A method for determining a corrosion inhibitor for aluminum-copper alloys

Abstract

The application provides a determination method of corrosion inhibitor for aluminum-copper alloy, which comprises three steps: (1) research on formula optimization scheme of the corrosion inhibitor; (2) evaluation and verification on additional influence of the formula of the corrosion inhibitor; and (3) research on use scheme of the corrosion inhibitor.

Description

Technical Field

[0001] This invention belongs to the field of aerospace vehicle ground testing technology, specifically relating to a method for determining corrosion inhibitors for aluminum-copper alloys. Background Technology

[0002] Aluminum is one of the most widely used metallic elements in modern industrial systems, second only to steel in terms of metal material usage. Aluminum alloys possess excellent properties such as relatively light weight, high strength, high temperature resistance, low melting point, and ease of processing. Due to their unique physical, chemical, and mechanical properties, aluminum and its alloys have wide applications in many fields. However, aluminum and its alloys are very reactive metals, resulting in poor corrosion resistance in aluminum alloys, which greatly limits their applications.

[0003] Aluminum alloys have a thin, protective oxide film on their surface, but this film is easily damaged under natural conditions, exposing the aluminum alloy substrate and making it susceptible to various forms of corrosion. From the perspective of corrosion causes, aluminum alloy corrosion mainly falls into two categories: chemical corrosion and electrochemical corrosion. Electrochemical corrosion is the most common type in practice. Methods to prevent aluminum alloy corrosion include surface treatment, environmental control, and the addition of corrosion inhibitors.

[0004] Adding trace amounts or small quantities of chemical substances (inorganic or organic) to a corrosive medium can significantly reduce, or even stop, the corrosion rate of metallic materials in that medium, while maintaining the original physical and mechanical properties of the metal. Such chemical substances are called corrosion inhibitors. Using corrosion inhibitors is an effective and economical means of corrosion prevention to mitigate and inhibit the corrosion of aluminum alloys. A corrosion inhibitor is a substance that, when added in an appropriate amount to a medium, can prevent or slow down metal corrosion, while not altering the original basic properties of the metallic material. Due to its good effectiveness and high economic benefits, corrosion inhibitor technology is one of the most widely used technologies in the field of corrosion prevention. By using corrosion inhibitors, aluminum alloy corrosion can be inhibited to a certain extent. Currently, the main types of corrosion inhibitors include inorganic, organic, and rare earth corrosion inhibitors, which play an important role in the protection of aluminum alloys. Adding suitable corrosion inhibitors to specific aluminum alloy application systems can significantly improve corrosion resistance. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the problem that aluminum alloys are prone to corrosion when stored in corrosive water for a long time, and to provide a method for determining the addition of an environmentally friendly corrosion inhibitor in an aqueous medium.

[0006] This invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys, comprising three steps: (1) Conduct research on the formulation optimization scheme of corrosion inhibitors; (2) Conduct an assessment and verification of the additional impact of the formulation of corrosion inhibitors; (3) Conduct research on the application scheme of corrosion inhibitors.

[0007] Further, step (1) includes the following steps: 1) Identify novel corrosion inhibitors and protectants The novel corrosion inhibitor is a water-soluble mixed solution containing silicon, including sebacic acid and benzotriazole; the proportion of the original corrosion inhibitor solution added to the novel corrosion inhibitor does not exceed 2%, including 0.25% concentration, 0.5% concentration, 1% concentration and 1.5% concentration of corrosion inhibitor. 2) Determine the experimental specimens and experimental water samples. The experimental specimens include aluminum alloy sheets, fasteners, and seals; the aluminum alloy sheets are of types 2219, 2A12, 5A06, and 2195; the fasteners are of types 304 and 316L; the seals are of types GH4169 and fluoroplastics; the experimental water samples include pure water, pure water stored in an open environment for 6 months, tap water, and corrosive water; 3) Conduct comparative experiments on the anti-corrosion effects of corrosion inhibitors. Two identical aluminum alloy sheets were simultaneously added to a corrosion solution containing a corrosion inhibitor and a corrosion solution without a corrosion inhibitor. After a specific time period, the two aluminum alloy sheets were taken out at the same time, and the corrosion phenomenon on the surface of the aluminum alloy sheets was observed. The corrosion rate was calculated by weighing the aluminum alloy sheets before and after the test.

