A nondestructive testing probe and method for thermal barrier coatings using eddy current-laser-liquid crystal smart materials

Abstract

A nondestructive detection probe and method for thermal barrier coatings that are coordinated by eddy current-laser-liquid crystal smart materials, the detection probe includes an eddy current probe, a laser ranging probe, and a probe combination detection component fixing device; the method performs a comprehensive nondestructive evaluation of the thickness of the thermal barrier coating ceramic layer, the dielectric constant, and the performance of the metal substrate below the thermal barrier coating. When evaluating the thermal barrier coating system, the distance between the eddy current probe and the upper surface of the metal substrate and the coating system performance parameters are inverted, and the distance between the laser ranging probe and the upper surface of the thermal barrier coating ceramic layer and the height difference between the laser ranging probe and the eddy current probe are measured with the help of liquid crystal smart materials and laser ranging probes, thereby obtaining the thickness of the thermal barrier coating ceramic layer. The present invention has the characteristics of non-contact, high precision and rapid detection, and can effectively avoid mechanical measurement errors caused by uncontrollable factors such as the mechanical contact state between the probe and the coating surface and surface roughness, thereby ensuring accurate evaluation of the thermal barrier coating and the metal substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of film thickness detection of metal-based film structures such as thermal barrier coatings, and in particular to a nondestructive detection probe and method for thermal barrier coatings coordinated by eddy current-laser-liquid crystal smart materials. Background Art

[0002] Among the typical electrical testing methods, eddy current testing is a testing technology widely used in the industrial field, especially in safety monitoring in key areas such as nuclear power, aerospace and energy. It is an advanced testing technology based on electromagnetic principles and one of the five conventional non-destructive testing methods. Eddy current testing has the characteristics of non-contact, fast detection speed, high accuracy and wide application range. When an eddy current coil is passed through an alternating current and approaches a conductor, eddy currents are generated inside the conductor. The reverse magnetic field formed by these eddy currents resists the change of the original magnetic field, resulting in a change in the equivalent impedance of the coil. The magnitude of this impedance change is closely related to many factors such as the electromagnetic properties of the sample (such as resistivity and permeability), geometric dimensions (such as conductor thickness) and the distance between the coil and the sample. By analyzing the change in the impedance of the detection coil, the geometric shape, size changes and changes in physical parameters of the sample can be effectively identified.

[0003] Thermal barrier coating is a coating system specially designed to protect high-temperature structures. It is widely used in aerospace, energy, and automotive fields. The ceramic layer is the core of the thermal barrier coating. It has excellent thermal insulation properties and can effectively reduce the temperature of the substrate surface. Under high temperature conditions, the thickness of the non-conductive ceramic layer of the thermal barrier coating may be reduced and the material properties may deteriorate; at the same time, the properties of the metal substrate material protected by the thermal barrier coating (material properties such as electrical conductivity and magnetic permeability) may change. This will significantly affect the safety of the structure, so it is crucial to evaluate the reliability of the coating structure. The traditional thickness measurement method of non-conductive ceramic coatings generally belongs to the contact measurement method. The contact measurement method has the following disadvantages: First, during the measurement process, the contact force between the probe and the coating will cause the micro-convex body on the coating surface to deform at the micron level. This micron-level deformation is uncontrollable and unmeasurable, which will eventually introduce coating thickness measurement errors; second, during the measurement process, the contact force between the probe and the coating will also cause a small deformation of the packaging structure under the probe. This deformation is also uncontrollable and unmeasurable, which will eventually introduce coating thickness measurement errors. In addition, there is wear between the probe and the coating, which may damage the coating surface. Furthermore, even if the coating is smooth in the macroscopic state, its surface is rough and uneven in the microscopic scale. What actually contacts the probe are the micro-protrusions on the coating surface, and the height difference of the micro-protrusions is usually in the micron range. This will cause the distance of the thickness measuring probe relative to the coating to change in the micron range during movement, and the final thickness measurement result will introduce errors. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a thermal barrier coating non-destructive testing probe and method that cooperates with eddy current-laser-liquid crystal intelligent materials, which can realize non-contact, high-sensitivity, and rapid non-destructive testing of metal-based film-based structure surfaces such as rough and variable curvature thermal barrier coatings under narrow and macro conditions.

