surface, making traditional flat etching processes difficult to directly apply. Therefore, developing an etching method for stainless steel with varying curvatures is crucial and holds significant practical value. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for etching micro-nano structures on the surface of curved stainless steel.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention relates to a method for etching micro-nano structures on a curved stainless steel surface, comprising the following steps:

[0007] Step 1, sandblasting of the stainless steel substrate: sandblasting is performed on the surface of the curved stainless steel to increase the roughness of the curved stainless steel surface, thereby obtaining a rough structure stainless steel sample;

[0008] Step 2, preparing the etching solution: taking the rough structure stainless steel sample prepared above, preparing a dilute hydrochloric acid solution as the etching medium;

[0009] Step 3, cathode motor preparation: Prepare a three-dimensional porous structure cathode of carbon nanotubes, and prepare a cathode electrode of the same shape and size according to the shape and size of the anode electrode. A template method can be used to guide the growth of carbon nanotubes using a porous template (such as foam metal or polymer template) to produce a cathode electrode with the same shape as the curved stainless steel surface; or 3D printing technology can be used to directly print the carbon nanotube slurry into a complex three-dimensional structure to produce a cathode electrode with the same shape as the curved stainless steel surface;

[0010] Step 4, etching treatment of the stainless steel substrate: The stainless steel sample is used as the anode and the carbon nanotube electrode is used as the cathode. The metal sheet and the carbon nanotube electrode are connected to form a path in the etching solution to carry out the etching reaction, thereby converting the acid etching into a galvanic cell reaction.

[0011] Step 5, ultrasonic assisted treatment: ultrasonic assistance is used during the etching process to accelerate the etching rate.

[0012] Preferably, step 1 further includes: pre-treating the stainless steel base material before sandblasting the stainless steel base; wherein the pre-treatment includes grinding, degreasing, cleaning, and drying the base material.

[0013] Preferably, in step 1, the sandblasting treatment is specifically as follows: the pretreated stainless steel sample is fixed on the surface of a steel plate with an inclination angle of 30°, the nozzle is fixed directly facing the sample at a distance of 50 cm from the sample, and the sample is sandblasted using 120 mesh corundum particles under a pressure of 0.8 MPa, and the treatment time is continuous for 10 to 30 seconds.

[0014] Preferably, in step 1, the curvature radius of the curved stainless steel is 20 to 80 mm.

[0015] Preferably, in step 1, the size of the curved stainless steel is 30*30 mm, and the thickness is 0.2-1 mm.

[0016] Preferably, step 1 further comprises: after sandblasting the surface of the curved stainless steel, placing the stainless steel sample in deionized water for ultrasonic cleaning for 20 to 30 minutes.

[0017] Preferably, in step 2, the molar concentration of the dilute hydrochloric acid solution is 2.5 to 3 mol / L. The chloride ions released by hydrochloric acid in the etching system form soluble complexes with metals due to their strong coordination ability, significantly enhancing the efficiency of the etching solution in dissolving the metal. On the other hand, the hydrogen ions generated by dissociation effectively lower the pH value of the system and can also specifically improve the etching kinetics of metals such as nickel and chromium.

[0018] Preferably, in step 4, the etching reaction time is 10 to 15 minutes and the temperature is 25 to 40°C.

[0019] The main chemical reaction equation of the etching reaction is as follows:

[0020] Fe+HCl=FeCl2+H2

[0021] 2FeCl2+H2O2+2HCl=2FeCl3+2H2O

[0022] Ni + 2HCl = NiCl2 + H2

[0023] 2Cr+6HCl=2CrCl3+3H2

[0024] The products after the etching reaction of the present invention are metal salts that can be removed by precipitation, and non-toxic and non-corrosive water and hydrogen. Compared with the method using fluoride, chromic acid and nitric acid, it is more friendly to the environment and operators.

[0025] Preferably, in step 5, the frequency of the ultrasonic wave is 20 to 40 kHz, and the duration is 10 to 15 minutes.

