Metal corrosion protection method and device for 3D rapid spraying large-area polarization

Abstract

The invention discloses a metal corrosion protection method and device for 3D rapid spraying and large-area polarization. Based on a passivation interval in-situ film forming mechanism, the device adopts a cantilever type C-shaped frame integrated nozzle and a three-axis moving platform, a dynamic electrochemical cell is formed on the surface of the aircraft metal skin by locally spraying electrolyte, and the size limitation of a traditional electrolytic cell is broken through; the method is characterized in that large-scale adaptation is achieved, specifically, electrolyte jet flow is matched with a moving platform to achieve surface self-adaptive spraying, and passivation film forming on the surfaces of aircraft metal skins with various large-area sizes can be treated; the mass per unit area of the micron-sized film layer is smaller than or equal to 0.03 g / m < 2 >, the weight gain ratio is smaller than 0.005%, and the lightweight requirement of the aircraft is met; after a passivated film is formed, high-pressure continuous jet flow is adopted for conducting surface strengthening on the film layer, and the mechanical, mechanical, pneumatic and corrosion-resistant performance requirements of the aircraft metal skin are met; and rapid forming is conducted, specifically, the multiple nozzles are matched with the moving platform to achieve rapid forming of the passive film of the large-area aircraft metal skin.

Description

Technical Field

[0001] This invention relates to the field of aircraft metal skin protection technology, specifically to a 3D rapid spraying method and device for large-area active metal corrosion protection. Background Technology

[0002] Aircraft skin is a crucial component of aircraft, playing a vital role in bearing and transmitting aerodynamic loads during flight. Due to the complex forces and significant loads it experiences, coupled with direct contact with the external environment, it is susceptible to damage. This is particularly true for military aircraft, which are subjected to intense daily flight training and prolonged exposure to complex atmospheric environments characterized by salt spray, moisture, and mold. This makes aluminum alloys, the primary material for aircraft skin, highly prone to structural corrosion and fatigue cracking. If these early damages are not detected and addressed promptly, the combined effects of load and corrosive environment will rapidly propagate, leading to reduced skin strength and posing serious safety hazards for flight. Simultaneously, lightweight design is essential for aircraft to reduce weight, significantly impacting fuel efficiency, range, and economic viability—a core technological objective of the aviation industry.

[0003] Traditional electrochemical passivation relies on stationary electrolytic cells, and the size of aircraft metal skin is limited by the volume of the cell (usually ≤1m). 3 In chloride-containing environments, the coating is prone to pitting corrosion, exhibiting microcracks and tensile stress, and is susceptible to peeling under dynamic loads. More critically, current technologies cannot achieve metallurgically bonded protective layers at the submicron scale, leading to an imbalance between protection efficiency and material consumption, and affecting the lightweight requirements of aircraft metal skin due to coating weight limitations. These deficiencies severely restrict the lightweight design requirements of aircraft and the long-term reliable operation of aircraft metal skin under corrosive conditions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, a method and device for large-area metal corrosion protection using 3D rapid spraying is provided. By developing a novel surface protection technology that combines ultra-low porosity, high-strength bonding, environmental friendliness, lightweight design, strong wear resistance, and adaptability to ultra-large area components, the corrosion resistance of metals in harsh environments is improved.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a 3D rapid spraying method and device for large-area active metal corrosion protection, characterized by comprising the following steps: Step 1: Based on the in-situ film formation mechanism in the passivation zone, and considering the voltage and current density of the polarization curve of the aircraft metal skin in the electrolyte, the current and voltage of the high-frequency pulse power supply are set according to the requirements of corrosion protection; Step 2: Weighing the aircraft metal skin, fixing the aircraft metal skin on a cantilevered C-frame platform, connecting it to the positive terminal of the power supply, preparing the electrolyte, connecting the nozzle to the negative terminal of the power supply, and setting the three-axis moving platform motion control nozzle movement trajectory; Step 3: Opening the high-frequency pulse power supply... The high-frequency pulse power supply outputs current and voltage, opens the shut-off valve of the low-voltage reciprocating pump, closes the shut-off valve of the high-voltage reciprocating pump, and simultaneously sprays electrolyte locally through multiple nozzles to form a dynamic electrochemical cell on the surface of the aircraft metal skin; Step 4: After the passivation film is formed, the high-frequency pulse power supply is cut off, the shut-off valve of the low-voltage reciprocating pump is closed, and the shut-off valve of the high-voltage reciprocating pump is opened. The film layer is then surface-strengthened using a high-pressure continuous jet; the resulting aircraft metal skin surface is then polished to reduce the surface roughness and improve the surface mechanical, aerodynamic, and corrosion resistance properties, followed by surface cleaning and drying; finally, the aircraft metal skin with the passivation film on its surface is weighed.

