Airborne water tank body accelerated corrosion experiment device and method

Abstract

The invention discloses an airborne water tank body accelerated corrosion experiment device and method, and relates to the technical field of reliability testing. The invention provides an airborne water tank body accelerated corrosion experiment device and an accelerated experiment testing method on the basis of the airborne water tank body accelerated corrosion experiment device, the service environment of an airborne water tank and the local corrosion characteristics of key structural parts are fully analyzed, and on the premise that a failure mode is not changed, main environmental factors are strengthened, secondary factors are ignored, and the service life of the airborne water tank is greatly prolonged. The corrosion effect equivalent to that of long-term service in a short period is achieved. The external field service corrosion characteristics can be truly reflected, the repeatability is high, the difference between a corrosion product and an external field sample is small, and the reliability of an experimental result is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reliability testing, in particular to an airborne water tank body accelerated corrosion experiment device and method. BACKGROUND

[0002] The aircraft serves a wide range of regions, and the corrosion damage in the severe use environment constitutes one of the main damage forms of the aircraft structure. The "pre-corrosion" effect of environmental factors during aircraft parking and the interaction or synergy of use environment and load environment will reduce the calendar life and service life of the aircraft, and will increase the maintenance / repair cost of the structure, seriously affecting the economy and safety of the aircraft structure. The airborne water tank of the aircraft is exposed to complex environment during long-term service, including alternating wet and hot, salt spray deposition and mechanical vibration and other factors. The comprehensive influence of these factors is easy to cause corrosion, pitting and fatigue cracks in the internal and connecting structure of the tank body. The existing single accelerated corrosion method (such as salt spray test or wet heat test) can usually only simulate part of the environment, and it is difficult to truly reproduce the corrosion morphology and failure mechanism in the field in a limited time.

[0003] Corrosion test is an important means to evaluate the severity of corrosion. In actual use environment, corrosion test cannot meet the requirements of design cycle, and the commonly used way is to carry out accelerated corrosion test in laboratory environment to shorten the test cycle. However, the traditional acceleration method lacks consideration of the synergistic effect of multiple factors, resulting in large difference between the corrosion products and the field samples, and the result reliability is insufficient. Therefore, a multi-environment spectrum block accelerated corrosion method based on mechanism analysis is needed to realize high-precision and repeatable corrosion acceleration evaluation. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide an airborne water tank body accelerated corrosion experiment device and method, which can truly reflect the corrosion characteristics of field service, has strong repeatability, small difference between corrosion products and field samples, and enhances the reliability of experimental results.

[0005] The technical solution of the present application to solve the above technical problems is as follows: an airborne water tank body accelerated corrosion experiment device is provided, which comprises an experiment tank body, an experiment platform for placing a sample to be tested is arranged in the experiment tank body, a lifting rod is connected with a lifting cylinder at the bottom of the experiment platform, a test groove is arranged at the bottom of the experiment tank body, a plurality of fixing rods are arranged at the bottom of the experiment tank body, the fixing rods are located in the test groove, the experiment platform is sleeved on the fixing rods at both ends, a pressurizing cylinder is arranged at the top of the experiment tank body, the output end of the pressurizing cylinder is connected with a pressure plate, and the pressure plate is sleeved on the fixing rods at both ends.

[0006] A plurality of heaters are arranged around the test tank, a water inlet is arranged on the test tank, the water inlet is connected with the water storage tank through a water inlet pipe, a sprayer is arranged on the test tank, the sprayer is connected with the liquid storage tank 1 through the liquid inlet pipe 1 and the peristaltic pump, the liquid inlet pipe 1 is also connected with the liquid storage tank 2 through the liquid inlet pipe 2, and the test tank is also connected with the constant potential instrument and the power supply.

[0007] Further, temperature sensors and humidity sensors are arranged in the test tank, and the temperature sensors, humidity sensors, lifting cylinders, pressure cylinders, heaters, sprayers, peristaltic pumps and constant potential instruments are connected with the control device.

[0008] Further, a plurality of air valves are arranged around the test tank and the experimental box body.

[0009] Further, the opening width of the test tank is greater than the width of the experimental platform.

[0010] Further, the liquid storage tank 1 and the liquid storage tank 2 are respectively used for storing corrosion salt water and deionized water.

