An in-situ test method for characterizing the thermal diffusivity of coatings

Abstract

This invention relates to an in-situ testing method for characterizing the thermal diffusion performance of coatings, belonging to the field of surface engineering technology. It solves the problems of long testing time and high cost associated with the flash method for testing the thermal diffusion performance of coatings. The testing method includes: preparing a coating on a substrate surface to obtain a coating sample, and cleaning the surface; placing the coating sample in a closed operating insulated chamber with a constant temperature of 25°C; determining whether and how the coating sample is connected to the heat source, depending on the type of heat source; placing a continuous infrared thermal imaging recorder in the closed operating insulated chamber; turning on the heat source, setting the heating temperature or total heat output according to the type of heat source, and recording infrared thermal imaging data at a specified frequency; analyzing the point value data of the center point of the infrared thermal imaging heat source to determine the thermal equilibrium temperature time range; analyzing the infrared thermal imaging image data to obtain the time point value at which the coating sample reaches thermal diffusion equilibrium; and using the thermal diffusion equilibrium time of the coating sample to measure the thermal diffusion performance.

Description

Technical Field

[0001] This invention relates to the field of surface engineering technology, and in particular to an in-situ test method for characterizing the thermal diffusion properties of coatings. Background Technology

[0002] With the development of aerospace technology, products are flying at increasingly higher speeds, and during high-speed flight, they face a thermo-mechanical coupling environment caused by aerodynamic heating. Localized rapid heating in specific parts of the product leads to concentrated thermal stress and deformation, affecting the overall shape and structure of the product and severely limiting the scope of structural design.

[0003] To address the problem of localized thermal stress concentration, an effective method is to prepare a thermally conductive coating inside the product structure to rapidly dissipate heat and disperse the concentrated heat. However, since the coating needs to be tightly bonded to the main load-bearing structure, directly measuring its thermal diffusivity in situ becomes impractical. Existing methods for characterizing thermal diffusivity typically employ the flash method to test thermally conductive test specimens. This method involves expensive equipment, high costs per measurement, and discrepancies between the test specimens and the actual parts, leading to low accuracy, long testing times, and high costs. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a test method for in-situ characterizing the thermal diffusion performance of coatings, at least to solve one of the following problems of the existing method for testing the thermal diffusion performance of coatings by using the flash method to test thermally conductive test pieces: 1. Low test accuracy and long test time; 2. High test cost.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides an in-situ testing method for characterizing the thermal diffusivity of a coating, comprising the following steps:

[0007] S1: Prepare a coating on the substrate surface to obtain a coated sample, and clean the upper and lower surfaces of the coated sample.

[0008] S2: Place the coating sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25°C to eliminate errors caused by changes in ambient temperature;

[0009] S3: Determine whether the coating sample is connected to the heat source and how it is connected, depending on the type of heat source;

[0010] S4: Place a continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function;

[0011] S5: Turn on the heat source, set the heating temperature or total heat according to the type of heat source, and record infrared thermal imaging image data and point value data at a specified frequency;

[0012] S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, form a fitting curve, and determine the thermal equilibrium temperature and time range according to the principle of thermal diffusion equilibrium determination.

[0013] S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value when the coated sample reaches the thermal diffusion equilibrium state.

[0014] S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

[0015] Furthermore, the surface cleanliness of the coated sample is ≤10μg / cm2.

[0016] Furthermore, in step S3, the heat source is a constant-temperature rapid heating semiconductor platform or a resistance heating device. The heat source and the coating sample need to be connected, and the gap created by the connection between the heat source and the coating sample is filled with thermally conductive silicone grease.

[0017] Furthermore, in step S3, the heat source is a laser instantaneous heating device, and it is not necessary to connect the heat source and the coating sample.

[0018] Furthermore, the thermal conductivity of the thermal grease is ≥12W / m·K.

[0019] Furthermore, in step S4, the imaging distance of the continuous infrared thermal imaging recorder is ≥0.1m, the thermal sensitivity is ≤0.05K, and the measurement temperature range is room temperature to 873K.