[0006] Specifically, the current and voltage of the high-frequency pulse power supply are the maximum current and maximum voltage in the passivation range.

[0007] Specifically, the three-axis moving platform maintains an angle ≤5° between the nozzle axis and the normal of the aircraft metal skin surface, a moving speed of 1-10 mm / s, a spraying distance of 1-100 mm, a spraying flow rate of 50-3000 mL / min, a spraying pressure of 1-150 MPa, and a nozzle diameter of 0.1-1 mm.

[0008] Specifically, the multiple nozzles combined with the three-axis moving platform can achieve rapid forming of passivation films on large-area aircraft metal skin.

[0009] Specifically, the dynamic electrochemical cell can process the formation of passivation films on the surface of various large-area aircraft metal skins, breaking through the size limitations of traditional electrolytic cells.

[0010] Specifically, a passivation film with a thickness of 10-200 μm is formed on the surface of the aircraft's metal skin.

[0011] Specifically, the unit area mass of the micron-scale film layer is ≤0.03 g / m². 2 The weight gain rate is <0.005%.

[0012] Specifically, the surface roughness Ra of the aircraft metal skin is ≤0.3μm.

[0013] Specifically, the bonding strength between the passivation film and the aircraft metal skin is ≥20 N / mm.2 The passivation film wear rate is <0.2mg / 1000 rpm.

[0014] Specifically, the corrosion current density of the aircraft metal skin with passivation film is reduced by 90%-99% compared to that without passivation film; the self-corrosion potential of the aircraft metal skin with passivation film is shifted positively by 100mV-1000mV compared to that without passivation film.

[0015] Specifically, the electrolyte is 0.01-1 mol / L ethylene glycol.

[0016] The present invention also protects the 3D rapid spraying method and apparatus for large-area active metal corrosion protection as described above for use in aerospace vehicles that require lightweighting, enhanced surface properties, and large-size, full-area corrosion resistance, such as aircraft wings.

[0017] The beneficial effects of this invention are as follows:

[0018] (I) Through electrochemical analysis and testing, the self-corrosion potential of aircraft metal skin with passivation film shifts positively, the corrosion current density decreases, and the corrosion resistance is significantly improved.

[0019] (II) The mobile local spray electrolyte forms a dynamic electrochemical cell, breaking through the size limitations of traditional electrolytic cells, and can process the formation of passivation films on the surface of various large-area aircraft metal skins.

[0020] (III) Compared with other metal surface protection technologies, the unit area mass of the micron-level film layer is ≤0.03 g / m². 2 The weight gain ratio is less than 0.005%, which meets the requirements for lightweight aircraft.

[0021] (IV) The passivation film has a wear rate of <0.2mg / 1000 rpm and excellent wear resistance; the bonding strength and fatigue strength are significantly improved; zero pollution emissions are achieved; and energy consumption is significantly reduced compared with surface protection technologies such as thermal spraying.

[0022] (V) Multiple nozzles combined with a three-axis moving platform can achieve rapid forming of passivation film on large-area aircraft metal skin. Attached Figure Description

[0023] Figure 1 A model diagram of the film formation mechanism in the passivation region of aircraft metal skin;

[0024] Figure 2 A schematic diagram of a metal corrosion protection device for large-area 3D rapid spraying.

