Thermal insulation coating failure detection method

Abstract

The invention relates to the technical field of aerospace, in particular to a thermal insulation coating failure detection method. Vertically arranging a heat insulation plate on the surface, plated with the heat insulation coating, of the to-be-detected plate body so as to divide the to-be-detected plate body into a first part with a larger area and a second part with a smaller area; the edge, far away from the heat insulation plate, of the second part is fixedly connected with a heat dissipation bottom plate; wherein the heat dissipation bottom plate is provided with a groove; piezoelectric ceramics are fixed in the grooves; spraying high-temperature flame by using a spray gun to heat the to-be-detected plate body; cooling the to-be-detected plate body by using a low-temperature fluid; receiving an electric signal transmitted by the piezoelectric ceramic by using a signal receiving and processing device; and processing the electric signal by using the signal receiving and processing device. The embodiment of the invention provides a thermal insulation coating failure detection method which can detect the failure process of a thermal insulation coating.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a thermal insulation coating failure detection method. Background Art

[0002] The working environment of the aircraft engine is in a high temperature environment. In order to protect the materials of the engine, a thermal insulation coating needs to be plated on the materials. However, the thermal insulation coating is prone to damage in a high temperature working environment, which in turn endangers the thermal insulation function of the coating. Therefore, failure detection of the thermal insulation coating is of great significance. Summary of the invention

[0003] An embodiment of the present invention provides a thermal insulation coating failure detection method, which can detect the failure process of the thermal insulation coating.

[0004] An embodiment of the present invention provides a thermal insulation coating failure detection method, comprising: The heat-insulating plate is vertically arranged on the surface of the plate to be tested coated with the heat-insulating coating, so as to separate the plate to be tested into a first part with a larger area and a second part with a smaller area; A heat dissipation base plate is fixedly connected to the edge of the second part away from the heat insulation plate; wherein the heat dissipation base plate is provided with a groove; Fixing the piezoelectric ceramic in the groove; Using a spray gun to spray high-temperature flame to heat the plate to be tested; Using low-temperature fluid to cool the plate to be tested; Using a signal receiving and processing device to receive the electrical signal emitted by the piezoelectric ceramic; The signal receiving and processing device is used to process the electrical signal.

[0005] In one possible design, the processing of the electrical signal by the signal receiving and processing device includes: Performing a first signal amplification, filtering process and a second signal amplification process on the electrical signal; Characteristics of the electrical signal are analyzed.

[0006] In one possible design, analyzing the characteristics of the electrical signal includes: Acquiring an acoustic emission signal of a failure type through an experiment; wherein the failure type includes interlaminar fracture and crack; Performing Fourier transform and wavelet packet transform decomposition on the acoustic emission signal of the failure type to obtain a first frequency feature; Processing the electrical signal using continuous wavelet transform to obtain a second frequency feature; By comparing the second frequency characteristic with the first frequency characteristic, the failure type of the thermal insulation coating that generates the electrical signal is obtained.

[0007] In a possible design, after fixing the piezoelectric ceramic in the groove and before using a spray gun to spray a high-temperature flame to heat the plate to be tested, the method further includes: A heat dissipation cover plate is arranged on the top of the heat dissipation base plate; wherein the heat dissipation cover plate and the heat dissipation base plate are both hollow shell structures, the heat dissipation base plate is filled with water, and the heat dissipation cover plate and the heat dissipation base plate are connected through evaporation holes.

[0008] In one possible design, it also includes: The heat-absorbing and evaporated gas is discharged through the exhaust channel preset on the heat dissipation cover plate; The gas discharged from the exhaust passage drives the preset first fan blade to rotate; After the first fan blade rotates, it drives the second fan blade coaxially connected thereto to rotate; wherein, the heat dissipation base plate is connected to a liquid replenishing device via a liquid inlet pipe, and the second fan blade is used to provide power for the liquid inlet pipe connected to the bottom of the heat dissipation base plate.

[0009] In one possible design, it also includes: Output the corrosive medium to the plate to be tested; The concentration of the corrosive medium in the gas above the plate to be tested is collected by using a collection pipeline; wherein the collection pipeline runs through the heat insulation board and the heat dissipation base plate, one end of the collection pipeline passes through the heat insulation board and is located above the first part, and the other end of the collection pipeline is connected to a gas concentration analysis device for detecting the concentration of the corrosive medium.

[0010] In a possible design, the method of collecting the concentration of the corrosive medium in the gas above the plate to be tested by using a collection pipeline includes: The flow rate of the gas collected by the collection pipeline is adjusted according to the temperature sensor preset on the heat dissipation bottom plate, and the temperature collected by the temperature sensor is inversely proportional to the gas flow rate of the collection pipeline; The collected gas is introduced into the gas analysis chamber through the collection pipeline to analyze the concentration of the corrosive medium in the gas.