[0008] Furthermore, step (2) includes the following steps: Low-temperature tensile tests and fatigue tests under corrosion inhibitor protection conditions were conducted on the experimental specimens to verify the protective effect of the corrosion inhibitor on the experimental specimens under different conditions. Accelerated life tests were conducted by increasing the temperature to verify the service life of the corrosion inhibitor.

[0009] Furthermore, step (3) includes the following steps: 1) Measure conductivity, pH value, ion concentration, density, and viscosity. Water media with added corrosion inhibitors were stored in an open tank for a long period of time, and the conductivity, pH value, ion concentration, density and viscosity of the water media were measured. The test cycles were 10 days, 30 days, 90 days, 180 days and 360 days, respectively. 2) Verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. Static immersion tests were conducted within a temperature range of 10°C to 40°C to verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. 3) Verify the permissible use conditions of the corrosion inhibitor. Immersion tests were conducted on water media with added corrosion inhibitors to measure the ion concentration in the solution. By adding different concentrations of corrosion inhibitors, the permissible use conditions of the corrosion inhibitors were verified. Water media with added corrosion inhibitors that were repeatedly used were evaluated. If the conditions were lower than the permissible use conditions, corrosion inhibitors were added. This led to the determination of the service life and control measures for water media with added corrosion inhibitors. 4) Verify the environmental friendliness of water media with added corrosion inhibitors. Environmental certification is conducted on water media with added corrosion inhibitors to determine whether they meet environmental characteristics and emission requirements. 5) Adjust the formulation of the corrosion inhibitor. By conducting water immersion tests with added corrosion inhibitors, the relationship between the concentration of harmful ions in the water medium and the concentration of corrosion inhibitors was studied, and the formulation of corrosion inhibitors was adjusted according to different water media.

[0010] The advantages of this invention compared to the prior art are as follows: a) This invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys. The novel corrosion inhibitor is a mixed solution containing silicic sebacic acid and benzotriazole, which can be adsorbed onto the alloy surface as an anodic corrosion inhibitor to reduce the dissolution of aluminum and copper, as well as reduce the adsorption and destructive effects of harmful ions in the solution, thereby protecting the copper-aluminum alloy.

[0011] (b) This invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys, wherein tap water with added corrosion inhibitors does not cause corrosion to the storage tanks containing the copper-aluminum alloys.

[0012] c) This invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys. Under alternating ambient and low temperature stress conditions, tap water with added corrosion inhibitors does not corrode the copper-aluminum alloy storage tank and produces no excess material.

[0013] d) The present invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys, wherein tap water with added corrosion inhibitor has no corrosive effect on copper-aluminum alloy storage tanks for a duration of not less than 24 months.

[0014] e) This invention provides a method for determining corrosion inhibitors for aluminum-copper alloys. The storage tank that has stored tap water with added corrosion inhibitors can be cleaned and the material properties of the storage tank do not change significantly, meeting the requirement of no extraneous matter in low-temperature medium tests.

[0015] f) This invention provides a method for determining corrosion inhibitors for aluminum-copper alloys, which meets the corrosion protection requirements of water media in long-term contact with the test specimen tank during aerospace ground tests, including static tests, outflow tests, and modal tests. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram showing the state of an aluminum-copper alloy after immersion in a corrosive aqueous solution containing a corrosion inhibitor, according to an embodiment of the present invention. Figure 2 This is a schematic diagram showing the state of an aluminum-copper alloy after immersion in a corrosive aqueous solution without a corrosion inhibitor, according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the polarization curves of aluminum-copper alloys with and without corrosion inhibitors according to embodiments of the present invention, and with 1.5% corrosion inhibitor added. Figure 4 This is a schematic diagram of the surface morphology of an aluminum-copper alloy after immersion in a test solution according to an embodiment of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0018] Example 1 This invention provides a method for determining a corrosion inhibitor for aluminum-copper alloys, comprising three steps: (1) Conduct research on the formulation optimization scheme of corrosion inhibitors; (2) Conduct an assessment and verification of the additional impact of the formulation of corrosion inhibitors; (3) Conduct research on the application scheme of corrosion inhibitors.

