Method for evaluating accelerated corrosion of metal in high-temperature, high-humidity and high-salt environment

Abstract

The invention belongs to the technical field of atmospheric corrosion detection methods, and discloses a method for evaluating accelerated corrosion of metal in a high-temperature, high-humidity and high-salt environment. The method comprises the following steps: enabling a metal sample to be tested to sequentially and circularly go through a salt spray environment and a humid environment in testing equipment; the temperature in the test equipment is constant 25-45 DEG C; the time for going through the salt mist environment and the humid environment is 4-8 hours, the time of the salt mist environment accounts for 30-50%, and the time of the humid environment accounts for 50-70%; the method comprises the following steps: continuously spraying corrosive liquid to a to-be-detected metal sample to form a salt-spray environment, and keeping the relative humidity of the salt-spray environment to be greater than or equal to 95%; according to the method, corrosive liquid is used for providing a humid environment for a to-be-detected metal sample, and the relative humidity of the humid environment is kept to be 70-90%; the corrosive liquid is an aqueous solution composed of at least two of sulfate, chlorine salt, calcium salt and silicate. The method provided by the invention can rapidly and reliably evaluate the corrosion resistance of the metal material used by the spacecraft in the high-temperature, high-humidity and high-salt environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of atmospheric corrosion detection methods, and more specifically, relates to a method for evaluating the accelerated corrosion of metals in a high-temperature, high-humidity, and high-salt environment. Background Art

[0002] The corrosion environment in high-temperature, high-humidity, and high-salt areas is extremely harsh. Given the harsh corrosion environment in high-temperature, high-humidity, and high-salt areas, spacecraft components located in such areas are at risk of corrosion and need to be evaluated for their corrosion resistance.

[0003] Currently, the most widely used corrosion evaluation method is the neutral salt spray test, which uses a 5wt.% NaCl aqueous solution, continuous spraying, and 35°C. Compared with the actual corrosion environment of the components, the neutral salt spray test method is too harsh to reliably evaluate the corrosion resistance of spacecraft components. Given the large difference between the neutral salt spray test method and the actual service environment, many studies have established accelerated corrosion evaluation methods based on the local environmental spectrum, which can reliably evaluate the corrosion resistance of metal materials.

[0004] However, these existing environmental spectra are different from the environment in high-temperature, high-humidity, and high-salt areas, and these methods cannot be used to evaluate the corrosion resistance of metal materials used in spacecraft located in high-temperature, high-humidity, and high-salt areas. Therefore, there is an urgent need to propose a metal corrosion equivalent evaluation technology for high-temperature, high-humidity, and high-salt environments, providing a scientific basis for spacecraft structure designers to effectively determine the reliability and safety of different metal applications during material selection, and ensuring the safe service performance of spacecraft components. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and propose a method for evaluating the accelerated corrosion of metals in a high-temperature, high-humidity, and high-salt environment. The method of the present invention can quickly and reliably evaluate the corrosion resistance of metal materials used in spacecraft in a high-temperature, high-humidity, and high-salt environment.

[0006] To achieve the above purpose, the present invention provides a method for evaluating the accelerated corrosion of metals in a high-temperature, high-humidity, and high-salt environment, the method comprising: successively subjecting a metal sample to be tested to a salt spray environment and a humid environment in a test device;

[0007] The temperature in the test device is kept constant at 25 - 45°C;

[0008] The time for experiencing one cycle of the salt spray environment and the humid environment is 4 - 8h, wherein the time ratio of the salt spray environment is 30 - 50%, and the time ratio of the humid environment is 50 - 70%;

[0009] The method uses a corrosive liquid to continuously spray the metal sample to be tested to form the salt spray environment, and maintains the relative humidity of the salt spray environment ≥ 95%;

[0010] The method uses a corrosive liquid to provide a humid environment for the metal sample to be tested, and maintains the relative humidity of the humid environment at 70-90%;

[0011] The corrosive liquid is an aqueous solution composed of at least two salts among sulfates, chlorides, calcium salts and silicate salts.

