An in-situ measurement method for thermal conductivity of coating materials based on transient heat transfer and its application

Abstract

The present invention discloses an in-situ measurement method and application of thermal conductivity of coating materials based on transient heat transfer, and the field of thermal conductivity measurement of coating materials includes the following steps: S1, building a measurement platform; S11, drilling radial measurement holes in the workpiece to be measured, and arranging thermocouples; S12, placing the workpiece to be measured in an insulating cylinder, and arranging a heater and a thermal imager; S2, heating the coating material and the workpiece to be measured, and obtaining the temperature of the measuring point during the heating process, and collecting the surface temperature of the coating material at the same time; S3, calculating the thermal conductivity and average thermal conductivity of the coating material that changes with temperature. The present invention adopts the above-mentioned in-situ measurement method and application of thermal conductivity of coating materials based on transient heat transfer, and performs in-situ measurement of the surface temperature of the coating material based on the principle of transient heat transfer, so as to achieve one measurement, and obtain all thermal conductivity information of the coating material within the measurement temperature range, thereby greatly shortening the measurement cycle and reducing the measurement cost.

Description

Technical Field

[0001] The present invention relates to the field of thermal conductivity measurement of coating materials, and in particular to an in-situ thermal conductivity measurement method of coating materials based on transient heat transfer and its application. Background Art

[0002] In order to protect the base material, it is necessary to spray the coating material on the base material. When the coating materials such as thermal barrier coating, wear-resistant coating and anti-corrosion coating are sprayed on the base material, the measurement of the thermal conductivity in the sprayed state is very difficult due to the unevenness of the sprayed coating, the porous structure and the interface effect between the coating and the substrate.

[0003] At present, most of the methods are to peel the coating material off the base material and then use traditional single temperature point measuring instruments such as laser thermal conductivity meters to measure. One measurement can only obtain the thermal conductivity information of a specific temperature point, which has the following defects:

[0004] 1. Representative limitations: One measurement can only obtain the thermal conductivity value at a specific temperature point, which cannot fully reflect the thermal conductivity performance of the material in a wide temperature range;

[0005] 2. Incompleteness: After stripping the coating, the test only reflects the thermal conductivity of the substrate material itself, ignoring the effect of the interface between the coating and the substrate on the thermal conductivity, and it is impossible to carry out in-situ measurement;

[0006] 3. Damage to the substrate: The process of stripping the coating may cause physical or chemical damage to the substrate material, affecting the accuracy of subsequent tests;

[0007] 4. Experimental time-consuming and complexity increases: In order to obtain a complete temperature-dependent thermal conductivity curve, it is necessary to test at multiple temperature points separately, which not only increases the time and cost of the experiment, but also increases the complexity of the operation;

[0008] 5. Difficulty in data integration: Data at different temperature points need to be integrated and analyzed to obtain a complete thermal conductivity-temperature relationship, and this process may introduce additional errors and uncertainties.

[0009] At the same time, during the service life of coating materials, the existence of temperature gradient inside the material often causes cracks to expand inside the coating, which can cause severe peeling of the coating material, thus seriously affecting the protective performance of the coating. The traditional coating material thermal conductivity measurement method cannot simulate the actual service conditions of the coating through in-situ measurement methods, nor can it provide an assessment of the service life. Summary of the invention

[0010] To solve the above problems, the present invention provides an in-situ measurement method and application of thermal conductivity of coating materials based on transient heat transfer. By performing in-situ measurement of the surface temperature of the coating material based on the principle of transient heat transfer, all thermal conductivity information of the coating material within the measurement temperature range can be obtained in one measurement, thereby greatly shortening the measurement cycle and reducing the measurement cost.

