Flexible internal and external coordinated excitation sensing test system and method for thermal barrier coatings in narrow spaces

Abstract

The present invention discloses a flexible internal and external coordinated excitation sensing test system and method for thermal barrier coatings in confined spaces. The test system includes a fully flexible test probe and an internal and external coordinated excitation sensing test device. The present invention also discloses a flexible internal and external coordinated excitation sensing test method for thermal barrier coatings in confined spaces. The fully flexible test probe collects electromagnetic response signals in the blade thermal barrier coating system and the surface temperature distribution signal of the blade to be tested, and the collected electromagnetic signals and temperature signals are integrated to achieve non-destructive quantitative identification and classification of two typical defects in the blade thermal barrier coating system: substrate crack defects and interface debonding defects. The present invention has the characteristics of a small test probe, fast response speed, and large detection range. It provides a fully flexible and efficient non-destructive testing method for the detection of composite defects in blade thermal barrier coating systems, overcomes the difficulty of limited space for in-situ testing of blades in confined spaces, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic non-destructive testing of typical defects in blade thermal barrier coating systems, and in particular to a flexible internal and external coordinated excitation sensing testing system and method for thermal barrier coatings in a narrow space. Background Art

[0002] Thermal barrier coatings (TBCs) are coating systems specifically designed to protect high-temperature structures. They are widely used in the aviation and energy sectors, such as aircraft engine turbine blades, power generation gas turbines, and rocket engine combustion chambers. These components are often critical to the entire system, resisting powerful impact forces, extremely high temperatures, and complex thermal stress variations, and thus determining the safe operation and service life of the entire engine. Prolonged exposure to high temperatures and physical and chemical corrosion can lead to various defects, starting with small defects and gradually progressing to coating delamination, resulting in immeasurable losses and disasters. Therefore, non-destructive testing of substrate cracks and interfacial debonding defects in TBC systems is crucial for reliability and lifespan assessment, as well as maintenance strategies, during the manufacturing and use of related products.

[0003] Typical existing technical methods for detecting substrate cracks and interfacial debonding defects in thermal barrier coating systems include eddy current testing, ultrasonic testing, infrared thermal imaging, and terahertz testing. These methods are only capable of detecting a single defect, and there is no testing technology or system capable of quantitatively identifying multiple defects. Eddy current testing requires manual scanning with a rigid probe, resulting in a small detection area and only the identification of a single defect, such as a substrate crack. The excitation unit of traditional eddy current infrared technology is made of a water-cooled copper tube with a thick wire diameter, large size, and difficult-to-change shape, making it impossible to electromagnetically excite complex curved structures in a small space. Furthermore, infrared thermal imagers require a certain field of view to collect temperature field signals, making it impossible to collect temperature signals in a small space. Summary of the Invention

[0004] To achieve nondestructive, quantitative identification and classification of two typical defects—substrate cracks and interface debonding—in thermal barrier coating systems on blades with complex configurations within confined spaces, the present invention aims to provide a flexible, internal and external synergistic excitation sensing testing system and method for thermal barrier coatings in confined spaces. This system and method offer effective, nondestructive, quantitative identification and classification of typical defects in thermal barrier coating systems on blades with complex configurations. The system and method offer advantages such as suitability for confined environments, adaptability to complex curved surfaces, high heating efficiency, rapid response, and integrated detection of multiple defects. These advantages fill an international gap in this field and are widely applicable for the nondestructive, quantitative identification and classification of multiple types of complex defects in thermal barrier coating systems on blades with confined spaces.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A flexible internal and external collaborative excitation sensing test system for thermal barrier coatings in a narrow space includes a fully flexible test probe 2 and an internal and external collaborative excitation sensing test device 1. Due to the use of the fully flexible test probe 2, the complex curved surface of the blade to be tested can be tested in a narrow space. The fully flexible test probe 2 includes a double-layer folded flexible excitation coil 3, an array-type flexible electromagnetic detection coil 4, an insulating aerogel 5 and a patch-type flexible array electronic ion temperature sensor 6. The array-type flexible electromagnetic detection coil 4 is placed above the double-layer folded flexible excitation coil 3, and the insulating aerogel 5 is placed between the array-type flexible electromagnetic detection coil 4 and the patch-type flexible array electronic ion temperature sensor 6 to isolate the influence of heat generation from internal and external heat sources; the internal and external collaborative excitation sensing test device 1 includes a temperature acquisition device 9, a control and storage device 10, a timing control device 11, a temperature acquisition device 12, a control and storage device 13, a timing control device 14, a temperature acquisition device 15, a temperature acquisition device 16, a temperature acquisition device 17, a temperature acquisition device 18, a temperature acquisition device 19, a temperature acquisition device 20, a temperature acquisition device 21, a temperature acquisition device 22, a temperature acquisition device 23, a temperature acquisition device 24, a temperature acquisition device 25, a temperature acquisition device 26, a temperature acquisition device 27, a temperature acquisition device 28, a temperature acquisition device 29, a temperature acquisition device 30, a temperature acquisition device 31, a temperature acquisition device 32, a temperature acquisition device 33, a temperature acquisition device 34, a temperature acquisition device 35, a temperature acquisition device 36, a temperature acquisition device 37, a temperature acquisition device 38, a temperature acquisition device 39, a temperature acquisition device 40, a temperature acquisition device 41 The control device 11, the high-power current source excitation device 12 and the electromagnetic signal acquisition device 13, the control and memory 10 are connected to the temperature acquisition device 9, the timing control device 11 and the electromagnetic signal acquisition device 13 to control the release of the excitation and the acquisition of the detection information to ensure that the excitation and acquisition are carried out synchronously; the timing control device 11 is connected to the high-power current source excitation device 12 to control the high-power current source excitation device 12 to output currents of different phases; in addition, the double-layer folded flexible excitation coil 3, the array-type flexible electromagnetic detection coil 4 and the thermal insulation aerogel 5 are integrated into the same circuit and are respectively connected to the high-power current source excitation device 12 and the electromagnetic signal acquisition device 13 to realize the excitation and acquisition of electromagnetic signals; the patch-type flexible array electronic ion temperature sensor is connected to the temperature acquisition device 9 to output the measured temperature signal;