[0019] Step (1) includes the following steps: 1) Identify novel corrosion inhibitors and protectants The novel corrosion inhibitor is a water-soluble mixed solution containing silicon, including sebacic acid and benzotriazole; the proportion of the original corrosion inhibitor solution added to the novel corrosion inhibitor does not exceed 2%, including 0.25% concentration, 0.5% concentration, 1% concentration and 1.5% concentration of corrosion inhibitor. 2) Determine the experimental specimens and experimental water samples. The test specimens included aluminum alloy sheets, fasteners, and seals; the aluminum alloy sheets were of the following types: 2219, 2A12, 5A06, and 2195; the fasteners were of the following types: 304 and 316L; the seals were of the following types: GH4169 and fluoroplastics; the test water samples included pure water, pure water stored in an open environment for 6 months, tap water, and corrosive water. 3) Conduct comparative experiments on the anti-corrosion effects of corrosion inhibitors. Two identical aluminum alloy sheets were simultaneously added to a corrosion solution containing a corrosion inhibitor and a corrosion solution without a corrosion inhibitor. After a specific time period, the two aluminum alloy sheets were taken out at the same time, and the corrosion phenomenon on the surface of the aluminum alloy sheets was observed. The corrosion rate was calculated by weighing the aluminum alloy sheets before and after the test.

[0020] Step (2) includes the following steps: Low-temperature tensile tests and fatigue tests under corrosion inhibitor protection conditions were conducted on the experimental specimens to verify the protective effect of the corrosion inhibitor on the experimental specimens under different conditions. Accelerated life tests were conducted by increasing the temperature to verify the service life of the corrosion inhibitor.

[0021] Step (3) includes the following steps: 1) Measure conductivity, pH value, ion concentration, density, and viscosity. Water media with added corrosion inhibitors were stored in an open tank for a long period of time, and the conductivity, pH value, ion concentration, density and viscosity of the water media were measured. The test cycles were 10 days, 30 days, 90 days, 180 days and 360 days, respectively. 2) Verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. Static immersion tests were conducted within a temperature range of 10°C to 40°C to verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. 3) Verify the permissible use conditions of the corrosion inhibitor. Immersion tests were conducted on water media with added corrosion inhibitors to measure the ion concentration in the solution. By adding different concentrations of corrosion inhibitors, the permissible use conditions of the corrosion inhibitors were verified. Water media with added corrosion inhibitors that were repeatedly used were evaluated. If the conditions were lower than the permissible use conditions, corrosion inhibitors were added. This led to the determination of the service life and control measures for water media with added corrosion inhibitors. 4) Verify the environmental friendliness of water media with added corrosion inhibitors. Environmental certification is conducted on water media with added corrosion inhibitors to determine whether they meet environmental characteristics and emission requirements. 5) Adjust the formulation of the corrosion inhibitor. By conducting water immersion tests with added corrosion inhibitors, the relationship between the concentration of harmful ions in the water medium and the concentration of corrosion inhibitors was studied, and the formulation of corrosion inhibitors was adjusted according to different water media.

[0022] Example 2 (1) Formulation optimization of novel corrosion inhibitors The study covered all material states within the tank, including 2219, 2A12, and 5A06 aluminum alloys, as well as fasteners and seals. Corrosion verification experiments were conducted to clarify the specific formulation of corrosion inhibitors added to the water medium. Physicochemical analysis was performed on the surface material generated from samples with feasible corrosion inhibitor formulations to clarify the composition and anti-corrosion mechanism.

[0023] To study the corrosion behavior of 2219, 2A12 and 5A06 aluminum alloys in an aqueous environment, the water sample needs to cover the entire ground test conditions, and the test specimens also need to meet the actual conditions.

[0024] The experimental water samples included: Table 1. Water used in experiments Corrosion water significantly increases ion concentration, which can be used as a basis for accelerated corrosion testing. Specific comparative standards are determined using the weight loss method.

[0025] Table 2 Preparation of Corrosion Water The experimental samples include: Table 3. Categories of Experimental Specimens (2) Cooperate with impact assessment and verification Based on the analysis of the application scenarios, the corrosion inhibitor is required to protect the material in both static and dynamic states without causing any additional damage. Low-temperature tensile tests, fatigue tests with the corrosion inhibitor, and accelerated life tests with increased temperature were conducted to verify that the corrosion inhibitor meets a 2-year service life requirement. This ensures it can cover ground testing on spacecraft and meets engineering application requirements.

[0026] (3) Study on the application scheme of water media with added corrosion inhibitors Storage conditions and storage period of water media with added corrosion inhibitors; service life and control methods of water media with added corrosion inhibitors; environmental protection characteristics and discharge requirements of water media with added corrosion inhibitors; water quality requirements of the corrosion inhibitor scheme.

