Hot corrosion damage test device for simulating ocean salt spray environment and test method thereof

Abstract

The invention discloses a hot corrosion damage test device for simulating a sea salt spray environment and a test method of the hot corrosion damage test device. The test device comprises a high-temperature test furnace, a layered high-temperature salt spray preheating wound pipe, a sectional high-temperature salt spray corrosion test box, a salt solution pump, a low-pressure air pump, a back pressure valve and the like. The test method comprises the following steps: acquiring a fitting curve of preset pressure of the back pressure valve; according to the fitting curve of the preset pressure of the back pressure valve, the test temperature and the corresponding back pressure valve pressure are set, and meanwhile the pressure of the low-pressure air pump and the flow of the salt solution pump are set; and the high-temperature test furnace, the low-pressure air pump and the salt solution pump are started, a mixed medium of a salt solution and low-pressure air sequentially enters the layered high-temperature salt spray preheating winding pipe and the sectional high-temperature salt spray corrosion test box, and a sample is subjected to hot corrosion. The problems that in the prior art, a marine salt spray environment hot corrosion damage testing device is insufficient in temperature rising capacity, low in atomization precision, distorted in environment simulation and the like are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal corrosion damage simulation test of metal materials, and particularly relates to a thermal corrosion damage test device simulating an ocean salt spray environment and a test method thereof. Background Art

[0002] With the construction of the aircraft carrier formation system, higher requirements are placed on the adaptability of carrier-based aircraft engines in complex marine environments. In addition to facing loads such as high temperature, high pressure, and high speed in the marine environment, their hot end components are also affected by corrosive environments such as high salt spray and high humidity.

[0003] As one of the working components with the highest failure rate in aircraft engines, turbine rotor components are often subjected to the impact of high-pressure gases in high-temperature environments, accompanied by huge centrifugal stress and vibration loads caused by high-speed rotation of tens of thousands of revolutions per minute. Combined with the penetration of deposited salt and erosion of high-temperature gases in the marine salt spray environment, this environment can cause severe thermal corrosion damage to turbine rotor components, thereby affecting the service life of aircraft engine turbine rotor components and causing premature failure. Therefore, how to simulate the thermal corrosion damage behavior of aircraft engine hot end components in high-temperature, high-salt spray marine environments is not only a key research topic for improving the service life of aircraft engines, but also a major challenge facing the maintenance and damage tolerance design of aircraft engine hot end components.

[0004] To ensure that aero-engine hot-end components can operate safely and for a long time in marine environments, it is necessary to conduct in-depth research on the development mechanism of thermal corrosion damage in hot-end components under high-temperature service conditions and the characterization method of thermal corrosion damage. To this end, it is urgent to develop a thermal corrosion damage test device and test method that simulates marine salt spray environments. This will provide an effective means to evaluate the impact of real thermal corrosion damage in marine environments on the service life of aero-engine hot-end components and design damage tolerance.

[0005] At present, domestic and foreign scholars have carried out certain experimental studies on the simulation of thermal corrosion damage of hot end components of aircraft engines in marine environments. However, these studies usually preheat the sample to a certain temperature, then use a spraying device to atomize a certain ratio of salt solution and spray it onto the sample surface. When the atomized salt solution contacts the preheated sample, the water in the atomized salt solution evaporates rapidly, leaving a layer of deposited salt on the surface of the sample. The sample is then subjected to high-temperature heat treatment for a certain period of time. However, this method can only simulate thermal corrosion damage under static salt deposition conditions, and cannot truly reproduce the dynamic salt spray atmosphere in the marine environment. Therefore, it is difficult to reveal the thermal corrosion mechanism in the actual salt spray environment.

[0006] The invention patent application publication number CN105987871A discloses a device for simulating high-temperature marine salt spray. The device atomizes the salt solution through a salt spray nozzle, and then uses airflow to carry 1-100 μm salt solution particles into a quartz tube in a high-temperature experimental furnace, and then impacts the surface of the sample in the quartz tube, causing thermal corrosion of the sample. Although this technical solution can simulate the marine salt spray environment, it still has the following defects: (1) The atomizing nozzle atomizes the salt solution into 1-100 μm solution particles, and the particle size control accuracy is low. The atomized salt solution particles are small droplets with too large a particle size, which exceeds the particle size range of real marine salt spray. (2) Under the action of the high temperature environment, a large part of the atomized salt spray particles quickly evaporate and lose water and precipitate, causing a large amount of solid salt to be deposited on the surface of the sample, and even on the inner wall of the quartz tube. This salt deposition mechanism often leads to excessively severe thermal corrosion, making it difficult to effectively reproduce the thermal corrosion conditions of the real marine environment with the synergistic effects of high temperature, high salt spray, and saturated humidity. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a thermal corrosion damage test device for simulating a marine salt spray environment. The test device comprises a high-temperature test furnace, a layered high-temperature salt spray preheating coil, a segmented high-temperature salt spray corrosion test chamber, a salt solution storage tank, a salt solution pump, a low-pressure air pump, a back pressure valve, a waste liquid storage tank, a thermocouple and a temperature display. The layered high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test chamber are located inside the high-temperature test furnace and are connected, with their central axes being on the same horizontal line.

[0008] The salt solution storage tank, the salt solution pump and the low-pressure air pump are located outside the high-temperature test furnace. The salt solution storage tank is connected to the salt solution pump through a suction pipe, and the salt solution pump and the low-pressure air pump are connected to the stratified high-temperature salt spray preheating coil through a three-way liquid inlet pipe.

[0009] The back pressure valve, the waste liquid storage tank, the thermocouple and the temperature display are located outside the high-temperature test furnace. The back pressure valve is arranged on the salt spray exhaust pipe and is close to the high-temperature test furnace. One end of the salt spray exhaust pipe is connected to the segmented high-temperature salt spray corrosion test box, and the waste liquid storage tank is placed below the other end. One end of the thermocouple extends into the segmented high-temperature salt spray corrosion test box along the salt spray exhaust pipe, and the other end is connected to the temperature display.

[0010] Preferably, the high-temperature test furnace is an integrated box-type muffle furnace, with a furnace door and a temperature control panel provided on the front, and a first through hole and a second through hole provided on the back; the first through hole is used to insert the three-way liquid inlet pipe, one end of the three-way liquid inlet pipe enters the high-temperature test furnace and is connected to the layered high-temperature salt spray preheating coil; the second through hole is used to insert the salt spray exhaust pipe, one end of the salt spray exhaust pipe enters the high-temperature test furnace and is connected to the segmented high-temperature salt spray corrosion test box.