[0007] The internal and external collaborative excitation sensing test device 1 sets the amplitude, frequency, phase and excitation time of the excitation current through the control and memory 10, and releases the excitation signal, controls and synchronizes the triggering of the temperature acquisition device 9, the timing control device 11 and the electromagnetic signal acquisition device 13 with the memory 10 to ensure that the excitation and acquisition are carried out synchronously; the timing control device 11 receives the excitation signal, and synchronously controls the high-power current source excitation device 12 to release the excitation, and inputs different phase currents to the double-layer folded flexible excitation coil 3 of the fully flexible test probe 2; the double-layer folded flexible excitation coil 3 generates an alternating magnetic field, i.e., a direct magnetic field, in free space under the current excitation of the high-power current source excitation device 12, thereby inducing eddy currents in the metal matrix of the blade to be tested; according to Joule's heat law, one side On the one hand, the induced eddy current inside the metal matrix of the blade to be tested generates an internal Joule heat source; on the other hand, the resistance of the double-layer folded flexible excitation coil 3 itself will cause the excitation current to generate an external Joule heat source when passing through the double-layer folded flexible excitation coil 3; because the double-layer folded flexible excitation coil 3 is in close contact with the surface of the thermal barrier coating system of the blade to be tested, the external Joule heat source generated by the coil itself is transmitted into the thermal barrier coating system of the blade to be tested by heat conduction, and cooperates with the internal Joule heat source to form thermal excitation; this internal and external coordinated excitation sensing method greatly improves the heating efficiency in the heating stage, and can enhance the temperature contrast between the defective area and the non-defective area in the thermal barrier coating system of the blade to be tested in the natural cooling stage, which is more conducive to the non-destructive evaluation of defects using the temperature signal in the cooling stage;

[0008] The thermal barrier coating system of the blade to be tested contains two typical defects: substrate crack defects and interface debonding defects. The interface debonding defect will affect the temperature field signal, while the substrate crack defect will affect not only the temperature field signal but also the electromagnetic field signal. Therefore, the electromagnetic signal and temperature signal are integrated to achieve non-destructive quantitative identification and classification of these two typical defects in the thermal barrier coating system of the blade to be tested.

[0009] The double-layer folding flexible excitation coil 3 is composed of two layers of coils, upper and lower, with the coil directions perpendicular to each other. The single-layer coil adopts a periodically symmetrical folding path and is evenly wound by folding back at equal intervals. When excitation is applied, different phase currents are passed through the two layers of coils. The two layers of coils with directions perpendicular to each other will induce multi-directional eddy currents in the metal matrix of the blade to be tested, effectively avoiding the missed detection phenomenon caused by the single eddy current direction being parallel to the defect direction. The uniformly distributed design of the double-layer folding flexible excitation coil 3 can generate a relatively uniform induced eddy current field in the metal matrix of the blade to be tested, and thus obtain a relatively uniformly distributed temperature field, which will greatly improve the contrast between the defect and non-defect areas in the temperature signal, and is conducive to the non-destructive quantitative identification of defects. The flexible structural design of the double-layer folding flexible excitation coil 3 enables it to be tightly attached to the surface of the thermal barrier coating system of the blade to be tested. It can not only fully adapt to the complex curved surface configuration of the blade to be tested, but also maximize the heating efficiency of the internal and external Joule heat sources, thereby improving the detection efficiency and detection accuracy.