[0011] To achieve the above object, the present invention provides an in-situ measurement method of thermal conductivity of a coating material based on transient heat transfer, comprising the following steps:

[0012] S1. Build a measurement platform;

[0013] S11, drilling a plurality of evenly arranged radial measuring holes on the outer side of the workpiece to be measured with the coating material coated on the end, arranging a thermocouple in each radial measuring hole, and connecting the thermocouple and the data acquisition instrument with a signal line;

[0014] S12, placing the workpiece to be tested with the coating material coated on the end in a heat-insulating cylinder, and arranging a heater and a thermal imager aligned with the coating material;

[0015] S2, turn on the thermal imager, data acquisition instrument and heater in sequence, use the heater to heat the coating material and the workpiece to be measured, and use multiple thermocouples to obtain the temperatures of multiple measuring points during the heating process, and use the thermal imager to collect the surface temperature of the coating material;

[0016] S3. Calculate the thermal conductivity and average thermal conductivity of the coating material that changes with temperature based on the temperatures of multiple measuring points and the surface temperature of the coating material.

[0017] Preferably, in step S11, the connecting line between the plurality of radial measuring holes is parallel to the connecting line between the heater and the coating material, the radial measuring holes extend from the end of the workpiece to be measured to the center, and one end of the radial measuring hole extending into the workpiece to be measured coincides with the center of the workpiece to be measured;

[0018] The distance between the radial measuring hole close to one end of the coating material and the end of the workpiece to be measured is equal to 1 / 2 of the distance between two adjacent radial measuring holes.

[0019] Preferably, in step S11, the coating material is a thermal barrier coating, a wear-resistant coating or an anti-corrosion coating.

[0020] Preferably, the thermocouple described in step S11 is a micro thermocouple.

[0021] Preferably, in step S12, the insulation tube is a nanoporous super insulation material, and a heating hole is opened at the end of the insulation tube, and the heating hole is placed between the heater and the coating material, so that the coating material meets the third type of thermal boundary conditions.

[0022] Preferably, in step S2, the heater is flame heating, laser heating or plasma heating, and the heater is heated by continuous heating or thermal shock cycle.

[0023] Preferably, step S3 specifically includes the following steps:

[0024] S31, initialization settings:

[0025] The temperature of the workpiece to be measured at the initial moment is set to room temperature, and the workpiece to be measured is set to be cylindrical. Five radial measuring holes are axially opened on the cylindrical workpiece to be measured. The five radial measuring holes are named measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 respectively. Measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 are distributed in sequence in the direction away from the coating material, and the spacing between adjacent measuring points is Δx;

[0026] S32, through the temperatures at measuring points 1, 2, and 3, estimate the temperature gradient at measuring point 1 based on high-order interpolation

[0027]

[0028] In the formula, T1 is the temperature at the first measuring point; T2 is the temperature at the second measuring point; T3 is the temperature at the third measuring point;

[0029] S33. Calculate the heat flux density q of the coating material s :

[0030]

[0031] Where k is the thermal conductivity of the cylindrical material, in W·m -1 ·K -1 ;

[0032] S34. Calculate the temperature T of the interface between the coating material and the workpiece to be tested int :

[0033]

[0034] S35, assuming the total thickness of the coating material is δ TBC , calculate the average thermal conductivity k of the coating material TBC :

[0035]

[0036] Where, T TBCs is the outer surface temperature of the coating material, which is acquired by a thermal imager; T int is the temperature of the interface between the coating material and the workpiece to be tested;

[0037] S36, based on temperature The thermal conductivity k of the coating material is TBC , calculate the average thermal conductivity T between the set temperature range T1 and T2 TBC_avg :

[0038]

[0039] Wherein, T1 represents the lower limit of the set temperature range; T2 represents the upper limit of the set temperature range.

[0040] Preferably, after step S3, step S4 is further included to verify by numerical experiments:

[0041] The temperature of the coating surface and the temperature of the measuring point of the workpiece to be tested are obtained through numerical simulation. Formula (1)-Formula (5) are used to obtain the calculated value of the average thermal conductivity of the coating material. The calculated value is compared with the standard value, and the effectiveness is verified based on the comparison result.