[0027] The specific experimental plan includes: 1) Aqueous media with added corrosion inhibitors are stored in an open tank for extended periods, and the solution's conductivity, pH value, ion concentration, density, viscosity, and other properties are measured. The testing periods are 10 days, 30 days, 90 days, 180 days, and 360 days.

[0028] 2) The effect of outdoor ambient temperature changes on the anti-corrosion effect of aqueous media with added corrosion inhibitors. Static immersion tests were conducted at temperatures ranging from low temperatures (10°C) to high temperatures (40°C), using the same test methods as those described in Part 1.

[0029] 3) After conducting immersion tests on water media with added corrosion inhibitors, measure the characteristics of the solution such as ion concentration. Verify the permissible use conditions of the corrosion inhibitors by using different concentrations of corrosion inhibitors. Through monitoring, evaluate the water media with added corrosion inhibitors that have been repeatedly used. Add corrosion inhibitors when the conditions are close to or below the permissible conditions to form the service life and control methods of water media with added corrosion inhibitors.

[0030] 4) Conduct environmental certification for water media with added corrosion inhibitors to determine whether they meet environmental protection characteristics and emission requirements, or whether the solution meets environmental protection characteristics and emission requirements.

[0031] 5) By conducting water immersion tests on different water samples with added corrosion inhibitors, the relationship between the concentration of harmful ions in the water medium and the concentration of corrosion inhibitors was studied, thereby guiding the adjustment of the corrosion inhibitor formulation scheme according to different water qualities.

[0032] Example 3 The green corrosion inhibitor for aluminum-copper alloys in this embodiment is a silicon-containing water-soluble mixed solution containing sebacic acid (50 ppm) and benzotriazole (0.01 g / mol).

[0033] 2g of the prepared corrosion inhibitor was added to 400g of a 0.5% (w / w) solution containing sodium chloride, sodium bicarbonate, and sodium sulfate, and mixed thoroughly. Then, a 2219 aluminum alloy sheet was immersed in the solution for 3860 hours. The 2219 aluminum alloy was then removed, and the surface corrosion was tested. A blank test was then performed by directly immersing the 2219 aluminum alloy in a 1.5% (NaCl, NaHCO3, Na2SO3) solution for 3860 hours. Figure 1 A photograph of a 2219 aluminum alloy sheet after being immersed in a corrosive aqueous solution with added corrosion inhibitor. Figure 2 Photographs of 2219 aluminum alloy after immersion in a corrosive aqueous solution without corrosion inhibitors. Figure 1 As can be seen, in the solution containing the corrosion inhibitor from Example 1, the surface of the 2219 aluminum alloy sheet remained largely intact, with only slight corrosion. However, in the solution without the corrosion inhibitor, the sample surface corroded and turned black, with many white products adhering to the surface.

[0034] Add 2g of the corrosion inhibitor prepared in Example 1 to 400g of a 0.5% salt solution, mix well, and perform an immersion experiment. At the same time, use 0.5% NaCl, NaHCO3, and Na2SO3 solutions as blank test groups. According to the weight loss method, the corrosion inhibition rate can be reduced to 1 / 2174.

[0035] Example 4 The green corrosion inhibitor for aluminum-copper alloys in this embodiment is a silicon-containing water-soluble mixed solution containing sebacic acid (50 ppm) and benzotriazole (0.01 g / mol).

[0036] 6g of the prepared corrosion inhibitor was added to 400g of a 1.5% (w / w) aqueous solution and mixed thoroughly. Then, a 2219 aluminum alloy sample was placed in the solution, using an Al-Cu alloy sheet as the working electrode. The polarization curves of the copper-aluminum alloy in the 1.5% corrosion solution containing and without the corrosion inhibitor were tested, as shown below. Figure 3 As shown. From Figure 3 It can be seen that the corrosion rate with the addition of corrosion inhibitor is significantly lower than that without corrosion inhibitor. According to... Figure 3 The fitting results are shown in the table below. The corrosion inhibitor significantly improved the corrosion resistance of the alloy.

[0037] Example 5 The green corrosion inhibitor for magnesium-lithium alloys in this embodiment is a silicon-containing water-soluble mixed solution containing sebacic acid (50 ppm) and benzotriazole (0.01 g / mol).