[0010] The array-type flexible electromagnetic detection coil 4 comprises multiple coils arranged in an array. Each coil can independently sense electromagnetic signals, providing a strong response capability to electromagnetic signals. By processing the signals output by each coil, the strength of the useful signal is effectively enhanced, the impact of noise signals is reduced, and the signal-to-noise ratio is improved. Adjusting the spacing and layout of the coils enables simultaneous signal acquisition over a larger area, expanding the detection area while also improving the sensitivity and resolution of detecting minor defects in the thermal barrier coating system of the blade under test. The coordination between the coils effectively suppresses noise signals, improves the signal-to-noise ratio, and thus enhances the accuracy of defect detection.

[0011] The patch-type flexible array electronic ion temperature sensor 6 has fully flexible physical properties, capable of tightly fitting the complex curved surface configuration of the blade to be measured, and obtaining a complete temperature signal from the contact area. Furthermore, the patch-type flexible array electronic ion temperature sensor 6 has a high sensitivity of 1mV / K and a millisecond-level dynamic response characteristic of 10ms. The patch-type flexible array electronic ion temperature sensor 6 is composed of individual patch-type flexible electronic ion temperature sensors 6-1 arranged in an array. Each individual patch-type flexible electronic ion temperature sensor 6-1 is composed of an ion conductor temperature measuring end 7 and an electronic conductor sensing end 8, wherein the ion conductor temperature measuring end 7 is made of a material having transparent and stretchable physical properties. Furthermore, commonly used materials for the ion conductor temperature measuring end 7 include ion gels, hydrogels, and ion elastomers, which have the physical properties of being transparent, stretchable, highly stable, and conductive.

[0012] Array-type multi-point temperature measurement can achieve temperature distribution measurement over a wide range and improve the spatial resolution of temperature signals. Compared to infrared thermal imagers, the patch-type flexible array electronic ion temperature sensor can achieve temperature measurement of complex curved surfaces with limited field of view in narrow spaces. Compared to thermocouples, the patch-type flexible array electronic ion temperature sensor has flexible automatic bonding characteristics, does not require manual bonding, and is easy to implement simple and fast operation; moreover, the patch-type flexible array electronic ion temperature sensor has millisecond-level dynamic response characteristics, which can quickly capture blade surface temperature changes in the initial cooling stage; in addition, the patch-type flexible array electronic ion temperature sensor will not scratch the blade surface material during the temperature measurement process, thereby protecting the integrity of the surface material of the measured blade specimen.

[0013] The induced eddy current inside the metal matrix of the blade to be tested can generate Joule heat internal heat source, and its heat conduction follows formula (1):

[0014]

[0015] Where, Indicates the density of the material; Indicates the specific heat capacity of the material; Indicates the thermal conductivity of the material; Indicates temperature; Indicates the temperature of the material Over time The instantaneous rate of change of Represents the internal heat source of Joule heat.

[0016] The testing method for the flexible internal and external coordinated excitation sensing testing system for thermal barrier coatings in confined spaces can achieve non-destructive quantitative identification and classification of substrate crack defects and interface debonding defects in thermal barrier coating systems for blades with complex configurations in confined spaces, and includes the following steps:

[0017] Step 1: Place the fully flexible test probe 2 on the surface of the blade to be tested, wherein the double-layer folded flexible excitation coil 3, the array-type flexible electromagnetic detection coil 4, the thermal insulation aerogel 5 and the patch-type flexible array electronic ion temperature sensor 6 are placed in sequence from bottom to top near the surface of the blade to be tested to form a multi-layer structure, and adjust the bending curvature of the fully flexible test probe 2 according to the actual configuration of the blade to be tested to ensure that the fully flexible test probe 2 is completely fitted with the surface of the blade to be tested; wherein the thermal insulation aerogel 5 is used to achieve thermal insulation between the patch-type flexible array electronic ion temperature sensor 6 and the double-layer folded flexible excitation coil 3 and the array-type flexible electromagnetic detection coil 4, to ensure that the patch-type flexible array electronic ion temperature sensor 6 is not affected by heat from internal and external heat sources during the excitation process;

[0018] Step 2: Before applying the excitation, the amplitude, frequency, phase, and excitation time of the excitation current are set through the control and memory 10 to ensure that the two layers of the double-layer folded flexible excitation coil 3 are fed with currents of different phases and generate induced eddy currents in different directions;