[0011] In any of the above schemes, it is preferred that the layered high-temperature salt spray preheating coil includes an inner coil, a middle coil and an outer coil connected in sequence from the inside to the outside, and the connection parts between the inner coil, the middle coil and the outer coil are connected in a smooth transition manner; the starting end of the inner coil is connected to the three-way liquid inlet pipe inserted into the high-temperature test furnace, and the tail end of the outer coil is connected to the segmented high-temperature salt spray corrosion test box.

[0012] In any of the above schemes, it is preferred that the inner layer winding tube is spirally wound from left to right in a clockwise direction starting from its starting end and ending at its tail end, with a total of 5-7 turns of the inner layer winding tube. The outer diameter of the inner layer winding tube is 5-7 mm, and the spacing between the central axes of two adjacent turns of the inner layer winding tube is 1-2 mm larger than the outer diameter of the inner layer winding tube. The 5-7 turns of the inner layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 6.5 times the outer diameter of the inner layer winding tube, and the wall thickness of the inner layer winding tube is 0.8-1 mm.

[0013] In any of the above schemes, it is preferred that the tail end of the inner layer winding tube is used as the starting end of the middle layer winding tube, and the middle layer winding tube is spirally wound from right to left in a counterclockwise direction from its starting end to its tail end, with a total of 5-7 turns of the middle layer winding tube. The outer diameter of the middle layer winding tube is 7-9 mm, and the distance between the central axes of two adjacent turns of the middle layer winding tube is 1-2 mm larger than the outer diameter of the middle layer winding tube. The 5-7 turns of the middle layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 7.5 times the outer diameter of the middle layer winding tube, and the wall thickness of the middle layer winding tube is 0.8-1 mm.

[0014] In any of the above schemes, it is preferred that the tail end of the middle layer winding tube is used as the starting end of the outer layer winding tube, and the outer layer winding tube is spirally wound from left to right in a clockwise direction from its starting end to its tail end, with a total of 5-7 turns of the outer layer winding tube. The outer diameter of the outer layer winding tube is 9-11 mm, and the distance between the central axes of two adjacent turns of the outer layer winding tube is 1-2 mm larger than the outer diameter of the outer layer winding tube. The 5-7 turns of the outer layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 8.5 times the outer diameter of the outer layer winding tube, and the wall thickness of the outer layer winding tube is 0.8-1 mm.

[0015] In any of the above schemes, it is preferred that the segmented high-temperature salt spray corrosion test chamber includes a transition section, a test section and a separation section connected in sequence from left to right, the starting end of the transition section is connected to the tail end of the outer layer winding tube, and the tail end of the separation section is connected to the salt spray exhaust pipe inserted into the high-temperature test furnace.

[0016] In any of the above schemes, it is preferred that the transition section is a conical structure, with a circular starting end and a square tail end, the ratio of the circular diameter to the square side length is 1:2.2-2.8, the diameter of the circle is the same as the diameter of the outer layer winding tube, and the height of the transition section is 2.6-3.2 times the diameter of the outer layer winding tube.

[0017] The test section has a cube structure, and its side length is the same as the side length of the square at the end of the transition section; a triangular fixture is set on the inner bottom surface of the test section, and the angle between the inclined surface of the triangular fixture and the horizontal plane is 30-60°. A circular groove is set on the inclined surface of the triangular fixture, and a circular specimen is installed in the circular groove. The diameter of the circular groove matches the diameter of the circular specimen.

[0018] The separation section is a conical structure with a square starting end and a circular tail end. The ratio of the circular diameter to the square side length is 1:3-3.5. The side length of the square is the same as the side length of the test section. The height of the separation section is 0.5-0.8 times the side length of the test section. Several wedge-shaped guide corrugations are arranged inside the separation section.

[0019] In any of the above schemes, preferably, the salt solution storage tank contains a salt solution, and the mass percentages of the substances in the salt solution are 90.91wt% of water, 6.82wt% of sodium sulfate, and 2.27wt% of sodium chloride; the three-way liquid inlet pipe and the salt spray exhaust pipe are made of high-temperature resistant materials; and the layered high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test chamber are made of quartz glass.

[0020] The present invention also provides a thermal corrosion damage test method for simulating a marine salt spray environment, using any of the thermal corrosion damage test devices for simulating a marine salt spray environment described above, the test method comprises the following steps in order:

[0021] Step 1: Assemble the test device according to the designed structure, put the salt solution into the salt solution storage tank according to the designed ratio, and seal all the joints in the test device to ensure that the test device can be used normally during the subsequent test process;

[0022] Step 2: Obtain the fitting curve of the back pressure valve preset pressure, including the following steps in order:

[0023] Step 2.1: Set the temperature of the high-temperature test furnace to 550°C, the pressure of the low-pressure air pump to 0.6 MPa, the flow rate of the salt solution pump to 1 L / h, and the initial pressure of the back pressure valve to 0.6 MPa;

[0024] Step 2.2: Turn on the high-temperature test furnace and gradually increase the furnace temperature to 550°C. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe and mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber;

[0025] Step 2.3: Dynamically adjust the pressure of the back pressure valve based on the initial pressure until the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds, and the number of open-close cycles is at least 5 times in a row. At this time, record the pressure of the back pressure valve and use it as the preset pressure of the back pressure valve at a test temperature of 550°C; Step 2.4: Repeat steps 2.1 to 2.3 several times, setting the furnace temperature of the high-temperature test furnace to 600°C, 650°C, 700°C, 750°C and 800°C, respectively, to obtain the preset pressures of the back pressure valve at test temperatures of 600°C, 650°C, 700°C, 750°C and 800°C, respectively;

[0026] Step 2.5: Plot a two-dimensional graph of the test temperature and the corresponding back pressure valve preset pressure and perform fitting to obtain a fitting curve and fitting function for the back pressure valve preset pressure; turn off the low-pressure air pump, salt solution pump, and high-temperature test furnace, and cool the high-temperature test furnace to room temperature;

[0027] Step 3: Place the circular specimen to be hot-corroded into the circular groove of the triangular fixture, then place the triangular fixture into the test section of the segmented high-temperature salt spray corrosion test chamber, and seal all the connection parts in the test device to ensure that the test device can be used normally during the subsequent test process;

[0028] Step 4: According to the obtained fitting curve of the back pressure valve preset pressure, set the test temperature and the corresponding back pressure valve pressure. At the same time, set the pressure of the low-pressure air pump to 0.6 MPa and the flow rate of the salt solution pump to 1 L / h.

