CN114199811A - Method and device for characterizing microstructure of ceramic layer of thermal barrier coating of turbine blade - Google Patents
Method and device for characterizing microstructure of ceramic layer of thermal barrier coating of turbine blade Download PDFInfo
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Abstract
The invention provides a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade, which comprises the following steps: obtaining terahertz time-domain spectral signals of at least three groups of coatings; calculating and evaluating the characteristic quantity by carrying out unimodal Gaussian fitting according to the terahertz time-domain spectral signal; and performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the correlation linear relation between the microstructure characteristic of the coating and the evaluation characteristic quantity. By adopting the technical scheme, the terahertz nondestructive testing can be conveniently implemented in an actual service state and a preparation state, the requirements and states of daily detection are more met, the detection precision is improved, and the detection requirements are met.
Description
Technical Field
The invention relates to the technical field of nondestructive testing of turbine blades of aero-engines, in particular to a method for representing microstructure characteristics of a ceramic layer of a thermal barrier coating of a turbine blade by adopting a reflective terahertz signal.
Background
The aircraft engine is the heart of the aircraft and is called the crown of modern industry, and the turbine blade is more known as the bright pearl on the crown. Thermal barrier coating technology is the core key technology which must be adopted for the thermal protection of the turbine blade of the advanced aeroengine at present. The use of the thermal barrier coating can delay the service life of the hot-end component by reducing the surface temperature of the structural material, has higher reliability requirement, and can cause the ablation perforation of the turbine blade or the engine failure once the coating is peeled off due to local quality abnormality.
The uniform coating technology of the thermal barrier coating can directly influence the oxidation resistance, the heat insulation effect, the thermal nonuniformity and the air film cooling effect of the turbine blade, and the overproof defect in the thermal barrier coating directly influences the performance of the coating, thereby seriously reducing the reliability of an engine. The traditional detection method for thermal barrier coatings in the industry is generally sampling damage detection, and the method has the problems of low detection efficiency, one-sided detection result, workpiece damage and the like. For homogeneous, multiphase and multi-interface thermal barrier coatings, no accurate and reliable measuring means exists, objective data relation between a high-performance design scheme and a production process cannot be established, and the optimal coating production process is explored without objective data support; internal microscopic defects such as cracks, delamination, oxidation and the like caused by the influence of multiple factors can obviously influence the service life of the thermal barrier coating and the service reliability of the turbine blade, and the development of an advanced nondestructive detection technology is imminent. At present, there is an urgent need to find a scientific, reasonable, accurate and effective rapid nondestructive testing method to replace the traditional destructive testing technology.
In recent years, ultrasonic detection technology and infrared thermal wave detection technology have been gradually applied to research. Although the ultrasonic detection technology and the infrared thermal wave detection technology have good advantages in defect detection, the couplant required by the ultrasonic detection technology also brings potential pollution influence, and the infrared thermal wave detection technology also has the defect that the resolution cannot reach the precision of the ultrasonic detection technology.
Disclosure of Invention
The invention solves the problem that the measurement precision of the ceramic layer microstructure characteristics of the existing thermal barrier coating of the turbine blade is poor. To solve the above problems, the present invention provides a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade, comprising:
obtaining terahertz time-domain spectral signals of at least three groups of coatings;
carrying out unimodal Gaussian fitting calculation on the terahertz time-domain spectral signals to evaluate the characteristic quantity;
and performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the correlation linear relation between the microstructure characteristic of the coating and the evaluation characteristic quantity.
In the scheme, the detection is performed by obtaining the terahertz time-domain spectral signal, the single-peak Gaussian fitting calculation evaluation characteristic quantity is performed by using the detected terahertz time-domain spectral signal, and the comparison is performed with the coating microstructure characteristic, so that the corresponding relation between the coating microstructure characteristic and the evaluation characteristic quantity can be obtained, and the corresponding coating microstructure characteristic can be obtained according to the evaluation characteristic quantity calculated from the terahertz time-domain spectral signal during actual measurement. The terahertz nondestructive testing is conveniently implemented in an actual service state and a preparation state, the requirements and states of daily testing are more met, the testing precision is improved, and the testing requirements are met.