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

[0006] A thermal barrier coating nondestructive testing probe with eddy current-laser-liquid crystal smart material collaboration, comprising a laser ranging probe 1, an eddy current probe 3 and a probe combination detection piece fixing device 2, wherein the eddy current probe 3 comprises a transparent thin plate 4, a coil 5 and a liquid crystal smart material dimming film 6, the coil 5 is arranged at the center of the lower surface of the transparent thin plate 4, and the liquid crystal smart material dimming film 6 is attached to the lower surface of the transparent thin plate 4; the probe combination detection piece fixing device 2 comprises a detection device partition 7, a laser ranging probe sleeve 8 and a fixing device shell 9, and the upper and lower parts of the detection device partition 7 are coaxially placed with lasers. The ranging probe 1 and the eddy current probe 3, the laser ranging probe sleeve 8 is used to fix the laser ranging probe 1, the laser ranging probe 1 is placed in the laser ranging probe sleeve 8 and fixed with the laser ranging probe sleeve 8 by interference fit; the eddy current probe 3, the detection device interlayer 7 and the laser ranging probe sleeve 8 are all placed in the fixing device shell 9; in order to prevent the eddy current probe 3 from blocking the laser beam emitted by the laser ranging probe 1 and ensure that the laser beam optical path passes through the eddy current probe 3 completely, the center of the coil 5 is not wound with a wire and the center of the transparent thin plate 4 is opened so that the laser beam emitted by the laser ranging probe 1 can pass through.

[0007] The liquid crystal smart material dimming film 6 is a sandwich structure, consisting of two electrodes with ITO films coated on the surface, a high molecular polymer matrix located between the electrodes, and an electrically driven liquid crystal in the high molecular polymer matrix. The orientation of the electrically driven liquid crystal small molecules in the liquid crystal smart material dimming film 6 is changed by applying an electric field, thereby realizing the switching of light transmission and light reflection states.

[0008] The fixture housing 9 is made of flexible material, and the contact portion with the thermal barrier coating is designed as a circumferential crescent-shaped cutout so as to stably fit with the thermal barrier coating system with an arc and variable curvature. The fixture housing 9 provides stable support for the entire probe.

[0009] The laser rangefinder probe 1 adopts a cylindrical design with an outer diameter of 8mm. This size design can ensure that the probe has good beam focusing performance during high-precision measurement, help to accurately control the laser focus point, achieve high spatial resolution in the probe's tiny measurement area, and ensure that the probe's position deviation is minimized when performing fine-scale and complex surface morphology detection. At the same time, this size design can also adapt to smaller operating spaces and narrow detection environments. The measurement accuracy of the laser rangefinder probe 1 is ±0.55μm, which meets high-demand precision measurement tasks.

[0010] The outer diameter of the coil 5 of the eddy current probe 3 is 4 mm, the inner diameter is 1 mm, and the measurement accuracy is ±1 μm. The eddy current probe 3 has a compact size design, and the smaller coil size helps to improve the sensitivity of the probe, which is particularly suitable for high-frequency eddy current detection. The hollow design of the coil allows the laser beam emitted by the upper laser ranging probe 1 to pass through the coil layer unobstructed, optimizes the working synergy between the eddy current probe 3 and the laser ranging probe 1, and improves the overall working efficiency of the probe.