[0012] In the present invention, the "relative humidity" refers to the percentage of the water vapor pressure in the air inside the test equipment to the saturated water vapor pressure at the same temperature.

[0013] According to the present invention, preferably, the number of cycles of the method through the salt spray environment and the humid environment is 20-50 times.

[0014] According to the present invention, preferably, the test equipment is a composite salt spray chamber.

[0015] In the present invention, the composite salt spray chamber is a composite salt spray chamber known to those skilled in the art, which is provided with a spray system, an environment control system and a circulation system;

[0016] The spray system is used to continuously spray the salt spray formed by the corrosive liquid onto the metal sample to be tested, form the salt spray environment, and maintain the relative humidity of the salt spray environment ≥95%;

[0017] The environment control system is used to control the temperature and humidity inside the test equipment to meet the parameter requirements of the humid environment and the dry environment. The corrosive medium required for the humid environment and the dry environment is added into the composite salt spray chamber by the environment control system.

[0018] The circulation system is used to realize the cyclic conversion of the salt spray, humid and dry environments, so that the metal sample to be tested is alternately exposed to different environments.

[0019] According to the present invention, preferably, the metal sample to be tested is a metal material for spacecraft.

[0020] According to the present invention, preferably, the metal sample to be tested is at least one of magnesium metal, magnesium alloy, aluminum metal, aluminum alloy and carbon steel. More preferably, the metal sample to be tested is ZM6 magnesium alloy and / or 7075 aluminum alloy.

[0021] According to the present invention, preferably, the concentration of sulfate in the corrosive liquid is 0.005-0.05 mol / L;

[0022] The concentration of chloride in the corrosive liquid is 0.001-0.025 mol / L;

[0023] The concentration of calcium salt in the corrosive liquid is 0.0005-0.005 mol / L;

[0024] The concentration of silicate in the corrosion liquid is 0.0001 - 0.001 mol / L.

[0025] In the present invention, the parameter conditions of the salt spray environment and the humid environment are actually set to simulate the high-temperature, high-humidity and high-salt environment. Therefore, the parameters of the high-temperature, high-humidity and high-salt environment correspondingly include: the temperature is a constant temperature of 25 - 45 °C; the relative humidity ≥ 70%; the corrosion medium in the environment is at least two of sulfates with a concentration of 0.005 - 0.05 mol / L, chlorides with a concentration of 0.001 - 0.025 mol / L, calcium salts with a concentration of 0.0005 - 0.005 mol / L, and silicates with a concentration of 0.0001 - 0.001 mol / L; the time proportion of the salt spray environment is 30 - 50%, and the time proportion of the humid environment is 50 - 70%.

[0026] According to the present invention, preferably, the method includes: making the metal sample to be tested sequentially cycle through a salt spray environment, a humid environment and a dry environment in a test device.

[0027] According to the present invention, preferably, the time for undergoing one cycle of the salt spray environment, the humid environment and the dry environment is 4 - 8 h, wherein the time proportion of the salt spray environment is 30 - 50%, the time proportion of the humid environment is 30 - 50%, and the time proportion of the dry environment is 0.01 - 20%.

[0028] According to the present invention, preferably, the method uses a corrosion liquid to provide a dry environment for the metal sample to be tested and maintains the relative humidity of the dry environment at 30 - 50%.

[0029] According to the present invention, preferably, the method includes the following steps:

[0030] S1: Weigh the metal sample to be tested and put it into the test device;

[0031] S2: In the test device, continuously spray the metal sample to be tested with the corrosion liquid to form the salt spray environment and maintain the relative humidity of the salt spray environment ≥ 95%;

[0032] S3: After completing step S2, in the test device, use the corrosion liquid to provide a humid environment for the metal sample to be tested and maintain the relative humidity of the humid environment at 70 - 90%;

[0033] S4: Cyclically perform steps S2 - S3 (make the metal sample to be tested sequentially cycle through a salt spray environment and a humid environment in the test device);

[0034] S5: Take out the corroded metal sample from the test device, after rinsing, photographing and removing the corrosion products on the surface of the corroded metal sample, obtain the corroded metal sample.