[0011] In a possible design, a sealing plate is provided on the upper portion of the groove to make the groove a sealed space, and a vacuum channel is provided on the inner wall of the groove, and the vacuum channel is used to make the groove a vacuum environment.

[0012] In a possible design, the piezoelectric ceramic is fixed on the heat dissipation base plate via at least one connecting column.

[0013] In a possible design, the distance between the end of the heat dissipation base plate close to the heat insulation plate and the groove is 8 to 15 cm.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: In this embodiment, the flame and the low-temperature fluid can be sprayed by a spray gun, and the heat insulation board separates the plate to be tested into a first part and a second part. The first part with a larger area is used to receive the flame sprayed by the spray gun, simulating the high temperature environment when the engine is working and the low temperature environment when it is not working, so as to test the service life of the thermal insulation coating; the second part with a smaller area is used to place the piezoelectric ceramics used to collect the sound wave signal generated by the damage of the thermal insulation coating. Since the test environment temperature is high and the use temperature of the piezoelectric ceramics does not exceed 200°C, the piezoelectric ceramics cannot be directly placed on the thermal insulation coating. If other high-temperature resistant waveguide devices are used to guide the sound wave signal to a lower temperature area, and then the piezoelectric ceramics are connected to the waveguide device in the lower temperature area, the waveguide device has a long waveguide path and many components, which easily causes the sound wave to be damaged to a certain extent, resulting in the distortion of the collected sound wave. Therefore, the present application directly places the piezoelectric ceramics on the thermal insulation coating. In order to avoid the high temperature problem, the heat insulation board is used to separate the second part where the piezoelectric ceramics are placed from the first part heated by the spray gun, which greatly prevents the heat from being transferred from the upper part of the thermal insulation coating to the piezoelectric ceramics. Furthermore, a small part of the high temperature will still be transferred to the second part through the thermal insulation coating. Although the transferred heat is much less than the heat output by the spray gun, the temperature output by the spray gun is extremely high, and a small part of the heat may still damage the piezoelectric ceramic. Therefore, a heat dissipation base plate is set on the second part, and the piezoelectric ceramic is set in the groove of the heat dissipation base plate. After the piezoelectric ceramic collects the sound wave signal, it is transmitted to the signal receiving and processing device in the form of current for analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 is a flow chart of a thermal insulation coating failure detection method provided by an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a thermal insulation coating failure detection device provided in an embodiment of the present invention.

[0017] In the figure: 100-plate to be tested; 1- Spray gun; 2- Insulation board; 3- heat dissipation base plate; 4- Heat dissipation cover; 5- groove; 6- piezoelectric ceramics; 7-evaporation hole; 8- Exhaust channel; 9-liquid inlet pipe; 10- Fluid replenishment device; 11- first fan blade; 12- second fan blade; 13- Collection pipeline; 14-connecting column; 15- Gas analysis chamber; 16-exhaust plate; 17- Collection port; 18- first exhaust port; 19- second exhaust port; 20-Gas concentration analysis device. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0021] Please refer to Figure 1 and Figure 2 , an embodiment of the present invention provides a thermal insulation coating failure detection method, comprising: The heat insulation board 2 is vertically arranged on the surface of the board body 100 to be tested which is coated with the heat insulation coating, so as to separate the board body 100 to be tested into a first part with a larger area and a second part with a smaller area; A heat dissipation base plate 3 is fixedly connected to the edge of the second part away from the heat insulation plate 2; wherein the heat dissipation base plate 3 is provided with a groove 5; Fixing the piezoelectric ceramic 6 in the groove 5; Using a spray gun 1 to spray a high-temperature flame to heat the plate 100 to be tested; Using low temperature fluid to cool down the plate body 100 to be tested; Using a signal receiving and processing device to receive the electrical signal emitted by the piezoelectric ceramic 6; The signal receiving and processing device is used to process the electrical signal.