[0011] Further, the heater is a resistance wire heater.

[0012] Further, a water outlet is arranged at the bottom of the test tank.

[0013] When the experiment is carried out, the to-be-tested airborne water tank body is placed on the experimental platform, the height of the experimental platform and the airborne water tank body is adjusted through the lifting cylinder and the lifting rod, the pressure cylinder and the pressure plate above the experimental platform are used for load action in the fatigue test, and the pressure plate and the experimental platform are sleeved on the fixed rod and move along the fixed rod in the up-down lifting process, so that the tank body on the experimental platform is uniformly stressed, the heater is used for heating the test tank, and the soaking stage, the humid heat stage and the salt spray stage are carried out in the test tank; the corrosion salt water in the liquid storage tank 1 is sprayed into the test tank through the peristaltic pump, the liquid inlet pipe 1 and the sprayer, and is used for the salt spray stage experiment, and the deionized water in the liquid storage tank 2 is used for improving the humidity in the test tank, the water storage tank, the water inlet pipe and the water inlet are used for water adding work in the soaking stage, and the constant potential instrument and the power supply are used for power-on. The temperature sensors and the humidity sensors are used for detecting the temperature and the humidity in the test tank, and ion sensors and the like can also be arranged to detect the solution condition in the salt spray and soaking stages, and the whole is controlled by the control device, so that the automation degree is high and the efficiency during the experiment is improved.

[0014] The application also provides an airborne water tank body accelerated corrosion experiment testing method, which adopts the above-mentioned airborne water tank body accelerated corrosion experiment device, and the testing method comprises the following steps:

[0015] (1) placing the tank body on the experimental platform, and then starting each device to implement the soaking-humid heat-salt spray circulation corrosion acceleration steps on the tank body;

[0016] (2) the force-bearing corrosion-prone parts are subjected to a salt fog-fatigue alternating loading step;

[0017] (3) the equivalent relationship between the experimental period and the field service time is calculated according to the acceleration factor formula F=f(T, RH, C, sigma), and the total test period is controlled to be 200-300 h, and the equivalent corrosion effect of one year of field service is controlled.

[0018] Further, the soaking stage: the electrochemical potential is kept at-0.45 to-0.55 V in deionized water;

[0019] The humid heat stage: the temperature is 40-60 DEG C, the relative humidity is 90-100%, the temperature of the plastic is raised at 0.5-1 DEG C / min, and the humidity fluctuation range is + / - 5%;

[0020] The salt fog stage: the salt fog concentration is 3.5-5% sodium chloride, the deposition rate is 1-2 mL / (80 cm 2 •h);

[0021] The fatigue stage: the fatigue stress ratio R is 0.1-0.3, and the loading frequency is 1-3 Hz.

[0022] Further, in step (1), when the periodic damage and regeneration process of the field corrosion film is simulated, the humid heat stage and the salt fog stage are alternated for 3-5 times.

[0023] Further, in the salt fog-fatigue alternating loading step, by adjusting the phase difference between the load action and the salt fog deposition time, the corrosion crack initiation and propagation stages are synchronized, and the fatigue corrosion coupling effect is enhanced.

[0024] The present application has the following beneficial effects:

[0025] 1. The present application adopts the acceleration corrosion sequence of "soaking-humid heat-salt fog circulation" for the water tank body area to simulate the uniform corrosion and crevice corrosion environment, and adopts the composite test process of "salt fog-fatigue alternating loading" for the force-bearing corrosion-prone parts to reproduce the crack initiation and propagation under mechanical load. Through the coupling limitation of the temperature and humidity change rate, the salt fog concentration, the electrochemical potential and the load stress ratio, the effect of about 200-300 h of experimental period corresponding to one year of field corrosion equivalent is achieved. The method is simple in process, strong in repeatability, high in consistency of corrosion morphology and field, and has significant engineering application value.

[0026] 2. The experimental device and the test method of the present application are matched, which can conveniently perform the soaking-humid heat-salt fog circulation and the salt fog-fatigue alternating loading experiment on the water tank body, is convenient for experimental test and observation, and has high overall automation degree, and is convenient for popularization and use.