[0019] Step 3: When applying excitation, the control and memory 10 synchronously releases signals to the temperature acquisition device 9, the timing control device 11, and the electromagnetic signal acquisition device 13 to ensure that excitation and acquisition are carried out synchronously; at this time, the timing control device 11 synchronously triggers the high-power current source excitation device 12 to release excitations of different phases, the electromagnetic signal acquisition device 13 collects electromagnetic signals, and the temperature acquisition device 9 collects temperature signals;

[0020] Step 4: When the excitation ends, the double-layer folded flexible excitation coil 3, the array-type flexible electromagnetic detection coil 4, and the thermal insulation aerogel 5 are quickly withdrawn, so that the patch-type flexible array electronic ion temperature sensor 6 automatically falls and adheres to the surface of the blade to be measured; the surface temperature signal of the blade to be measured during the natural cooling stage after the excitation ends is measured, and the measured temperature signal is collected by the temperature acquisition device 9;

[0021] Step 5: Analyze the collected electromagnetic and temperature signals:

[0022] The substrate crack defect in the thermal barrier coating system of the blade to be tested will disturb the distribution of the induced eddy current field in the metal substrate of the blade to be tested, and the disturbance of the eddy current field will affect the secondary magnetic field; by using the array-type flexible electromagnetic detection coil 4 to collect the changes in the secondary magnetic field, the electromagnetic signal can be used to identify the substrate crack in the excitation stage; in addition, during the heat conduction process of the fully flexible test probe, the presence of substrate cracks and interface debonding defects will affect the heat conduction process, and ultimately lead to changes in the surface temperature distribution of the blade to be tested; therefore, by measuring the temperature signal of the cooling stage of the surface of the blade to be tested through the patch-type flexible array electronic ion temperature sensor 6 and the temperature acquisition device 9, and fusing the electromagnetic signals measured in the excitation stage, non-destructive quantitative identification and classification of two typical defects, substrate crack defects and interface debonding defects, in the thermal barrier coating system of the blade to be tested can be achieved.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] 1) Aiming at defect detection of blade thermal barrier coating systems in confined spaces, the present invention has developed a fully flexible test probe and an internal and external coordinated excitation sensing test device, overcoming the difficulty of limited space during in-situ blade testing. Compared to the large size and rigidity of the excitation sensing devices in traditional detection systems, the test system in the present invention is relatively small and fully flexible, allowing for a perfect fit with complex blade curves in a confined space. Compared to the acquisition method of traditional infrared thermal imagers, the test system in the present invention can acquire blade surface temperature in a confined space with a limited field of view, avoiding blind spots or missed detections.

[0025] 2) Compared to traditional non-flexible test probes, the fully flexible test probe employed in this invention innovatively addresses the challenges of small contact area, high heat transfer losses, and difficulty in acquiring detection signals when testing thermal barrier coating systems on complex blades within confined spaces. The double-layer, folded-back flexible excitation coil adheres closely to the complex curved surface of the blade under test, increasing the contact area between the excitation coil and the blade surface and improving heat transfer efficiency. The close fit of the array of flexible electromagnetic detection coils and the flexible temperature measurement device to the blade ensures a detection signal with no blind spots, enhancing detection accuracy.

[0026] 3) The double-layer folded-back flexible excitation coil adopted in the present invention effectively avoids the problem of missed detection caused by the parallelism of the crack direction and the eddy current direction, and has the advantage of being able to detect substrate cracks in any direction. By passing currents of different phases through the double-layer folded-back flexible excitation coil, eddy currents of different directions can be induced in the metal matrix of the blade to be tested, thus avoiding missed detection caused by the parallelism of the eddy current in a single direction with the crack direction, and improving the detection capability of substrate cracks in different directions. In addition, the straight segment configuration of the folded-back coil can generate a relatively uniform eddy current field inside the metal matrix of the blade to be tested, and then generate relatively uniformly distributed internal and external heat sources. The relatively uniform heat source will generate a relatively uniform temperature field in the conductor to be tested, which will greatly improve the temperature contrast between the defective and non-defective areas in the temperature signal, thereby improving the defect detection capability.

[0027] 4) The array of flexible electromagnetic detection coils employed in this invention can effectively capture minute electromagnetic signal changes, improving the sensitivity and resolution of crack defect detection. The array of flexible electromagnetic detection coils consists of multiple small coils, each capable of independent sensing and possessing a strong response to electromagnetic signals. The array layout enables simultaneous signal acquisition over a large area, expanding the detection area while also improving sensitivity and resolution for detecting minute defects. The coordination between the individual coils effectively suppresses noise signals, improving the signal-to-noise ratio and, consequently, enhancing defect detection accuracy.