[0022] In this embodiment, flames and low-temperature fluids can be sprayed out through a spray gun 1, and the thermal insulation plate 2 separates the plate body 100 to be tested into a first part and a second part. The first part with a larger area is used to receive the flame sprayed from the spray gun 1, simulating the high temperature environment of the engine when it is working and the low temperature environment when it is not working, so as to test the service life of the thermal insulation coating; the second part with a smaller area is used to place the piezoelectric ceramic 6 for collecting the sound wave signal generated by the damage of the thermal insulation coating. Since the test environment temperature is high and the operating temperature of the piezoelectric ceramic 6 does not exceed 200°C, the piezoelectric ceramic 6 cannot be placed directly on the thermal insulation coating. If other high-temperature resistant waveguide devices are used to guide the sound wave signal to a lower temperature area, and then the piezoelectric ceramic 6 is set in the lower temperature area to connect with the waveguide device, since the waveguide device has a longer waveguide path and more components, it is easy to cause a certain degree of damage to the sound wave, resulting in distortion of the collected sound wave. Therefore, the present application directly places the piezoelectric ceramic 6 on the thermal insulation coating. In order to avoid the high temperature problem, the second part where the piezoelectric ceramic 6 is placed is separated from the first part heated by the spray gun 1 by the thermal insulation plate 2, which largely prevents the heat from being transferred from the upper part of the thermal insulation coating to the piezoelectric ceramic 6. Furthermore, a small part of the high temperature will still be transferred to the second part through the thermal insulation coating. Although the transferred heat is much less than the heat output by the spray gun 1, the temperature output by the spray gun 1 is extremely high, and a small part of the heat may still damage the piezoelectric ceramic 6. Therefore, a heat dissipation base plate 3 is provided on the second part, and the piezoelectric ceramic 6 is provided in the groove 5 of the heat dissipation base plate 3. After the piezoelectric ceramic 6 collects the acoustic wave signal, it is transmitted to the signal receiving and processing device in the form of an electric current for analysis.

[0023] In some embodiments of the present invention, processing the electrical signal using the signal receiving and processing device includes: Performing initial signal amplification, filtering and re-signal amplification on the electrical signal; Analyze the characteristics of electrical signals.

[0024] In this embodiment, the electrical signal is first amplified, then filtered using a filter to eliminate clutter, and finally processed again to obtain an electrical signal with a high signal-to-noise ratio for analysis.

[0025] In some embodiments of the present invention, analyzing the characteristics of the electrical signal includes: Acquiring acoustic emission signals of failure types through experiments; wherein the failure types include interlaminar fracture and crack; Perform Fourier transform and wavelet packet transform decomposition on the acoustic emission signal of the failure type to obtain the first frequency feature; Processing the electrical signal using continuous wavelet transform to obtain a second frequency feature; By comparing the second frequency characteristic with the first frequency characteristic, the failure type of the thermal insulation coating that generates the electrical signal is obtained.

[0026] In this embodiment, the first frequency feature represents the signal feature of the failure type and has a characteristic frequency range. It is determined which failure type the frequency of the second frequency feature falls into the range defined by the first frequency feature to determine the actual failure type.

[0027] In some embodiments of the present invention, after the piezoelectric ceramic 6 is fixed in the groove 5 and before the spray gun 1 is used to spray a high-temperature flame to heat the plate 100 to be tested, the method further includes: A heat dissipation cover plate 4 is arranged on the top of the heat dissipation base plate 3; wherein, the heat dissipation cover plate 4 and the heat dissipation base plate 3 are both hollow shell structures, the heat dissipation base plate 3 is filled with water, and the heat dissipation cover plate 4 and the heat dissipation base plate 3 are connected through the evaporation hole 7.

[0028] In this embodiment, the heat dissipation base plate 3 is filled with water, and its bottom is directly connected to the heat source insulation coating. After the heat is conducted to the water in the heat dissipation base plate 3, the water is heated and vaporized, and the vaporization absorbs a large amount of heat, so that the piezoelectric ceramics 6 in the groove 5 are at a suitable temperature. The heat dissipation cover plate 4 on the top of the heat dissipation base plate 3 receives the high-temperature steam that is vaporized and expanded, and dissipates it, achieving the effect of efficient heat dissipation.

[0029] In some embodiments of the present invention, the method further comprises: The heat-absorbing and evaporated gas is discharged through the exhaust channel 8 preset on the heat dissipation cover plate 4; The gas discharged from the exhaust passage 8 drives the preset first fan blade 11 to rotate; After the first fan blade 11 rotates, it drives the second fan blade 12 coaxially connected thereto to rotate; wherein, the heat dissipation base plate 3 is connected to a liquid replenishing device 10 via a liquid inlet pipe 9, and the second fan blade 12 is used to provide power for the liquid inlet pipe 9 connected to the bottom of the heat dissipation base plate 3.