[0025] Figure 3 This is a schematic diagram of the device structure for electrochemical analysis and testing;

[0026] Figure 4A schematic diagram of the process for spraying the skin of an aircraft wing surface;

[0027] Figure 5 This is a schematic diagram of the polarization curve of 2024-T3 aluminum alloy;

[0028] In the diagram: 1-Aircraft metal skin; 2-Passivation film; 3-Platform for fixing aircraft metal skin; 4-Low-pressure reciprocating pump; 5-Electrolytic cell; 6-Filter; 7-Stop valve; 8-High-pressure reciprocating pump; 9-Booster; 10-High-frequency pulse power supply; 11-Pressure gauge; 12-Nozzle; 13-Computer; 14-Industrial control computer; 15-Three-axis moving platform; 16-Electrolyte tank; 17-Working electrode; 18-Reference electrode; 19-Counter electrode; 20-Power supply for electrochemical workstation; 21-Aircraft wing; 22-Fixed bracket; 23-Active dissolution zone; 24-Passivation zone; 25-Overpassivation zone. Detailed Implementation

[0029] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0030] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0031] Example 1:

[0032] Combination Figure 1 , Figure 2 and Figure 5 This embodiment provides a method and apparatus for large-area active metal corrosion protection using 3D rapid spraying. The method specifically includes the following steps:

[0033] Step 1: Based on the voltage and current density of the passivation range (24) of the polarization curve of the 2024-T3 aluminum alloy (1) used to make aircraft skin in 0.01-1 mol / L ethylene glycol electrolyte, set the current and voltage of the high-frequency pulse power supply (10) to the maximum value of the passivation range (24).

[0034] Step 2: Weigh the 2024-T3 aluminum alloy (1), fix the 2024-T3 aluminum alloy (1) with a length, width and height of 5m×1m×0.3m on the cantilever C-shaped frame platform (3), connect it to the positive terminal of the power supply (10), prepare ethylene glycol electrolyte, connect the nozzle (12) to the negative terminal of the power supply (10), and set the motion control of the three-axis moving platform (15) to control the motion trajectory of the nozzle (12);

[0035] Step 3: Turn on the high-frequency pulse power supply (10) to output current and voltage, open the shut-off valve (7) of the low-pressure reciprocating pump (4), close the shut-off valve (7) of the high-pressure reciprocating pump (8), and at the same time, spray 0.01-1mol / L ethylene glycol electrolyte locally through multiple nozzles (12) to form a dynamic electrochemical cell on the surface of 2024-T3 aluminum alloy (1). Control the current range of the high-frequency pulse power supply (10) to be -5-5A and the voltage range to be -10-10V, the moving speed of the three-axis moving platform (15) to be 1-10mm / s, the spraying distance to be 20-100mm, the spraying flow rate to be 50-200mL / min, and the spraying pressure to be 1-10MPa to maintain the optimal passivation state.

[0036] Step 4: After the passivation film (2) is formed, cut off the high-frequency pulse power supply (10), close the shut-off valve (7) of the low-pressure reciprocating pump (4), open the shut-off valve (7) of the high-pressure reciprocating pump (8), and use high-pressure continuous jet to strengthen the surface of the film layer. The film layer thickness is 10-200μm, the spraying distance is 1-100mm, the spraying flow rate is 0.2-3L / min, the spraying pressure is 10-150MPa, and the nozzle diameter is 0.1-1mm to maintain the optimal surface strengthening state.

[0037] Step 5: Polish the surface of the obtained 2024-T3 aluminum alloy (1) to reduce the surface roughness Ra≤0.3μm and stop polishing to improve the surface mechanical, mechanical, aerodynamic and corrosion resistance properties. Take out the 2024-T3 aluminum alloy (1) for surface cleaning and drying, and then weigh the 2024-T3 aluminum alloy (1) with passivation film (2) on the surface.

[0038] Example 2:

[0039] Combination Figure 3 This embodiment provides a method for testing the corrosion resistance of 2024-T3 aluminum alloy with a passivation film on its surface in HCl. The method specifically includes the following steps:

[0040] In this embodiment, steps one, three, four, and five are exactly the same as steps one, three, four, and five in embodiment 1.

[0041] Step 2: Weigh the 2024-T3 aluminum alloy (1), fix the 2024-T3 aluminum alloy (1) with a length, width and height of 10mm×5mm×1mm on the platform (3) of the cantilever C-shaped frame, connect it to the positive terminal of the power supply (10), prepare the ethylene glycol electrolyte, connect the nozzle (12) to the negative terminal of the power supply (10), and set the motion control of the three-axis moving platform (15) to control the motion trajectory of the nozzle (12);

[0042] Step Six: Perform electrochemical analysis and testing. The electrochemical experiment uses a three-electrode system: a saturated calomel electrode as the reference electrode (18), a platinum sheet electrode as the counter electrode (19), and a working electrode (17) made of 2024-T3 aluminum alloy (1). First, the open circuit potential is tested. A 0.5 mol / L HCl aqueous solution is selected as the test solution, the temperature is 25℃, and the test time lasts for 120 minutes.