[0011] The transparent thin plate 4 has a thickness of 3-5 mm and is made of aluminosilicate glass with high light transmittance, high temperature resistance and good adhesion to other materials. Within the thickness range of 3-5 mm, the transparent thin plate 4 can achieve an effective balance between optical transmittance and structural strength. The thickness selection in this range ensures the laser transmission efficiency required for high-precision measurement, effectively reduces signal attenuation, and meets the needs of rapid response of the probe. At the same time, the aluminosilicate glass material has high light transmittance, and its low thermal expansion coefficient and high temperature resistance enable the transparent thin plate 4 to remain stable in harsh high temperature environments, and can effectively withstand mechanical stress, ensuring that the probe is reliable and durable for a long time under complex working conditions such as high temperature.

[0012] The nondestructive testing method of the thermal barrier coating nondestructive testing probe using eddy current-laser-liquid crystal smart materials can realize the thickness evaluation of the thermal barrier coating ceramic layer, and specifically includes the following steps:

[0013] Step 1: fix the probe above the thermal barrier coating system but not in contact with the thermal barrier coating system, wherein the thermal barrier coating system includes a metal substrate 11 and a thermal barrier coating ceramic layer 10 on the surface of the metal substrate;

[0014] Step 2: The distance between the eddy current probe 3 and the upper surface of the metal substrate 11 is detected by the eddy current probe 3 placed on the lower side of the detection device interlayer 7 ;

[0015] Step 3: The liquid crystal smart material dimming film 6 is not powered, and the liquid crystal smart material dimming film 6 is in a transparent state; the laser emitted by the laser ranging probe 1 passes through the liquid crystal smart material dimming film 6 and is reflected on the upper surface of the thermal barrier coating ceramic layer 10, and the laser ranging probe 1 detects the distance between the laser ranging probe 1 and the upper surface of the thermal barrier coating ceramic layer 10 ;

[0016] Step 4: Power on the liquid crystal smart material dimming film 6, the liquid crystal smart material dimming film 6 is in an opaque state, the laser emitted by the laser ranging probe 1 cannot penetrate the liquid crystal smart material dimming film 6, and is reflected on the upper surface of the liquid crystal smart material dimming film 6. The laser ranging probe 1 detects the height difference between the eddy current probe 3 and the laser ranging probe 1. ;

[0017] Step 5: Based on the measured distance between the laser ranging probe 1 and the upper surface of the thermal barrier coating ceramic layer 10 , the height difference between the eddy current probe 3 and the laser ranging probe 1 , the distance between the eddy current probe 3 and the upper surface of the metal substrate 11 According to formula (1), the thickness of the thermal barrier coating ceramic layer 10 of the thermal barrier coating system is calculated as The measurement results;

[0018] After the readings stabilize, the probe moves as a whole to detect the next position.

[0019] The nondestructive testing method can realize the performance evaluation of the thermal barrier coating ceramic layer and the metal matrix material, and specifically comprises the following steps:

[0020] Step 1: Give the coil 5 in the eddy current probe 3 four alternating excitation frequencies. Due to the principle of electromagnetic induction, eddy currents will be generated in the metal substrate 11 of the thermal barrier coating system, affecting the impedance of the coil 5 in the eddy current probe 3. The impedance change of the coil 5 is measured to be ;

[0021] Step 2: Impedance Change The theoretical value of is affected by four parameters, namely the distance between the eddy current probe and the upper surface of the metal substrate , the dielectric constant ɛ of the thermal barrier coating ceramic layer, the electrical conductivity σ of the metal substrate, and the magnetic permeability μ of the metal substrate are expressed as formula (2).

[0022] in: is the angular excitation frequency of the eddy current probe, is the magnetic permeability of vacuum, is the spatial frequency of the magnetic field, is the reflection coefficient, It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ The coil coefficient when It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ Coil coefficient at ;

[0023] Using four different excitation frequencies, four different impedance changes of the coil were measured experimentally. , and the theoretical values ​​of the four corresponding impedance changes of the coil are calculated by formula (2) ;

[0024] Step 3: Based on the experimental measurement values ​​of the four different impedance changes of the coil and the four corresponding theoretical values ​​of impedance changes, the four parameters are inverted using the nonlinear least squares method. , the objective function of the nonlinear least squares method is in: is the calculated coil i The theoretical value of the impedance change is The coil is measured experimentally. i The experimental measurement value of the impedance change value, .