[0035] S6: Weigh the corroded metal sample, and calculate the corrosion rate of the metal sample to be measured according to Equation (1);

[0036]

[0037] In Equation (1):

[0038] The weight of the metal sample to be measured is denoted as W0 (g);

[0039] The weight of the corroded metal sample is denoted as W1 (g);

[0040] The test surface area of the metal sample to be measured is denoted as S (cm 2 );

[0041] The test time is denoted as T (h);

[0042] The density of the metal sample to be measured is denoted as D (g / cm 3 );

[0043] The corrosion rate is denoted as R (mm / a).

[0044] According to the present invention, preferably, in step S4: in the test equipment, use the corrosion liquid to provide a dry environment for the metal sample to be measured, and keep the relative humidity of the dry environment at 30 - 50%; make the metal sample to be measured sequentially cycle through a salt spray environment, a humid environment and a dry environment in the test equipment.

[0045] In the present invention, the preparation of the metal sample to be measured includes: grinding the sample to 2000# sandpaper, and removing the oil stain on the surface layer of the sample with alcohol to obtain the metal sample to be measured.

[0046] In the present invention, the "test time" is the number of cycles (20 - 50 times) of cycling through the salt spray environment and the humid environment × the time (4 - 8 h) of experiencing one salt spray environment and one humid environment, or, is the number of cycles (20 - 50 times) of cycling through the salt spray environment, the humid environment and the dry environment × the time (4 - 8 h) of experiencing one salt spray environment, one humid environment and one dry environment.

[0047] The beneficial effects of the technical solution of the present invention are as follows:

[0048] The method of the present invention can quickly and reliably evaluate the corrosion resistance of metal materials used in spacecraft in high - temperature, high - humidity and high - salt environments. Each environmental parameter (such as temperature, time, relative humidity, corrosion medium) in the salt spray, humid and dry environments can be adjusted with reference to the actual atmospheric environment of the high - temperature, high - humidity and high - salt area to be measured. In the present invention, for the drying link, according to the local climate conditions, if the humidity is basically kept above 70% all the time, there is no drying link, otherwise a drying link needs to be added.

[0049] The present invention can determine the corrosion damage of metal materials used in spacecraft in a coastal high-temperature, high-humidity and high-salt environment by using a shorter corrosion test time, providing a basis for the safe service performance of metal materials.

[0050] The method of the present invention is simple, reliable, easy to operate and applicable to a variety of common metals.

[0051] Other features and advantages of the present invention will be described in detail in the following specific implementation part. Specific implementation mode

[0052] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0053] Example 1

[0054] This embodiment provides a method for evaluating the accelerated corrosion of metals in a high-temperature, high-humidity and high-salt environment. The metal sample to be tested is 7075 aluminum alloy, and the test equipment is a JK-YW-120 composite salt spray chamber with a constant temperature of 35 °C inside;

[0055] The corrosion liquid is an aqueous solution composed of potassium sulfate with a concentration of 0.01 mol / L, calcium chloride with a concentration of 0.005 mol / L, and sodium silicate with a concentration of 0.0005 mol / L.

[0056] The method includes the following steps:

[0057] S1: Grind the 7075 aluminum alloy sample to 2000# sandpaper, remove the oil stain on the surface layer of the 7075 aluminum alloy sample with alcohol to obtain the metal sample to be tested. Weigh the metal sample to be tested and put it into the composite salt spray chamber;

[0058] S2: In the composite salt spray chamber, continuously spray the metal sample to be tested with the corrosion liquid to form the salt spray environment, and keep the relative humidity of the salt spray environment ≥ 95%; the time of the salt spray environment is 144 min (accounting for 40% of 6 h);

[0059] S3: After completing step S2, in the composite salt spray chamber, use the corrosion liquid to provide a humid environment for the metal sample to be tested, and keep the relative humidity of the humid environment at 80%; the time of the humid environment is 180 min (accounting for 50% of 6 h);

[0060] S4: After completing step S3, in the compound salt spray chamber, use the corrosive liquid to provide a dry environment for the metal sample to be tested, and maintain the relative humidity of the dry environment at 30%; the time of the dry environment is 36 min (10% of 6 h);

[0061] S5: Repeat steps S2 - S4 cyclically, where: the time for one cycle of steps S2 - S4 is 6 h; the number of cycles of the method repeating steps S2 - S4 is 20 times, that is, the time of the metal sample to be tested in the compound salt spray chamber is 5 days, and the macroscopic corrosion state of the surface of the metal sample to be tested needs to be observed regularly every day.