In an preferable technical solution, the calculating an evaluation token according to the terahertz time-domain spectral signal includes:
after single-peak Gaussian fitting of the first echo and the second echo, the peak height difference value and the half-height width difference value of the first echo and the second echo which have no thickness influence factors are multiplied, so that the influence of the peak height difference value and the half-height width difference value on the thickness can be avoided.
In a preferred technical solution, the calculating and evaluating the characterization quantity by performing the unimodal gaussian fitting according to the terahertz time-domain spectral signal includes:
after single-peak Gaussian fitting of the first echo and the second echo, obtaining a first peak height A1 and a first full width at half maximum FWHM1 of the first echo, and obtaining a second peak height A2 and a second full width at half maximum FWHM2 of the second echo;
after single-peak Gaussian fitting of the first echo and the second echo, obtaining a peak height difference value and a half-height width difference value of the first echo and the second echo, wherein the peak height difference value and the half-height width difference value of the first echo and the second echo are free of thickness influence factors, and the method comprises the following steps: calculating the peak height difference between the first peak height A1 and the second peak height A2, wherein the delta H is A1-A2; calculating the peak height difference delta of the thickness influence factorh，δh(a1-a2)/d, wherein d is the actual thickness parameter value of the sample;
calculating a difference between the first full width at half maximum FWHM1 and the second full width at half maximum FWHM2, Δ FWHM2-FWHM 1; calculating the half-height width difference value delta of eliminating thickness influence factorsF，δF(FWHM2-FWHM1)/d, where d is the actual thickness parameter value of the sample;
the calculation and evaluation of the characteristic quantity by carrying out unimodal Gaussian fitting according to the terahertz time-domain spectral signal comprises the following steps: obtaining an evaluation characterization quantity deltar，δr＝δh*δF。
In a preferred technical scheme, the microstructure characteristics of the coating are measured by a quantitative metallographic method, and the microstructure characteristics of the coating comprise the porosity and/or the content of unmelted particles of the ceramic coating.
The porosity and/or the content of unmelted particles of the ceramic coating are/is measured by a quantitative metallographic method, so that the more accurate porosity and/or content of unmelted particles of the ceramic coating can be obtained, and an accurate comparison object is provided for the evaluation characterization quantity. And in combination with the characterization method, the corresponding relation can be formed by only utilizing the coating microstructure characteristics measured by a quantitative metallographic method, so that terahertz time-domain spectral signals can be obtained by using terahertz nondestructive measurement in different situations in future detection, and further the corresponding coating microstructure characteristics can be obtained.
The thermal barrier coating is a ceramic coating, the ceramic coating is an 8YSZ type thermal barrier coating, and the bottom of the ceramic coating is provided with a substrate and at least one metal bonding layer.
In the preferable technical scheme, the coatings at different positions on the surfaces of the workpieces or test pieces in different batches are measured, the obtained terahertz reflection signals and the linear rules thereof are contrasted and reversely deduced, the microstructure characteristics of the coatings in different batches are represented and evaluated, and the quality and performance characteristics of the coatings are fed back.
The invention provides a method for measuring the microstructure characteristics of a ceramic layer of a thermal barrier coating of a turbine blade,
obtaining terahertz time-domain spectral signals of at least three groups of coatings;
carrying out unimodal Gaussian fitting calculation on the terahertz time-domain spectral signals to evaluate the characteristic quantity;
and performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the correlation linear relation between the microstructure characteristic of the coating and the evaluation characteristic quantity.
The method adopts a nondestructive testing technology, has the non-contact characteristic and non-destructive property of nondestructive testing, and compared with destructive testing, the non-contact mode of nondestructive testing can greatly reduce the testing cost. Meanwhile, the non-destructive property of the nondestructive testing enables the reusability of the product after testing to be greatly improved. In addition, the boundary of the operation of the method, the traditional destructive detection process and the operation steps are complicated, and the final detection result can be obtained only by the steps of preparation, grinding and polishing, observation, analysis and the like. And the advanced terahertz nondestructive testing mode can obtain corresponding data only by placing the tested sample in nondestructive testing system equipment, thereby greatly simplifying the operation steps and improving the operation convenience of the test.
