Method for measuring surface temperature of thermal barrier coating in ultra-high temperature environment
By using XRD analysis and exponential models, the challenge of measuring the internal temperature of thermal barrier coatings has been solved, achieving high-precision non-destructive measurement. This method is applicable to temperature assessment of aero-engines and gas turbines, and provides a new approach for performance evaluation and life prediction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEAT UNIV OF SCI & TECH
- Filing Date
- 2026-03-17
- Publication Date
- 2026-04-17
AI Technical Summary
Existing technologies struggle to accurately measure the internal and interface temperatures of thermal barrier coatings without damaging their structure, especially in yttrium-stabilized zirconia coatings. The diffusion behavior of the stabilizer yttrium oxide leads to changes in phase structure, affecting thermal insulation and mechanical properties. There is a lack of systematic concentration-temperature models and high-precision non-destructive analysis methods.
An XRD analysis combined with multiple scans and averaging calculations was used to establish a stabilizer concentration-temperature relationship model. The coating temperature was accurately calculated using an exponential model. A mathematical model was constructed using phase diagram data of the zirconium oxide-yttrium oxide system to invert the coating temperature.
It achieves high-precision, non-destructive measurement of the internal temperature of thermal barrier coatings in ultra-high temperature environments, applicable to temperature assessment of aero-engines and gas turbines, and provides a new means for performance evaluation and life prediction.
Smart Images
Figure CN121877930A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of surface temperature measurement technology for thermal barrier coatings in ultra-high temperature environments. More specifically, this invention relates to a method for measuring the surface temperature of thermal barrier coatings in ultra-high temperature environments. Background Technology
[0002] Thermal barrier coatings (TBCs) serve as the core protective layer for critical high-temperature hot-end components such as aero-engines and gas turbines. By isolating the metal substrate from the direct attack of high-temperature combustion gases, they significantly improve the service temperature and reliability of these components (MRS Bulletin 37 (2012) 891–898). Their core function—thermal insulation performance—is directly related to the service life, structural integrity, and operational safety of the components (International Materials Reviews 58 (2013) 315–348). However, accurate measurement of the internal and interface temperatures of the coating is crucial for assessing its service condition and predicting its lifespan (International Journal of Applied Ceramic Technology 2.5 (2005):414-421). Traditional temperature monitoring methods, such as embedded thermocouples or non-contact infrared thermometry, have significant limitations when applied to TBCs: the invasive installation of thermocouples can damage the coating structure and introduce stress concentration points (Journal of Colloid and Interface Science 680 (2025): 1042-1052); infrared thermometry is easily affected by ambient thermal radiation, flue gas interference, and changes in the emissivity of the coating surface, and both methods are difficult to penetrate the coating to obtain the true temperature distribution information inside and at the interface (Infrared Physics & Technology 80 (2017): 120-130).
[0003] Currently, the most widely used thermal barrier coating material system is yttria-stabilized zirconia (YSZ) (Science 296 (2002) 280–284). During long-term high-temperature service, the stabilizer yttria (Y2O3) undergoes significant diffusion behavior, and its concentration distribution evolves with temperature gradient and time (Ceramics International 48 (2022) 31652–31660). This diffusion process is directly related to the phase structure stability of YSZ: with changes in Y2O3 concentration, the coating material may undergo a degradation transformation from a metastable tetragonal phase (t') to a stable cubic phase (c) and a harmful monoclinic phase (m), thereby deteriorating its thermal insulation and mechanical properties (Acta materialia 69 (2014):397-406). This key phenomenon reveals an important physical correlation: by accurately analyzing the Y2O3 concentration distribution of the heat-treated YSZ coating, and based on the phase composition and Y2O3 concentration correspondence established by the phase diagram of the YSZ system, the actual heat treatment temperature of the coating can theoretically be deduced in reverse (i.e., a "concentration-temperature" mapping relationship is established), thus providing a potential, non-invasive measurement approach for the inversion of the internal temperature field of TBCs.
[0004] While this principle is quite attractive, its practical application still faces significant challenges. Currently, there is a lack of a systematic, universal, and fully validated quantitative model for "Y₂O₃ concentration-temperature," which requires comprehensive consideration of the coupled effects of multiple factors such as temperature, time, initial concentration, and microstructure. Simultaneously, there is a lack of mature and reliable technologies capable of high-precision, high-resolution, non-destructive or minimal-destructive quantitative analysis of Y₂O₃ concentration within coatings (especially in subsurface regions). These deficiencies in key technologies and theoretical models constitute the main obstacles to accurately inverting the internal temperature of thermal barrier coatings using stabilizer diffusion behavior, severely restricting the promotion and application of this technology in engineering practice. Summary of the Invention
[0005] This invention further optimizes the measurement method, including: adding multiple scans and average value calculation in XRD analysis to improve the reliability of stabilizer concentration measurement; when establishing the concentration-temperature relationship model, a comparative analysis of linear model, quadratic polynomial model and exponential model is introduced, and error calculation proves that the exponential model has significantly higher accuracy in ultra-high temperature environment (average error is less than 0.5%, while the error of other models is greater than 2%).