[0028] 5) The patch-type flexible array electronic ion temperature sensor proposed in the present invention has fully flexible physical properties, can fit tightly to the complex curved surface configuration of the blade to be measured, and obtain the complete temperature signal of the contact area; at the same time, it has high sensitivity and millisecond-level dynamic response characteristics; array-type multi-point temperature measurement can achieve temperature measurement in a large range, and improve the spatial resolution of the temperature signal. Compared with infrared thermal imagers, the temperature sensor of the present invention can achieve complex curved surface temperature measurement in narrow spaces with limited field of view. Compared with thermocouples, the temperature sensor of the present invention has flexible automatic fitting characteristics, does not require additional pasting tools for manual bonding, and is easy to implement simple and fast operation; and, the temperature sensor has millisecond-level dynamic response characteristics, which can quickly capture the temperature changes on the blade surface during the initial cooling stage; in addition, the sensor will not scratch the blade surface material during the temperature measurement process, protecting the integrity of the surface material of the blade specimen to be measured.

[0029] 6) The present invention's nondestructive testing method using electromagnetic thermal internal and external cooperative excitation sensing cleverly combines the internal Joule heat source generated by the induced eddy current field within the metal matrix of the blade being tested with the external Joule heat source generated by the resistive thermal effect of the excitation coil. Compared to traditional single thermal excitation methods, this electromagnetic thermal internal and external cooperative excitation method greatly improves heating efficiency, thereby increasing detection efficiency and sensitivity. During the natural cooling phase, compared to a single excitation method, the internal and external cooperative excitation method can greatly improve the temperature contrast between defective and non-defective areas during the cooling phase, making it more conducive to the nondestructive quantitative identification of defects.

[0030] 7) The flexible internal and external synergistic excitation sensing testing system and method for thermal barrier coatings in confined spaces disclosed herein can enable nondestructive quantitative identification and classification of complex defects in blade thermal barrier coating systems. Typical defects in thermal barrier coating systems include substrate cracks and interface debonding. Substrate cracks disrupt the distribution of eddy currents in the metal substrate of the blade under test, which in turn affects the secondary magnetic field signal. Using an array of flexible electromagnetic detection coils to capture changes in the secondary magnetic field, the electromagnetic signal can be used during the excitation phase to nondestructively quantitatively identify substrate cracks. Furthermore, during heat conduction under the synergistic excitation of electromagnetic heating, both substrate cracks and interface debonding can affect the heat conduction process, ultimately leading to changes in the blade surface temperature distribution. Therefore, the temperature signal collected by the patch-type flexible array electronic ion temperature sensor contains information about both substrate cracks and interface debonding. Since substrate cracks are already identified through electromagnetic signals, combining them with the temperature signal enables quantitative identification of interface debonding defects, ultimately enabling nondestructive quantitative identification and classification of both typical defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the fully flexible test probe proposed by the present invention.

[0032] Figure 2 This is a schematic diagram of the flexible internal and external collaborative excitation sensing test system for thermal barrier coatings in narrow spaces proposed by the present invention and its effect verification.

[0033] Figure 3 This is a schematic diagram of the electromagnetic signal changes detected by the array-type flexible electromagnetic detection coil of the present invention.

[0034] Figure 4 This is a temperature measurement effect diagram of the patch-type flexible array electronic ion temperature sensor of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, the terms used herein are only for describing specific embodiments and are not intended to limit the embodiments of the present application.

[0037] like Figure 1 and Figure 2 As shown, the flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in confined spaces of the present invention includes a fully flexible test probe 2 and an internal and external coordinated excitation sensing test device 1. The fully flexible test probe 2 comprises: a double-layer folded flexible excitation coil 3, an array-type flexible electromagnetic detection coil 4, a thermal insulation aerogel 5, and a patch-type flexible array electronic ion temperature sensor 6. The array-type flexible electromagnetic detection coil 4 covers the double-layer folded flexible excitation coil 3, and the thermal insulation aerogel 5 is placed between the array-type flexible electromagnetic detection coil 4 and the patch-type flexible array electronic ion temperature sensor 6 to isolate the heat generated by internal and external heat sources. Among them, the patch-type flexible array electronic ion temperature sensor 6 is composed of individual patch-type flexible electronic ion temperature sensors 6-1 arranged in an array. The individual patch-type flexible electronic ion temperature sensor 6-1 consists of an ion conductor temperature measurement end 7 and an electronic conductor sensing end 8.

[0038] like Figure 2As shown, the internal and external collaborative excitation sensing test device 1 includes a temperature acquisition device 9, a control and memory 10, a timing control device 11, a high-power current source excitation device 12 and an electromagnetic signal acquisition device 13. The control and memory 10 is connected to the temperature acquisition device 9, the timing control device 11 and the electromagnetic signal acquisition device 13 to control the release of excitation and the acquisition of detection information to ensure that the excitation and acquisition are carried out synchronously; the timing control device 11 is connected to the high-power current source excitation device 12 to control the high-power current source excitation device 12 to output currents of different phases; in addition, the double-layer folded flexible excitation coil 3, the array-type flexible electromagnetic detection coil 4 and the thermal insulation aerogel 5 are integrated into the same circuit and are respectively connected to the high-power current source excitation device 12 and the electromagnetic signal acquisition device 13 to realize the excitation and acquisition of electromagnetic signals; the patch-type flexible array electronic ion temperature sensor 6 is connected to the temperature acquisition device 9 to output the measured temperature signal.