The method has the advantages of high efficiency, high precision and convenience from the technical point of view, can quickly establish the characteristics of a standard process sample and a deviation process sample under a specific process condition, establishes a rule, and is applied to an actual production link. The method simultaneously considers the influence of various microstructure factors on the terahertz signal fitting parameter calculated value, and establishes a corresponding correlation linear relation. The method for qualitatively characterizing the microstructure of the ceramic coating, namely the porosity, the unmelted particles and the sum of the porosity and the unmelted particles provides favorable support for the development of the stability of the technological process.
The invention provides a characterization device for a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade, which comprises the following steps:
the device comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining terahertz time-domain spectral signals of at least three groups of coatings;
the first calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
and the second obtaining module is used for performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the corresponding relation between the microstructure characteristic of the coating and the evaluation characteristic quantity.
The invention provides an application device of a method for characterizing the microstructure characteristics of a ceramic layer of a thermal barrier coating of a turbine blade, which comprises the following steps:
the third obtaining module is used for obtaining a terahertz time-domain spectral signal of the coating;
the second calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
and the conversion module is used for obtaining the microstructure characteristics of the ceramic layer of the thermal barrier coating of the turbine blade by utilizing the evaluation characterization quantity and the corresponding correlation linear relation obtained by utilizing the characterization device.
Drawings
FIG. 1 is a schematic flow chart of a method of characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade according to the present invention;
FIG. 2 is a schematic diagram showing the relationship between the porosity and the evaluation characteristic quantity change rule obtained in example 1 of the method for characterizing the microstructure of the thermal barrier coating ceramic layer of the turbine blade according to the present invention;
FIG. 3 is a schematic diagram showing the correlation between the content of unmelted particles and the change rule of the evaluation characteristic quantity obtained in example 2 of the method for characterizing the microstructure of the thermal barrier coating ceramic layer of the turbine blade according to the invention;
FIG. 4 is a schematic diagram showing the correlation between the sum of porosity and unmelted particle content and the change law of the evaluated characteristic quantity obtained in example 3 of the method for characterizing the microstructure of the thermal barrier coating ceramic layer of the turbine blade according to the invention;
FIG. 5 is a schematic representation of a characterization apparatus for a method of characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade in an embodiment of the present invention;
FIG. 6 is a schematic diagram of an apparatus for use in a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
FIG. 1 is a schematic flow chart of a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade in accordance with an embodiment of the invention, the method comprising:
s101, obtaining terahertz time-domain spectral signals of at least three groups of coatings;
specifically, in order to reflect the influence of different preparation processes on the microstructure characteristics, the atmospheric plasma spraying process can be adopted to respectively prepare the ceramic coatings with different microstructure characteristics under the condition that the production process is met and the condition that the production process is deviated. The ceramic coating may be an 8YSZ ceramic coating having a substrate and at least one metallic bond coat.
The 36 angles of a sample need to be detected 20 times by using a reflection type terahertz nondestructive detection method, and signal data of the same sample at 36 angles and 20 times at each angle are subjected to averaging processing.
Preferably, the coating microstructure characteristics are measured by quantitative metallographic methods and include ceramic coating porosity and/or unmelted particle content. The quantitative metallographic method is characterized in that image software is utilized to select pores and/or unmelted particles meeting requirements, and actual measurement work of the quantitative metallographic method is carried out, wherein the actual measurement work comprises multiple groups of averaging processing operations.
The porosity and/or the content of unmelted particles of the ceramic coating are/is measured by a quantitative metallographic method, so that the more accurate porosity and/or content of unmelted particles of the ceramic coating can be obtained, and an accurate comparison object is provided for the evaluation characterization quantity. And in combination with the characterization method, the corresponding relation can be formed by only utilizing the coating microstructure characteristics measured by a quantitative metallographic method, so that terahertz time-domain spectral signals can be obtained by using terahertz nondestructive testing in different situations in future detection, and further the corresponding coating microstructure characteristics can be obtained.
S103, calculating and evaluating a characteristic quantity by single-peak Gaussian fitting according to the terahertz time-domain spectral signal; the method specifically comprises the following steps:
after single-peak Gaussian fitting of the first echo and the second echo, the peak height difference value and the half-height width difference value of the first echo and the second echo which have no thickness influence factors are multiplied, so that the influence of the peak height difference value and the half-height width difference value on the thickness can be avoided.