[0029] Step 5: Turn on the high-temperature test furnace, and gradually increase the furnace temperature to the set test temperature. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe to mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber to perform constant-temperature thermal corrosion on the circular specimen for 50-1000 hours. During the thermal corrosion test, the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds to ensure that the air pressure in the inner coil, the middle coil and the outer coil remains consistent.

[0030] Step 6: After the thermal corrosion test is completed, turn off the low-pressure air pump, salt solution pump and high-temperature test furnace, cool the high-temperature test furnace to room temperature, take out the circular specimen after thermal corrosion, and conduct subsequent tests.

[0031] The high-temperature test furnace, salt solution pump, low-pressure air pump, back-pressure valve, thermocouple, and temperature display used in this invention are all state-of-the-art equipment and instruments. Specific models can be selected based on test requirements or actual conditions, and all models can be used interchangeably. For example, the high-temperature test furnace can be an integrated box-type muffle furnace with integrated on / off, timing, and temperature control functions. It can operate at temperatures up to 1200°C and can last for over 1000 hours within the operating temperature range. The salt solution pump can be an electromagnetic diaphragm metering pump with a built-in pipette and valve. The pipette is inserted into the salt solution storage tank, and the valve controls the quantitative intake and discharge of salt solution. The mass percentages of the salt solution are 90.91 wt% water, 6.82 wt% sodium sulfate, and 2.27 wt% sodium chloride, consistent with marine salt spray environments. The low-pressure air pump can be a miniature air pump suitable for laboratory use. The back-pressure valve has automatic on / off or automatic adjustment functions, and its caliber and pressure setting range can be selected based on test requirements or actual conditions.

[0032] The thermocouple can use a high-temperature resistant K-type thermocouple wire as a temperature sensor with an operating temperature of up to 1200°C. One end of the thermocouple extends through the salt spray exhaust pipe to the test section of the segmented high-temperature salt spray corrosion test chamber, and the other end is connected to a temperature display for real-time monitoring of the temperature of the sample environment. Under normal circumstances, the temperature displayed in real time by the temperature display is consistent with or close to the preset temperature of the high-temperature test furnace (i.e., the test temperature). The waste liquid storage tank is placed below the tail end of the salt spray exhaust pipe. A glass container of appropriate size can be selected according to actual conditions to receive the droplets generated by condensation at the exhaust port of the high-temperature salt spray gas discharged from the salt spray exhaust pipe.

[0033] In the present invention, the method for placing and removing samples from the test section is as follows: first, separate the test section and the separation section, and push the separation section toward the back side of the high-temperature test furnace, while driving the salt spray exhaust pipe connected to it to move from the second through hole to the outside of the high-temperature test furnace, leaving a certain space at the tail end of the test section; secondly, place the circular sample into the circular groove of the triangular clamp, and then place the triangular clamp into the interior of the test section from the tail end of the test section; then, restore the separation section to its original position and connect it to the test section, and use high-temperature sealant to seal the connection parts between the test section and the separation section, and between the salt spray exhaust pipe and the second through hole, and at the same time check the sealing of each connection part in the entire test device, and further seal it with high-temperature sealant; finally, after the thermal corrosion test is completed and the temperature in the high-temperature test furnace drops to room temperature, separate the test section and the separation section again, and take out the triangular clamp and the circular sample. In addition, a window can be opened on the side of the test section facing the front of the high-temperature test furnace for placing and removing the triangular fixture and the specimen. The specific placement and removal method can be determined according to the actual situation. In short, it must be ensured that all connection parts in the entire test device have good sealing properties.

[0034] The thermal corrosion damage test device and test method of the present invention that simulates a marine salt spray environment have the following beneficial effects:

[0035] (1) The present invention addresses the shortcomings of existing marine salt spray environment thermal corrosion damage test devices, such as insufficient heating capacity, low atomization accuracy, and environmental simulation distortion. This invention proposes a simulation solution that conforms to the actual marine salt spray environment and has high accuracy. The test device of the present invention can reproduce the extreme operating conditions of high temperature and high salt spray in a marine salt spray environment for aircraft engine components or materials, achieving efficient preparation of thermal corrosion damage and providing standardized test samples for the characterization and mechanism research of thermal corrosion damage in aircraft engine materials.

[0036] (2) The high-temperature test furnace of the present invention adopts an integrated box-type muffle furnace, which has high thermal field uniformity and stability, can significantly improve the quality of furnace temperature control and can operate stably for a long time. Compared with the salt spray nozzle device of the prior art, the present invention fully generates a high-temperature and high-salt spray atmosphere through a layered high-temperature salt spray preheating coil, effectively solving the problem of insufficient atomization capacity of the salt spray nozzle and more realistically simulating the thermal corrosion damage conditions in the marine salt spray environment; in addition, the high-temperature and high-salt spray atmosphere generated by the layered high-temperature salt spray preheating coil has excellent continuity, which can further improve the reliability of the thermal corrosion test.

[0037] (3) In the test device of the present invention, the salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe to mix, and the mixed medium enters the layered high-temperature salt spray preheating coil to fully form a high-temperature high-salt spray atmosphere. The high-temperature high-salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber to perform thermal corrosion on the sample. During the entire thermal corrosion process, the back pressure valve maintains a stable open and close cycle state, on the one hand to ensure that the air pressure in the inner coil, the middle coil and the outer coil remains consistent, and on the other hand to prevent the medium from backflowing or clogging; the high-temperature high-salt spray gas discharged from the salt spray exhaust pipe condenses at the exhaust port to form water droplets, which drip into the waste liquid storage tank. The salt spray exhaust pipe can ensure that a continuous high-temperature high-salt spray atmosphere is formed in the segmented high-temperature salt spray corrosion test chamber.