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] 1) The probe and nondestructive testing method of the present invention effectively eliminate the detection error of several microns caused by the difficulty in accurately controlling the mechanical contact state between the detection device and the coating surface and the uncontrollable roughness of the coating surface. The entire measurement process is completely measured by optical and electrical technology, avoiding the error caused by mechanical measurement. Mechanical errors include the following factors: During the measurement process, the contact force between the probe and the coating will cause the micro-convex body on the coating surface to deform at the micron level. This micron-level deformation is uncontrollable and cannot be measured, and will eventually introduce coating thickness measurement errors; During the measurement process, the contact force between the probe and the coating will also cause a small deformation of the packaging structure under the probe, which is also uncontrollable and cannot be measured, and will eventually introduce coating thickness measurement errors; In addition, even if the coating is smooth in the macroscopic state, its surface is rough and uneven at the microscopic scale. What actually contacts the probe is the micro-convex body on the coating surface, and the height difference of the micro-convex body is often in the micron level, which will cause the distance relative to the coating to change at the micron level during the movement of the probe, and eventually lead to errors in the thickness measurement results. The overall measurement accuracy of the method of the present invention can reach ±1μm, realizing high-precision coating thickness measurement, which is suitable for industrial detection scenarios requiring high precision.

[0027] 2) The probe and non-destructive testing of the present invention innovatively solve the error problem caused by inconsistent detection positions due to the non-coaxiality of the eddy current probe and the laser ranging probe. By designing a detection probe with the same coaxial laser source, the present invention realizes the precise coordination of the eddy current probe and the laser ranging probe, ensuring that the two detection technologies act on the same position, thereby greatly improving the accuracy and consistency of the detection results.

[0028] 3) The present invention uses non-contact, non-destructive technology to accurately measure the thickness of the thermal barrier coating system and evaluate the safety of material performance degradation, avoiding the damage to the coating structure that may be caused by traditional contact detection, ensuring the integrity of the coating under the premise of high precision. Due to its non-contact, non-destructive detection method, it is particularly suitable for coating systems with long-term durable service, such as coating detection of high-temperature structures such as aircraft engines and gas turbines. At the same time, this method is also applicable to similar metal-based film-based systems, especially systems with an oxide layer on the surface and the oxide layer is difficult to distinguish from the air layer.

[0029] 4) The present invention organically combines optical and electrical measurement technologies, making the advantages of optical and electrical measurement technologies complementary in the detection range. It not only retains the advantages of high precision and high sensitivity of the eddy current detection method under the condition of short-distance small lift-off detection, but also highlights the advantages of high directionality and stability of laser ranging technology, which can be detected at a longer distance. Laser has high directionality and stability, and can still maintain measurement accuracy even in the face of small fluctuations and complex structures on the surface of thermal barrier coatings. This makes optical ranging technology particularly suitable for detecting the thickness of thermal barrier coating ceramic layers. The eddy current probe is sensitive to the total lift-off size above the conductive substrate material (the distance from the probe to the upper surface of the conductive substrate), and the measurement accuracy reaches 1μm. Compared with conventional thermal barrier coating detection probes, the combination of these two optical and electrical technologies can effectively avoid mechanical measurement errors caused by uncontrollable factors such as the mechanical contact state between the probe and the coating surface and surface roughness, so that the overall measurement accuracy of this method can reach 1μm, ensuring accurate and reliable thickness measurement of the thermal barrier coating system.