More specifically, the steps include:
after single-peak Gaussian fitting of the first echo and the second echo, obtaining a first peak height A1 and a first full width at half maximum FWHM1 of the first echo, and obtaining a second peak height A2 and a second full width at half maximum FWHM2 of the second echo;
after single-peak Gaussian fitting of the first echo and the second echo, calculating the peak height difference between the first peak height A1 and the second peak height A2 by using the peak height difference and the half-height width difference of the first echo and the second echo which have no thickness influence factors, wherein delta H is A1-A2; calculating the peak height difference delta of the thickness influence factorh，δh(a1-a2)/d, wherein d is the actual thickness parameter value of the sample;
calculating a difference between the first full width at half maximum FWHM1 and the second full width at half maximum FWHM2, Δ FWHM2-FWHM 1; calculating the half-height width difference value delta of eliminating thickness influence factorsF，δF(FWHM2-FWHM1)/d, where d is the actual thickness parameter value of the sample;
obtaining an evaluation characterization quantity deltar，δr＝δh*δF。
S105, carrying out linear fitting on the evaluation characteristic quantity and the measured coating microstructure characteristic to obtain the correlation linear relation between the coating microstructure characteristic and the evaluation characteristic quantity.
Measuring coatings at different positions on the surfaces of workpieces and test pieces in different batches, comparing and reversely deducing the obtained terahertz reflection signals and the linear rule thereof, characterizing and evaluating the microstructure characteristics of the coatings in different batches, and further feeding back the quality and performance characteristics of the coatings.
Due to the increase of physical parameters of the coating microstructure, namely porosity, unmelted particle content and the sum of the porosity and the unmelted particle content, the evaluation characterization quantity of the corresponding reflective terahertz signal fitting can be increased, and the porosity and the unmelted particle content show a linear correlation relationship. Therefore, the detection can be performed by obtaining the terahertz time-domain spectral signal, the detected terahertz time-domain spectral signal is used for operation, and the operation is compared with the coating microstructure characteristic, so that the corresponding relation between the coating microstructure characteristic and the evaluation characteristic quantity can be obtained, and the corresponding coating microstructure characteristic can be obtained according to the evaluation characteristic quantity obtained by calculating the terahertz time-domain spectral signal during actual measurement. The terahertz nondestructive testing is convenient to implement in an actual service state and a preparation state, and more approaches to the requirement and state of daily testing, so that the testing requirement is met.
In order to more clearly describe the above characterization method, the following three embodiments are specifically illustrated. Although the reflective terahertz nondestructive testing technology is adopted in the following three embodiments, the present application does not exclude other terahertz nondestructive testing methods, such as transmissive terahertz nondestructive testing.
Example 1-method for the characterization of the porosity of a ceramic layer of a thermal barrier coating by a reflective terahertz signal:
the embodiment is based on a terahertz reflective nondestructive testing mode, takes an 8YSZ type ceramic thermal barrier coating as a sample object, and concretely implements the porosity characterization of the reflective terahertz signal fitting parameter value coating. The specific implementation method comprises the following steps:
step 1: under the condition of production process and deviating production process, the ceramic coating with different microstructure characteristics is prepared by adopting the atmospheric plasma spraying process.
Specifically, the ceramic coating in step 1 is 8YSZ, and the bottom of the ceramic coating is provided with a substrate and at least one metal bonding layer.
Specifically, the microstructure in step 1 is characterized in that the porosity of the ceramic coating is obtained by a quantitative metallographic method, wherein the quantitative metallographic method is realized by selecting pores meeting requirements by using image software and performing actual measurement work of the quantitative metallographic method, and the actual measurement work comprises averaging multiple groups of processing operations and the like.
Step 2: obtaining terahertz time-domain spectral signals of different coatings, selecting a first echo and a second echo to perform unimodal Gaussian fitting, calculating a peak height difference value delta H/d and a full width at half maximum difference value delta FWHM/d of the first echo and the second echo without thickness influence factors, and adopting a difference product to obtain a value as an evaluation characteristic quantity.
Specifically, the reflective terahertz nondestructive testing is performed on 36 angles of a sample, each angle is tested 20 times, and for data processing, signal data of 36 angles of the same sample and 20 times of each angle are averaged. Based on the above, the first and second echo single peak selection and Gaussian fitting process are performed.