[0038] (4) The present invention innovatively integrates two core structures inside the high-temperature test furnace, namely, a layered high-temperature salt spray preheating coil and a segmented high-temperature salt spray corrosion test chamber. Among them, the layered high-temperature salt spray preheating coil adopts a three-layer structure design (inner preheating layer, middle vaporization layer and outer balancing layer), which realizes mixed medium preheating by extending the path, thereby preparing a stable and continuous high-temperature and high-salt spray atmosphere; the segmented high-temperature salt spray corrosion test chamber adopts a three-stage design, and its transition section can effectively suppress airflow mutations and prevent salt spray condensation, thereby ensuring the stability of the thermal corrosion test environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of a preferred embodiment of a thermal corrosion damage test device simulating a marine salt spray environment according to the present invention;

[0040] Figure 2 for Figure 1 A schematic structural diagram of the test device in the illustrated embodiment from another perspective;

[0041] Figure 3 for Figure 1 A schematic diagram of the front structure of the high-temperature test furnace in the embodiment shown;

[0042] Figure 4 for Figure 1 A schematic diagram of the back structure of the high-temperature test furnace in the embodiment shown;

[0043] Figure 5 for Figure 1 A schematic diagram of the connection structure between the layered high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test chamber in the illustrated embodiment;

[0044] Figure 6 for Figure 1 A schematic structural diagram of a layered high-temperature salt spray preheating coil in the embodiment shown;

[0045] Figure 7 for Figure 1 A schematic structural diagram of the layered high-temperature salt spray preheating coil in the embodiment shown in FIG. 1 from another perspective;

[0046] Figure 8 for Figure 1 A side view of the layered high-temperature salt spray preheating coil in the illustrated embodiment;

[0047] Figure 9 for Figure 1 A schematic structural diagram of a segmented high-temperature salt spray corrosion test chamber in the embodiment shown;

[0048] Figure 10 for Figure 1 A schematic structural diagram of the triangular clamp in the embodiment shown;

[0049] Figure 11 for Figure 1 A schematic diagram of the internal structure of the separation section in the embodiment shown;

[0050] Figure 12 for Figure 1 The fitting curve of the back pressure valve preset pressure obtained in the embodiment shown;

[0051] Figure 13 for Figure 1 Surface optical micrographs of the circular specimens in the embodiment shown after high temperature and high salt spray corrosion, including: (a) 650°C × 50h corrosion, (b) 650°C × 800h corrosion, (c) 650°C × 1000h corrosion;

[0052] Figure 14 for Figure 1 Photographs of the internal metallographic structures of the circular specimens in the embodiment shown after high-temperature, high-salt mist corrosion, including: (a) uncorroded original specimen, (b) 650°C × 50h corrosion, (c) 650°C × 800h corrosion, and (d) 650°C × 1000h corrosion.

[0053] Notes in the figure:

[0054] 1-high temperature test furnace, 101-furnace door, 102-temperature control panel, 103-first through hole, 104-second through hole;

[0055] 2-layered high temperature salt spray preheating winding pipe, 201-inner winding pipe, 202-middle winding pipe, 203-outer winding pipe;

[0056] 3-segmented high temperature salt spray corrosion test chamber, 301-transition section, 302-test section, 303-separation section, 304-triangular fixture, 305-circular groove, 306-wedge-shaped guide corrugation;

[0057] 4-salt solution storage tank, 5-salt solution pump, 6-low-pressure air pump, 7-back pressure valve, 8-waste liquid storage tank, 9-thermocouple, 10-temperature display, 11-suction tube, 12-three-way liquid inlet pipe, 13-salt spray exhaust pipe. DETAILED DESCRIPTION

[0058] In order to further understand the content of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0059] Example 1:

[0060] like Figures 1-11 As shown, according to a preferred embodiment of the thermal corrosion damage test device for simulating a marine salt spray environment of the present invention, the test device includes a high-temperature test furnace 1, a layered high-temperature salt spray preheating coil 2, a segmented high-temperature salt spray corrosion test box 3, a salt solution storage tank 4, a salt solution pump 5, a low-pressure air pump 6, a back pressure valve 7, a waste liquid storage tank 8, a thermocouple 9 and a temperature display 10; the layered high-temperature salt spray preheating coil 2 and the segmented high-temperature salt spray corrosion test box 3 are located inside the high-temperature test furnace 1, and the two are connected, and the central axes of the two are on the same horizontal line.

[0061] The salt solution storage tank 4, the salt solution pump 5 and the low-pressure air pump 6 are located outside the high-temperature test furnace 1. The salt solution storage tank 4 is connected to the salt solution pump 5 through a suction pipe 11, and the salt solution pump 5 and the low-pressure air pump 6 are connected to the stratified high-temperature salt spray preheating coil 2 through a three-way liquid inlet pipe 12.

[0062] The back pressure valve 7, the waste liquid storage tank 8, the thermocouple 9 and the temperature display 10 are located outside the high temperature test furnace 1. The back pressure valve 7 is arranged on the salt spray exhaust pipe 13 and is close to the high temperature test furnace 1. One end of the salt spray exhaust pipe 13 is connected to the segmented high temperature salt spray corrosion test box 3, and the waste liquid storage tank 8 is placed below the other end. One end of the thermocouple 9 extends into the segmented high temperature salt spray corrosion test box 3 along the salt spray exhaust pipe 13, and the other end is connected to the temperature display 10.

[0063] The high-temperature test furnace 1 is an integrated box-type muffle furnace, with a furnace door 101 and a temperature control panel 102 provided on the front, and a first through hole 103 and a second through hole 104 provided on the back; the first through hole 103 is used to insert the three-way liquid inlet pipe 12, one end of the three-way liquid inlet pipe 12 enters the high-temperature test furnace 1 and is connected to the layered high-temperature salt spray preheating coil 2; the second through hole 104 is used to insert the salt spray exhaust pipe 13, one end of the salt spray exhaust pipe 13 enters the high-temperature test furnace 1 and is connected to the segmented high-temperature salt spray corrosion test box 3.

[0064] The layered high-temperature salt spray preheating winding 2 includes an inner layer winding 201, a middle layer winding 202 and an outer layer winding 203 connected in sequence from the inside to the outside, and the connection parts between the inner layer winding 201, the middle layer winding 202 and the outer layer winding 203 are connected in a smooth transition manner; the starting end of the inner layer winding 201 is connected to the three-way liquid inlet pipe 12 inserted into the high-temperature test furnace 1, and the tail end of the outer layer winding 203 is connected to the segmented high-temperature salt spray corrosion test box 3.

[0065] The inner layer winding tube 201 is spirally wound from left to right in a clockwise direction starting from its starting end and ending at its tail end, with a total of 6 turns of the inner layer winding tube. The outer diameter of the inner layer winding tube is 5 mm, and the distance between the central axes of two adjacent turns of the inner layer winding tube is 1 mm larger than the outer diameter of the inner layer winding tube. The 6 turns of the inner layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 6.5 times the outer diameter of the inner layer winding tube, and the wall thickness of the inner layer winding tube is 0.8 mm.

[0066] The tail end of the inner layer winding tube 201 is used as the starting end of the middle layer winding tube 202. The middle layer winding tube 202 is spirally wound from right to left in a counterclockwise direction from its starting end to its tail end, and a total of 6 turns of the middle layer winding tube are wound. The outer diameter of the middle layer winding tube is 7 mm, and the distance between the central axes of two adjacent turns of the middle layer winding tube is 1 mm larger than the outer diameter of the middle layer winding tube. The 6 turns of the middle layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 7.5 times the outer diameter of the middle layer winding tube, and the wall thickness of the middle layer winding tube is 0.8 mm.