[0006] To achieve these and other advantages according to the present invention, a method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions is provided, comprising the following steps; Step 1: Obtain micro-area samples from the ceramic layer on the surface of the thermal barrier coating, perform cleaning pretreatment, and then perform heat treatment on the samples; Step 2: The crystal structure of the sample is determined using X-ray powder diffraction, and crystal structure analysis is performed using Search-Match. Step 3: Based on the diffraction peak positions of the crystal structure characteristics, identify the crystal structure with a higher concentration of stabilizer, and calculate the concentration of stabilizer in the sample; Step 4: Determine the relationship between stabilizer concentration and temperature based on the phase diagram data of the obtained coating material system; Step 5: Based on the data from Steps 3 and 4, establish a stabilizer concentration-temperature relationship model through mathematical fitting or thermodynamic calculations; Step 6: Substitute the measured stabilizer concentration of the sample into the stabilizer concentration-temperature relationship model to calculate the temperature at the corresponding location of the thermal barrier coating.
[0007] Preferably, in step one, the thermal barrier coating material is yttrium-stabilized zirconium oxide, and the thermal barrier coating is prepared by a sol-spray pyrolysis process to create a nano-fully stabilized tetragonal phase thermal barrier coating material. The atmospheric plasma spray coating of the thermal barrier coating material is subjected to ultra-high temperature heat treatment at a temperature greater than 1200°C, during which the stabilizer yttrium oxide in the thermal barrier coating undergoes thermal diffusion, and the concentration of yttrium oxide varies at different heat treatment temperatures.
[0008] Preferably, in step one, the specific method for heat-treating the sample includes: placing the sample in a high-temperature furnace, placing it directly below a thermocouple, raising the temperature from room temperature to the target temperature at a heating rate of 2℃ / min, and holding it at the target temperature for a certain period of time to ensure that the thermal barrier coating Y2O3 stabilizer diffuses, resulting in a phase transition, that is, ensuring that obvious c-phase (cubic phase) diffraction peaks are observed in XRD detection; wherein, the target temperature is 1300℃~1600℃, and the corresponding holding time is 2h~100h.
[0009] Preferably, in step one, the thermal barrier coating is a ceramic layer with a pure tetragonal phase structure.
[0010] Preferably, in step one, after the thermal barrier coating undergoes ultra-high temperature treatment, the stabilizer diffuses and other phase structures different from the initial state appear, including cubic yttrium oxide-stabilized zirconium oxide with a high concentration of stabilizer, the concentration range of which is 8~18 mol.
[0011] Preferably, in step two, the specific method for determining the crystal structure of the sample using X-ray powder diffraction includes: a first scan range of 2θ = 10°~90°, a step size of 0.25°, and a maximum high-voltage power of 3 kW to determine whether there is an m-phase (monoclinic phase); a second scan range of 2θ = 72°~76°, a step size of 0.01°, to determine whether there is a c-phase (cubic phase); to improve the accuracy of crystal structure analysis, each sample undergoes at least 3 XRD scans, and the average value of the diffraction peak positions is used for calculation to reduce random errors; Crystal structure analysis was performed using Search-Match software. The background of the test sample was removed, and then the crystal structure and phase content of the thermal barrier coating were analyzed and calculated. The cubic phase content in the cubic crystal structure is not less than 20%.
[0012] Preferably, in step three, the formula for calculating the concentration of stabilizer Y2O3 in the sample is: c [ YO 1.5 ]=77059 a 2 -76316 a +18877 in, a The lattice constant of the cubic phase of Y₂O₃; Preferably, in step four, the phase diagram data includes the known system phase region distribution, phase transition temperature, and concentration boundary of the thermal barrier coating material system.
[0013] Preferably, in step five, the stabilizer concentration-temperature relationship model is a polynomial fitting model or an exponential model.
[0014] Preferably, when the stabilizer concentration-temperature relationship model is an exponential model, its fitting equation is: T = -645.297676·e 6.339764C + 3032.213604 Where T is temperature, and C is... c Concentration of phase stabilizer Y2O3.