[0027] 3、The accelerated corrosion method of the application realizes rapid and real evaluation of the corrosion degree of the airborne water tank body, has the advantages of short cycle (about 1 / 10 of the field time), high consistency of corrosion morphology with field samples, good repeatability and scalability, and can be popularized to corrosion reliability evaluation of other aviation structural parts. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of an airborne water tank body accelerated corrosion experiment device;

[0029] Figure 2 is an internal test environment reference spectrum of the airborne water tank body;

[0030] Figure 3 is an external test environment reference spectrum of the airborne water tank body;

[0031] 1, experimental tank; 2, lifting cylinder; 3, lifting rod; 4, fixed rod; 5, pressure plate; 6, pressure cylinder; 7, experimental platform; 8, test tank; 9, heater; 10, water inlet pipe; 11, water storage tank; 12, water inlet; 13, water outlet; 14, sprayer; 15, liquid inlet pipe 1; 16, peristaltic pump; 17, liquid storage tank 1; 18, liquid storage tank 2; 19, liquid inlet pipe 2; 20, constant potential instrument. DETAILED DESCRIPTION

[0032] The principles and characteristics of the application are described below, and the examples are only used to explain the application and not to limit the scope of the application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are conventional products that can be purchased on the market.

[0033] Example 1

[0034] The application provides an airborne water tank body accelerated corrosion experiment device, as shown in Figure 1As shown, including experimental box 1, experimental box 1 is provided with experimental platform 7 for placing sample to be tested, experimental platform 7 bottom is connected with lifting cylinder 2 through lifting rod 3, experimental box 1 bottom is provided with test groove 8, experimental box 1 bottom is provided with several fixed rods 4, fixed rods 4 are located in test groove 8, experimental platform 7 both ends are sleeved on fixed rods 4, experimental box 1 top is provided with pressure cylinder 6, pressure cylinder 6 output end is connected with pressure plate 5, pressure plate 5 both ends are sleeved on fixed rods 4; Test groove 8 is provided with several heaters 9 around, test groove 8 is provided with water inlet 12, water inlet 12 is connected with water storage tank 11 through water inlet pipe 10, test groove 8 is provided with sprayer 14, sprayer 14 is connected with liquid storage tank 1 7 through inlet pipe 1 5 and peristaltic pump 16, inlet pipe 1 5 is also connected with liquid storage tank 2 18 through inlet pipe 2 19, test groove 8 is also connected with constant potential instrument 20 and power supply.

[0035] At the same time, PT100 type temperature sensor and BME280 type humidity sensor are arranged in test groove 8, temperature sensor, humidity sensor, lifting cylinder 2, pressure cylinder 6, heater 9, sprayer 14, peristaltic pump 16 and constant potential instrument 20 are connected with control device, control device is Omron CP1H-X40DT-D type PLC controller. Test groove 8 and experimental box 1 are provided with several air valves around, test groove 8 opening width is greater than experimental platform 7 width. Corrosive brine and deionized water are respectively stored in liquid storage tank 1 7 and liquid storage tank 2 18. Heater 9 is resistance wire heating; Test groove 8 bottom is provided with water outlet 13.

[0036] Example 2

[0037] The above-mentioned on-board water tank box body accelerated corrosion test device acceleration test method, including the following steps:

[0038] (1) Place the box on the experimental platform 7, then start each device to implement the immersion-humid heat-salt spray cycle corrosion acceleration step;

[0039] (2) Implement salt spray-fatigue alternating loading step for force-carrying corrosion-prone parts;

[0040] (3) According to the acceleration factor formula F=f(T,RH,C,σ), calculate the equivalent relationship between experimental period and field service time, and control the total test period to be 200-300 h, and the equivalent corrosion effect of one year of experimental field service.

[0041] Wherein, the immersion stage: keep the electrochemical potential in deionized water at-0.45~-0.55 V;

[0042] Humid heat stage: temperature 40-60 ℃, relative humidity 90-100%, temperature rise plastic 0.5-1 ℃ / min, humidity fluctuation range ±5%;

[0043] Salt spray stage: salt spray concentration 3.5-5% sodium chloride, deposition rate 1-2 mL / (80 cm 2 •h);

[0044] Fatigue stage: fatigue stress ratio R=0.1-0.3, loading frequency 1-3 Hz.