[0042] The application of the in-situ measurement method of thermal conductivity of coating materials based on transient heat transfer in the prediction of service life of coating materials comprises the following steps:

[0043] The first step is to output the curve of thermal conductivity of coating material changing with the number of cycles and heating temperature;

[0044] The second step is to detect coating material defects based on the change curve: the average thermal conductivity parameters obtained during each thermal cycle are compared with the average thermal conductivity parameters obtained during the first heating. When the average thermal conductivity of the coating material increases or decreases by 10%-15%, it is determined that the coating material has defects;

[0045] The third step is to predict the service life of the coating material based on the number of thermal cycles when defects occur.

[0046] The present invention has the following beneficial effects:

[0047] 1. The in-situ measurement technology is adopted to achieve one-time measurement, which can obtain all the thermal conductivity information of the coating material within the measurement temperature range, thereby greatly shortening the measurement cycle and reducing the measurement cost;

[0048] 2. It can meet the requirements of any intensity of heating and cooling conditions (there is almost no restriction on the choice of heating and cooling methods, and it is particularly suitable for measuring the thermal conductivity of coating materials at a high temperature of 400°C), and can measure the thermal conductivity of coating materials such as thermal barrier coatings, wear-resistant coatings, and anti-corrosion coatings sprayed on workpieces of various shapes (cylindrical structures, or polygonal prism structures such as triangular prisms and quadrangular prisms);

[0049] 3. Through thermal shock cycles (heating and cooling cycles), the evolution of thermal conductivity of coating materials during thermal shock cycles is continuously monitored, so as to monitor the defects inside the coating (such as cracks inside the coating, coating peeling, coating sintering, etc.), so as to evaluate the service life of the coating material under similar service conditions;

[0050] 4. A method for obtaining the thermal conductivity of coating materials through simple algebraic calculations during transient heat transfer, and controlling the measurement error within ±5%.

[0051] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a flow chart of an in-situ measurement method of thermal conductivity of a coating material based on transient heat transfer of the present invention;

[0053] Figure 2 A schematic diagram of the arrangement of a measurement platform according to an embodiment of the present invention;

[0054] Figure 3 A schematic diagram of the structure of a workpiece to be tested according to an embodiment of the present invention;

[0055] Figure 4 It is a comparison diagram of the calculated value and the standard value of the thermal conductivity of the coating material under the condition of single heating and the thermal conductivity of the coating material increases with the increase of temperature as described in the embodiment of the present invention;

[0056] Figure 5 A comparison diagram of the calculated value and the standard value of the thermal conductivity of the coating material under the condition of single heating and the thermal conductivity of the coating material decreasing with increasing temperature according to an embodiment of the present invention;

[0057] Figure 6 It is a comparison chart of the calculated value and the standard value of the thermal conductivity of the coating material under the condition that the thermal conductivity of the coating material increases with the increase of temperature in the thermal shock cycle described in the embodiment of the present invention.

[0058] Among them: 1. Thermal imager; 2. Heater; 3. Coating material; 4. Workpiece to be measured; 5. Insulation tube; 6. Thermocouple; 7. Data acquisition instrument; 8. Radial measuring hole. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0060] It should be noted that the terms "include", "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or devices.

[0061] Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0062] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0063] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] like Figure 1 As shown, a method for in-situ measurement of thermal conductivity of coating materials based on transient heat transfer includes the following steps:

[0065] S1. Build a measurement platform;

[0066] S11, drilling a plurality of evenly arranged radial measuring holes 8 on the outer side of the workpiece 4 to be measured with the coating material 3 on the end, arranging a thermocouple 6 in each radial measuring hole 8, and connecting the thermocouple 6 and the data acquisition instrument 7 with a signal line;

[0067] In this embodiment, the coating material 3 can be sprayed on one end of the workpiece 4 to be measured and the thermal conductivity can be measured by single-side heating, or the coating material 3 can be sprayed on both ends of the workpiece 4 to be measured and the thermal conductivity can be measured by symmetrical heating at both ends.