[0039] like Figure 2 As shown in the figure, the flexible internal and external synergistic excitation sensing test system and effect verification diagram of thermal barrier coating in narrow space. Figure 1 , which quantitatively identifies and classifies typical defects of thermal barrier coating systems of complex blade configurations, such as substrate crack defects and interface debonding defects, and includes the following steps:

[0040] 1) Set up the test system: Place the fully flexible test probe 2 on the surface of the blade to be tested and adjust its curvature according to the actual blade configuration to ensure that it is in perfect contact with the surface. Adjust the amplitude, frequency, phase, and excitation time of the high-power current source excitation device 12 to ensure that the test is performed under optimal parameters.

[0041] 2) Quantitative identification and classification of two typical defects in blade thermal barrier coating systems: substrate cracks and interfacial debonding. During testing using a fully flexible test probe 2, currents of varying phases are applied to the double-layer, folded-back flexible excitation coil 3. Based on the principle of electromagnetic induction, an alternating magnetic field (direct magnetic field) is generated in free space. This in turn induces eddy currents in the metal substrate of the blade under test. These eddy currents generate a secondary magnetic field. The presence of substrate cracks perturbs the magnetic field signal. An array of flexible electromagnetic detection coils 4 is used to capture changes in the secondary magnetic field. During the excitation phase, the electromagnetic signal is used to quantitatively identify substrate cracks. According to Joule's law of heating, the induced eddy currents within the metal substrate of the blade under test generate an internal Joule heat source. Furthermore, the double-layer, folded-back flexible excitation coil 3 generates an external Joule heat source through heat conduction due to its inherent resistance effect. These external Joule heat sources, acting in concert with the internal Joule heat source, form a thermal excitation. Both substrate cracks and interfacial debonding defects affect the heat conduction process, ultimately leading to changes in the blade surface temperature distribution. Therefore, by measuring the temperature signal of the cooling stage of the blade surface to be tested using the patch-type flexible array electronic ion temperature sensor 6 and the temperature acquisition device 9, and fusing the electromagnetic signal measured in the excitation stage, non-destructive quantitative identification and classification of two typical defects, substrate crack defects and interface debonding, in the thermal barrier coating system of the blade to be tested can be achieved.

[0042] like Figure 3 As shown in FIG, a schematic diagram of the electromagnetic signal detected by a single coil in the array type flexible electromagnetic detection coil 4 of the present invention is shown. Each coil in the array coil can sense independently. The electromagnetic signal obtained by each coil is processed and the signal peak is observed to infer the relative position of the defect. Figure 3 At the position indicated by the middle circle, quantitative identification of matrix crack defects is achieved.

[0043] like Figure 4 The data shown in the figure shows the test results of the patch-type flexible array electronic ion temperature sensor 6 of the present invention. From the perspective of the sensing mechanism, a single patch-type flexible electronic ion temperature sensor 6-1 mainly includes a three-layer structure of electrolyte, dielectric and electrode. During operation, electrons accumulate at the interface between the electrode and dielectric, and ions accumulate at the interface between the electrolyte and dielectric, forming an ion cloud. Due to the charge imbalance between the ionic charge and the electronic charge at the two interfaces, an electric field is formed in the electrolyte. Changes in the temperature of the measuring point will affect the thickness of the ion cloud. When the temperature rises, the ion cloud expands; when the temperature drops, the ion cloud contracts. Changes in the thickness of the ion cloud will affect the electric field in the electrolyte, thereby causing changes in the open circuit voltage of the electrode. The change in the open circuit voltage of the electrode follows formula (2):

[0044]

[0045] Where, represents the open circuit voltage of the electrode, It represents the accumulated ionic charge per unit area at the interface between electrolyte and dielectric. It represents the electron charge accumulated per unit area at the interface between the electrode and the dielectric. represents the dielectric constant of the dielectric, represents the dielectric constant of the electrolyte, represents the Debye length, Represents the thickness of the dielectric. Using this principle, the surface temperature change of the blade thermal barrier coating system under test is measured. The electromagnetic signal detected by the array-type flexible electromagnetic detection coil 4 is integrated with the temperature signal to generate a temperature comparison map, enabling non-destructive quantitative identification and classification of substrate crack defects and interface debonding defects in the blade thermal barrier coating system under test.

