A method for verifying corrosion protection of offshore aircraft

Abstract

The present application belongs to the technical field of aircraft corrosion protection testing, and in particular to a method for verifying corrosion protection of offshore aircraft. The method comprises step S1, dividing each aircraft structural area into an internal closed area, an internal semi-closed area and an open exposed area according to the relative humidity of the aircraft structural area and whether it is exposed to the marine atmosphere; step S2, testing each aircraft structural area; step S3, performing environmental test compliance testing on the appearance and coating inspection requirements of each aircraft structural area according to given moisture and heat resistance test, mildew resistance test, salt spray resistance test and acidic atmosphere test. The present application conducts tests of different cycles on different structural areas of the aircraft, and can more accurately verify the environmental resistance performance of parts in various areas of offshore aircraft.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft corrosion protection testing, and in particular, relates to a method for verifying corrosion protection of offshore aircraft. Background Art

[0002] As a complex structure of aircraft, the local environment of different areas and parts of the aircraft is different. In addition, the seaplane should be able to withstand the marine environment of high humidity, high salt spray and mold. Due to its harsh service environment, in order to ensure the environmental adaptability of the aircraft, the corrosion resistance of typical parts of the aircraft needs to be verified. However, due to the complex structure of the aircraft, the local environment of different areas and parts is different. The single verification index and method of the previous domestic model can no longer meet the environmental resistance requirements of seaplanes. Therefore, it is particularly important to design a reasonable verification method for corrosion protection of seaplanes. Summary of the invention

[0003] In order to solve at least one of the above-mentioned technical problems, the present application designs a method for verifying corrosion protection of offshore aircraft. According to the local environment of various parts of offshore aircraft and combined with the characteristics of the marine environment, differentiated verification indicators and scientific verification methods are proposed, providing a scientific and reasonable method for verifying the corrosion protection performance of aircraft.

[0004] The marine aircraft corrosion protection verification method provided in this application mainly includes:

[0005] Step S1, dividing each aircraft structure area into an internal closed area, an internal semi-closed area and an open exposed area according to the relative humidity of the aircraft structure area and whether it is exposed to the marine atmosphere;

[0006] Step S2: testing each aircraft structure area, including:

[0007] Step S21, performing a humidity and heat resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 10 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 15 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 10 times;

[0008] Step S22, performing a mold resistance test with set parameters on each aircraft structure area, wherein the test period for the aircraft structure area belonging to the internal closed area is 28 days, the test period for the aircraft structure area belonging to the internal semi-closed area is 84 days, and the test period for the aircraft structure area belonging to the open exposed area is 84 days;

[0009] Step S23, performing a salt spray resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 2 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 4 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 5 times;

[0010] Step S24, performing an acidic atmosphere test with set parameters on each aircraft structure area, wherein the aircraft structure area belonging to the internal closed area is cycled three times, and a single cycle includes spraying for 2 hours and storing for 22 hours; the aircraft structure area belonging to the internal semi-closed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days; the aircraft structure area belonging to the open exposed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days;

[0011] Step S3: Perform environmental test compliance testing on the appearance and coating inspection requirements of each aircraft structure area according to given moisture and heat resistance test, mildew resistance test, salt spray resistance test and acid atmosphere test.

[0012] Preferably, in step S1, the aircraft structure area with a relative humidity not greater than 80% and not directly exposed to the marine atmosphere is an internal closed area, the aircraft structure area with a relative humidity between 80% and 95% and not directly exposed to the marine atmosphere is an internal semi-closed area, and the aircraft structure area with a relative humidity greater than 95% and directly exposed to the marine atmosphere is an open exposed area.

[0013] Preferably, in step S21, the humidity and heat resistance test of setting parameters includes:

[0014] Within 2 hours, increase the test chamber temperature from 30±2℃ to 60±2℃ and the relative humidity to 95±5%, and then maintain for 6 hours;

[0015] Within 8 hours, gradually lower the temperature to 30±2℃ and the humidity to greater than 85%;

[0016] Maintain the temperature at 30℃±2 and the humidity at 95±5% for 8 hours.