[0068] In step S11, the connecting line between the plurality of radial measuring holes 8 is parallel to the connecting line between the heater 2 and the coating material 3, the radial measuring holes 8 extend from the end of the workpiece 4 to be measured to the center, and one end of the radial measuring hole 8 extending into the workpiece 4 to be measured coincides with the center of the workpiece 4 to be measured; the distance between the radial measuring hole 8 close to one end of the coating material 3 and the end of the workpiece 4 to be measured is equal to 1 / 2 of the spacing between two adjacent radial measuring holes 8.

[0069] In step S11, the coating material 3 is a thermal barrier coating, a wear-resistant coating or an anti-corrosion coating.

[0070] The thermocouple 6 described in step S11 is a micro thermocouple.

[0071] S12, placing the workpiece 4 to be tested, the end of which is coated with the coating material 3, in the heat-insulating tube 5, and arranging the heater 2 and the thermal imager 1 in alignment with the coating material 3;

[0072] In step S12, the insulation tube 5 is a nanoporous super insulation material, and a heating hole is opened at the end of the insulation tube 5, and the heating hole is placed between the heater 2 and the coating material 3, so that the coating material 3 meets the third type of thermal boundary conditions.

[0073] S2, turn on the thermal imager 1, the data acquisition instrument 7 and the heater 2 in sequence, use the heater 2 to heat the coating material 3 and the workpiece 4 to be measured, and use multiple thermocouples 6 to obtain the temperatures of multiple measuring points during the heating process, and use the thermal imager 1 to collect the surface temperature of the coating material 3;

[0074] In step S2, the heater is flame heating, laser heating or plasma heating, and the heater is heated by continuous heating or thermal shock cycle.

[0075] S3. Calculate the thermal conductivity and average thermal conductivity of the coating material that changes with temperature based on the temperatures of multiple measuring points and the surface temperature of the coating material.

[0076] Step S3 specifically includes the following steps:

[0077] S31, initialization settings:

[0078] The temperature of the workpiece to be measured at the initial moment is set to room temperature, and the workpiece to be measured is set to be cylindrical. Five radial measuring holes are axially opened on the cylindrical workpiece to be measured. The five radial measuring holes are named measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 respectively. Measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 are distributed in sequence in the direction away from the coating material, and the spacing between adjacent measuring points is Δx;

[0079] S32, through the temperatures at measuring points 1, 2, and 3 (measuring points 4 and 5 are used for auxiliary monitoring and do not need to be included in the calculation), estimate the temperature gradient at measuring point 1 based on high-order interpolation

[0080] In the formula, T1 is the temperature at the first measuring point; T2 is the temperature at the second measuring point; T3 is the temperature at the third measuring point;

[0081] S33. Calculate the heat flux density q of the coating material s :

[0082]

[0083] Where k is the thermal conductivity of the cylindrical material, in W·m -1 ·K -1 ;

[0084] Based on the characteristics of heat transfer under normal conditions, the heat flux density of the coating material surface is calculated, which provides a basis for the determination of the thermal conductivity of the coating material.

[0085] S34. Calculate the temperature T of the interface between the coating material and the workpiece to be tested int :

[0086]

[0087] S35, assuming the total thickness of the coating material is δ TBC , calculate the average thermal conductivity k of the coating material TBC :

[0088]

[0089] Where, T TBCs is the outer surface temperature of the coating material, which is acquired by a thermal imager; T int is the temperature of the interface between the coating material and the workpiece to be tested;

[0090] S36, based on temperature The thermal conductivity k of the coating material is TBC , calculate the average thermal conductivity T between the set temperature range T1 and T2 TBC_avg :

[0091]

[0092] Wherein, T1 represents the lower limit of the set temperature range; T2 represents the upper limit of the set temperature range.