[0046] The electromagnetic detection technology of the present invention, which uses electromagnetic thermal internal and external synergistic excitation sensing, is a new type of non-destructive testing technology with the advantages of high heating efficiency, high detection sensitivity, diverse defect detection types, and strong anti-interference ability. This technology generates a direct magnetic field by applying an alternating current to the excitation coil. The direct magnetic field will generate induced eddy currents in the metal body, and the eddy currents will then generate a secondary magnetic field. By collecting the electromagnetic signals of the secondary magnetic field through an array of flexible electromagnetic detection coils, quantitative non-destructive identification of substrate cracks can be achieved. In addition, the induced eddy currents will generate an internal Joule heat source inside the metal substrate of the blade, and the external Joule heat source of the coil itself will also be transmitted into the interior of the blade specimen. The two will work together to form thermal excitation. During the heat conduction process, both substrate cracks and interface debonding will disturb the heat conduction process. The temperature signal of the specimen surface can be collected by a patch-type electronic ion temperature sensor. Finally, by fusing the collected electromagnetic signals and temperature signals, non-destructive quantitative identification and classification of two typical defects in the thermal barrier coating system: substrate crack defects and interface debonding defects can be achieved.

Claims

1. Flexible internal and external synergistic excitation sensing test system for thermal barrier coatings in narrow spaces, characterized by: The test system comprises a fully flexible test probe (2) and an internal and external synergistic excitation sensing test device (1). Due to the use of the fully flexible test probe (2), the complex curved surface of the blade to be tested can be tested in a narrow space. The fully flexible test probe (2) comprises a double-layer folded flexible excitation coil (3), an array-type flexible electromagnetic detection coil (4), a heat-insulating aerogel (5) and a patch-type flexible array electronic ion temperature sensor (6). The array-type flexible electromagnetic detection coil (4) is placed above the double-layer folded flexible excitation coil (3), and the heat-insulating aerogel (5) is placed between the array-type flexible electromagnetic detection coil (4) and the patch-type flexible array electronic ion temperature sensor (6) to isolate the influence of heat generation from internal and external heat sources. The internal and external synergistic excitation sensing test device (1) comprises a temperature acquisition device ( 9), control and memory (10), timing control device (11), high-power current source excitation device (12) and electromagnetic signal acquisition device (13), the control and memory (10) is connected to the temperature acquisition device (9), the timing control device (11) and the electromagnetic signal acquisition device (13), the timing control device (11) is connected to the high-power current source excitation device (12), and controls the high-power current source excitation device (12) to output currents of different phases; the double-layer folded flexible excitation coil (3), the array type flexible electromagnetic detection coil (4) and the thermal insulation aerogel (5) are integrated into the same circuit and are respectively connected to the high-power current source excitation device (12) and the electromagnetic signal acquisition device (13), and the patch type flexible array electronic ion temperature sensor (6) is connected to the temperature acquisition device (9); The internal and external cooperative excitation sensing test device (1) sets the amplitude, frequency, phase and excitation time of the excitation current through the control and memory (10), and releases the excitation signal. The control and memory (10) synchronously triggers the temperature acquisition device (9), the timing control device (11) and the electromagnetic signal acquisition device (13). The timing control device (11) receives the excitation signal and synchronously controls the high-power current source excitation device (12) to release the excitation, thereby inputting different phase currents to the double-layer folded flexible excitation coil (3) of the fully flexible test probe (2); the double-layer folded flexible The excitation coil (3) generates an alternating magnetic field, i.e., a direct magnetic field, in free space under current excitation, thereby inducing eddy currents in the metal matrix of the blade to be measured; the induced eddy currents in the metal matrix of the blade to be measured generate an internal Joule heat source; the resistance of the double-layer folded-back flexible excitation coil (3) itself causes the excitation current to pass through the double-layer folded-back flexible excitation coil (3) and generate an external Joule heat source; the external Joule heat source generated by the double-layer folded-back flexible excitation coil (3) itself is transmitted into the thermal barrier coating system of the blade to be measured by heat conduction, and cooperates with the internal Joule heat source to form thermal excitation.

2. The flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in narrow spaces according to claim 1 is characterized by: The double-layer folded-back flexible excitation coil (3) is composed of two layers of coils, one above the other, with coil directions perpendicular to each other. The single-layer coil adopts a periodically symmetrical folded-back path and is evenly wound by folding back at equal intervals. When excitation is applied, currents of different phases are passed through the two layers of coils, and the two layers of coils with directions perpendicular to each other will induce multi-directional eddy currents in the metal matrix of the blade to be tested.