[0020] Further, in step S5, the heat source is a constant-temperature rapid heating semiconductor platform or a resistance heating device, and the set heating temperature satisfies: the lowest glass transition temperature among all the constituent materials of the coating sample < the set heating temperature T ≤ the lowest melting point value among all the constituent materials of the coating sample.

[0021] Further, in step S5, the heat source is a laser instantaneous heating device, and the total heat satisfies:

[0022] Q = mcΔT + 1000J

[0023] Wherein, ΔT = T - 25℃;

[0024] Q represents the total heat, in J;

[0025] m is the mass of the coated sample, in kg;

[0026] c represents the specific heat capacity of the constituent material corresponding to the minimum melting point value in the coating sample, in J / kg·℃;

[0027] T represents the set heating temperature, in °C;

[0028] ΔT represents the temperature change, in °C.

[0029] Furthermore, in step S5, the specified frequency is 1 frame per second to 1 frame per 5 seconds.

[0030] Furthermore, in step S6, the principle for determining thermal diffusion equilibrium is: when the slope of the curve is <0.05, the coating sample reaches a state of thermal diffusion equilibrium.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] 1. This invention connects the coating sample to a heat source and combines an infrared thermal imaging device with the heat source. The accuracy is adjusted by changing the number of frames captured per second by the infrared thermal imaging device. The thermal equilibrium temperature time range of the coating sample is quickly determined using the point value data from the center point of the heat source in the infrared thermal imaging. By comparing and analyzing the infrared thermal imaging data, the time point at which the coating sample reaches thermal diffusion equilibrium is quickly determined. The thermal equilibrium temperature time range and the time point at which the coating sample reaches thermal diffusion equilibrium are cross-validated to improve test accuracy. Finally, the thermal diffusion equilibrium time is used as the standard to characterize the thermal diffusion effect of the coating sample under the same conditions. This method can test the thermal conductivity without damaging the coating structure. The testing method for the thermal diffusion performance of coatings can be performed on the surfaces of products with different structures, making its application universal.

[0033] 2. The method of the present invention can characterize the thermal conductivity of the coating in a flat plate sample, including but not limited to flat plate test pieces. It can be used to characterize different complex structures and has the advantages of low cost, speed, accurate and effective measurement results, direct in-situ characterization and strong scalability.

[0034] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0035] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0036] Figure 1 This is a schematic diagram of the thermal diffusion of the coating in Embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic diagram of the thermal diffusion of the coating in Embodiment 2 of the present invention;

[0038] Figure 3 This is a schematic diagram of the thermal diffusion of the coating in Comparative Example 1 of the present invention;

[0039] Figure 4 The figures shown are fitting curves for Embodiment 1, Embodiment 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0040] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0041] This invention provides an in-situ testing method for characterizing the thermal diffusivity of a coating, comprising the following steps:

[0042] S1: Prepare a coating on the substrate surface to obtain a coated sample, and clean the upper and lower surfaces of the coated sample.

[0043] S2: Place the coating sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25°C to eliminate errors caused by changes in ambient temperature;

[0044] S3: Determine whether the coating sample is connected to the heat source and how it is connected, depending on the type of heat source;

[0045] S4: Place a continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function;

[0046] S5: Turn on the heat source, set the heating temperature or total heat according to the type of heat source, and record infrared thermal imaging image data and point value data at a specified frequency;

[0047] S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, form a fitting curve, and determine the thermal equilibrium temperature and time range according to the principle of thermal diffusion equilibrium determination.

[0048] S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value when the coated sample reaches the thermal diffusion equilibrium state.

[0049] S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

[0050] Specifically, in step S1, the cleaning method involves wiping with acetone or other organic solvents and then blowing clean with compressed air. Both the upper and lower surfaces of the coating sample must be thoroughly cleaned. The surface cleanliness of the part is then tested using a cleanliness tester, and the surface cleanliness of the coating sample must meet the requirement of ≤10 μg / cm². 2 .