[0030] In this embodiment, the vaporized gas is discharged through the exhaust channel 8, and the gas expands rapidly at high temperature, forming a higher air pressure under the restriction of the exhaust channel 8. The high pressure provides a stronger power for the gas circulation, and then when passing through the first fan blade 11, it drives it to rotate. The first fan blade 11 is axially connected to the second fan blade 12, and then drives the second fan blade 12 to rotate. The second fan blade 12 replenishes the low-temperature water in the liquid replenishing device 10 to the heat dissipation base plate 3 through the liquid inlet pipe 9, thereby realizing continuous and efficient heat dissipation.

[0031] It should be noted that the first blade 11 and the second blade 12 on different axes can be linked together by means of a gear set.

[0032] In some embodiments of the present invention, the method further comprises: Outputting the corrosive medium to the plate body 100 to be detected; The collection pipe 13 is used to collect the concentration of the corrosive medium in the gas above the plate body 100 to be tested; wherein the collection pipe 13 passes through the insulation board 2 and the heat dissipation base plate 3, one end of the collection pipe 13 passes through the insulation board 2 and is located above the first part, and the other end of the collection pipe 13 is connected to a gas concentration analysis device for detecting the concentration of the corrosive medium.

[0033] In the real working environment of the aircraft, in addition to facing high temperatures, it will also be corroded by volcanic ash, PM2.5 and gaseous corrosive media. The superposition of corrosive media and high temperature is an important factor causing the failure of the thermal insulation coating. Therefore, in order to more realistically reflect the service life of the thermal insulation coating, in addition to creating a high temperature environment, a corrosive medium environment must also be created. Therefore, in addition to spraying high-temperature flames, the spray gun 1 also sprays a corrosive medium with adjustable concentration. However, the concentration of the corrosive medium in the spray gun 1 is different from the concentration on the surface of the thermal insulation coating. Therefore, the concentration of the corrosive medium must be collected. Specifically, the gas above the thermal insulation coating is collected through the collection pipe 13. Similarly, the gas detection device cannot be detected at high temperatures. Therefore, the collection pipe 13 passes through the heat dissipation base plate 3. After the collected gas passes through the heat dissipation base plate 3, the heat is dissipated through the heat dissipation base plate 3, and the temperature drops rapidly. Finally, it is received and tested by the gas concentration analysis device 20 to obtain the concentration of the corrosive medium.

[0034] The gas concentration analysis device 20 can be arranged in the gas analysis chamber 15, and the gas analysis chamber 15 includes a collection port 17 connected to the collection pipeline 13, a first exhaust port 18 and a second exhaust port 19. The gas analysis chamber 15 includes a reciprocating exhaust plate 16, and the exhaust plate 16 divides the gas analysis chamber 15 into two parts. The collection port 17 and the first exhaust port 18 are respectively located on two opposite chamber walls of the gas analysis chamber 15, and the second exhaust port 19 and the collection port 17 are located on the chamber wall on the same side. When collecting gas, the exhaust plate 16 moves from the chamber wall on the side where the collection port 17 is set to the side of the first exhaust port 18, so that the gas to be detected fills the gas analysis chamber 15 for concentration detection. After the detection is completed, the collection port 17 is closed, the first exhaust port 18 and the second exhaust port 19 are opened, and the exhaust plate 16 is controlled to move to the chamber wall where the collection port 17 is set, and the internal gas is discharged from the second exhaust port 19, and then the second exhaust port 19 is closed, and the collection port 17 is opened to continue collecting gas.

[0035] In some embodiments of the present invention, the concentration of the corrosive medium in the gas above the plate body 100 to be tested is collected by using the collection pipeline 13, including: The flow rate of the gas collected by the collection pipeline 13 is adjusted according to the temperature sensor preset on the heat dissipation base plate 3, and the temperature collected by the temperature sensor is inversely proportional to the gas flow rate of the collection pipeline 13; The collected gas is passed into the gas analysis chamber 15 through the collection pipeline 13 to analyze the concentration of the corrosive medium in the gas.

[0036] If the temperature of the heat dissipation base plate 3 is too high, it will affect the performance of the concentration sensor and the piezoelectric ceramic 6. Therefore, the collected gas flow is adjusted according to the collected temperature. If the temperature is too high, the collected gas volume is reduced to reduce the heat dissipation pressure.

[0037] In some embodiments of the present invention, a sealing plate is provided on the upper portion of the groove 5 to make the groove 5 a sealed space, and a vacuum channel is provided on the inner wall of the groove 5 to make the groove 5 a vacuum environment.

[0038] In this embodiment, the vacuum can provide heat insulation and create a suitable working environment for the piezoelectric ceramic 6 .

[0039] The inner wall of the groove 5 is provided with a line pipe for connecting the lines, and the port of the line pipe is provided with a sealing ring to keep the groove 5 sealed.