Specifically, the calculated value of the fitting parameter of the reflective terahertz signal includes a peak height difference Δ H of two-wave gaussian single-peak fitting, which is a1-a 2; eliminating the peak height difference of the fitting peak of the two-Bouss single peak of the thickness influence factor, namely eliminating the peak height difference value delta of the thickness influence factorh(a1-a2)/d, where d is the actual thickness for the sample; ③ the difference between the full widths at half maximum of the fitting of the two-Bouss singlet, namely FWHM2-FWHM 1; fourthly, the difference of the fitting half-height width of the two-wave Gaussian single peak of the thickness influence factors is eliminated, namely the half-height width difference value delta of the thickness influence factors is eliminatedF(FWHM2-FWHM 1)/d; fifthly, multiplying the microstructure influence signal to obtain an estimated characterization quantity deltar＝((A1-A2)/d)×(FWHM2-FWHM1)/d)。
And step 3: not less than three groups of coatings deltarAnd performing linear fitting on the data to obtain the correlation between the microstructure difference of the coating and the change rule of the evaluation characterization quantity. The linear law is shown in table 1 and fig. 2.
TABLE 1
| Porosity (%) | (ΔA/d)*(ΔFWHM/d) |
| 3.92 | 1.66703 |
| 7.85 | 4.06688 |
| 9.29 | 4.25759 |
Specifically, as the physical parameter (porosity) of the coating microstructure increases, the calculated value delta of the corresponding fitting parameter of the reflective terahertz signalrThe relationship between the two shows a linear relationship.
And 4, step 4: and (3) measuring coatings at different positions on the surfaces of workpieces and test pieces in different batches, comparing the obtained terahertz reflection signals with the linear rule in the step (3) to perform reverse-pushing, characterizing and evaluating the microstructure characteristics, namely the porosity, of the coatings in different batches, and further feeding back the quality and the performance characteristics of the coatings.
Embodiment 2-method for representing content of unmelted particles in ceramic layer of thermal barrier coating by using reflective terahertz signal:
the embodiment is an explanation of specific implementation of representing the content of unmelted particles of the coating by using an 8YSZ type ceramic thermal barrier coating as a sample object based on a terahertz reflection type nondestructive detection mode and performing reflection type terahertz signal fitting parameter value. The specific implementation method comprises the following steps:
step 1: under the condition of production process and deviating production process, the ceramic coating with different microstructure characteristics is prepared by adopting the atmospheric plasma spraying process.
Specifically, the ceramic coating in step 1 is 8YSZ, and the bottom of the ceramic coating is provided with a substrate and at least one metal bonding layer.
Specifically, the microstructure in step 1 is characterized in that the content of unmelted particles of the ceramic coating is obtained by a quantitative metallographic method, wherein the quantitative metallographic method is realized by selecting unmelted particles meeting requirements by using image software and performing actual measurement work of the quantitative metallographic method, and the actual measurement work comprises averaging multiple groups of processing operations and the like.
Step 2: obtaining terahertz time-domain spectral signals of different coatings, selecting a first echo and a second echo to perform unimodal Gaussian fitting, calculating a peak height difference value delta H/d and a full width at half maximum difference value delta FWHM/d of the first echo and the second echo without thickness influence factors, and adopting a difference product to obtain a value as an evaluation characteristic quantity.
Specifically, the reflective terahertz nondestructive testing is performed on 36 angles of a sample, each angle is tested 20 times, and for data processing, signal data is averaged for 36 angles of the same sample and 20 times per angle. Based on the above, the first and second echo single peak selection and Gaussian fitting process are performed.
Specifically, the calculated value of the fitting parameter of the reflective terahertz signal includes a peak height difference Δ H of two-wave gaussian single-peak fitting, which is a1-a 2; eliminating the peak height difference of the fitting peak of the two-Bouss single peak of the thickness influence factor, namely eliminating the peak height difference value delta of the thickness influence factorh(a1-a2)/d, where d is the actual thickness for the sample; ③ the difference between the full widths at half maximum of the fitting of the two-Bouss singlet, namely FWHM2-FWHM 1; fourthly, the difference of the fitting half-height width of the two-wave Gaussian single peak of the thickness influence factors is eliminated, namely the half-height width difference value delta of the thickness influence factors is eliminatedF(FWHM2-FWHM 1)/d; fifthly, multiplying the microstructure influence signal to obtain an estimated characterization quantity deltar＝((A1-A2)/d)×((FWHM2-FWHM1)/d)。
And step 3: not less than three groups of coatings deltarAnd performing linear fitting on the data to obtain the correlation between the microstructure difference of the coating and the change rule of the evaluation characterization quantity. The linear law is shown in table 2 and fig. 3.