[0043] Step 7: Using the potentiodynamic scanning method, a linear scanning signal is used to control a potentiostat, causing the electrode potential to change linearly and continuously. Simultaneously, the polarization current is measured, and a polarization curve is plotted. The scanning voltage range is -8 to 3V, and the scanning rate is 1mV / s.

[0044] Example 3:

[0045] This embodiment provides a method for testing the corrosion resistance of 2024-T3 aluminum alloy with a passivation film on its surface in H2SO4. The method specifically includes the following steps:

[0046] In this embodiment, steps one, two, three, four, five, and seven are exactly the same as steps one, two, three, four, five, and seven in embodiment 2.

[0047] Step Six: Electrochemical analysis and testing were performed. The electrochemical experiment used a three-electrode system: a saturated calomel electrode as the reference electrode (18), a platinum sheet electrode as the counter electrode (19), and a working electrode (17) made of 2024-T3 aluminum alloy (1). First, the open circuit potential was tested. A 0.5 mol / L H2SO4 aqueous solution was selected as the test solution, the temperature was 25℃, and the test lasted for 120 minutes.

[0048] Example 4:

[0049] This embodiment provides a method for testing the corrosion resistance of 2024-T3 aluminum alloy with a passivation film on its surface in NaCl. The method specifically includes the following steps:

[0050] In this embodiment, steps one, two, three, four, five, and seven are exactly the same as steps one, two, three, four, five, and seven in embodiment 2.

[0051] Step Six: Electrochemical analysis and testing were performed. The electrochemical experiment used a three-electrode system: a saturated calomel electrode as the reference electrode (18), a platinum sheet electrode as the counter electrode (19), and a working electrode (17) made of 2024-T3 aluminum alloy (1). First, the open circuit potential was tested using a 0.6 mol / L NaCl aqueous solution as the test solution at a temperature of 25°C for 120 minutes.

[0052] Example 5:

[0053] To illustrate the advantages of this invention for corrosion protection and strengthening of complex curved surfaces and large-area surfaces, combined with Figure 4 This embodiment provides a method and device for metal corrosion protection of large areas of aircraft wings using ultra-fast 3D spraying. The method is basically the same as that in embodiment 1, except that the aircraft wing (21) is used instead of 2024-T3 aluminum alloy (1).

[0054] Comparative Example 1:

[0055] This comparative example presents a method for testing the corrosion resistance of 2024-T3 aluminum alloy in HCl. The method specifically includes the following steps:

[0056] Step 1: Electrochemical analysis and testing were performed. The electrochemical experiment used a three-electrode system: a saturated calomel electrode as the reference electrode (18), a platinum sheet electrode as the counter electrode (19), and a working electrode (17) made of 2024-T3 aluminum alloy (1). First, the open circuit potential was tested. A 0.5 mol / L HCl aqueous solution was selected as the test solution, the temperature was 25℃, and the test lasted for 120 minutes.

[0057] Step 2: Using the potentiodynamic scanning method, a linear scanning signal is used to control a potentiostat, causing the electrode potential to change linearly and continuously. Simultaneously, the polarization current is measured, and a polarization curve is plotted. The scanning voltage range is -8 to 3V, and the scanning rate is 1mV / s.

[0058] Comparative Example 2:

[0059] This comparative example provides a method for testing the corrosion resistance of 2024-T3 aluminum alloy in H2SO4. The method is basically the same as that of Comparative Example 1, except that the test solution is a 0.5 mol / L aqueous solution of H2SO4.

[0060] Comparative Example 3:

[0061] This comparative example provides a method for testing the corrosion resistance of 2024-T3 aluminum alloy in NaCl. This method is basically the same as that of Comparative Example 1, except that the test solution is a 0.6 mol / L NaCl aqueous solution.