[0040] In some embodiments of the present invention, the piezoelectric ceramic 6 is fixed on the heat dissipation base plate 3 via at least one connecting column 14 .

[0041] In this embodiment, the contact area between the piezoelectric ceramic 6 and the heat dissipation base plate 3 is reduced by the connection column 14, which is helpful to reduce heat transfer.

[0042] In some embodiments of the present invention, the distance between the end of the heat dissipation base plate 3 close to the heat insulation plate 2 and the groove 5 is 8-15 cm.

[0043] In this embodiment, the distance of 8-15 cm can dissipate most of the heat in time, thereby protecting the piezoelectric ceramic 6 in the rear position.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thermal insulation coating failure detection method, characterized in that: include: The heat-insulating plate is vertically arranged on the surface of the plate to be tested coated with the heat-insulating coating, so as to separate the plate to be tested into a first part with a larger area and a second part with a smaller area; A heat dissipation base plate is fixedly connected to the edge of the second part away from the heat insulation plate; wherein the heat dissipation base plate is provided with a groove; Fixing the piezoelectric ceramic in the groove; Using a spray gun to spray high-temperature flame to heat the plate to be tested; Using low-temperature fluid to cool the plate to be tested; Using a signal receiving and processing device to receive the electrical signal emitted by the piezoelectric ceramic; The signal receiving and processing device is used to process the electrical signal.

2. The method according to claim 1, characterized in that The step of processing the electrical signal by using the signal receiving and processing device comprises: Performing a first signal amplification, filtering process and a second signal amplification process on the electrical signal; Characteristics of the electrical signal are analyzed.

3. The method according to claim 2, characterized in that The analyzing the characteristics of the electrical signal comprises: Acquiring an acoustic emission signal of a failure type through an experiment; wherein the failure type includes interlaminar fracture and crack; Performing Fourier transform and wavelet packet transform decomposition on the acoustic emission signal of the failure type to obtain a first frequency feature; Processing the electrical signal using continuous wavelet transform to obtain a second frequency feature; By comparing the second frequency characteristic with the first frequency characteristic, the failure type of the thermal insulation coating that generates the electrical signal is obtained.

4. The method according to claim 1, characterized in that After the piezoelectric ceramic is fixed in the groove and before the high-temperature flame is sprayed by the spray gun to heat the plate to be tested, the method further includes: A heat dissipation cover plate is arranged on the top of the heat dissipation base plate; wherein the heat dissipation cover plate and the heat dissipation base plate are both hollow shell structures, the heat dissipation base plate is filled with water, and the heat dissipation cover plate and the heat dissipation base plate are connected through evaporation holes.

5. The method according to claim 4, characterized in that Also includes: The heat-absorbing and evaporated gas is discharged through the exhaust channel preset on the heat dissipation cover plate; The gas discharged from the exhaust passage drives the preset first fan blade to rotate; After the first fan blade rotates, it drives the second fan blade coaxially connected thereto to rotate; wherein, the heat dissipation base plate is connected to a liquid replenishing device via a liquid inlet pipe, and the second fan blade is used to provide power for the liquid inlet pipe connected to the bottom of the heat dissipation base plate.

6. The method according to claim 1, characterized in that Also includes: Output the corrosive medium to the plate to be tested; The concentration of the corrosive medium in the gas above the plate to be tested is collected by using a collection pipeline; wherein the collection pipeline runs through the heat insulation board and the heat dissipation base plate, one end of the collection pipeline passes through the heat insulation board and is located above the first part, and the other end of the collection pipeline is connected to a gas concentration analysis device for detecting the concentration of the corrosive medium.

7. The method according to claim 6, characterized in that The method of collecting the concentration of the corrosive medium in the gas above the plate to be detected by using a collection pipeline comprises: The flow rate of the gas collected by the collection pipeline is adjusted according to the temperature sensor preset on the heat dissipation bottom plate, and the temperature collected by the temperature sensor is inversely proportional to the gas flow rate of the collection pipeline; The collected gas is introduced into the gas analysis chamber through the collection pipeline to analyze the concentration of the corrosive medium in the gas.

8. The method according to claim 1, characterized in that A sealing plate is arranged on the upper part of the groove to make the groove a sealed space, and a vacuum channel is arranged on the inner wall of the groove to make the groove a vacuum environment.

9. The method according to claim 1, characterized in that: The piezoelectric ceramic is fixed on the heat dissipation base plate through at least one connecting column.

10. The method according to claim 1, characterized in that The distance between the end of the heat dissipation base plate close to the heat insulation plate and the groove is 8-15 cm.

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