TABLE 2
Specifically, with the increase of the physical parameter of the coating microstructure, namely the content of unmelted particles, the calculated value delta of the corresponding fitting parameter of the reflective terahertz signalrThe relationship between the two shows a linear relationship.
And 4, step 4: and (3) measuring coatings at different positions on the surfaces of workpieces and test pieces in different batches, comparing the obtained terahertz reflection signals with the linear rule in the step (3) for reverse-pushing, characterizing and evaluating the microstructure characteristics of the coatings in different batches, namely the content of unmelted particles, and further feeding back the quality and performance characteristics of the coatings.
Example 3-method for the characterization of the porosity and unmelted particles of the ceramic layer of the thermal barrier coating by a reflective terahertz signal:
the embodiment is based on a terahertz reflection type nondestructive testing mode, takes an 8YSZ type ceramic thermal barrier coating as a sample object, and concretely implements the representation of the porosity of the coating and the content of unmelted particles by reflection type terahertz signal fitting parameter values. The specific implementation method comprises the following steps:
step 1: under the condition of production process and deviating production process, the ceramic coating with different microstructure characteristics is prepared by adopting the atmospheric plasma spraying process.
Specifically, the ceramic coating in step 1 is 8YSZ, and the bottom of the ceramic coating is provided with a substrate and at least one metal bonding layer.
Specifically, the microstructure in step 1 is characterized by the sum of the porosity of the ceramic coating and the content of unmelted particles, and is obtained by a quantitative metallographic method, wherein the quantitative metallographic method is realized by selecting the pores and the unmelted particles meeting the requirements by using image software, and performing actual measurement work of the quantitative metallographic method, and the actual measurement work comprises averaging multiple groups of processing operations and the like.
Step 2: obtaining terahertz time-domain spectral signals of different coatings, selecting a first echo and a second echo to perform unimodal Gaussian fitting, calculating a peak height difference value delta H/d and a full width at half maximum difference value delta FWHM/d of the first echo and the second echo without thickness influence factors, and adopting a difference product to obtain a value as an evaluation characteristic quantity.
Specifically, the reflective terahertz nondestructive testing is implemented for 36 angles of a sample, and each angle is tested for 20 times; for the data processing, the signal data is averaged for 36 angles of the same sample, 20 times per angle. Based on the above, the first and second echo single peak selection and Gaussian fitting process are performed.
Specifically, the calculated value of the fitting parameter of the reflective terahertz signal includes a peak height difference Δ H of two-wave gaussian single-peak fitting, which is a1-a 2; ② elimination of the difference of the fitted peak heights of the two-Bouss single peak of the thickness influencing factors, i.e.Peak height difference delta eliminating thickness influencing factorsh(a1-a2)/d, where d is the actual thickness for the sample); ③ the difference between the full widths at half maximum of the fitting of the two-Bouss singlet, namely FWHM2-FWHM 1; fourthly, the difference of the fitting half-height width of the two-wave Gaussian single peak of the thickness influence factors is eliminated, namely the half-height width difference value delta of the thickness influence factors is eliminatedF(FWHM2-FWHM 1)/d; fifthly, multiplying the microstructure influence signal to obtain an estimated characterization quantity deltar＝((A1-A2)/d)×((FWHM2-FWHM1)/d)。
And step 3: not less than three groups of coatings deltarAnd performing linear fitting on the data to obtain the correlation between the microstructure difference of the coating and the change rule of the evaluation characterization quantity. The linear law is shown in table 3 and fig. 4.
TABLE 3
| Porosity and unmelted particle content (%) | (ΔA/d)*(ΔFWHM/d) |
| 5.92 | 1.66703 |
| 15.35 | 4.06688 |
| 17.59 | 4.25759 |
Specifically, with the increase of the sum of the porosity and the content of unmelted particles, which is a physical parameter of the coating microstructure, the calculated value delta of the corresponding fitting parameter of the reflective terahertz signalrThe relationship between the two shows a linear relationship.