[0015] This invention offers at least the following advantages: By employing high-temperature offline measurement and high-precision XRD crystal structure analysis, the present invention calculates the stabilizer concentration and, combined with phase diagram data of the zirconium oxide-yttrium oxide system, constructs a mathematical model to accurately calculate the temperature experienced by the coating. This invention possesses the advantages of universality and offline high-temperature measurement, making it suitable for temperature assessment of thermal barrier coatings in high-temperature components such as aero-engines and gas turbines. It can be widely applied in aerospace, energy, and other fields, providing a new technical means for performance evaluation and lifetime prediction of thermal barrier coatings.
[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description
[0017] Figure 1 The XRD phase diagram of the YSZ coating subjected to high-temperature heat treatment in Example 1; Figure 2 for Figure 1 Enlarged view within the range of 2θ = 72°~76°; Figure 3 Example 1: Y2O3 concentration distribution of the YSZ coating after high-temperature heat treatment; Figure 4 The binary phase diagram is ZrO2-Y2O3; Figure 5 The XRD phase diagram of the YSZ coating after thermal cycling in Example 1; Figure 6 for Figure 5 Enlarged view within the range of 2θ = 72°~76°. Detailed Implementation
[0018] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.
[0019] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1 A method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions includes the following steps; Step 1: Taking the fully stable tetragonal YSZ thermal barrier coating prepared from spherical thin-walled hollow shell powder as an example, the initial state of the YSZ coating YO 1.5 Micro-area samples with a concentration of 8.1 mol% were obtained from the ceramic layer on the surface of the YSZ thermal barrier coating. After cleaning and pretreatment, the YSZ thermal barrier coating samples were heat-treated at 1300℃, 1400℃, and 1600℃. The samples heat-treated in the high-temperature furnace were placed directly below a thermocouple, and the temperature was increased from room temperature to the target temperature at a rate of 2℃ / min. The samples were then held at 1300℃, 1400℃, and 1600℃ for 100h, 20h, and 2h, respectively, to ensure the diffusion of the Y2O3 stabilizer in the YSZ thermal barrier coating, leading to a phase transition, and to ensure the observation of obvious c-phase diffraction peaks in XRD analysis. Figure 1 and Figure 2 As shown; Step 2: X-ray powder diffraction was used to determine the crystal structure of the sample, and Search-Match analysis was performed. Specifically, this included: testing the YSZ thermal barrier coating at least twice, with the following main parameters: range scan 2θ = 10°~90°, step size 0.25°, maximum high-voltage generation power 3 kW, to determine the presence of the m-phase (monoclinic phase); secondly, range scan 2θ = 72°~76°, step size 0.01°, to determine the presence of the c-phase (cubic phase). (See [link to relevant documentation]). Figure 5 and Figure 6 ; Step 3: Based on the diffraction peak positions characteristic of the crystal structure, identify the crystal structure corresponding to a higher concentration of stabilizer, and then utilize... c [ YO 1.5 ]=77059 a 2 -76316 a +18877 (of which, a The concentration data of Y2O3 stabilizer after high-temperature heat treatment of YSZ thermal barrier coating were obtained by calculating the formula (for c-phase lattice constant). Step 4: Obtain the ZrO2-Y2O3 binary phase diagram of the coating material system (e.g.) Figure 4 As shown in the figure, the relationship between stabilizer concentration and temperature was determined, and Table 1 was obtained: Table 1. Information on Y2O3 concentration and phase diagram temperature of YSZ coating under high-temperature heat treatment Step 5: Based on the data from Steps 3 and 4, establish a stabilizer concentration-temperature relationship model through mathematical fitting: T = -645.297676·e 6.339764C + 3032.213604 Where T is temperature, and C is... c Concentration of phase stabilizer Y2O3.
[0020] Step 6: Substitute the measured stabilizer concentration of the sample into the exponential model to calculate the temperature. The result shows that the error between the calculated value and the phase diagram is less than 0.5%, which verifies the high accuracy of the model.
[0021] Comparative Example 1 The difference between this comparative example and Example 1 is that the stabilizer concentration-temperature relationship model established in step five of this comparative example is a linear model obtained by least squares fitting: T = 1250°C + 1200°C Where T is temperature, and C is... c Concentration of phase stabilizer Y2O3.
[0022] The methods and parameters for the remaining steps in this comparative example are the same as those in Example 1.
[0023] Comparative Example 2 The difference between this comparative example and Example 1 is that the stabilizer concentration-temperature relationship model established in step five of this comparative example is a quadratic polynomial model: T = 8000C 2 - 2000C + 1500 Where T is temperature, and C is... c Concentration of phase stabilizer Y2O3.
[0024] The methods and parameters for the remaining steps in this comparative example are the same as those in Example 1.