[0051] Specifically, in step S2, the coating sample is placed in a closed operating insulated chamber, and the temperature inside the chamber is adjusted to a constant 25°C to eliminate the influence of ambient temperature changes on the coating sample.

[0052] Specifically, in step S3, the heat source can be one of a constant-temperature rapid heating semiconductor platform, a laser instantaneous heating device, or a resistance heating device. The laser instantaneous heating device does not require the coating sample to be connected to the heating device. The gaps between the coating sample and the heat source can be filled with thermally conductive silicone grease, wherein the thermal conductivity of the thermally conductive silicone grease needs to be ≥12W / m·K. Preferably, the thermally conductive silicone grease is filled with liquid gold or liquid silver. It should be noted that resistance heating is not instantaneous heating, and the existence of pores between the sample and the heat source will affect the test accuracy. Thermally conductive silicone grease can fill these pores.

[0053] Specifically, in step S4, a continuous infrared thermal imaging recorder is placed in a closed operating insulated box, connected to a multimedia device, and the recording function is turned on; wherein, the continuous infrared thermal imaging recorder used needs to meet the following requirements: imaging distance ≥ 0.1m, thermal sensitivity ≤ 0.05K, and measurement temperature range of room temperature to 873K.

[0054] Specifically, in step S5, the heat source is turned on. If the heat source is a constant-temperature rapid heating semiconductor platform or a resistance heating device, then the lowest glass transition temperature among all the constituent materials of the coating sample < the set heating temperature T ≤ the lowest melting point value among all the constituent materials of the coating sample; if the heat source is a laser instantaneous heating device, then:

[0055] The total heat Q = mcΔT + 1000J, ΔT = T - 25℃;

[0056] Where Q is the total heat, in J;

[0057] m is the mass of the coated sample, in kg;

[0058] c represents the specific heat capacity of the constituent material corresponding to the minimum melting point of the coating sample, in J / kg·℃.

[0059] ΔT represents the temperature change, in °C.

[0060] The specified frequency is 1 frame per second to 1 frame per 5 seconds. It should be noted that when the temperature rise rate at the center of the heat source exceeds 1℃ / s, the specified frequency is 1 frame per second. When the temperature rise rate at the center is below 1℃ / s, the specified frequency can be freely set within the range of 1 frame per second to 1 frame per 5 seconds. If the specified frequency is higher than 1 frame per 5 seconds, the accuracy of the infrared thermal imaging image data and point value data will be poor, and the temperature change point cannot be clearly observed.

[0061] Specifically, in step S6, the point value data of the infrared thermal imaging heat source center point is analyzed, the temperature and time of the heat source center point are fitted to form a fitting curve, and the thermal equilibrium temperature time range is determined according to the thermal diffusion balance determination principle. It should be noted that the heat source center point refers to the point with the highest temperature in the infrared image. This point represents the pixel point with the highest temperature in the monitoring area. The point value data of the infrared thermal imaging heat source center point is analyzed, the temperature and time of the heat source center point are fitted to form a fitting curve, and then the thermal equilibrium temperature time range is determined according to the thermal diffusion balance determination principle. The thermal diffusion balance determination principle is: based on the curve slope, the temperature and time point of the thermal diffusion balance of the coating sample are considered to be in thermal diffusion balance when the curve slope is close to 0. This invention determines that when the curve slope < 0.05, the coating sample has reached thermal diffusion balance. The temperature and time point corresponding to the fitted curve when the curve slope < 0.05 are recorded, that is, the thermal equilibrium temperature time range of the coating sample is determined.

[0062] Specifically, in step S7, the infrared thermal imaging image data is compared and analyzed to record the heat distribution on the surface of the coated sample and obtain the time point value at which the coated sample reaches the thermal diffusion equilibrium state.

[0063] Then, the thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-checked to determine the thermal diffusion equilibrium state time point value of the coating sample obtained in step S7. If the thermal equilibrium temperature time range of the coating sample obtained in step S6 is within the range, then the point value obtained in step S7 is the time point value at which the coating sample reaches the thermal diffusion equilibrium state. This time point value can measure the thermal diffusion performance of the coating sample.