[0026] The present invention has the following advantages:

[0027] (1) The present invention forms a stable current path through the self-generated chemical reaction between the stainless steel curved sheet and the carbon nanotubes, accelerates the oxidation and dissolution of the anode metals such as Fe and Cr, and at the same time efficiently reduces the hydrogen ions on the cathode surface, significantly improving the etching kinetics. In addition, the present invention replaces the traditional external power supply device with the self-polarization potential generated by the galvanic cell effect, significantly reducing the process energy consumption and avoiding the etching uniformity problem caused by power supply fluctuations.

[0028] (2) When the etching solution of the present invention is used to process curved stainless steel samples, the reaction products are mainly metal salts that can be precipitated and separated, and environmentally friendly by-products (water and hydrogen). Efficient separation of the products can be achieved through a simple precipitation method. Compared with traditional etching systems containing chromic acid or nitric acid, the present invention significantly reduces the risk of environmental pollution.

[0029] (3) The present invention prepares a three-dimensional carbon nanotube network structure electrode with the same size and dimensions as the anode as the cathode, so that during the etching process, the anode and cathode have the same contact area with the etching solution, reducing the local current density difference, making the electric field distribution more uniform, and the current density tends to be consistent on the anode surface, which is conducive to achieving uniform etching; the symmetrical electrode design of the present invention can also reduce the current concentration in the ineffective area and improve the energy utilization rate of the effective etching area.

[0030] (4) The present invention uses ultrasonic assistance during the etching process to produce acoustic streaming and cavitation effects. Ultrasonic waves induce high-frequency vibrations in the liquid, forming macroscopic eddies and microscale turbulence, enhancing solution mixing, reducing the thickness of the diffusion layer, and accelerating the transport of reactants to the material surface and the removal of products. At the same time, cavitation bubbles are formed in the ultrasonic negative pressure area. When the bubbles collapse, local high temperature and high pressure are released, generating microjets and shock waves, destroying the oxide layer on the surface of the material or directly breaking chemical bonds, thereby promoting etching. Ultrasonic waves also increase the temperature of the solution, and the etching rate can be increased to a certain extent by controlling parameters such as frequency and time.

[0031] (5) The present invention achieves efficient, uniform, and low-cost etching of stainless steel surfaces through the innovation of primary cell reaction and electrode structure, breaking through the kinetic limitations of traditional pickling processes and forming a green surface treatment system with self-regulating functions. The core advantage of the present invention is that it transforms the electrochemical corrosion mechanism into a controllable process, which is both environmentally friendly and industrially adaptable. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a process flow chart of a method for etching micro-nano structures on curved stainless steel surfaces according to the present invention;

[0033] Figure 2 is an SEM image of the sandblasted area of the curved stainless steel in Example 1;

[0034] Figure 3 is an SEM image of the etched area of the curved stainless steel with a curvature radius of 20 mm in Example 1;

[0035] Figure 4 is an SEM image of the etched area of the curved stainless steel with a curvature radius of 30 mm in Example 2;

[0036] Figure 5 is an SEM image of the etched area of the curved stainless steel with a curvature radius of 40 mm in Example 3;

[0037] Figure 6 This is the EDS image of the curved stainless steel etched area with a curvature radius of 40 mm in Example 3. DETAILED DESCRIPTION

[0038] The present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments are only for further explanation of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] This embodiment relates to a method for etching micro-nanostructures on curved stainless steel surfaces. Figure 1 As shown, the following steps are included:

[0041] Step 1: Pre-treat the curved stainless steel surface

[0042] Polishing: The stainless steel sample was polished with 600 mesh, 1000 mesh, 2000 mesh, and 5000 mesh SiC sandpaper in sequence;

[0043] A curved stainless steel sheet with a thickness of 0.2 mm and a curvature radius of 20 mm is used as the base material. 304 stainless steel has excellent mechanical properties.

[0044] Degreasing: After polishing, the curved stainless steel sample is placed in anhydrous ethanol and acetone for ultrasonic cleaning in turn, each cleaning time is 10 to 15 minutes, and then taken out and dried at 60 to 80 ° C to remove surface grease and debris.