[0025] Use the data in Table 1 to perform fitting error analysis (based on temperature estimation from the phase diagram): Table 2 Mean Absolute Error and Maximum Error of Different Models The results show that the exponential model used in Example 1 has a significantly lower error than other models, therefore the exponential model was selected as the final relational model.
[0026] Model comparison and validation: To further demonstrate the inventiveness of the exponential model, the same thermal barrier coating sample (YO) was used. 1.5 Temperatures were calculated using linear, quadratic polynomial, and exponential models for concentrations ranging from 8 to 18 mol%, and compared with actual heat treatment temperatures.
[0027] The results show that in the ultra-high temperature range (1300-1600℃), the predicted temperature of the exponential model consistently deviates from the actual temperature by less than 1%, while the deviation of the linear model reaches 5%~10%, and the deviation of the quadratic polynomial model is 2-4%. This confirms the unique advantages of the exponential model in complex phase transition environments.
[0028] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.
[0029] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.
Claims
1. A method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions, characterized in that, Includes the following steps; Step 1: Obtain micro-area samples from the ceramic layer on the surface of the thermal barrier coating, perform cleaning pretreatment, and then perform heat treatment on the samples; Step 2: The crystal structure of the sample is determined using X-ray powder diffraction, and crystal structure analysis is performed using Search-Match. Step 3: Based on the diffraction peak positions of the crystal structure characteristics, identify the crystal structure with a higher concentration of stabilizer, and calculate the concentration of stabilizer in the sample; Step 4: Determine the relationship between stabilizer concentration and temperature based on the phase diagram data of the obtained coating material system; Step 5: Based on the data from Steps 3 and 4, establish a stabilizer concentration-temperature relationship model through mathematical fitting or thermodynamic calculations; Step 6: Substitute the measured stabilizer concentration of the sample into the stabilizer concentration-temperature relationship model to calculate the temperature at the corresponding location of the thermal barrier coating.
2. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step one, the thermal barrier coating material is yttrium-stabilized zirconium oxide. The thermal barrier coating is prepared by a sol-spray pyrolysis process to create a nano-fully stabilized tetragonal phase thermal barrier coating material. The atmospheric plasma spray coating of the thermal barrier coating material is subjected to ultra-high temperature heat treatment at more than 1200°C. The stabilizer yttrium oxide in the thermal barrier coating undergoes thermal diffusion, and the concentration of yttrium oxide is different at different heat treatment temperatures.
3. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step one, the specific method for heat-treating the sample includes: placing the sample in a high-temperature furnace, directly below a thermocouple, raising the temperature from room temperature to the target temperature at a rate of 2℃ / min, and holding it at the target temperature for a certain period of time to ensure that the thermal barrier coating Y2O3 stabilizer diffuses, resulting in a phase transition, that is, ensuring that obvious cubic phase diffraction peaks are observed in XRD detection; wherein, the target temperature is 1300℃~1600℃, and the corresponding holding time is 2h~100h.
4. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step one, the thermal barrier coating is a ceramic layer with a pure tetragonal phase structure.
5. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step one, after the thermal barrier coating is treated at ultra-high temperature, the stabilizer diffuses and other phase structures different from the initial state appear, including cubic yttrium oxide stabilized zirconium oxide with a high concentration of stabilizer, the concentration range of which is 8~18 mol.
6. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step two, the specific method for determining the crystal structure of the sample using X-ray powder diffraction includes: a first scan range of 2θ = 10°~90°, a step size of 0.25°, and a maximum high-voltage power of 3 kW to determine whether a monoclinic phase exists; a second scan range of 2θ = 72°~76°, a step size of 0.01°, to determine whether a cubic phase exists; each sample undergoes at least three XRD scans, and the average value of the diffraction peak positions is used for calculation; Crystal structure analysis was performed using Search-Match software. The background of the test sample was removed, and then the crystal structure and phase content of the thermal barrier coating were analyzed and calculated. The cubic phase content in the cubic crystal structure is not less than 20%.
7. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step three, the formula for calculating the concentration of stabilizer Y2O3 in the sample is: c [ YO 1.5 ]=77059 a 2 -76316 a +18877 in, a is the lattice constant of the cubic phase of Y₂O₃.
8. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step four, the phase diagram data includes the known system phase region distribution, phase transition temperature, and concentration boundary of the thermal barrier coating material system.
9. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 1, characterized in that, In step five, the stabilizer concentration-temperature relationship model is a polynomial fitting model or an exponential model.
10. The method for measuring the surface temperature of a thermal barrier coating under ultra-high temperature conditions as described in claim 6, characterized in that, When the stabilizer concentration-temperature relationship model is an exponential model, its fitting equation is: T = -645.297676 · e 6.339764C + 3032.213604 Where T is the temperature and C is the concentration of the cubic phase stabilizer Y2O3.