[0067] The tail end of the middle layer winding tube 202 is used as the starting end of the outer layer winding tube 203. The outer layer winding tube 203 is spirally wound from left to right in a clockwise direction from its starting end to its tail end, with a total of 6 turns of the outer layer winding tube. The outer diameter of the outer layer winding tube is 9 mm, and the distance between the central axes of two adjacent turns of the outer layer winding tube is 1 mm larger than the outer diameter of the outer layer winding tube. The 6 turns of the outer layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 8.5 times the outer diameter of the outer layer winding tube, and the wall thickness of the outer layer winding tube is 0.8 mm.

[0068] The segmented high-temperature salt spray corrosion test chamber 3 includes a transition section 301, a test section 302 and a separation section 303 connected in sequence from left to right. The starting end of the transition section 301 is connected to the tail end of the outer layer winding tube 203, and the tail end of the separation section 303 is connected to the salt spray exhaust pipe 13 inserted into the high-temperature test furnace 1.

[0069] The transition section 301 is a conical structure with a circular starting end and a square tail end. The ratio of the circular diameter to the square side length is 1:2.2. The circular diameter is the same as the diameter of the outer winding tube, and the height of the transition section is 2.6 times the diameter of the outer winding tube.

[0070] The test section 302 is a cube structure, and its side length is the same as the side length of the square at the end of the transition section; a triangular fixture 304 is set on the inner bottom surface of the test section 302, and the angle between the inclined surface of the triangular fixture 304 and the horizontal plane is 30°. A circular groove 305 is set on the inclined surface of the triangular fixture 304, and a circular specimen is installed in the circular groove 305. The diameter of the circular groove 305 matches the diameter of the circular specimen.

[0071] The separation section 303 is a conical structure with a square starting end and a circular tail end. The ratio of the circular diameter to the square side length is 1:3. The side length of the square is the same as the side length of the test section. The height of the separation section is 0.5 times the side length of the test section. Several wedge-shaped guide corrugations 306 are arranged inside the separation section 303.

[0072] The salt solution storage tank 4 contains a salt solution, wherein the mass percentages of the substances in the salt solution are 90.91 wt% water, 6.82 wt% sodium sulfate, and 2.27 wt% sodium chloride; the three-way liquid inlet pipe 12 and the salt spray exhaust pipe 13 are made of high-temperature resistant materials; the layered high-temperature salt spray preheating coil 2 and the segmented high-temperature salt spray corrosion test chamber 3 are made of quartz glass.

[0073] This embodiment also provides a thermal corrosion damage test method for simulating a marine salt spray environment. Using the thermal corrosion damage test device for simulating a marine salt spray environment, the test method includes the following steps in order:

[0074] Step 1: Assemble the test device according to the designed structure, put the salt solution into the salt solution storage tank according to the designed ratio, and seal all the joints in the test device to ensure that the test device can be used normally during the subsequent test process;

[0075] Step 2: Obtain the fitting curve of the back pressure valve preset pressure, including the following steps in order:

[0076] Step 2.1: Set the temperature of the high-temperature test furnace to 550°C, the pressure of the low-pressure air pump to 0.6 MPa, the flow rate of the salt solution pump to 1 L / h, and the initial pressure of the back pressure valve to 0.6 MPa;

[0077] Step 2.2: Turn on the high-temperature test furnace and gradually increase the furnace temperature to 550°C. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe and mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber;

[0078] Step 2.3: Dynamically adjust the pressure of the back pressure valve based on the initial pressure until the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds, and the number of open-close cycles is at least 5 times in a row. At this time, record the pressure of the back pressure valve and use it as the preset pressure of the back pressure valve at a test temperature of 550°C; Step 2.4: Repeat steps 2.1 to 2.3 several times, setting the furnace temperature of the high-temperature test furnace to 600°C, 650°C, 700°C, 750°C and 800°C, respectively, to obtain the preset pressures of the back pressure valve at test temperatures of 600°C, 650°C, 700°C, 750°C and 800°C, respectively;

[0079] Step 2.5: Plot a two-dimensional graph of the test temperature and the corresponding back pressure valve preset pressure and perform fitting to obtain a fitting curve and fitting function for the back pressure valve preset pressure; turn off the low-pressure air pump, salt solution pump, and high-temperature test furnace, and cool the high-temperature test furnace to room temperature;

[0080] Step 3: Place the circular specimen to be hot-corroded into the circular groove of the triangular fixture, then place the triangular fixture into the test section of the segmented high-temperature salt spray corrosion test chamber, and seal all the connection parts in the test device to ensure that the test device can be used normally during the subsequent test process;

[0081] Step 4: According to the obtained fitting curve of the back pressure valve preset pressure, set the test temperature and the corresponding back pressure valve pressure. At the same time, set the pressure of the low-pressure air pump to 0.6 MPa and the flow rate of the salt solution pump to 1 L / h.

[0082] Step 5: Turn on the high-temperature test furnace, and gradually increase the furnace temperature to the set test temperature. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe and mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber to perform constant-temperature thermal corrosion on the circular specimen. During the thermal corrosion test, the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds to ensure that the air pressure in the inner coil, the middle coil, and the outer coil remains consistent.

[0083] Step 6: After the thermal corrosion test is completed, turn off the low-pressure air pump, salt solution pump and high-temperature test furnace, cool the high-temperature test furnace to room temperature, take out the circular specimen after thermal corrosion, and conduct subsequent tests.

[0084] The fitting curve of the back pressure valve preset pressure obtained in this embodiment is as follows: Figure 12In this embodiment, three circular specimens were subjected to thermal corrosion under the same test conditions. The test temperature was 650°C and the thermal corrosion time was 50h, 800h and 1000h respectively. The optical micrographs of the surfaces of the three circular specimens after high temperature and high salt spray corrosion are shown in FIG. Figure 13 As shown in the figure, (a) 650℃×50h corrosion, (b) 650℃×800h corrosion, and (c) 650℃×1000h corrosion. As can be seen from the figure, after the circular specimen was subjected to high temperature and high salt spray corrosion, defects such as corrosion pits and small cracks appeared on the surface.