[0062] Comparing the results of three examples and three comparative examples, it can be seen that by generating a passivation film through the in-situ film formation mechanism in the passivation zone (24), the corrosion performance of 2024-T3 aluminum alloy (1) is significantly improved: the corrosion current density of 2024-T3 aluminum alloy (1) with passivation film in 0.5mol / L HCl, 0.5mol / L H2SO4, and 0.6mol / L NaCl is 90% lower than that of 2024-T3 aluminum alloy (1) without passivation film. The corrosion rate of 2024-T3 aluminum alloy (1) with a passivation film is 99%, indicating that the corrosion rate is slower. The self-corrosion potential of 2024-T3 aluminum alloy (1) with a passivation film shifts positively by 100mV-1000mV compared to that without a passivation film, indicating that 2024-T3 aluminum alloy (1) with a passivation film is more difficult to corrode. At the same time, by weighing 2024-T3 aluminum alloy (1) before and after corrosion, it was found that the unit area mass of the micron-level film layer is ≤0.03g / m². 2 The weight gain rate is <0.005%.

Claims

1. A method and apparatus for large-area active metal corrosion protection using 3D rapid spraying, characterized in that, The process includes the following steps: Step 1: Based on the in-situ film formation mechanism within the passivation region, and considering the voltage and current density of the polarization curve of the aircraft metal skin in the electrolyte, set the current and voltage of the high-frequency pulse power supply according to the required corrosion protection. Step 2: Weigh the aircraft metal skin, fix it to the cantilevered C-frame platform, connect it to the positive terminal of the power supply, prepare the electrolyte, connect the nozzle to the negative terminal of the power supply, and set the three-axis moving platform motion control for nozzle movement trajectory. Step 3: Turn on the high-frequency pulse power supply to output current and voltage, open the shut-off valve of the low-pressure reciprocating pump, and close... Step 4: After the passivation film has formed, cut off the high-frequency pulse power supply, close the shut-off valve of the low-pressure reciprocating pump, open the shut-off valve of the high-pressure reciprocating pump, and use high-pressure continuous jet to strengthen the surface of the film layer; then polish the obtained aircraft metal skin surface to reduce the surface roughness and improve the surface mechanical, aerodynamic and corrosion resistance properties, and then clean and dry the surface; finally, weigh the aircraft metal skin with the passivation film on the surface.

2. The 3D rapid spraying method and apparatus for large-area active metal corrosion protection as described in claim 1, characterized in that, The current and voltage of the high-frequency pulse power supply are the maximum current and maximum voltage in the passivation range.

3. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in claim 1, characterized in that, The three-axis moving platform maintains an angle of ≤5° between the nozzle axis and the normal of the aircraft metal skin surface, and moves at a speed of 1-10 mm / s.

4. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in any one of claims 1 to 3, characterized in that, The multiple nozzles, combined with a three-axis moving platform, enable rapid forming of passivation films on large-area aircraft metal skins.

5. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in claim 1, characterized in that, The dynamic electrochemical cell can process passivation film formation on various large-area aircraft metal skin surfaces, breaking through the size limitations of traditional electrolytic cells.

6. The 3D rapid spraying method and apparatus for large-area active metal corrosion protection as described in claim 1, characterized in that, A passivation film with a thickness of 10-200 μm is formed on the surface of the aircraft's metal skin.

7. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in claim 6, characterized in that, The mass per unit area of ​​the micron-sized film layer is ≤0.03 g / m². 2 The weight gain rate is <0.005%.

8. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in claim 1, characterized in that, The bonding strength between the passivation film and the aircraft metal skin is ≥20 N / mm. 2 The passivation film wear rate is <0.2mg / 1000 rpm.

9. The 3D rapid spraying method and apparatus for large-area active metal corrosion protection as described in claim 1, characterized in that, The corrosion current density of the aircraft metal skin with passivation film decreased by 90%-99% compared with that of the aircraft metal skin without passivation film; the self-corrosion potential of the aircraft metal skin with passivation film shifted positively by 100mV-1000mV compared with that of the aircraft metal skin without passivation film.

10. The 3D rapid spraying method and apparatus for large-area metal corrosion protection as described in any one of claims 1 to 9 is used in aerospace vehicles that require lightweight construction, enhanced surface properties, and large-size, full-area corrosion resistance.

Images