3. The flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in narrow spaces according to claim 1 is characterized by: The array-type flexible electromagnetic detection coil (4) is composed of a plurality of coils arranged in an array, and each coil is capable of independent sensing; adjusting the spacing and layout between the coils can achieve synchronous acquisition of signals in a large area, and also improves the detection sensitivity and resolution of tiny defects in the thermal barrier coating system of the blade to be tested.

4. The flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in narrow spaces according to claim 1 is characterized by: The patch-type flexible array electronic ion temperature sensor (6) has a fully flexible physical property and can closely fit the complex curved surface configuration of the blade to be measured to obtain a complete temperature signal of the contact area; at the same time, the patch-type flexible array electronic ion temperature sensor (6) has a high sensitivity of 1mV / K and a millisecond-level dynamic response characteristic of 10ms; the patch-type flexible array electronic ion temperature sensor (6) is composed of a single patch-type flexible electronic ion temperature sensor (6-1) combined in an array layout, and the single patch-type flexible electronic ion temperature sensor (6-1) is composed of an ion conductor temperature measuring end (7) and an electronic conductor sensing end (8), wherein the ion conductor temperature measuring end (7) is made of a material with transparent and stretchable physical properties.

5. The flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in narrow spaces according to claim 4 is characterized by: The material of the ion conductor temperature measuring end (7) is ion gel, hydrogel or ion elastomer.

6. The flexible internal and external coordinated excitation sensing test system for thermal barrier coatings in narrow spaces according to claim 1 is characterized by: The induced eddy current inside the metal matrix of the blade to be tested generates Joule heat internal heat source, and its heat conduction follows formula (1): Where, Indicates the density of the material; Indicates the specific heat capacity of the material; Indicates the thermal conductivity of the material; Indicates temperature; Indicates the temperature of the material Over time t The instantaneous rate of change of Represents the internal heat source of Joule heat.

7. The testing method of the flexible internal and external coordinated excitation sensing testing system for thermal barrier coatings in narrow spaces according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Place a fully flexible test probe (2) on the surface of the blade to be tested, wherein a double-layer folded flexible excitation coil (3), an array-type flexible electromagnetic detection coil (4), a thermal insulation aerogel (5) and a patch-type flexible array electronic ion temperature sensor are placed in sequence from bottom to top near the surface of the blade to be tested to form a multi-layer structure, and adjust the curvature of the fully flexible test probe (2) according to the actual configuration of the blade to be tested to fit the surface of the blade to be tested; the thermal insulation aerogel (5) ensures that the patch-type flexible array electronic ion temperature sensor (6) is not affected by the heat of internal and external heat sources during the excitation process; Step 2: Before applying the excitation, the amplitude, frequency, phase and excitation time of the excitation current are set by the control and memory (10) to ensure that the two layers of the double-layer folded flexible excitation coil (3) are fed with currents of different phases and generate induced eddy currents in different directions; Step 3: When applying excitation, the control and memory (10) synchronously releases signals to the temperature acquisition device (9), the timing control device (11), and the electromagnetic signal acquisition device (13), ensuring that excitation and acquisition are performed synchronously; the timing control device (11) synchronously triggers the high-power current source excitation device (12) to release excitations of different phases, the electromagnetic signal acquisition device (13) acquires electromagnetic signals, and the temperature acquisition device (9) acquires temperature signals; Step 4: When the excitation is applied, the double-layer folded flexible excitation coil (3), the array-type flexible electromagnetic detection coil (4) and the thermal insulation aerogel (5) are quickly withdrawn, so that the patch-type flexible array electronic ion temperature sensor (6) automatically falls on the surface of the blade to be measured; the temperature signal measured by the patch-type flexible array electronic ion temperature sensor (6) is collected by the temperature acquisition device (9), which is the temperature signal of the surface of the blade to be measured in the natural cooling stage after the excitation is completed; Step 5: Analyze the collected electromagnetic and temperature signals: The substrate crack defect in the thermal barrier coating system of the blade to be tested will disturb the distribution of the induced eddy current field in the metal substrate of the blade to be tested, and the disturbance of the eddy current field will affect the secondary magnetic field; an array-type flexible electromagnetic detection coil (4) is used to collect the change of the secondary magnetic field, that is, the electromagnetic signal is used to realize the identification of the substrate crack in the excitation stage; in addition, during the heat conduction process of the fully flexible test probe, the presence of the substrate crack defect and the interface debonding defect will affect the heat conduction process, and ultimately lead to the change of the surface temperature distribution of the blade to be tested; therefore, the temperature signal of the natural cooling stage of the surface of the blade to be tested measured by the patch-type flexible array electronic ion temperature sensor (6) is collected by the temperature acquisition device (9), and the electromagnetic signal measured in the excitation stage is integrated to realize the non-destructive quantitative identification and classification of the substrate crack defect and the interface debonding defect in the thermal barrier coating system of the blade to be tested.

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