[0062] S6: After 5 days, take out the corroded metal sample from the compound salt spray chamber, rinse it with deionized water, then take a photo with a digital camera to observe the corrosion morphology of the metal sample. Then, after cleaning to remove the corrosion products on the surface of the metal sample, dry it for 24 h to obtain the corroded metal sample;

[0063] S7: Weigh the corroded metal sample, and calculate the corrosion rate of the metal sample to be tested according to formula (1).

[0064]

[0065] In formula (1):

[0066] The weight of the metal sample to be tested is denoted as W0 (g);

[0067] The weight of the corroded metal sample is denoted as W1 (g);

[0068] The test surface area of the metal sample to be tested is denoted as S (cm 2 );

[0069] The test time is denoted as T (h);

[0070] The density of the metal sample to be tested is denoted as D (for 7075 aluminum alloy, it is 2.8 g / cm 3 );

[0071] The corrosion rate is denoted as R (mm / a).

[0072] The corrosion rate of the 7075 aluminum alloy in this embodiment is 0.0324 mm / a.

[0073] Example 2

[0074] This embodiment provides a method for evaluating the accelerated corrosion of metals in a high - temperature, high - humidity, and high - salt environment. The metal sample to be tested is a ZM6 magnesium alloy, and the test equipment is a JK - YW - 120 compound salt spray chamber with a constant temperature of 40 °C inside;

[0075] The corrosive liquid is an aqueous solution composed of sodium sulfate with a concentration of 0.008 mol / L and calcium chloride with a concentration of 0.008 mol / L.

[0076] The method includes the following steps:

[0077] S1: Polish the ZM6 magnesium alloy sample to 2000# sandpaper, remove the oil stain on the surface layer of the ZM6 magnesium alloy sample with alcohol to obtain the metal sample to be tested. Weigh the metal sample to be tested and put it into the composite salt spray chamber;

[0078] S2: In the composite salt spray chamber, continuously spray the metal sample to be tested with the corrosive liquid to form the salt spray environment, and keep the relative humidity of the salt spray environment ≥ 95%; the time of the salt spray environment is 120 min (accounting for 50% of 4 h);

[0079] S3: After completing step S2, in the composite salt spray chamber, use the corrosive liquid to provide a humid environment for the metal sample to be tested, and keep the relative humidity of the humid environment at 85%; the time of the humid environment is 120 min (accounting for 50% of 4 h);

[0080] S4: Repeat steps S2 - S3, where: the time for one cycle of steps S2 - S3 is 4 h; the number of cycles of the method repeating steps S2 - S3 is 30 times, that is, the time of the metal sample to be tested in the composite salt spray chamber is 5 days, and the surface macroscopic corrosion state of the metal sample to be tested needs to be observed regularly every day.

[0081] S5: After 5 days, take out the corroded metal sample from the composite salt spray chamber, rinse it with deionized water, then take a photo with a digital camera to observe the corrosion morphology of the metal sample. Then, after cleaning to remove the corrosion products on the surface of the metal sample, dry it for 24 h to obtain the corroded metal sample;

[0082] S6: Weigh the corroded metal sample and calculate the corrosion rate of the metal sample to be tested according to formula (1).

[0083]

[0084] In formula (1):

[0085] The weight of the metal sample to be tested is denoted as W0 (g);

[0086] The weight of the corroded metal sample is denoted as W1 (g);

[0087] The test surface area of the metal sample to be tested is denoted as S (cm 2 );

[0088] The test time is denoted as T (h);

[0089] The density of the metal sample to be measured is denoted as D (for ZM6 magnesium alloy, it is 1.8 g / cm 3 );

[0090] The corrosion rate is denoted as R (mm / a).