[0045] Specifically, the following experiments can be carried out:

[0046] For the external structure area, such as Figure 2 As shown: damp heat exposure test: the internal area of the box has a gap, which causes the same temperature and humidity environment conditions as the outer surface. The temperature and humidity conditions of the upper surface can be taken, that is, under the conditions of relative humidity RH=95%-100% and temperature T=(43±2) ℃. Considering that part of the water enters the internal structure during the cleaning process, the moisture volatilizes to form a damp heat environment. On the basis of the action time, multiply by a coefficient of 1.5, so the action time is 7 days.

[0047] Normal temperature fatigue test: the internal structure temperature of the box is normal temperature. In the fatigue test, the stress level is determined according to the random stress spectrum of the highest stress level of the specific structure part of the internal structure / part. According to the principle of equivalent fatigue damage, each level of stress in the load spectrum is converted to the stress corresponding to 500 cycles. The conditions of the fatigue test are: σ max = 0.1, f=5 Hz, and the cycle number is 500.

[0048] Acidic atmosphere test: the same as the salt spray action of the outer surface, the acidic atmosphere action time of the box is 3 days, and the pH value is 4.5.

[0049] Neutral salt spray test: the closed structure inside the box contains neutral salt spray in addition to acidic salt spray. The neutral salt spray test conditions refer to GJB150.A. A 5% NaCl solution is taken, the salt spray deposition amount is (1-2) ml / h•80 cm 2 , and the test temperature T=35 ℃. The action time is the same as the acidic salt spray action, that is, 1 day (24 h).

[0050] For the internal structure area, such as Figure 3 As shown: the equivalent acceleration relationship can be conservatively determined as 1 cycle of environmental spectrum equivalent to 1 year of field use.

[0051] Immersion test: soak in solution for 2 days. The immersion solution is: sodium chloride 234 g / L, potassium nitrate 50 g / L, and concentrated sulfuric acid 6.8 mL / L; pH value=4, temperature T=43±2 ℃.

[0052] Room temperature fatigue test: apply cross-section load several times under room temperature atmosphere, frequency f=4 Hz, cross-section load can be converted to the maximum level of stress in 1 year according to the principle of equivalent fatigue damage, and each level of stress in random stress spectrum is equivalent to the damage.

[0053] For the above test process, the accelerated corrosion test of a certain type of aircraft simulation test piece was carried out by using the accelerated test environment spectrum of "EXCO solution changing acid composition solution immersion for 2 days (adjusting HNO3 to H2SO4, concentrated sulfuric acid 3 mL / L, so that the solution pH=4.0; and considering the temperature effect, the environmental temperature is T=43±2 ℃) + room temperature fatigue (apply constant amplitude load several times under room temperature atmosphere, f=4 Hz)". There is no obvious difference between the composition of accelerated corrosion products and that of field corrosion products, especially the content of S is basically the same as that in field corrosion products. The corrosion damage form of the test piece produced by accelerated corrosion test reproduces the corrosion damage form of the fuel tank part of the certain type of series aircraft in the field, thereby further proving the rationality of the accelerated test environment spectrum.

[0054] By comparing the results of laboratory accelerated corrosion test and the corrosion structure under actual service environment, the equivalent acceleration relationship is determined. That is: for the aircraft parked at inland airport, 1 cycle of accelerated test environment spectrum is equivalent to 1.5 years of service in the field; for the aircraft parked at coastal airport, 1 cycle of accelerated test environment spectrum is equivalent to 0.75 years of service in the field.

[0055] Example 3

[0056] An aluminum alloy airborne water tank was used for accelerated corrosion test, and the process was as follows:

[0057] (1) Sample preparation: select typical tank body material of aluminum alloy airborne water tank, size 100 mm×50 mm×2 mm.

[0058] (2) Environmental condition analysis: according to the actual flight working condition, the main corrosion factors are determined as temperature and humidity alternation, salt spray deposition and mechanical stress.

[0059] (3) Tank body area corrosion test:

[0060] The temperature is controlled at 45 ℃, and the humidity is 95%;

[0061] The salt spray concentration is 3.5% NaCl;

[0062] Each cycle includes: humid heat 8 h→ salt spray 4 h→ immersion 2 h, a total of 5 cycles.

[0063] (4) Fatigue corrosion test of load-bearing part:

[0064] The alternating load stress ratio R=0.2 under salt spray environment, frequency 2 Hz;

[0065] Total cycle 10 5 After 250 h of cumulative test time.