[0038] 4g of the prepared corrosion inhibitor was added to 400g of a 1% (w / w) solution of sodium chloride, sodium bicarbonate, and sodium sulfate, and mixed thoroughly. Then, a 2219 aluminum alloy sheet was immersed in the solution and soaked at 40℃ for 3860 hours. The 2219 aluminum alloy was then removed and the surface corrosion was examined. Alternatively, the 2219 aluminum alloy was directly immersed in a 1% (NaCl, NaHCO3, sodium sulfate) solution for 3860 hours, and then removed and the surface corrosion was examined. Figure 4 It is the surface morphology of aluminum-copper alloy after immersion in solution.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining a corrosion inhibitor for aluminum-copper alloys, characterized in that, It includes three steps: (1) Conduct research on the formulation optimization scheme of corrosion inhibitors; (2) Conduct an assessment and verification of the additional impact of the formulation of corrosion inhibitors; (3) Conduct research on the application scheme of corrosion inhibitors.

2. The method for determining a corrosion inhibitor for aluminum-copper alloys according to claim 1, characterized in that, Step (1) includes the following steps: 1) Identify novel corrosion inhibitors and protectants The novel corrosion inhibitor is a water-soluble mixed solution containing silicon, including sebacic acid and benzotriazole; the proportion of the original corrosion inhibitor solution added to the novel corrosion inhibitor does not exceed 2%, including 0.25% concentration, 0.5% concentration, 1% concentration and 1.5% concentration of corrosion inhibitor. 2) Determine the experimental specimens and experimental water samples. The experimental specimens include aluminum alloy sheets, fasteners, and seals; the aluminum alloy sheets are of types 2219, 2A12, 5A06, and 2195; the fasteners are of types 304 and 316L; the seals are of types GH4169 and fluoroplastics; the experimental water samples include pure water, pure water stored in an open environment for 6 months, tap water, and corrosive water; 3) Conduct comparative experiments on the anti-corrosion effects of corrosion inhibitors. Two identical aluminum alloy sheets were simultaneously added to a corrosion solution containing a corrosion inhibitor and a corrosion solution without a corrosion inhibitor. After a specific time period, the two aluminum alloy sheets were taken out at the same time, and the corrosion phenomenon on the surface of the aluminum alloy sheets was observed. The corrosion rate was calculated by weighing the aluminum alloy sheets before and after the test.

3. The method for determining a corrosion inhibitor for aluminum-copper alloys according to claim 1, characterized in that, Step (2) includes the following steps: Low-temperature tensile tests and fatigue tests under corrosion inhibitor protection conditions were conducted on the experimental specimens to verify the protective effect of the corrosion inhibitor on the experimental specimens under different conditions. Accelerated life tests were conducted by increasing the temperature to verify the service life of the corrosion inhibitor.

4. The method for determining a corrosion inhibitor for aluminum-copper alloys according to claim 1, characterized in that, Step (3) includes the following steps: 1) Measure conductivity, pH value, ion concentration, density, and viscosity. Water media with added corrosion inhibitors were stored in an open tank for a long period of time, and the conductivity, pH value, ion concentration, density and viscosity of the water media were measured. The test cycles were 10 days, 30 days, 90 days, 180 days and 360 days, respectively. 2) Verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. Static immersion tests were conducted within a temperature range of 10°C to 40°C to verify the effect of outdoor ambient temperature changes on the anti-corrosion effect of water media with added corrosion inhibitors. 3) Verify the permissible use conditions of the corrosion inhibitor. Immersion tests were conducted on water media with added corrosion inhibitors to measure the ion concentration in the solution. By adding different concentrations of corrosion inhibitors, the permissible use conditions of the corrosion inhibitors were verified. Water media with added corrosion inhibitors that were repeatedly used were evaluated. If the conditions were lower than the permissible use conditions, corrosion inhibitors were added. This led to the determination of the service life and control measures for water media with added corrosion inhibitors. 4) Verify the environmental friendliness of water media with added corrosion inhibitors. Environmental certification is conducted on water media with added corrosion inhibitors to determine whether they meet environmental characteristics and emission requirements. 5) Adjust the formulation of the corrosion inhibitor. By conducting water immersion tests with added corrosion inhibitors, the relationship between the concentration of harmful ions in the water medium and the concentration of corrosion inhibitors was studied, and the formulation of corrosion inhibitors was adjusted according to different water media.

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