[0045] Step 2: Sandblast the curved stainless steel surface

[0046] The cleaned stainless steel sample was fixed on the surface of a steel plate with an inclination angle of 30°. The nozzle was fixed at a distance of 50 cm from the sample and the sample was sandblasted with 120-mesh corundum particles under a pressure of 0.8 MPa. The sandblasting duration was 10 to 30 seconds. After the sandblasting, the stainless steel sample was ultrasonically cleaned in deionized water for 20 to 30 minutes to remove surface impurities.

[0047] like Figure 2 As shown in the figure, after sandblasting, the surface of the stainless steel becomes grooved and the surface roughness is greatly increased. The sandblasted area is flat and the roughness is uniform.

[0048] Step 3: Etch the curved stainless steel surface

[0049] Prepare 100 ml of dilute hydrochloric acid etching solution with a hydrochloric acid concentration of 2.5-3 mol / L.

[0050] Step 4: Use 3D printing technology to directly print the carbon nanotube slurry into a three-dimensional structure with the same shape and size as the stainless steel sample to make a cathode electrode. The stainless steel sample is clamped on a polytetrafluoroethylene fixture as the anode, and the carbon nanotube electrode is used as the cathode. The metal sheet and the carbon nanotube electrode are connected and placed vertically in a low-concentration hydrochloric acid solution to form a path in the etching solution, converting the acid etching into a galvanic cell reaction.

[0051] Step 5: During the etching process, ultrasonic assistance is used. The ultrasonic frequency is 20-40 kHz and the time is 10-15 minutes. The stainless steel sample is etched in the etching solution for 10-15 minutes. The system temperature is controlled at 25-40°C. After the etching is completed, the stainless steel sample is ultrasonically cleaned in deionized water for 10 minutes. The pH value of the stainless steel etching solution is less than or equal to 2.

[0052] The micro-nanostructure of the etched stainless steel sample was observed using a scanning electron microscope.

[0053] like Figure 3 As shown in the figure, the surface roughness of the stainless steel increases greatly after etching, showing a rough and porous microscopic surface.

[0054] The surface structure has a large number of holes of different sizes and unevenness. The holes are densely distributed and relatively evenly distributed, with no obvious;

[0055] Local aggregation or sparse areas indicate that the etching process is relatively uniform in the entire observation area and the roughness is uniform.

[0056] Example 2

[0057] This embodiment relates to a method for etching micro-nanostructures on a curved stainless steel surface, comprising the following steps:

[0058] Step 1: Pre-treat the curved stainless steel surface

[0059] Polishing: The stainless steel sample was polished with 600 mesh, 1000 mesh, 2000 mesh, and 5000 mesh SiC sandpaper in sequence;

[0060] A curved stainless steel sheet with a thickness of 0.2 mm and a curvature radius of 30 mm is used as the base material. 304 stainless steel has excellent mechanical properties.

[0061] Degreasing: After polishing, the curved stainless steel sample is placed in anhydrous ethanol and acetone for ultrasonic cleaning in turn, each cleaning time is 10 to 15 minutes, and then taken out and dried at 60 to 80 ° C to remove surface grease and debris.

[0062] Step 2: Sandblast the curved stainless steel surface

[0063] The cleaned stainless steel sample was fixed on the surface of a steel plate with an inclination angle of 30°. The nozzle was fixed at a distance of 50 cm from the sample and the sample was sandblasted with 120 mesh corundum particles under a pressure of 0.8 MPa. The sandblasting duration was 10 to 30 seconds. After the sandblasting, the stainless steel sample was ultrasonically cleaned in deionized water for 20 to 30 minutes to remove surface impurities.

[0064] Step 3: Etch the curved stainless steel surface

[0065] Prepare 100 ml of dilute hydrochloric acid etching solution with a hydrochloric acid concentration of 2.5-3 mol / L.