[0093] Preferably, after step S3, step S4 is further included to verify by numerical experiments:

[0094] The temperature of the coating surface and the temperature of the measuring point of the workpiece to be tested are obtained through numerical simulation. Formula (1)-Formula (5) are used to obtain the calculated value of the average thermal conductivity of the coating material. The calculated value is compared with the standard value, and the effectiveness is verified based on the comparison result.

[0095] Example

[0096] like Figure 3 As shown, in this embodiment, a cylindrical workpiece to be measured is coated with a coating material at one end as the measurement object, and the cylindrical workpiece to be measured has a length of L = 100 mm, a diameter of D = 10 mm, and is made of 304 stainless steel. The thermal barrier coating is sprayed on one end of the workpiece to be measured by atmospheric plasma spraying, and the thickness of the thermal barrier coating is δ TBC =2mm.

[0097] Five radial measuring holes are axially processed in sequence on one end of the workpiece to be measured close to the thermal barrier coating. The diameter of the radial measuring holes is 1 mm and the depth is 5 mm. The distance between adjacent radial measuring holes is Δx=6 mm. The distance between the first radial measuring hole and the end face of the workpiece to be measured coated with the thermal barrier coating is Δx / 2=3 mm.

[0098] Build as Figure 2 After the measurement platform shown in the figure, the thermal conductivity of the thermal barrier coating is measured by the in-situ measurement method of the coating material thermal conductivity based on transient heat transfer described in the present invention, and numerical simulation is performed to obtain the results as shown in the figure. Figure 4-Figure 6 The calculated values ​​shown (it should be noted that Figure 6 The outer contour of the calculated value in each thermal cycle is the thermal conductivity value of the coating material. ), after comparing with the standard value, it can be seen that the prediction error of the thermal conductivity of the coating material of the present invention is within ± 5%, which verifies the effectiveness of the present invention.

[0099] The application of the in-situ measurement method of thermal conductivity of coating materials based on transient heat transfer in the prediction of service life of coating materials comprises the following steps:

[0100] The first step is to output the curve of thermal conductivity of coating material changing with the number of cycles and heating temperature;

[0101] The second step is to detect coating material defects based on the change curve: the average thermal conductivity parameters obtained during each thermal cycle are compared with the average thermal conductivity parameters obtained during the first heating. When the average thermal conductivity of the coating material increases or decreases by 10%-15%, it is determined that the coating material has defects (such as cracks inside the coating, coating peeling, coating sintering, etc.);

[0102] The third step is to predict the service life of the coating material based on the number of thermal cycles when defects occur.

[0103] Therefore, the present invention adopts the above-mentioned in-situ measurement method and application of thermal conductivity of coating materials based on transient heat transfer. By performing in-situ measurement of the surface temperature of the coating material based on the principle of transient heat transfer, all thermal conductivity information of the coating material within the measurement temperature range can be obtained in one measurement, thereby greatly shortening the measurement cycle and reducing the measurement cost.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An in-situ measurement method for thermal conductivity of coating materials based on transient heat transfer, characterized in that: The following steps are involved: S1. Build a measurement platform; S11, drilling a plurality of evenly arranged radial measuring holes on the outer side of the workpiece to be measured with the coating material coated on the end, arranging a thermocouple in each radial measuring hole, and connecting the thermocouple and the data acquisition instrument with a signal line; S12, placing the workpiece to be tested with the coating material coated on the end in a heat-insulating cylinder, and arranging a heater and a thermal imager aligned with the coating material; S2, turn on the thermal imager, data acquisition instrument and heater in sequence, use the heater to heat the coating material and the workpiece to be measured, and use multiple thermocouples to obtain the temperatures of multiple measuring points during the heating process, and use the thermal imager to collect the surface temperature of the coating material; S3, calculating the thermal conductivity and average thermal conductivity of the coating material as it changes with temperature based on the temperatures of multiple measuring points and the surface temperature of the coating material; Step S3 specifically includes the following steps: S31, initialization settings: The temperature of the workpiece to be measured at the initial moment is set to room temperature, and the workpiece to be measured is set to be cylindrical. Five radial measuring holes are axially opened on the cylindrical workpiece to be measured. The five radial measuring holes are named measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 respectively. Measuring point 1, measuring point 2, measuring point 3, measuring point 4 and measuring point 5 are distributed in sequence in the direction away from the coating material, and the spacing between adjacent measuring points is Δx; S32, through the temperatures at measuring points 1, 2, and 3, estimate the temperature gradient at measuring point 1 based on high-order interpolation In the formula, T1 is the temperature at the first measuring point; T2 is the temperature at the second measuring point; T3 is the temperature at the third measuring point; S33. Calculate the heat flux density q of the coating material s : Where k is the thermal conductivity of the cylindrical material, in W·m -1 ·K -1 ; S34. Calculate the temperature T of the interface between the coating material and the workpiece to be tested int : S35, assuming the total thickness of the coating material is δ TBC , calculate the thermal conductivity k of the coating material TBC : Where, T TBCs is the outer surface temperature of the coating material, which is acquired by a thermal imager; T int is the temperature of the interface between the coating material and the workpiece to be tested; S36, based on temperature The thermal conductivity k of the coating material is TBC , calculate the set temperature range T min ~T max The average thermal conductivity T TBC_avg : Where, T min Indicates the lower limit of the set temperature range; T max Indicates the upper limit of the set temperature range.