[0064] The existing method for testing the thermal diffusion performance of coatings involves testing thermally conductive test pieces using the flash method during the coating preparation process, under the same parameter conditions. This method is expensive, has a high cost per measurement, and the test pieces do not match the actual parts, thus failing to provide true thermal diffusion data of the coating prepared on the substrate surface. In fact, it is also impossible to obtain the actual thermal diffusion performance of the coating itself. This invention connects a coating sample to a heat source and combines an infrared thermal imaging device with the heat source. The accuracy is adjusted by changing the number of frames captured per second by the infrared thermal imaging device. The thermal equilibrium temperature time range of the coating sample is quickly determined using point values ​​from the center point of the heat source in the infrared thermal imaging. By comparing and analyzing the infrared thermal imaging data, the time point at which the coating sample reaches thermal diffusion equilibrium is quickly determined. The thermal equilibrium temperature time range and the time point at which the coating sample reaches thermal diffusion equilibrium are cross-validated to improve testing accuracy. Finally, the thermal diffusion equilibrium time is used as a standard to characterize the thermal diffusion effect of the coating sample under the same conditions. This method can test the thermal conductivity without damaging the coating structure. The testing method for coating thermal diffusion performance can be performed on the surfaces of products with different structures, making its application universal.

[0065] Example 1

[0066] This embodiment provides an in-situ testing method for characterizing the thermal diffusivity of a coating, comprising the following steps:

[0067] S1: A coating (containing Cu powder, Ag powder, and NiCoCrAlY powder) was prepared on the surface of a GH4099 substrate to obtain a coated sample. The upper and lower surfaces of the coated sample were cleaned with acetone, and the surface cleanliness of the coated sample was 5 μg / cm². 2 ;

[0068] S2: Place the coating sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25°C to eliminate errors caused by changes in ambient temperature;

[0069] S3: Determine whether and how the coating sample is connected to the heat source, depending on the type of heat source:

[0070] This embodiment uses a constant temperature rapid heating semiconductor platform. The coated sample needs to be connected to the heat source, and the gaps are filled with thermally conductive silicone grease (Shin-Etsu FW-1600, thermal conductivity 16W / m·K).

[0071] S4: Place the Fluke Ti480U continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function;

[0072] The Fluke Ti480U infrared thermal imager meets the requirements of imaging distance ≥0.1m, thermal sensitivity ≤0.05K, and measurement temperature range of room temperature to 873K.

[0073] S5: Turn on the heat source. Since the heat source is a constant temperature rapid heating semiconductor platform, the heating temperature is set to 200℃. Record infrared thermal imaging image data and point value data at a specified frequency of 1 frame per second.

[0074] S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, and form a fitting curve, such as... Figure 4 As shown in the figure, when the slope of the curve is less than 0.05, the coating sample reaches the thermal diffusion equilibrium state. The temperature and time points corresponding to the fitted curve when the curve efficiency is less than 0.05 are recorded, that is, the thermal equilibrium temperature time range of the coating sample is determined to be 40-65s.

[0075] S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value of the coated sample reaching the thermal diffusion equilibrium state as 60s. Figure 1 The image shown is an infrared thermal image of the coating sample in this embodiment, illustrating the thermal diffusion of the coating.

[0076] S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

[0077] The coated sample in this embodiment reached thermal diffusion equilibrium in 60 seconds.