[0085] The original uncorroded sample and three heat-corroded samples were electroplated, longitudinally cut, mounted, and polished. The metallographic structures of the longitudinal sections were then observed. Figure 14 Figure 1 shows the following: (a) uncorroded original sample, (b) 650°C × 50h corrosion, (c) 650°C × 800h corrosion, and (d) 650°C × 1000h corrosion. As can be seen from the figure, after hot corrosion, the sample has defects such as corrosion pits, corrosion boundaries, and corrosion damage.

[0086] In this embodiment, the method for placing and removing samples from the test section is as follows: first, separate the test section and the separation section, and push the separation section toward the back side of the high-temperature test furnace, which will simultaneously drive the salt spray exhaust pipe connected to it to move from the second through hole to the outside of the high-temperature test furnace. At this time, a certain space is left at the tail end of the test section; secondly, place the circular sample into the circular groove of the triangular fixture, and then place the triangular fixture into the interior of the test section from the tail end of the test section; then, restore the separation section to its original position and connect it to the test section, and use high-temperature sealant to seal the connection parts between the test section and the separation section, and between the salt spray exhaust pipe and the second through hole. At the same time, check the sealing of each connection part in the entire test device, and further seal it with high-temperature sealant; finally, after the thermal corrosion test is completed and the temperature in the high-temperature test furnace drops to room temperature, separate the test section and the separation section again, and take out the triangular fixture and the circular sample.

[0087] This embodiment has the following beneficial effects: (1) It solves the problems of insufficient heating capacity, low atomization accuracy, and environmental simulation distortion in the existing marine salt spray environment thermal corrosion damage test device, and can reproduce the extreme working conditions of high temperature and high salt spray in the marine salt spray environment of aircraft engine components or materials, realize efficient preparation of thermal corrosion damage, and provide standardized test samples for the characterization and mechanism research of thermal corrosion damage of aircraft engine materials. (2) The high-temperature test furnace adopts an integrated box-type muffle furnace, which has high thermal field uniformity and stability, can significantly improve the furnace temperature control quality and can operate stably for a long time; the high-temperature and high-salt spray atmosphere is fully generated by the layered high-temperature salt spray preheating coil, which effectively solves the problem of insufficient atomization capacity of the salt spray nozzle and more realistically simulates the thermal corrosion damage working conditions in the marine salt spray environment. In addition, the high-temperature and high-salt spray atmosphere generated by the layered high-temperature salt spray preheating coil has excellent continuity, which can further improve the reliability of the thermal corrosion test. (3) The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe and mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature high-salt spray atmosphere. The high-temperature high-salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber to perform thermal corrosion on the sample. During the entire corrosion process, the back pressure valve maintains a stable open and close cycle state, on the one hand to ensure that the air pressure in the inner coil, the middle coil and the outer coil remains consistent, and on the other hand to prevent the medium from backflowing or clogging. (4) Two core structures are innovatively integrated inside the high-temperature test furnace, namely the stratified high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test chamber; the stratified high-temperature salt spray preheating coil adopts a three-layer structure design, which realizes the preheating of the mixed medium by extending the path, thereby preparing a stable and continuous high-temperature high-salt spray atmosphere. The segmented high-temperature salt spray corrosion test chamber adopts a three-stage design, and its transition section can effectively suppress the sudden change of airflow and prevent salt spray condensation, thereby ensuring the stability of the thermal corrosion test environment.

[0088] Example 2:

[0089] According to another preferred embodiment of the thermal corrosion damage test device simulating a marine salt spray environment of the present invention, the overall structure of the test device, the connection relationship between the various components, the test method, the technical principle, the equipment used, and the beneficial effects are basically the same as those of the first embodiment, except that:

[0090] The inner layer winding tube is spirally wound from left to right in a clockwise direction starting from its starting end and ending at its tail end, with a total of 5 turns of the inner layer winding tube. The outer diameter of the inner layer winding tube is 6 mm, and the spacing between the central axes of two adjacent turns of the inner layer winding tube is 1.5 mm larger than the outer diameter of the inner layer winding tube. The 5 turns of the inner layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 6.5 times the outer diameter of the inner layer winding tube, and the wall thickness of the inner layer winding tube is 0.9 mm.

[0091] The tail end of the inner layer winding tube is used as the starting end of the middle layer winding tube. The middle layer winding tube is spirally wound from right to left in a counterclockwise direction from its starting end to its tail end, and a total of 5 turns of the middle layer winding tube are wound. The outer diameter of the middle layer winding tube is 8 mm, and the distance between the central axes of two adjacent turns of the middle layer winding tube is 1.5 mm larger than the outer diameter of the middle layer winding tube. The 5 turns of the middle layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 7.5 times the outer diameter of the middle layer winding tube, and the wall thickness of the middle layer winding tube is 0.9 mm.

[0092] The tail end of the middle layer winding tube is used as the starting end of the outer layer winding tube. The outer layer winding tube is spirally wound from left to right in a clockwise direction from its starting end to its tail end, and a total of 5 turns of the outer layer winding tube are wound. The outer diameter of the outer layer winding tube is 10 mm, and the distance between the central axes of two adjacent turns of the outer layer winding tube is 1.5 mm larger than the outer diameter of the outer layer winding tube. The 5 turns of the outer layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 8.5 times the outer diameter of the outer layer winding tube, and the wall thickness of the outer layer winding tube is 0.9 mm.

[0093] The transition section is a conical structure with a circular starting end and a square tail end. The ratio of the circular diameter to the square side length is 1:2.5. The circular diameter is the same as the diameter of the outer winding tube, and the height of the transition section is 2.9 times the diameter of the outer winding tube.

[0094] The test section has a cubic structure, and its side length is the same as the side length of the square at the end of the transition section; a triangular fixture is set on the inner bottom surface of the test section, and the angle between its inclined surface and the horizontal plane is 45°. A circular groove is set on the inclined surface, and a circular specimen is installed in the circular groove. The diameter of the circular groove matches the diameter of the circular specimen.

[0095] The separation section is a conical structure with a square starting end and a circular tail end. The ratio of the circular diameter to the square side length is 1:3.2. The side length of the square is the same as the side length of the test section. The height of the separation section is 0.65 times the side length of the test section. Several wedge-shaped guide corrugations are arranged inside the separation section.

[0096] Example 3:

[0097] According to another preferred embodiment of the thermal corrosion damage test device simulating a marine salt spray environment of the present invention, the overall structure of the test device, the connection relationship between the various components, the test method, the technical principle, the equipment used, and the beneficial effects are basically the same as those of the first embodiment, except that:

[0098] The inner layer winding tube is spirally wound from left to right in a clockwise direction starting from its starting end and ending at its tail end, with a total of 7 turns of the inner layer winding tube. The outer diameter of the inner layer winding tube is 7 mm. The spacing between the central axes of two adjacent turns of the inner layer winding tube is 2 mm larger than the outer diameter of the inner layer winding tube. The 7 turns of the inner layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 6.5 times the outer diameter of the inner layer winding tube, and the wall thickness of the inner layer winding tube is 1 mm.