[0030] 5) The probe of the present invention adopts liquid crystal smart materials, and cleverly utilizes the photoelectric control characteristics of the liquid crystal smart materials to control the two measurement modes of the laser ranging probe, giving the present invention a response speed and non-contact control capability, avoiding the mechanical error caused by moving the eddy current probe to switch the two measurement modes of the laser ranging probe.

[0031] 6) The probe fixture housing is made of flexible material and the lower circumferential crescent cut design allows the probe to fit the surface of the thermal barrier coating system with arcs and variable curvatures, making the lower part of the probe more flexible and suitable for surface detection needs with arcs, variable curvatures and complex shapes. Traditional non-destructive testing devices often find it difficult to fully fit the target surface when facing complex curved surfaces, resulting in data errors or signal loss during the measurement process, reducing the detection accuracy. The circumferential crescent cut design adopted by the present invention effectively solves this problem.

[0032] 7) Laser ranging adopts the principle of coaxial laser ranging, which solves the problem of large size and inability to focus for close-range ranging of the laser ranging system based on the principle of triangulation ranging. It can realize close-range measurement, and makes the height difference of the coaxial placement of the laser ranging probe and the eddy current probe smaller. The size of the entire probe is small, which is suitable for complex industrial inspection scenarios, such as turbine blades or the outer wall of the pipeline group and other difficult-to-reach locations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the thermal barrier coating nondestructive testing probe and thermal barrier coating system of the present invention.

[0034] Figure 2 It is a schematic diagram of the fixing device of the probe assembly detection part.

[0035] Figure 3 Schematic diagram of eddy current probe.

[0036] Figure 4 Schematic diagram of the structure of liquid crystal smart material dimming film.

[0037] Figure 5 It is a schematic diagram of the size and cross-section of the thermal barrier coating nondestructive testing probe and the thermal barrier coating system of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0039] 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. Exemplary embodiments according to the present application will be described in more detail below with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein.

[0040] like Figure 1As shown, the present embodiment is a nondestructive detection probe for thermal barrier coatings using eddy current-laser-liquid crystal smart materials, including a laser ranging probe 1, a probe assembly detection component fixing device 2 and an eddy current probe 3. Before use, the components are installed in the order shown in the figure, that is, the laser ranging probe 1 is inserted into the laser ranging probe sleeve 8, and the eddy current probe 3 is installed under the detection device partition 7.

[0041] like Figure 2 As shown, it is a schematic diagram of the fixing device of the probe combination detection part, including a detection device partition 7, a laser ranging probe sleeve 8 and a fixing device shell 9; the laser ranging probe 1 and the eddy current probe 3 are placed on the upper and lower parts of the detection device partition 7 respectively, and the laser ranging probe sleeve 8 is used to fix the laser ranging probe 1. The diameter of the laser ranging probe 1 is slightly larger than that of the laser ranging probe sleeve 8, and the two are fixed by interference fit.

[0042] like Figure 3 The figure shows a schematic diagram of an eddy current probe, which includes a transparent sheet 4, a coil 5 and a liquid crystal smart material dimming film 6. The coil 5 is a spiral coil tightly wound with a 1mm diameter enameled wire. The center of the coil is not wound with a wire, and is attached to the center of the transparent sheet 4. The center of the transparent sheet 4 has a hole, and the liquid crystal smart material dimming film 6 is attached to the transparent sheet 4. The center of the coil 5 is not wound with a wire, and the center of the transparent sheet 4 has a hole, so that the laser beam emitted by the laser ranging probe 1 can pass through. During detection, an alternating current is passed through the coil 5, and after the detection signal is stable, the next position is detected.

[0043] like Figure 4 , which is a schematic diagram of the structure of the liquid crystal smart material dimming film. The liquid crystal smart material dimming film 6 has a "sandwich" structure, which consists of two electrodes with a thin conductive layer of ITO (indium tin oxide) film coated on the surface, a high molecular polymer matrix located between the electrodes, and an electrically driven liquid crystal, namely, PSLC material, in the high molecular polymer matrix.