[0066] (5) Effect verification: through SEM and EDS analysis, the consistency of the corrosion morphology with the field service sample is 92%, and the corrosion rate is equivalent to that of the field service sample for one year.

[0067] Comparative experiment: using the traditional single salt spray method for accelerated test, the results show that the corrosion product is unevenly distributed, the crack morphology is inconsistent with the field sample, and the corrosion rate is low.

[0068] In comparison, the device and method of the present application realize multi-factor synergistic acceleration, the corrosion uniformity is improved by 30%, the crack initiation rate is increased by 2.5 times, and the significant technical effect and unpredictability of the present application are verified.

[0069] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An on-board water tank box accelerated corrosion test device, characterized by, The utility model relates to an experimental device for accelerating corrosion experiment of airborne water tank body, which comprises an experimental box (1) in which an experimental platform (7) for placing samples to be tested is arranged, the bottom of the experimental platform (7) is connected with a lifting cylinder (2) through a lifting rod (3), a test groove (8) is arranged at the bottom of the experimental box (1), a plurality of fixing rods (4) are arranged at the bottom of the experimental box (1), the fixing rods (4) are located in the test groove (8), the experimental platform (7) is sleeved on the fixing rods (4) at both ends, and a load loading device is arranged at the top of the experimental box (1). A plurality of heaters (9) are arranged around the test groove (8), a water inlet (12) is arranged on the test groove (8), the water inlet (12) is connected with a water storage tank (11) through a water inlet pipe (10), a sprayer (14) is arranged on the test groove (8), the sprayer (14) is connected with a liquid storage tank (17) through a liquid inlet pipe (15) and a peristaltic pump (16), the liquid inlet pipe (15) is also connected with a liquid storage tank (18) through a liquid inlet pipe (19), and the test groove (8) is also connected with a constant potential instrument (20) and a power supply.

2. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein Temperature sensors and humidity sensors are arranged in the test groove (8), and the temperature sensors, the humidity sensors, the lifting cylinder (2), the heaters (9), the sprayer (14), the peristaltic pump (16) and the constant potential instrument (20) are connected with a control device.

3. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein A plurality of air valves are arranged around the test groove (8) and the experimental box (1).

4. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein The opening width of the test groove (8) is greater than the width of the experimental platform (7).

5. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein The liquid storage tank (17) and the liquid storage tank (18) are respectively used for storing corrosive brine and deionized water.

6. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein The load loading device comprises a pressurizing cylinder (6), the output end of the pressurizing cylinder (6) is connected with a pressure plate (5), and the pressure plate (5) is sleeved on the fixing rods (4) at both ends.

7. The accelerated corrosion test apparatus for an on-board water tank body according to claim 1, wherein A water outlet (13) is arranged at the bottom of the test groove (8).

8. An accelerated corrosion test method for an on-board water tank, characterized in that, The test method comprises the following steps: (1) placing the box on the experimental platform, and then starting each device to implement the immersion-humid heat-salt spray cycle corrosion acceleration steps on the box; (2) implementing the salt spray-fatigue alternate loading steps on the force-bearing corrosion-prone parts; (3) calculating the equivalent relationship between the experimental period and the field service time according to the acceleration factor formula F=f (T, RH, C, sigma), and controlling the total test period to be 200-300 h.

9. The accelerated corrosion test method for an on-board water tank according to claim 8, wherein In the immersion stage, the electrochemical potential is kept at-0.45 to-0.55 V in deionized water; In the humid heat stage, the temperature is 40-60 DEG C, the relative humidity is 90-100%, the temperature of the plastic is increased at a rate of 0.5-1 DEG C / min, and the humidity fluctuation range is ± 5%; Salt spray phase: salt spray concentration 3.5-5% sodium chloride, settlement rate 1-2 mL / (80 cm 2 • h); In the fatigue stage, the fatigue stress ratio R is 0.1-0.3, and the loading frequency is 1-3 Hz.

10. The accelerated corrosion test method for an on-board water tank according to claim 8, wherein In step (1), when the periodic damage and regeneration process of the field corrosion film is simulated, the humid heat stage and the salt spray stage are alternated for 3-5 times.

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