[0099] The tail end of the inner layer winding tube is used as the starting end of the middle layer winding tube. The middle layer winding tube is spirally wound from right to left in a counterclockwise direction from its starting end to its tail end, and a total of 7 turns of the middle layer winding tube are wound. The outer diameter of the middle layer winding tube is 9 mm. The distance between the central axes of two adjacent turns of the middle layer winding tube is 2 mm larger than the outer diameter of the middle layer winding tube. The 7 turns of the middle layer winding tube are wound into a cylindrical shape. The outer diameter of the cylinder is 7.5 times the outer diameter of the middle layer winding tube, and the wall thickness of the middle layer winding tube is 1 mm.

[0100] The tail end of the middle layer winding tube is used as the starting end of the outer layer winding tube. The outer layer winding tube is spirally wound from left to right in a clockwise direction from its starting end to its tail end, with a total of 7 turns of the outer layer winding tube. The outer diameter of the outer layer winding tube is 11 mm. The distance between the central axes of two adjacent turns of the outer layer winding tube is 2 mm larger than the outer diameter of the outer layer winding tube. The 7 turns of the outer layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 8.5 times the outer diameter of the outer layer winding tube, and the wall thickness of the outer layer winding tube is 1 mm.

[0101] The transition section is a conical structure with a circular starting end and a square tail end. The ratio of the circular diameter to the square side length is 1:2.8. The circular diameter is the same as the diameter of the outer winding tube, and the height of the transition section is 3.2 times the diameter of the outer winding tube.

[0102] The test section has a cube structure, and its side length is the same as the side length of the square at the end of the transition section; a triangular fixture is set on the inner bottom surface of the test section, and the angle between its inclined surface and the horizontal plane is 60°. A circular groove is set on the inclined surface, and a circular specimen is installed in the circular groove. The diameter of the circular groove matches the diameter of the circular specimen.

[0103] The separation section is a conical structure with a square starting end and a circular tail end. The ratio of the circular diameter to the square side length is 1:3.5. The side length of the square is the same as the side length of the test section. The height of the separation section is 0.8 times the side length of the test section. Several wedge-shaped guide corrugations are arranged inside the separation section.

[0104] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant improvements of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive testing. The inventors have recorded extensive experimental data for each parameter and their combinations. Due to space limitations, the specific experimental data will not be disclosed here.

[0105] Those skilled in the art will readily understand that the present invention encompasses any combination of the components described in the Summary and Detailed Description of the Invention and the accompanying drawings. Due to space limitations and for the sake of clarity, not all of the various solutions resulting from these combinations are described. Any modifications, equivalent substitutions, and improvements within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A thermal corrosion damage test device simulating a marine salt spray environment, characterized by: The test device includes a high-temperature test furnace, a layered high-temperature salt spray preheating coil, a segmented high-temperature salt spray corrosion test chamber, a salt solution storage tank, a salt solution pump, a low-pressure air pump, a back pressure valve, a waste liquid storage tank, a thermocouple, and a temperature display; the layered high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test chamber are located inside the high-temperature test furnace, and the two are connected, and the central axes of the two are on the same horizontal line; The salt solution storage tank, the salt solution pump and the low-pressure air pump are located outside the high-temperature test furnace, the salt solution storage tank is connected to the salt solution pump through a suction pipe, and the salt solution pump and the low-pressure air pump are connected to the stratified high-temperature salt spray preheating coil through a three-way liquid inlet pipe; The back pressure valve, the waste liquid storage tank, the thermocouple and the temperature display are located outside the high-temperature test furnace. The back pressure valve is arranged on the salt spray exhaust pipe and is close to the high-temperature test furnace. One end of the salt spray exhaust pipe is connected to the segmented high-temperature salt spray corrosion test box, and the waste liquid storage tank is placed below the other end. One end of the thermocouple extends into the segmented high-temperature salt spray corrosion test box along the salt spray exhaust pipe, and the other end is connected to the temperature display.

2. The thermal corrosion damage test device for simulating a marine salt spray environment according to claim 1, wherein: The high-temperature test furnace is an integrated box-type muffle furnace, with a furnace door and a temperature control panel provided on the front, and a first through hole and a second through hole provided on the back; the first through hole is used to insert the three-way liquid inlet pipe, one end of the three-way liquid inlet pipe enters the high-temperature test furnace and is connected to the layered high-temperature salt spray preheating coil; the second through hole is used to insert the salt spray exhaust pipe, one end of the salt spray exhaust pipe enters the high-temperature test furnace and is connected to the segmented high-temperature salt spray corrosion test box.

3. The thermal corrosion damage test device for simulating a marine salt spray environment according to claim 2, wherein: The layered high-temperature salt spray preheating coil includes an inner coil, a middle coil and an outer coil connected in sequence from the inside to the outside, and the connection parts between the inner coil, the middle coil and the outer coil are connected in a smooth transition manner; the starting end of the inner coil is connected to the three-way liquid inlet pipe inserted into the high-temperature test furnace, and the tail end of the outer coil is connected to the segmented high-temperature salt spray corrosion test box.

4. The thermal corrosion damage test device for simulating a marine salt spray environment according to claim 3, wherein: The inner layer winding tube is spirally wound from left to right in a clockwise direction starting from its starting end and ending at its tail end, with a total of 5-7 turns of the inner layer winding tube. The outer diameter of the inner layer winding tube is 5-7 mm, and the distance between the central axes of two adjacent turns of the inner layer winding tube is 1-2 mm larger than the outer diameter of the inner layer winding tube. The 5-7 turns of the inner layer winding tube are wound into a cylindrical shape, the outer diameter of the cylinder is 6.5 times the outer diameter of the inner layer winding tube, and the wall thickness of the inner layer winding tube is 0.8-1 mm.

5. The thermal corrosion damage test device for simulating a marine salt spray environment according to claim 4, wherein: The tail end of the inner layer winding tube is used as the starting end of the middle layer winding tube. The middle layer winding tube is spirally wound from right to left in a counterclockwise direction from its starting end to its tail end, and a total of 5-7 turns of the middle layer winding tube are wound. The outer diameter of the middle layer winding tube is 7-9 mm. The distance between the central axes of two adjacent turns of the middle layer winding tube is 1-2 mm larger than the outer diameter of the middle layer winding tube. The 5-7 turns of the middle layer winding tube are wound into a cylindrical shape. The outer diameter of the cylinder is 7.5 times the outer diameter of the middle layer winding tube, and the wall thickness of the middle layer winding tube is 0.8-1 mm.