[0091] The corrosion rate of the ZM6 magnesium alloy in this embodiment is 0.108 mm / a.

[0092] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment, characterized in that: The method comprises: allowing the metal sample to be tested to cycle through a salt spray environment and a humid environment in a testing device in sequence; The temperature in the test equipment is a constant temperature of 25-45°C; The time of experiencing the salt spray environment and the humid environment once is 4-8 hours, wherein the time of the salt spray environment accounts for 30-50%, and the time of the humid environment accounts for 50-70%; The method uses a corrosive liquid to continuously spray the metal sample to be tested to form the salt spray environment, and maintains the relative humidity of the salt spray environment ≥ 95%; The method uses a corrosive liquid to provide a humid environment for the metal sample to be tested, and maintains the relative humidity of the humid environment at 70-90%; The corrosive liquid is an aqueous solution composed of at least two salts of sulfate, chloride, calcium and silicate.

2. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 1, wherein: The method cycles through the salt spray environment and the humid environment 20-50 times.

3. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 1, wherein: The testing equipment is a composite salt spray chamber.

4. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 1, wherein: The metal sample to be tested is a metal material for spacecraft.

5. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 4, wherein: The metal sample to be tested is at least one of magnesium metal, magnesium alloy, aluminum metal, aluminum alloy and carbon steel.

6. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 1, wherein: The concentration of sulfate in the corrosive liquid is 0.005-0.05 mol / L; The concentration of chloride salt in the corrosive liquid is 0.001-0.025 mol / L; The concentration of calcium salt in the corrosive liquid is 0.0005-0.005 mol / L; The concentration of silicate in the corrosion liquid is 0.0001-0.001 mol / L.

7. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to any one of claims 1 to 6, wherein: The method comprises: making the metal sample to be tested cycle through a salt spray environment, a humid environment and a dry environment in a testing device in sequence.

8. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 7, wherein: The time for experiencing the salt spray environment, the humid environment and the dry environment once is 4-8 hours, wherein the time in the salt spray environment accounts for 30-50%, the time in the humid environment accounts for 30-50%, and the time in the dry environment accounts for 0.01-20%.

9. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to claim 7, wherein: The method uses corrosive liquid to provide a dry environment for the metal sample to be tested, and maintains the relative humidity of the dry environment at 30-50%.

10. The method for evaluating accelerated corrosion of metals in a high temperature, high humidity and high salt environment according to any one of claims 1 to 6, wherein: The method comprises the following steps: S1: weighing the metal sample to be tested and placing it into the testing equipment; S2: In the test equipment, the corrosive liquid is continuously sprayed onto the metal sample to be tested to form the salt spray environment, and the relative humidity of the salt spray environment is maintained at ≥ 95%; S3: After completing step S2, in the testing device, using the corrosive liquid to provide a humid environment for the metal sample to be tested, and maintaining the relative humidity of the humid environment at 70-90%; S4: looping through steps S2-S3; S5: taking out the corroded metal sample from the testing device, washing, photographing and removing corrosion products on the surface of the corroded metal sample to obtain a corroded metal sample; S6: weighing the corroded metal sample, and calculating the corrosion rate of the metal sample to be tested according to formula (1); In formula (1): The weight of the metal sample to be tested is recorded as W0 (g); The weight of the metal sample after corrosion is recorded as W1 (g); The surface area of ​​the metal sample to be tested is recorded as S (cm 2 ); The test time is recorded as T (h); The density of the metal sample to be tested is recorded as D (g / cm 3 ); The corrosion rate is recorded as R (mm / a); Preferably, step S4: in the test equipment, using the corrosive liquid to provide a dry environment for the metal sample to be tested, and maintaining the relative humidity of the dry environment at 30-50%; allowing the metal sample to be tested to cycle through a salt spray environment, a humid environment and a dry environment in the test equipment in sequence.

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