[0078] Example 2

[0079] This embodiment provides an in-situ testing method for characterizing the thermal diffusivity of a coating, comprising the following steps:

[0080] S1: A coating (containing Cu powder, Ag powder, and NiCoCrAlY powder) was prepared on the surface of a GH4099 substrate to obtain a coated sample. The upper and lower surfaces of the coated sample were cleaned with acetone, and the surface cleanliness of the coated sample was 8 μg / cm². 2 ;

[0081] S2: Place the coating sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25°C to eliminate errors caused by changes in ambient temperature;

[0082] S3: Determine whether and how the coating sample is connected to the heat source, depending on the type of heat source:

[0083] This embodiment uses a resistance heating device, which requires the coated sample to be connected to the heat source, and the gaps are filled with thermally conductive silicone grease (Ausbon A8 liquid metal thermal paste, thermal conductivity 128W / m·K);

[0084] S4: Place the Fluke Ti480U continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function;

[0085] The Fluke Ti480U infrared thermal imager meets the requirements of imaging distance ≥0.1m, thermal sensitivity ≤0.05K, and measurement temperature range of room temperature to 873K.

[0086] S5: Turn on the heat source. Since the heat source is a resistance heating device, set the heating temperature to 200℃ and record infrared thermal imaging image data and point value data at a specified frequency of 1 frame every 3 seconds.

[0087] S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, and form a fitting curve, such as... Figure 4 As shown in the figure, when the slope of the curve is less than 0.05, the coating sample reaches the thermal diffusion equilibrium state. The temperature and time points corresponding to the fitted curve when the curve efficiency is less than 0.05 are recorded, that is, the thermal equilibrium temperature time range of the coating sample is determined to be 40-60s.

[0088] S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value of the coated sample reaching the thermal diffusion equilibrium state as 50s. Figure 2 The image shown is an infrared thermal image of the coating sample in this embodiment, illustrating the thermal diffusion of the coating.

[0089] S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

[0090] The coated sample in this embodiment reached thermal diffusion equilibrium in 50 seconds.

[0091] Comparative Example 1

[0092] This comparative example provides an in-situ test method for characterizing the thermal diffusivity of a coating, including the following steps:

[0093] S1: No coating is prepared on the substrate; the surface is directly cleaned with acetone. GH4099 is used as the substrate material, and the surface cleanliness is 5 μg / cm². 2 ;

[0094] S2: Place the matrix sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25℃;

[0095] S3: Connect the substrate sample to the heat source, use a constant temperature rapid heating semiconductor platform, and fill the gap between the coating sample and the heat source with thermally conductive silicone grease (Shin-Etsu FW-1600, thermal conductivity 16W / m·K);

[0096] S4: Place the Fluke Ti480U continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function;

[0097] The Fluke Ti480U infrared thermal imager meets the requirements of imaging distance ≥0.1m, thermal sensitivity ≤0.05K, and measurement temperature range of room temperature to 873K.

[0098] S5: Turn on the heat source. Since the heat source is a constant temperature rapid heating semiconductor platform, the heating temperature is set to 200℃. Record infrared thermal imaging image data and point value data at a specified frequency of 1 frame per second.

[0099] S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, and form a fitting curve, as shown in Figure 4. It can be seen from the figure that when the slope of the curve is <0.05, the coating sample reaches the thermal diffusion equilibrium state. Record the temperature and time points corresponding to the fitting curve when the curve efficiency is <0.05, that is, determine the thermal equilibrium temperature and time range of the coating sample as 130-160s.

[0100] S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value of the coated sample reaching the thermal diffusion equilibrium state as 150s. Figure 3 The image shown is an infrared thermal image of the comparative coating sample, illustrating the thermal diffusion of the coating.

[0101] S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

[0102] The coating sample in this comparative example reached thermal diffusion equilibrium at 150 s.

[0103] Comparative Example 2

[0104] This comparative example uses the flash method to test the thermal conductivity of the thermally conductive test piece to test the thermal diffusivity of the coating sample in Example 1:

[0105] The thermally conductive test piece used is 13.7 mm thick and 1 mm in diameter.

[0106] The measured thermal conductivity of the coating sample in this comparative example was 77.89 μm. 2 / s.