6. The thermal corrosion damage test device for simulating a marine salt spray environment according to claim 5, wherein: The tail end of the middle layer winding tube is used as the starting end of the outer layer winding tube. The outer layer winding tube is spirally wound from left to right in a clockwise direction from its starting end to its tail end, and a total of 5-7 turns of the outer layer winding tube are wound. The outer diameter of the outer layer winding tube is 9-11 mm. The distance between the central axes of two adjacent turns of the outer layer winding tube is 1-2 mm larger than the outer diameter of the outer layer winding tube. The 5-7 turns of the outer layer winding tube are wound into a cylindrical shape. The outer diameter of the cylinder is 8.5 times the outer diameter of the outer layer winding tube, and the wall thickness of the outer layer winding tube is 0.8-1 mm.

7. The thermal corrosion damage testing device for simulating a marine salt spray environment according to claim 6, wherein: The segmented high-temperature salt spray corrosion test chamber includes a transition section, a test section, and a separation section connected in sequence from left to right. The starting end of the transition section is connected to the tail end of the outer layer winding tube, and the tail end of the separation section is connected to the salt spray exhaust pipe inserted into the high-temperature test furnace.

8. The thermal corrosion damage testing device for simulating a marine salt spray environment according to claim 7, wherein: The transition section is a tapered structure with a circular start end and a square end end. The ratio of the circular diameter to the square side length is 1:2.2-2.

8. The circular diameter is the same as the diameter of the outer winding tube. The height of the transition section is 2.6-3.2 times the diameter of the outer winding tube. The test section is a cube structure, and its side length is the same as the side length of the square at the end of the transition section; a triangular fixture is provided on the inner bottom surface of the test section, and the angle between the inclined surface of the triangular fixture and the horizontal plane is 30-60 degrees. A circular groove is provided on the inclined surface of the triangular fixture, and a circular specimen is installed in the circular groove. The diameter of the circular groove is consistent with the diameter of the circular specimen. The separation section is a conical structure with a square starting end and a circular tail end. The ratio of the circular diameter to the square side length is 1:3-3.

5. The side length of the square is the same as the side length of the test section. The height of the separation section is 0.5-0.8 times the side length of the test section. Several wedge-shaped guide corrugations are arranged inside the separation section.

9. The thermal corrosion damage testing device for simulating a marine salt spray environment according to claim 8, wherein: The salt solution storage tank contains a salt solution, wherein the mass percentages of the substances in the salt solution are 90.91 wt% of water, 6.82 wt% of sodium sulfate, and 2.27 wt% of sodium chloride; the three-way liquid inlet pipe and the salt spray exhaust pipe are made of high-temperature resistant materials; the layered high-temperature salt spray preheating coil and the segmented high-temperature salt spray corrosion test box are made of quartz glass.

10. A thermal corrosion damage test method simulating a marine salt spray environment, characterized by: Using the thermal corrosion damage test device simulating a marine salt spray environment according to any one of claims 1 to 9, the test method comprises the following steps in order: Step 1: Assemble the test device according to the designed structure, put the salt solution into the salt solution storage tank according to the designed ratio, and seal all the joints in the test device to ensure that the test device can be used normally during the subsequent test process; Step 2: Obtain the fitting curve of the back pressure valve preset pressure, including the following steps in order: Step 2.1: Set the temperature of the high-temperature test furnace to 550°C, the pressure of the low-pressure air pump to 0.6 MPa, the flow rate of the salt solution pump to 1 L / h, and the initial pressure of the back pressure valve to 0.6 MPa; Step 2.2: Turn on the high-temperature test furnace and gradually increase the furnace temperature to 550°C. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe and mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber; Step 2.3: Dynamically adjust the pressure of the back pressure valve based on the initial pressure until the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds, and the number of open-close cycles is at least 5 times in a row. At this time, record the pressure of the back pressure valve and use it as the preset pressure of the back pressure valve at a test temperature of 550°C; Step 2.4: Repeat steps 2.1 to 2.3 several times, setting the furnace temperature of the high-temperature test furnace to 600°C, 650°C, 700°C, 750°C and 800°C, respectively, to obtain the preset pressures of the back pressure valve at test temperatures of 600°C, 650°C, 700°C, 750°C and 800°C, respectively; Step 2.5: Plot a two-dimensional graph of the test temperature and the corresponding back pressure valve preset pressure and perform fitting to obtain a fitting curve and fitting function for the back pressure valve preset pressure; turn off the low-pressure air pump, salt solution pump, and high-temperature test furnace, and cool the high-temperature test furnace to room temperature; Step 3: Place the circular specimen to be hot-corroded into the circular groove of the triangular fixture, then place the triangular fixture into the test section of the segmented high-temperature salt spray corrosion test chamber, and seal all the connection parts in the test device to ensure that the test device can be used normally during the subsequent test process; Step 4: According to the obtained fitting curve of the back pressure valve preset pressure, set the test temperature and the corresponding back pressure valve pressure. At the same time, set the pressure of the low-pressure air pump to 0.6 MPa and the flow rate of the salt solution pump to 1 L / h. Step 5: Turn on the high-temperature test furnace, and gradually increase the furnace temperature to the set test temperature. When the furnace temperature reaches a stable state, turn on the low-pressure air pump and the salt solution pump. The salt solution pumped out from the salt solution storage tank by the salt solution pump and the low-pressure air blown in by the low-pressure air pump enter the three-way liquid inlet pipe to mix. The mixed medium enters the stratified high-temperature salt spray preheating coil to fully form a high-temperature salt spray atmosphere. The high-temperature salt spray atmosphere then enters the segmented high-temperature salt spray corrosion test chamber to perform constant-temperature thermal corrosion on the circular specimen for 50-1000 hours. During the thermal corrosion test, the back pressure valve maintains a stable open-close cycle, that is, the back pressure valve is in the open state for 60±5 minutes and the closed state for 25±5 seconds to ensure that the air pressure in the inner coil, the middle coil and the outer coil remains consistent. Step 6: After the thermal corrosion test is completed, turn off the low-pressure air pump, salt solution pump and high-temperature test furnace, cool the high-temperature test furnace to room temperature, take out the circular specimen after thermal corrosion, and conduct subsequent tests.

Images