[0044] like Figure 5 The figure is a schematic cross-sectional diagram of the dimensions of the thermal barrier coating nondestructive testing probe and the thermal barrier coating system of the present invention, which is intended to more clearly explain the relationship between the dimensions mentioned above in the embodiment. Figure 5 The following parameters are highlighted:

[0045] : The distance between the eddy current probe 3 and the upper surface of the metal substrate 11.

[0046] : The distance between the laser ranging probe 1 and the upper surface of the thermal barrier coating ceramic layer 10.

[0047] : The height difference between the laser ranging probe 1 and the eddy current probe 3.

[0048] : The thickness of the thermal barrier coating ceramic layer is given by the formula get.

[0049] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 The detection steps of the eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing method are described as follows:

[0050] 1) System installation and calibration: Fix the probe of the present invention above the thermal barrier coating system through the support system to ensure that the probe is stably aligned with the detection area. After the installation is completed, perform preliminary calibration to ensure that the distance between the eddy current probe 3 and the surface of the thermal barrier coating ceramic layer to be detected is appropriate. Considering that the refractive index of the laser is different in different detection environments, the focal length of the laser ranging probe 1 needs to be adjusted to adapt to different detection environments.

[0051] 2) Performance evaluation of thermal barrier coating ceramic layer and metal substrate material: When evaluating and measuring the performance of thermal barrier coating ceramic layer 10 and metal substrate 11, four different alternating excitation frequencies are given to the eddy current probe. Due to the principle of electromagnetic induction, eddy currents are generated in the metal substrate 11, affecting the impedance of the coil 5 in the eddy current probe 3. The impedance change of the coil is measured to be , The theoretical value is affected by four parameters (the distance between the eddy current probe and the upper surface of the metal substrate , the dielectric constant ɛ of the thermal barrier coating ceramic layer, the electrical conductivity σ of the metal substrate, and the magnetic permeability μ of the metal substrate), which can be expressed as formula (2): in: is the angular excitation frequency of the eddy current probe, is the magnetic permeability of vacuum, is the spatial frequency of the magnetic field, is the reflection coefficient, It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ The coil coefficient when It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ Coil coefficient at ;

[0052] Using four different excitation frequencies, the experimental measurement values ​​of the four impedance changes of the coil were measured. , and the theoretical values ​​of the four corresponding impedance changes of the coil are calculated by formula (2) , and the above four parameters are obtained by inverting using the nonlinear least squares method.

[0053] 3) Thermal barrier coating ceramic layer thickness assessment: The distance between the eddy current probe 3 placed on the lower side of the detection device interlayer 7 is detected by the eddy current probe and the upper surface of the metal substrate 11 At this time, the liquid crystal smart material dimming film 6 is not powered, and the liquid crystal smart material dimming film 6 is in a transparent state. The laser emitted by the laser ranging probe 1 placed on the upper side of the detection device interlayer 7 can pass through the liquid crystal smart material dimming film 6 and be reflected on the upper surface of the thermal barrier coating ceramic layer 10. The laser ranging probe 1 detects the distance between the laser ranging probe 1 and the upper surface of the thermal barrier coating ceramic layer 10. After the readings are stable, the liquid crystal smart material dimming film 6 is powered on, and the liquid crystal smart material dimming film 6 is in an opaque state. The laser emitted by the laser ranging probe 1 placed on the upper side of the detection device interlayer 7 cannot penetrate the liquid crystal smart material dimming film 6, and is reflected on the upper surface of the liquid crystal smart material dimming film 6. The laser ranging probe 1 detects the height difference between the eddy current probe 3 and the laser ranging probe 1. . Calculate the thickness of the thermal barrier coating ceramic layer of the thermal barrier coating system The measurement results are: After the readings stabilize, the probe moves as a whole to detect the next position.