[0107] The difference between Example 1 and Comparative Example 1 lies in whether the substrate surface contains a thermally diffusing coating. That is, the comparison between the original substrate material and the substrate material with the thermally conductive coating shows that the time to reach thermal diffusion equilibrium is significantly different between Example 1 and Comparative Example 1. This indicates that the method of the present invention can effectively show the heat change trend of substrates with different thermal conductivity after contact with heat. The thermal diffusion performance of the coating sample can be measured by the thermal diffusion equilibrium time of the coating sample. The method of the present invention is accurate and feasible.

[0108] Compared with Comparative Example 2, Example 1 does not require the preparation of a thermally conductive test piece, and the testing cost is much lower than that of the flash method, while the testing time is shorter.

[0109] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A test method for in-situ characterizing the thermal diffusivity of a coating, characterized in that, Includes the following steps: S1: Prepare a coating on the substrate surface to obtain a coated sample, and clean the upper and lower surfaces of the coated sample. S2: Place the coating sample in a closed operating insulated chamber and adjust the temperature inside the chamber to a constant 25°C to eliminate errors caused by changes in ambient temperature; S3: Determine whether the coating sample is connected to the heat source and how it is connected, depending on the type of heat source; S4: Place a continuous infrared thermal imaging recorder in a closed operating insulated box, connect it to a multimedia device, and turn on the recording function; S5: Turn on the heat source, set the heating temperature or total heat according to the type of heat source, and record infrared thermal imaging image data and point value data at a specified frequency; S6: Analyze the point value data of the center point of the infrared thermal imaging heat source, fit the temperature and time of the center point of the heat source, form a fitting curve, and determine the thermal equilibrium temperature and time range according to the principle of thermal diffusion equilibrium determination. S7: Compare and analyze the infrared thermal imaging data, record the heat distribution on the surface of the coated sample, and obtain the time point value when the coated sample reaches the thermal diffusion equilibrium state. S8: The thermal equilibrium temperature time range in step S6 and the thermal diffusion equilibrium state time point value in step S7 are cross-verified to obtain the thermal diffusion equilibrium time of the coating sample. The thermal diffusion performance of the coating sample is measured based on the thermal diffusion equilibrium time of the coating sample.

2. The test method according to claim 1, characterized in that, The surface cleanliness of the coated sample is ≤10 μg / cm². 2 .

3. The test method according to claim 1, characterized in that, In step S3, the heat source is a constant temperature rapid heating semiconductor platform or a resistance heating device. The heat source and the coating sample need to be connected, and the gap created by the connection between the heat source and the coating sample is filled with thermally conductive silicone grease.

4. The test method according to claim 1, characterized in that, In step S3, the heat source is a laser instantaneous heating device, and it is not necessary to connect the heat source and the coating sample.

5. The test method according to claim 3, characterized in that, The thermal conductivity of the thermal grease is ≥12W / m·K.

6. The test method according to claim 1, characterized in that, In step S4, the imaging distance of the continuous infrared thermal imaging recorder is ≥0.1m, the thermal sensitivity is ≤0.05K, and the measurement temperature range is room temperature to 873K.

7. The test method according to claim 1, characterized in that, In step S5, the heat source is a constant-temperature rapid heating semiconductor platform or a resistance heating device, and the set heating temperature satisfies the following: the lowest glass transition temperature among all the constituent materials of the coating sample < the set heating temperature T ≤ the lowest melting point value among all the constituent materials of the coating sample.

8. The test method according to claim 7, characterized in that, In step S5, the heat source is a laser instantaneous heating device, and the total heat satisfies: Q = mcΔT + 1000J Wherein, ΔT = T - 25℃; Q represents the total heat, in J; m is the mass of the coated sample, in kg; c represents the specific heat capacity of the constituent material corresponding to the minimum melting point value in the coating sample, in J / kg·℃; T represents the set heating temperature, in °C; ΔT represents the temperature change, in °C.

9. The test method according to claim 8, characterized in that, In step S5, the specified frequency is 1 frame per second to 1 frame per 5 seconds.

10. The test method according to claim 1, characterized in that, In step S6, the principle for determining thermal diffusion equilibrium is: when the slope of the curve is <0.05, the coating sample reaches a state of thermal diffusion equilibrium.

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