And 4, step 4: and (3) measuring coatings at different positions on the surfaces of workpieces and test pieces in different batches, comparing the obtained terahertz reflection signals with the linear rule in the step (3) for reverse-pushing, characterizing and evaluating the microstructure characteristics of the coatings in different batches, namely the sum of porosity and the content of unmelted particles, and further feeding back the quality and performance characteristics of the coatings.
FIG. 5 is a schematic structural view of a characterizing means of a ceramic layer microstructure feature of a thermal barrier coating of a turbine blade in an embodiment of the invention. The characterization device comprises:
the device comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining terahertz time-domain spectral signals of at least three groups of coatings;
the first calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
and the second obtaining module is used for performing linear fitting on the evaluation characteristic quantity and the measured coating microstructure characteristic to obtain the corresponding relation between the coating microstructure characteristic and the evaluation characteristic quantity.
The first calculation module is used for calculating the following calculation:
after single-peak Gaussian fitting of the first echo and the second echo, the peak height difference value and the half-height width difference value of the first echo and the second echo which have no thickness influence factors are multiplied, so that the influence of the peak height difference value and the half-height width difference value on the thickness can be avoided.
Specifically, the first calculation module is configured to perform the following calculation:
after single-peak Gaussian fitting of the first echo and the second echo, obtaining a first peak height A1 and a first full width at half maximum FWHM1 of the first echo, and obtaining a second peak height A2 and a second full width at half maximum FWHM2 of the second echo;
after single-peak Gaussian fitting of the first echo and the second echo, calculating the peak height difference between the first peak height A1 and the second peak height A2 by using the peak height difference and the half-height width difference of the first echo and the second echo which have no thickness influence factors, wherein delta H is A1-A2; calculating the peak height difference delta of the thickness influence factorh，δh(a1-a2)/d, wherein d is the actual thickness parameter value of the sample;
calculating a difference between the first full width at half maximum FWHM1 and the second full width at half maximum FWHM2, Δ FWHM ═ FWHM2-FWHM 1; calculating the half-height width difference value delta of eliminating thickness influence factorsF，δF(FWHM2-FWHM1)/d, where d is the actual thickness parameter value of the sample;
obtaining an evaluation characterization quantity deltar，δr＝δh*δF。
FIG. 6 is a schematic structural view of an apparatus for applying ceramic layer microstructure features to a thermal barrier coating of a turbine blade in accordance with an embodiment of the present invention. The application device comprises:
the third obtaining module is used for obtaining a terahertz time-domain spectral signal of the coating;
the second calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
and the conversion module is used for obtaining the microstructure characteristics of the ceramic layer of the thermal barrier coating of the turbine blade by utilizing the corresponding correlation linear relation obtained by the evaluation characterization quantity and the characterization device.
Wherein the second calculation module is configured to perform the following calculations:
after single-peak Gaussian fitting of the first echo and the second echo, the peak height difference value and the half-height width difference value of the first echo and the second echo which have no thickness influence factors are multiplied, so that the influence of the peak height difference value and the half-height width difference value on the thickness can be avoided.
Specifically, the second calculation module is configured to perform the following calculation:
after single-peak Gaussian fitting of the first echo and the second echo, obtaining a first peak height A1 and a first full width at half maximum FWHM1 of the first echo, and obtaining a second peak height A2 and a second full width at half maximum FWHM2 of the second echo;
after single-peak Gaussian fitting of the first echo and the second echo, calculating the peak height difference between the first peak height A1 and the second peak height A2 by using the peak height difference and the half-height width difference of the first echo and the second echo which have no thickness influence factors, wherein delta H is A1-A2; calculating the peak height difference delta of the thickness influence factorh，δh(a1-a2)/d, wherein d is the actual thickness parameter value of the sample;
calculating a difference between the first full width at half maximum FWHM1 and the second full width at half maximum FWHM2, Δ FWHM2-FWHM 1;calculating the half-height width difference value delta of eliminating thickness influence factorsF，δF(FWHM2-FWHM1)/d, where d is the actual thickness parameter value of the sample;
obtaining an evaluation characterization quantity deltar，δr＝δh*δF。
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the characterization device and the application device disclosed by the embodiment, the description is simpler because of the method for characterizing the microstructure of the ceramic layer of the thermal barrier coating of the turbine blade disclosed by the embodiment, and the relevant points can be referred to the description of the method part.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.