[0066] Step 4: Use 3D printing technology to directly print the carbon nanotube slurry into a three-dimensional structure with the same shape and size as the stainless steel sample to make a cathode electrode. The stainless steel sample is clamped on a polytetrafluoroethylene fixture as the anode, and the carbon nanotube electrode is used as the cathode. The metal sheet and the carbon nanotube electrode are connected and placed vertically in a low-concentration hydrochloric acid solution to form a path in the etching solution, converting the acid etching into a galvanic cell reaction.

[0067] Step 5: Ultrasonic assistance is used during the etching process. The ultrasonic frequency is 20-40 kHz and the time is 10-15 min. The stainless steel sample is etched in the etching solution for 10-15 min. The system temperature is controlled at 25-40°C. After etching, the stainless steel sample is placed in deionized water for ultrasonic cleaning for 10 min. The pH value of the stainless steel etching solution is less than or equal to 2.

[0068] The micro-nanostructure of the etched stainless steel sample was observed using a scanning electron microscope.

[0069] like Figure 4 As shown in the figure, the surface roughness of the stainless steel is greatly increased after etching, showing a rough and porous microscopic surface;

[0070] The surface structure has a large number of holes of different sizes and unevenness. The holes are densely distributed and relatively evenly distributed, with no obvious;

[0071] Local aggregation or sparse areas indicate that the etching process is relatively uniform in the entire observation area and the roughness is uniform.

[0072] Example 3

[0073] This embodiment relates to a method for etching micro-nanostructures on a curved stainless steel surface, comprising the following steps:

[0074] Step 1: Pre-treat the curved stainless steel surface

[0075] Polishing: The stainless steel sample was polished with 600 mesh, 1000 mesh, 2000 mesh, and 5000 mesh SiC sandpaper in sequence;

[0076] A curved stainless steel sheet with a thickness of 0.2 mm and a curvature radius of 40 mm is used as the base material. 304 stainless steel has excellent mechanical properties.

[0077] Degreasing: After polishing, the curved stainless steel sample is placed in anhydrous ethanol and acetone for ultrasonic cleaning in turn, each cleaning time is 10 to 15 minutes, and then taken out and dried at 60 to 80 ° C to remove surface grease and debris.

[0078] Step 2: Sandblast the curved stainless steel surface

[0079] The cleaned stainless steel sample was fixed on the surface of a steel plate with an inclination angle of 30°. The nozzle was fixed at a distance of 50 cm from the sample and the sample was sandblasted with 120 mesh corundum particles under a pressure of 0.8 MPa. The sandblasting duration was 10 to 30 seconds. After the sandblasting, the stainless steel sample was ultrasonically cleaned in deionized water for 20 to 30 minutes to remove surface impurities.

[0080] Step 3: Etch the curved stainless steel surface

[0081] Prepare 100 ml of dilute hydrochloric acid etching solution with a hydrochloric acid concentration of 2.5-3 mol / L.

[0082] Step 4: Using 3D printing technology, the carbon nanotube slurry is directly printed into a three-dimensional structure with the same shape and size as the stainless steel sample to make a cathode electrode; the stainless steel sample is clamped on a polytetrafluoroethylene fixture as the anode, and the carbon nanotube electrode is used as the cathode. The metal sheet and the carbon nanotube electrode are connected and placed vertically in a low-concentration hydrochloric acid solution to form a path in the etching solution, converting the acid etching into a galvanic cell reaction;

[0083] Step 5: Ultrasonic assistance is used during the etching process. The ultrasonic frequency is 20-40 kHz and the time is 10-15 min. The stainless steel sample is etched in the etching solution for 10-15 min. The system temperature is controlled at 25-40°C. After etching, the stainless steel sample is placed in deionized water for ultrasonic cleaning for 10 min. The pH value of the stainless steel etching solution is less than or equal to 2.

[0084] The micro-nanostructure of the etched stainless steel sample was observed using a scanning electron microscope.

[0085] like Figure 5 As shown in the figure, the surface roughness of the stainless steel is greatly increased after etching, showing a rough and porous microscopic surface;

[0086] The surface structure has a large number of holes of different sizes and unevenness. The holes are densely distributed and relatively evenly distributed, with no obvious;

[0087] Local aggregation or sparse areas indicate that the etching process is relatively uniform in the entire observation area and the roughness is uniform.

