GB/T 47375-2026Salt fog test methods for manned spacecraft materials (English PDF)

6.1 Determination of Test Items

6.1.1 Salt spray testing of materials should be conducted according to the environmental conditions experienced by the materials throughout their entire life cycle. Project. When spacecraft materials need to undergo multiple types of salt spray tests, the sequence of corrosive environments the materials experience during the mission should be determined. The order of salt spray test items.

6.1.2 The three types of test items are ranked from highest to lowest according to the severity of the test conditions. exposure to coastal (atmospheric) salt spray test Salt spray test in indoor/uncontrolled humidity environment, and salt spray test in temperature and humidity controlled environment. If the specimen can pass the stringent requirements... For high-severity testing projects, low-severity testing projects may be omitted.

6.2 Specimen Requirements

6.2.1 The type, quantity, shape, and size of the test specimens shall be selected according to the relevant specifications for the tested material. If no specifications exist, the testing party and the commissioning party shall determine the appropriate selection. The agreement was reached through consultation between the parties.

6.2.2 The surface of the specimen should be free of contaminants that could cause the surface water film to break, such as oil, grease, or dirt (dust), and should be free of scratches and oxidation discoloration. defect.

6.2.3 The specimen should be thoroughly cleaned before the test. The cleaning method depends on the properties of the specimen material. The surface of the specimen and its contaminants should not be cleaned using [specific cleaning methods]. Abrasives or solvents that may corrode the surface of the specimen.

6.3 Requirements for Test Equipment The requirements for the test equipment are as follows:

a) The salt spray chamber should have the capability to perform combined tests of salt spray, humidification, and drying.

b) The materials used in the manufacture of the testing equipment, salt spray chamber, temperature control device, spraying device, salt spray collector, etc., shall comply with GB/T 10125. Regulation.

c) The temperature and humidity chamber should meet the following requirements. 1) The constant temperature and humidity chamber can conduct constant humidity and heat tests for no less than 30 days, during which the temperature can be controlled at (30±2)°C and the relative humidity... It can be controlled within (60±10)%; 2) Use temperature and humidity sensors placed in the workspace to monitor the temperature and relative humidity inside the test chamber; 3) Condensate should be continuously drained from the test chamber; the chamber should not be used again without purification. 4) The resistivity of the water used as the moisture source in the constant temperature and humidity chamber should not be less than 500 Omega·m; 5) The temperature and humidity in the workspace should be uniform and consistent with the conditions near the monitoring sensors; 6) The electrical load on the test specimen should not significantly affect the conditions inside the test chamber; 7) Condensation on the walls and top of the constant temperature and humidity chamber should not drip onto the test specimens.

6.4 Laboratory Environmental Requirements Laboratory environments generally meet the following requirements.

a) Temperature. 15°C~35°C;

b) Relative humidity. 20%~80%;

c) Atmospheric pressure. 78 kPa~103 kPa.

7.1 Salt spray test for exposure to coastal (atmospheric) environment

7.1.1 Test Conditions The experimental conditions are as follows:

a) The concentration (mass fraction) of the NaCl solution used in the experiment was (5±1)%, and the preparation method was as follows: 1) NaCl of chemical purity or higher should be used for preparation; 2) The pH value of the precipitated NaCl solution collected in the salt spray chamber should be maintained at 6.5~

7.2 at a temperature of (35±2)°C; 3) The pH value should be adjusted using chemically pure or higher-purity hydrochloric acid or sodium hydroxide; 4) pH value can be measured by electrochemical or colorimetric methods.

b) Salt spray deposition rate is 1 mL/(80 cm2·h) to 3 mL/(80 cm2·h).

7.1.2 Test Procedure The experimental steps are as follows:

a) Before the test, the appearance of the specimen should be checked and photographed.

b) Inject the NaCl solution that meets the requirements of 7.1.1a) into the salt spray chamber, ensuring that the NaCl solution remains at the lowest possible level in the salt spray chamber throughout the experiment. Above the small scale line.

c) Place the test specimens face up in the salt spray chamber, with the test surface at an angle of 15° to 30° to the vertical, ensuring that the specimens do not obstruct each other. For non- The specimens for the test should closely resemble the above-mentioned specifications.

d) Adjust the temperature inside the salt spray chamber to (35±2)°C and keep it at that temperature for at least 2 hours.

e) Spray salt spray for 24 hours, during which the temperature inside the salt spray chamber is (35±2)°C.

f) The salt spray chamber automatically switches to a drying state and maintains this state for 24 hours. During this period, the temperature inside the salt spray chamber is (35±2)°C, completing one cycle.

f) until a total of 2 cycles are completed. The cycle period of the test can be adjusted according to the actual conditions of the test material or product. Sure.