[0017] Preferably, in step S22, the mold resistance test of setting parameters includes:

[0018] The bacterial strains are the bacterial strains given according to the national military standard and Scopulariopsis brevis; the culture conditions are temperature T=30°C±1°C and relative humidity of 95%±5%.

[0019] Preferably, in step S23, the salt spray resistance test of setting parameters includes:

[0020] The temperature is 35±2℃; the salt spray uses 5±1% NaCl solution, its pH value is 3.5±0.5, and the salt spray deposition rate is 1.0~3.0mL / 80cm 2 ·h, a single cycle is 48h, including 24h continuous spraying and 24h drying.

[0021] Preferably, the pH value of the salt spray is adjusted by adding chemically pure dilute sulfuric acid or chemically pure sodium hydroxide.

[0022] Preferably, in step S24, the acidic atmosphere test of setting parameters includes:

[0023] Temperature T = 35 ± 2 ° C; relative humidity greater than 85%; the test solution is a mixed aqueous solution of sulfuric acid and nitric acid (11.9 mg of 95% to 98% sulfuric acid and 8.8 mg of 68% to 71% nitric acid are added to every 4L of solution), the pH value is 3.5 ± 0.5 (the pH value is adjusted by dilute hydrochloric acid or sodium hydroxide solution); the solution sedimentation rate is 1.0 to 3.0 mL / 80 cm 2 ·h.

[0024] Preferably, the ratio of the test solution is to add 11.9 mg of 95% to 98% sulfuric acid and 8.8 mg of 68% to 71% nitric acid per 4 L of solution, and the pH value of the test solution is adjusted by adding dilute hydrochloric acid or sodium hydroxide solution.

[0025] This application can more accurately verify the environmental resistance of parts in various regions of maritime aircraft. The verification process is simple and only four conventional environmental tests need to be carried out. The equipment requirements for the test are low and the test can be carried out using common environmental test equipment. This application determines the structural area and environmental type of different parts of the aircraft, clarifies the test requirements and qualified criteria, and establishes an effective, scientific and reasonable method for verifying the corrosion protection performance of maritime aircraft, which plays a decisive role in improving the overall corrosion protection and control level of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of one implementation method of the marine aircraft corrosion protection verification method of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0028] The present application provides a method for verifying corrosion protection of marine aircraft, mainly comprising:

[0029] Step S1, dividing each aircraft structure area into an internal closed area, an internal semi-closed area and an open exposed area according to the relative humidity of the aircraft structure area and whether it is exposed to the marine atmosphere;

[0030] Step S2: testing each aircraft structure area, including:

[0031] Step S21, performing a humidity and heat resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 10 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 15 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 10 times;

[0032] Step S22, performing a mold resistance test with set parameters on each aircraft structure area, wherein the test period for the aircraft structure area belonging to the internal closed area is 28 days, the test period for the aircraft structure area belonging to the internal semi-closed area is 84 days, and the test period for the aircraft structure area belonging to the open exposed area is 84 days;

[0033] Step S23, performing a salt spray resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 2 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 4 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 5 times;

[0034] Step S24, performing an acidic atmosphere test with set parameters on each aircraft structure area, wherein the aircraft structure area belonging to the internal closed area is cycled three times, and a single cycle includes spraying for 2 hours and storing for 22 hours; the aircraft structure area belonging to the internal semi-closed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days; the aircraft structure area belonging to the open exposed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days;

[0035] Step S3: Perform environmental test compliance testing on the appearance and coating inspection requirements of each aircraft structure area according to given moisture and heat resistance test, mildew resistance test, salt spray resistance test and acid atmosphere test.

[0036] In some optional embodiments, in step S1, the aircraft structure area with a relative humidity not greater than 80% and not directly exposed to the marine atmosphere is an internal closed area, the aircraft structure area with a relative humidity between 80% and 95% and not directly exposed to the marine atmosphere is an internal semi-closed area, and the aircraft structure area with a relative humidity greater than 95% and directly exposed to the marine atmosphere is an open exposed area.