[0088] like Figure 6 As shown in the figure, during the etching process, the potential difference of Cr in the sample is the largest, so the etching solution reacts preferentially with Cr atoms, forming grooves on the etched surface due to the loss of Cr atoms. Some of the formed Cr salts adhere to the groove surface, so the grooves in the figure coincide with the distribution of Cr elements.

[0089] The present invention forms a stable current path through the self-generated electrochemical reaction between the stainless steel curved sheet and the carbon nanotubes, accelerating the oxidation and dissolution of anode metals such as Fe and Cr, while simultaneously efficiently reducing hydrogen ions on the cathode surface, significantly improving etching kinetics. Furthermore, the present invention replaces the traditional external power supply device with the self-polarization potential generated by the galvanic cell effect, significantly reducing process energy consumption while avoiding etching uniformity issues caused by power supply fluctuations. When the etching solution of the present invention is used to process curved stainless steel samples, its reaction products are mainly precipitable and separable metal salts and environmentally friendly byproducts (water and hydrogen), and efficient product separation can be achieved through a simple precipitation method. Compared with traditional etching systems containing chromic acid or nitric acid, the present invention significantly reduces the risk of environmental pollution.

[0090] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for etching micro-nanostructures on curved stainless steel surfaces, characterized in that: The following steps are involved: Step 1, sandblasting of the stainless steel substrate: sandblasting is performed on the surface of the curved stainless steel to increase the roughness of the curved stainless steel surface, thereby obtaining a rough structure stainless steel sample; Step 2, preparing the etching solution: taking the rough structure stainless steel sample prepared above, preparing a dilute hydrochloric acid solution as the etching medium; Step 3, cathode motor preparation: Prepare a three-dimensional porous carbon nanotube cathode, and use a porous template to guide the growth of carbon nanotubes to produce a cathode electrode that conforms to the shape of the curved stainless steel surface; or use 3D printing technology to directly print the carbon nanotube slurry into a complex three-dimensional structure to produce a cathode electrode that conforms to the shape of the curved stainless steel surface; Step 4, etching treatment of the stainless steel substrate: The stainless steel sample is used as the anode and the carbon nanotube electrode is used as the cathode. The metal sheet and the carbon nanotube electrode are connected to form a path in the etching solution to carry out the etching reaction, thereby converting the acid etching into a galvanic cell reaction. Step 5, ultrasonic assisted treatment: ultrasonic assistance is used during the etching process to accelerate the etching rate.

2. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: Step 1 also includes: pre-treating the stainless steel base material before sandblasting the stainless steel base; wherein the pre-treatment includes grinding, degreasing, cleaning, and drying the base material.

3. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 1, the sandblasting treatment is specifically as follows: the pretreated stainless steel sample is fixed on the surface of the steel plate with an inclination angle of 30°, the nozzle is fixed directly on the sample at a distance of 50 cm from the sample, and the sample is sandblasted using 120 mesh corundum particles under a pressure of 0.8 MPa, and the treatment time is continuous for 10 to 30 seconds.

4. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 1, the curvature radius of the curved stainless steel is 20 to 80 mm.

5. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 1, the size of the curved stainless steel is 30*30 mm and the thickness is 0.2-1 mm.

6. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: Step 1 further includes: sandblasting the surface of the curved stainless steel, and then placing the stainless steel sample in deionized water for ultrasonic cleaning for 20 to 30 minutes.

7. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 2, the molar concentration of the dilute hydrochloric acid solution is 2.5 to 3 mol / L.

8. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 4, the etching reaction time is 10 to 15 minutes, and the temperature is 25 to 40°C.

9. The method for etching micro-nanostructures on curved stainless steel surfaces according to claim 1, wherein: In step 5, the frequency of the ultrasonic wave is 20 to 40 kHz, and the time is 10 to 15 minutes.

Images