7.2 Salt spray test in indoor/uncontrolled environment

7.2.1 Test Conditions The test conditions are as follows:

a) The concentration (mass fraction) of the NaCl solution used in the experiment was (0.8±0.1)%, prepared using the same method as 7.1.1a);

b) Salt spray deposition rate is 1 mL/(80 cm2·h) to 3 mL/(80 cm2·h).

7.2.2 Test Procedure The experimental steps are as follows:

a) Before the test, the appearance of the specimen should be checked and photographed.

b) Inject the NaCl solution that meets the requirements of 7.2.1a) into the salt spray chamber according to the test time, ensuring that the NaCl solution remains constant throughout the test. Hold it above the minimum graduation mark of the salt spray chamber.

c) The test specimens are placed face up in the salt spray chamber, with the test surface at an angle of 15° to 30° to the vertical. Specimens should not obstruct each other. For irregular... The specimens used should be close to the above-mentioned specifications.

d) The recommended salt spray time is 5 minutes, during which the temperature inside the salt spray chamber is set to 35°C. If the actual measured indoor/no humidity control... The annual average chloride ion deposition rate (x) differs significantly from

2.33 mg/(m^2·d), therefore the salt spray test can still be used. Use a 0.8% NaCl solution, but adjust the salt spray time to (5x/2.33) min.

e) Humidify for 30 minutes, during which the relative humidity is 95%~100% and the humidification temperature is (35±2)°C.

f) Dry for 65 minutes, during which the drying temperature is (35±2)°C.

f) until the specified number of cycles is completed. d)~f) represent one cycle, corresponding to one month of material for manned spacecraft in an uncontrolled indoor environment; if the material is in an uncontrolled indoor environment... If the indoor environment is controlled for less than one month, the time for salt spray, humidification, and drying processes should be reduced proportionally based on the actual situation.

7.3 Salt spray test under temperature and humidity controlled environment

7.3.1 Test Conditions The test conditions are as follows:

a) The concentration (mass fraction) of the NaCl solution used in the experiment was (0.5±0.1)%, prepared using the same method as 7.1.1a);

b) Salt spray deposition rate is 1 mL/(80 cm2·h) to 3 mL/(80 cm2·h).

7.3.2 Test Procedure The experimental steps are as follows:

a) Before the test, the appearance of the specimen should be checked and photographed with a camera.

b) Inject the NaCl solution that meets the requirements of 7.3.1a) into the salt spray chamber according to the test time, ensuring that the NaCl solution remains constant throughout the test. Hold it above the minimum graduation mark of the salt spray chamber.

c) The test specimens are placed face up in the salt spray chamber, with the test surface at an angle of 15° to 30° to the vertical. Specimens should not obstruct each other. For irregular... The specimens used should be close to the above-mentioned specifications.

d) Spray salt spray for 5 minutes, during which the temperature inside the salt spray chamber is set to 35°C. If the actual measured annual average temperature and humidity control environment... The average chloride ion deposition rate (x) differs significantly from

1.46 mg/(m^2·d), therefore, 0.5% NaCl can still be used in the salt spray test. The solution should be prepared, but the salt spray time should be adjusted to (5x/1.46) min.

e) The salt spray chamber automatically switches to the drying state and maintains it for 55 minutes, during which the temperature is (35±2)°C.

f) The specimens were transferred to a constant temperature and humidity chamber for a 30-day constant temperature and humidity test, during which the temperature of the chamber was (30±2)°C. The humidity is (60±10)%.

f) until the specified number of cycles is completed. d)~f) represent one cycle, corresponding to one month for materials used in manned spacecraft in a temperature and humidity controlled indoor environment; if the materials are in a temperature and humidity controlled indoor environment... For indoor environments with controlled humidity and heat, the duration of salt spray and constant humidity and heat tests should be reduced proportionally based on actual conditions, if the duration is less than one month.