[0037] In this embodiment, the environmental factors and usage characteristics of the internal enclosed area are as follows: the relative humidity is generally not greater than 80%, and it is usually not directly exposed to the marine atmosphere, but is occasionally affected by a small amount of moisture, salt spray and fuel exhaust gas (during maintenance, the doors of the cockpit, working cabin, equipment cabin, etc. are often opened, and high humidity, high salt spray and corrosive atmosphere containing fuel exhaust gas will enter the cabin). For example, the cockpit, working cabin, and equipment cabin.

[0038] For the internal semi-enclosed area, its environmental factors and usage characteristics are: relative humidity is not more than 95%, not directly exposed to the marine atmosphere, but affected by its sealing, affected by general moisture (a small amount of rain, condensation), salt spray, fuel exhaust gas, etc. (non-airtight / sealed structure, some rain, condensation generated by the external structure can flow into or penetrate into the interior through the gap, gradually gather at the structural connection parts or dead corners, and the evaporation of water leads to the formation of a high humidity and heat environment in the structure; at the same time, the external humid air containing chloride ions and corrosive media of fuel exhaust can also penetrate into the internal structure / cavity to form a more severe local environment). For example, the fuselage, wings (non-airtight), engine heat-affected zone, swivel cover assembly and bracket.

[0039] For open and exposed areas, the environmental factors and usage characteristics are: relative humidity greater than 95%, directly exposed to the harsh marine atmosphere, and directly subjected to high humidity, heat, high salt fog and fuel-containing exhaust gas corrosive atmosphere for a long time. For example, the outside of the aircraft, the outside of the wing rear beam, the outside of the tail rear beam, the outside of the wing folding rib, and the landing gear compartment.

[0040] In some optional implementations, in step S21, the humidity and heat resistance test of setting parameters includes:

[0041] Within 2 hours, increase the test chamber temperature from 30±2℃ to 60±2℃ and the relative humidity to 95±5%, and then maintain for 6 hours;

[0042] Within 8 hours, gradually lower the temperature to 30±2℃ and the humidity to greater than 85%;

[0043] Maintain the temperature at 30℃±2 and humidity at 95±5% for 8 hours. The single cycle of the alternating damp heat test is 24 hours.

[0044] In some optional embodiments, in step S22, setting parameters for the fungus resistance test includes:

[0045] The bacterial strains are those given by the national military standard (for example, Class 2 bacterial strains in GJB150.10A-2009) and Scopulariopsis brevicaulis; the culture conditions are temperature T=30°C±1°C and relative humidity of 95%±5%.

[0046] In some optional embodiments, in step S23, setting parameters for the salt spray resistance test includes:

[0047] The temperature is 35±2℃; the salt spray uses 5±1% NaCl solution, its pH value is 3.5±0.5, and the salt spray deposition rate is 1.0~3.0mL / 80cm 2 ·h, a single cycle is 48h, including 24h continuous spraying and 24h drying.

[0048] In some optional embodiments, the pH value of the salt spray is adjusted by adding chemically pure dilute sulfuric acid or chemically pure sodium hydroxide.

[0049] In some optional embodiments, in step S24, setting parameters for the acidic atmosphere test includes:

[0050] Temperature T = 35 ± 2 ° C; relative humidity greater than 85%; the test solution is a mixed aqueous solution of sulfuric acid and nitric acid (11.9 mg of 95% to 98% sulfuric acid and 8.8 mg of 68% to 71% nitric acid are added to every 4L of solution), the pH value is 3.5 ± 0.5 (the pH value is adjusted by dilute hydrochloric acid or sodium hydroxide solution); the solution sedimentation rate is 1.0 to 3.0 mL / 80 cm 2 ·h.