[0054] The present invention organically cooperates the optical and electrical measurement methods. The eddy current detection method has high precision and high sensitivity in the close-range and small lift-off detection state. As the detection distance increases, the precision and sensitivity of the eddy current detection method decrease. Therefore, when the eddy current detection method is used to detect the workpiece, the probe needs to be close to the workpiece; the laser ranging technology benefits from the high directionality and stability of the laser and can be detected at a position far from the surface. By placing the laser ranging probe 1 and the eddy current probe 3 coaxially up and down, the eddy current probe can be placed non-contact but close to the surface of the coating to be measured, giving full play to its high-precision detection advantage. At the same time, the laser ranging probe adopts the coaxial laser ranging principle, so that it can still accurately measure at a distance of 5mm, effectively solving the problem that the traditional optical measurement method of the laser needs to be fully focused at a certain distance (generally beyond 5mm). This makes the height difference of the coaxial placement of the laser ranging probe 1 and the eddy current probe 3 small, and the size of the entire probe is compact. The compact probe design makes it more flexible in a narrow detection environment, and can be measured in scenes with limited space. It is particularly suitable for complex industrial detection scenes, such as turbine blades or the outer wall of a pipeline group and other difficult-to-reach locations.

Claims

1. An eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe, comprising a laser ranging probe (1), an eddy current probe (3) and a probe assembly detection component fixing device (2), characterized in that: The eddy current probe (3) comprises a transparent thin plate (4), a coil (5) and a liquid crystal smart material dimming film (6); the coil (5) is arranged at the center of the lower surface of the transparent thin plate (4); and the liquid crystal smart material dimming film (6) is attached to the lower surface of the transparent thin plate (4); the probe assembly detection component fixing device (2) comprises a detection device partition (7), a laser ranging probe sleeve (8) and a fixing device housing (9); the laser ranging probe (1) and the eddy current probe (3) are coaxially placed at the upper and lower parts of the detection device partition (7), respectively; the laser ranging probe (1) and the eddy current probe (3) are coaxially placed at the upper and lower parts of the detection device partition (7), respectively; The head sleeve (8) is used to fix the laser ranging probe (1); the laser ranging probe (1) is placed in the laser ranging probe sleeve (8) and fixed to the laser ranging probe sleeve (8) by interference fit; the eddy current probe (3), the detection device interlayer (7) and the laser ranging probe sleeve (8) are all placed in the fixing device housing (9); in order to prevent the eddy current probe (3) from blocking the laser beam emitted by the laser ranging probe (1) and ensure that the laser beam optical path completely passes through the eddy current probe (3), the center of the coil (5) is not wound with a wire and the center of the transparent thin plate (4) is opened.

2. The eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe according to claim 1, characterized in that: The liquid crystal smart material dimming film (6) is a sandwich structure, consisting of two electrodes with ITO thin films on their surfaces, a high molecular polymer matrix located between the electrodes, and an electrically driven liquid crystal in the high molecular polymer matrix. The orientation of the electrically driven liquid crystal small molecules in the liquid crystal smart material dimming film (6) is changed by applying an electric field, thereby achieving switching between light transmission and light reflection states.

3. The eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe according to claim 1, characterized in that: The fixture housing (9) is made of a flexible material, and a circumferential crescent-shaped cutout is designed at the point of contact with the thermal barrier coating so as to stably fit the thermal barrier coating system with an arc and variable curvature. The fixture housing (9) provides stable support for the entire probe.

4. The eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe according to claim 1, characterized in that: The laser distance measuring probe (1) is cylindrical, has an outer diameter of 8 mm, and a measurement accuracy of ±0.55 μm.

5. The eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe according to claim 1, characterized in that: The outer diameter of the coil (5) of the eddy current probe (3) is 4 mm, and the inner diameter is 1 mm. The measurement accuracy of the eddy current probe (3) is ±1 μm.