Claims (10)
1. A method of characterizing a turbine blade thermal barrier coating ceramic layer microstructure, comprising:
obtaining terahertz time-domain spectral signals of at least three groups of coatings;
carrying out unimodal Gaussian fitting calculation on the terahertz time-domain spectral signals to evaluate the characteristic quantity;
and performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the correlation linear relation between the microstructure characteristic of the coating and the evaluation characteristic quantity.
2. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade according to claim 1, wherein the calculating an evaluation characterization quantity from the terahertz time-domain spectral signal comprises:
after single-peak Gaussian fitting of the first echo and the second echo, multiplying the peak height difference value and the half-height width difference value of the first echo and the second echo which have no thickness influence factors.
3. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade as claimed in claim 2 wherein: the terahertz time-domain spectral signal unimodal Gaussian fitting calculation evaluation characterization quantity comprises the following steps:
after the first echo and the second echo are subjected to single peak Gaussian fitting, a first peak height A1 and a first full width at half maximum FWHM1 of the first echo are obtained, and a second peak height A2 and a second full width at half maximum FWHM2 of the second echo are obtained.
4. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade as claimed in claim 2 wherein: obtaining the peak height difference value and the half-height width difference value of the first echo and the second echo, which are free from thickness influence factors, after single-peak Gaussian fitting of the first echo and the second echo, wherein the peak height difference value and the half-height width difference value compriseCalculating the peak height difference between the first peak height A1 and the second peak height A2, wherein the delta H is A1-A2; calculating the peak height difference delta of the thickness influence factorh，δh(a1-a2)/d, d being the actual thickness parameter value of the sample; calculating a difference between the first full width at half maximum FWHM1 and the second full width at half maximum FWHM2, Δ FWHM2-FWHM 1; calculating the half-height width difference value delta of eliminating thickness influence factorsF，δF(FWHM2-FWHM1)/d, d being the actual thickness parameter value for the sample.
5. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade according to claim 4, wherein the evaluating the characterization quantity by performing a single-peak Gaussian fitting calculation on the terahertz time-domain spectral signal comprises:
obtaining an evaluation characterization quantity deltar，δr＝δh*δF。
6. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade as claimed in claim 1 wherein: the microstructure characteristics of the coating are measured by a quantitative metallographic method, and the microstructure characteristics of the coating comprise the porosity and/or the unmelted particle content of the ceramic coating.
7. The method for characterizing the microstructure of a thermal barrier coating ceramic layer of a turbine blade as claimed in claim 1 wherein: the thermal barrier coating is a ceramic coating, the ceramic coating is an 8YSZ type thermal barrier coating, and the bottom of the ceramic coating is provided with a substrate and at least one metal bonding layer.
8. The method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade as claimed in claims 1 to 7, wherein: measuring coatings at different positions on the surfaces of workpieces or test pieces in different batches, comparing and reversely deducing the obtained terahertz reflection signals and the linear rule thereof, characterizing and evaluating the microstructure characteristics of the coatings in different batches, and further feeding back the quality and performance characteristics of the coatings.
9. A characterization device for characterizing a microstructure of a ceramic layer of a thermal barrier coating of a turbine blade, comprising:
the device comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining terahertz time-domain spectral signals of at least three groups of coatings;
the first calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
and the second obtaining module is used for performing linear fitting on the evaluation characteristic quantity and the measured microstructure characteristic of the coating to obtain the corresponding relation between the microstructure characteristic of the coating and the evaluation characteristic quantity.
10. An application device of a method for characterizing the microstructure of a ceramic layer of a thermal barrier coating of a turbine blade is characterized by comprising the following steps:
the third obtaining module is used for obtaining a terahertz time-domain spectral signal of the coating;
the second calculation module is used for calculating an evaluation characterization quantity according to the terahertz time-domain spectral signal;
a transformation module for obtaining the microstructure characteristics of the thermal barrier coating ceramic layer of the turbine blade by using the corresponding correlation linear relationship obtained by the evaluation characterization quantity and the characterization device of claim 9.
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