[0051] In some optional embodiments, the ratio of the test solution is to add 11.9 mg 95% to 98% sulfuric acid and 8.8 mg 68% to 71% nitric acid per 4 L of solution, and the pH value of the test solution is adjusted by adding dilute hydrochloric acid or sodium hydroxide solution.

[0052] In step S3, for the moisture and heat resistance test item, the product can be used normally after being subjected to the moisture and heat environment, and the appearance and coating inspection meet the following requirements:

[0053] a) Except for the edges and corners (within 5 mm of the edges and corners), the corrosion area of ​​the protective layer shall not exceed 5% of the area of ​​the protective layer of the part;

[0054] b) The base metal shall not be corroded except at the edges and corners;

[0055] c) The coating gloss and color are allowed to fade and there are a small amount of bubbles with a diameter of no more than 0.5mm. Except for the local edges, there are no bubbles, wrinkles, cracks or shedding, and the surface coating and base metal shall not be corroded;

[0056] d) There should be no corrosion at the contact points;

[0057] e) Metal components may be slightly darkened but must not be corroded;

[0058] f) Non-metallic materials shall have no obvious defects such as discoloration, expansion, blistering, wrinkling, cracking, falling off, and pitting.

[0059] For the mold resistance test items, the functions and performances meet the requirements after being subjected to the above-mentioned mold environment, and the mold resistance requirements of the appearance inspection are better than or equal to Level 1.

[0060] For the salt spray resistance test items, the product can work normally after being subjected to the above salt spray environment, and the appearance and coating inspection meet the following requirements:

[0061] a) The paint layer shall be free of bubbles, wrinkles, cracks or peeling except for the local edges and corners (within 5mm of the edges and corners), and the surface coating and base metal shall not be corroded;

[0062] b) The corrosion area of ​​the metal protective layer does not exceed 10% of the area of ​​the metal protective layer;

[0063] c) There should be no corrosion at metal joints;

[0064] d) Except for the edges and corners (within 5 mm of the edges and corners), the corrosion area of ​​the paint coating shall not exceed 5% of the area of ​​the protective layer of the part;

[0065] e) Non-metallic materials have no obvious defects such as discoloration, expansion, blistering, cracking, and pitting.

[0066] For the acidic atmosphere test items, they can work normally after being subjected to the above acidic atmosphere environment, and the appearance and coating inspections meet the following requirements:

[0067] a) The base metal shall not be corroded except for the edges and corners (within 5mm of the edges and corners);

[0068] b) There should be no corrosion at the joints;

[0069] c) The corrosion area of ​​the surface treatment layer does not exceed 10% of the area of ​​the metal protective layer;

[0070] d) Except for the edges and corners (within 5 mm of the edges and corners), the corrosion area of ​​the paint coating shall not exceed 5% of the area of ​​the protective layer of the part;

[0071] e) Non-metallic materials shall have no obvious defects such as discoloration, expansion, blistering, wrinkling, cracking, falling off, and pitting.

[0072] This application determines the test time of the above-mentioned various environmental areas based on the expected proportional relationship between the aircraft's expected working time at sea and the time parked on shore, and in combination with the main parameters of the sea environment; determines the pH value of the salt spray test in the above-mentioned various environmental areas based on the specific environmental characteristics and requirements of each area of ​​the aircraft, and in combination with the salt spray ion precipitation in the offshore and sea areas; determines the pH value of the above-mentioned acidic atmosphere test based on the sulfur dioxide concentration in each sea environment; determines the type of fungus in the above-mentioned fungus test based on the characteristics of mold growth in each sea environment. Based on the above test parameters, this application conducts tests of different cycles on different structural areas of the aircraft, which can more accurately verify the environmental resistance of parts in various areas of the sea aircraft.