6. The eddy current-laser-liquid crystal smart material collaborative thermal barrier coating nondestructive testing probe according to claim 1, characterized in that: The transparent thin plate (4) has a thickness of 3-5 mm and is made of aluminosilicate glass.

7. The nondestructive testing method of a thermal barrier coating nondestructive testing probe using eddy current-laser-liquid crystal smart materials as described in any one of claims 1 to 6, characterized in that: It is possible to evaluate the thickness of the ceramic layer of thermal barrier coating, which specifically includes the following steps: Step 1: Fixing a probe above a thermal barrier coating system but not contacting the thermal barrier coating system, wherein the thermal barrier coating system comprises a metal substrate (11) and a thermal barrier coating ceramic layer (10) on the surface of the metal substrate; Step 2: The distance between the eddy current probe (3) and the upper surface of the metal substrate (11) is detected by the eddy current probe (3) placed on the lower side of the detection device partition (7). ; Step 3: The liquid crystal smart material dimming film (6) is not powered, and the liquid crystal smart material dimming film (6) is in a transparent state; the laser emitted by the laser ranging probe (1) passes through the liquid crystal smart material dimming film (6) and is reflected on the upper surface of the thermal barrier coating ceramic layer (10), and the laser ranging probe (1) detects the distance between the laser ranging probe (1) and the upper surface of the thermal barrier coating ceramic layer (10). ; Step 4: Power is supplied to the liquid crystal smart material dimming film (6), and the liquid crystal smart material dimming film (6) becomes opaque. The laser emitted by the laser ranging probe (1) cannot pass through the liquid crystal smart material dimming film (6), and is reflected on the upper surface of the liquid crystal smart material dimming film (6). The laser ranging probe (1) detects the height difference between the eddy current probe (3) and the laser ranging probe (1). ; Step 5: Based on the measured distance between the laser ranging probe (1) and the upper surface of the thermal barrier coating ceramic layer (10), , the height difference between the eddy current probe (3) and the laser ranging probe (1) , the distance between the eddy current probe (3) and the upper surface of the metal substrate (11) According to formula (1), the thickness of the thermal barrier coating ceramic layer (10) of the thermal barrier coating system is calculated as follows: The measurement results; After the readings stabilize, the probe moves as a whole to detect the next position.

8. The nondestructive testing method according to claim 7, characterized in that: It can realize the performance evaluation of thermal barrier coating ceramic layer and metal matrix material, which specifically includes the following steps: Step 1: Give the coil (5) in the eddy current probe (3) four alternating excitation frequencies. Due to the principle of electromagnetic induction, eddy currents will be generated in the metal substrate (11) of the thermal barrier coating system, affecting the impedance of the coil (5) in the eddy current probe (3). The impedance change of the coil (5) is measured to be ; Step 2: Impedance Change The theoretical value of is affected by four parameters, namely the distance between the eddy current probe and the upper surface of the metal substrate , the dielectric constant ɛ of the thermal barrier coating ceramic layer, the electrical conductivity σ of the metal substrate, and the magnetic permeability μ of the metal substrate are expressed as formula (2); in: is the angular excitation frequency of the eddy current probe, is the magnetic permeability of vacuum, is the spatial frequency of the magnetic field, is the reflection coefficient, It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ The coil coefficient when It is in the magnetic field m In the order mode, the spatial frequency of the magnetic field is υ Coil coefficient at ; Using four different excitation frequencies, four different impedance changes of the coil were measured experimentally. , and the theoretical values ​​of the four corresponding impedance changes of the coil are calculated by formula (2) ; Step 3: Based on the experimental measurement values ​​of the four different impedance changes of the coil and the four corresponding theoretical values ​​of impedance changes, the four parameters are inverted using the nonlinear least squares method. , the objective function of the nonlinear least squares method is in: is the calculated coil i The theoretical value of the impedance change is The coil is measured experimentally. i The experimental measurement value of the impedance change value, .

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