2. The in-situ measurement method of thermal conductivity of coating materials based on transient heat transfer according to claim 1 is characterized in that: In step S11, the connecting line between the plurality of radial measuring holes is parallel to the connecting line between the heater and the coating material, the radial measuring holes extend from the end of the workpiece to be measured to the center, and one end of the radial measuring hole extending into the workpiece to be measured coincides with the center of the workpiece to be measured; The distance between the radial measuring hole close to one end of the coating material and the end of the workpiece to be measured is equal to 1 / 2 of the distance between two adjacent radial measuring holes.

3. The in-situ measurement method of thermal conductivity of coating materials based on transient heat transfer according to claim 2 is characterized in that: In step S11, the coating material is a thermal barrier coating, a wear-resistant coating or an anti-corrosion coating.

4. The method for in-situ measurement of thermal conductivity of coating materials based on transient heat transfer according to claim 3 is characterized in that: The thermocouple described in step S11 is a micro thermocouple.

5. The method for in-situ measurement of thermal conductivity of coating materials based on transient heat transfer according to claim 4, characterized in that: In step S12, the insulation tube is a nanoporous super insulation material, and a heating hole is opened at the end of the insulation tube. The heating hole is placed between the heater and the coating material, so that the coating material meets the third type of thermal boundary conditions.

6. The method for in-situ measurement of thermal conductivity of coating materials based on transient heat transfer according to claim 5, characterized in that: In step S2, the heater is flame heating, laser heating or plasma heating, and the heater is heated by continuous heating or thermal shock cycle.

7. The method for in-situ measurement of thermal conductivity of coating materials based on transient heat transfer according to claim 1, characterized in that: After step S3, the method further includes step S4, a numerical experiment verification: The temperature of the coating surface and the temperature of the measuring point of the workpiece to be tested are obtained through numerical simulation. Formula (1)-Formula (5) are used to obtain the calculated value of the average thermal conductivity of the coating material. The calculated value is compared with the standard value, and the effectiveness is verified based on the comparison result.

8. The application of the in-situ measurement method of thermal conductivity of coating materials based on transient heat transfer as described in claim 7 in predicting the service life of coating materials is characterized by: The following steps are involved: The first step is to output the curve of thermal conductivity of coating material changing with the number of cycles and heating temperature; The second step is to detect coating material defects based on the change curve: the average thermal conductivity parameters obtained during each thermal cycle are compared with the average thermal conductivity parameters obtained during the first heating. When the average thermal conductivity of the coating material increases or decreases by 10%-15%, it is determined that the coating material has defects; The third step is to predict the service life of the coating material based on the number of thermal cycles when defects occur.

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