[0073] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for verifying corrosion protection of offshore aircraft, characterized in that: include: Step S1, dividing each aircraft structure area into an internal closed area, an internal semi-closed area and an open exposed area according to the relative humidity of the aircraft structure area and whether it is exposed to the marine atmosphere; Step S2: testing each aircraft structure area, including: Step S21, performing a humidity and heat resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 10 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 15 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 10 times; Step S22, performing a mold resistance test with set parameters on each aircraft structure area, wherein the test period for the aircraft structure area belonging to the internal closed area is 28 days, the test period for the aircraft structure area belonging to the internal semi-closed area is 84 days, and the test period for the aircraft structure area belonging to the open exposed area is 84 days; Step S23, performing a salt spray resistance test with set parameters on each aircraft structure area, wherein the number of cycles for the aircraft structure area belonging to the internal closed area is 2 times, the number of cycles for the aircraft structure area belonging to the internal semi-closed area is 4 times, and the number of cycles for the aircraft structure area belonging to the open exposed area is 5 times; Step S24, performing an acidic atmosphere test with set parameters on each aircraft structure area, wherein the aircraft structure area belonging to the internal closed area is cycled three times, and a single cycle includes spraying for 2 hours and storing for 22 hours; the aircraft structure area belonging to the internal semi-closed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days; the aircraft structure area belonging to the open exposed area is cycled four times, and a single cycle includes spraying for 2 hours and storing for 7 days; Step S3: Perform environmental test compliance testing on the appearance and coating inspection requirements of each aircraft structure area according to given moisture and heat resistance test, mildew resistance test, salt spray resistance test and acid atmosphere test.

2. The method for verifying corrosion protection of marine aircraft according to claim 1, characterized in that: In step S1, the aircraft structure area with a relative humidity not greater than 80% and not directly exposed to the marine atmosphere is an internal closed area, the aircraft structure area with a relative humidity between 80% and 95% and not directly exposed to the marine atmosphere is an internal semi-closed area, and the aircraft structure area with a relative humidity greater than 95% and directly exposed to the marine atmosphere is an open exposed area.

3. The method for verifying corrosion protection of marine aircraft according to claim 1, characterized in that: In step S21, the humidity and heat resistance test of setting parameters includes: Within 2 hours, increase the test chamber temperature from 30±2℃ to 60±2℃ and the relative humidity to 95±5%, and then maintain for 6 hours; Within 8 hours, gradually lower the temperature to 30±2℃ and the humidity to greater than 85%; Maintain the temperature at 30℃±2 and the humidity at 95±5% for 8 hours.

4. The method for verifying corrosion protection of marine aircraft according to claim 1, characterized in that: In step S22, the mold resistance test of setting parameters includes: The bacterial strains are the bacterial strains given according to the national military standard and Scopulariopsis brevis; the culture conditions are temperature T=30°C±1°C and relative humidity of 95%±5%.

5. The method for verifying corrosion protection of marine aircraft according to claim 1, characterized in that: In step S23, the salt spray resistance test of setting parameters includes: The temperature is 35±2℃; the salt spray uses 5±1% NaCl solution, its pH value is 3.5±0.5, and the salt spray deposition rate is 1.0~3.0mL / 80cm 2 ·h, a single cycle is 48h, including 24h continuous spraying and 24h drying.

6. The method for verifying corrosion protection of marine aircraft according to claim 5, characterized in that: The pH value of the salt spray is adjusted by adding chemically pure dilute sulfuric acid or chemically pure sodium hydroxide.

7. The method for verifying corrosion protection of marine aircraft according to claim 1, characterized in that: In step S24, the acidic atmosphere test of setting parameters includes: Temperature T = 35 ± 2 ° C; relative humidity greater than 85%; the test solution is a mixed aqueous solution of sulfuric acid and nitric acid, the pH value is 3.5 ± 0.5; the solution sedimentation rate is 1.0 ~ 3.0mL / 80cm 2 ·h.

8. The method for verifying corrosion protection of marine aircraft according to claim 7, characterized in that: The ratio of the test solution is to add 11.9 mg of 95% to 98% sulfuric acid and 8.8 mg of 68% to 71% nitric acid to every 4 L of solution. The pH value of the test solution is adjusted by adding dilute hydrochloric acid or sodium hydroxide solution.

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