CN217005751U - Thermal wave imaging coating thickness measuring system - Google Patents
Thermal wave imaging coating thickness measuring system Download PDFInfo
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- CN217005751U CN217005751U CN202121508711.1U CN202121508711U CN217005751U CN 217005751 U CN217005751 U CN 217005751U CN 202121508711 U CN202121508711 U CN 202121508711U CN 217005751 U CN217005751 U CN 217005751U
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- 238000000576 coating method Methods 0.000 title claims abstract description 40
- 239000011248 coating agent Substances 0.000 title claims abstract description 36
- 238000003384 imaging method Methods 0.000 title claims abstract description 18
- 238000012360 testing method Methods 0.000 claims abstract description 40
- 238000001514 detection method Methods 0.000 claims abstract description 28
- 230000005284 excitation Effects 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 5
- 238000012937 correction Methods 0.000 claims description 2
- 238000001931 thermography Methods 0.000 claims 1
- 238000005259 measurement Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 description 11
- 238000005516 engineering process Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 238000011088 calibration curve Methods 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009675 coating thickness measurement Methods 0.000 description 1
- 239000007822 coupling agent Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
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- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention relates to a thermal wave imaging coating detection system, which integrates a reference test piece, is positioned in a field of view of a thermal imager together with a tested piece, simultaneously carries out thermal excitation and thermal wave imaging detection, and corrects a primary detection value of the tested piece by using a measurement result of the reference test piece with known coating parameters to obtain an accurate result of the tested piece.
Description
Technical Field
The invention relates to a coating thickness detection system based on a thermal wave imaging technology, and belongs to the technical field of infrared nondestructive detection.
Background
With the rapid development of scientific technology, the application of coatings is more and more extensive, and the industry has raised higher requirements for measuring the thickness of the coatings and defects, such as the requirements of on-line, non-contact, real-time detection and the like. The conventional means used for detecting the thickness of the coating at present mainly comprise eddy current, ultrasonic, X-ray, probe method, optical method and the like, but the methods cannot completely meet the requirements of modern industry on the detection of the coating, such as the eddy current method has the requirements on the properties of the substrate material and must have electromagnetic characteristics; the ultrasonic method requires a coupling agent and cannot effectively measure thin coatings; the X-ray requires that the sample can be subjected to transmission detection and has special safety protection requirements; the probe method belongs to contact detection and has damage to a sample; optical methods require that the film layer be a transparent medium, have a high degree of finish, and the like. At present, most coatings have the characteristics of thin thickness, non-transparency, fragility, easy damage and the like, so that more advanced technical means are required to meet the measurement requirement of the film layers.
The thermal wave imaging technology is a nondestructive testing means developed recently, and the basic principle of the nondestructive testing method is that a thermal excitation source is adopted to heat the surface of a test piece, so that a thermal pulse is generated and is transmitted to the interior of the test piece, when thermal waves encounter defects or the thermal impedance changes in the interior of the test piece, a part of the thermal energy is generated and is reflected back to the surface of the test piece, and dynamic temperature distribution is formed on the surface of the test piece. And recording information of the surface temperature of the test piece along with the time change by adopting a thermal infrared imager, and correcting, processing data and analyzing the thermal wave signal by image processing to realize the detection of the thickness of the film layer. Compared with the traditional nondestructive detection means, the thermal wave imaging technology has unique advantages, such as non-contact, large-area rapid imaging, suitability for non-transparent coating, sensitivity to the thermal property of the material and the like, and can meet the requirement of the modern industry on film thickness detection.
However, the thermal wave imaging technique is an indirect measurement method, and the result is obtained by comprehensively measuring and calculating various physical parameters, so that the system is susceptible to system drift caused by various external factors, such as aging of parts, changes in environmental conditions, and changes in operation methods. These all affect the accuracy of detection and require compensation corrections. In addition, when the coating is detected by thermal wave imaging, the relation between the detected signal and the thickness of the coating is complex, and the calculation cannot be carried out by using a simple formula, so that the difficulty is brought to the accurate measurement of the thickness of the coating.
Disclosure of Invention
The invention aims to provide a new detection system aiming at the defects of the current thermal wave imaging coating detection technology, the system is based on the traditional thermal wave imaging nondestructive detection technology, integrates one or more reference test pieces, is placed in an imaging view field of a thermal imager and is synchronously detected with a tested piece, the system drift amount is calculated by using the detection result of the reference test piece with known parameters, and the detection value of the tested piece is corrected to obtain a correct result.
For the detection of the thickness of the coating, the reference test pieces adopt the coating which is the same as or similar to the coating of the tested piece, the thickness is distributed in a certain range, the range comprises the thickness of the coating of the tested piece, the reference test pieces are detected, and the detection result is fitted to obtain a relation curve reflecting the thickness of the coating and the measured value of the thermal wave imaging. Thus, when the tested piece is detected, the corresponding coating thickness can be obtained on the relation curve by using the obtained measured value.
Drawings
FIG. 1 is a schematic view of an apparatus of the present invention;
FIG. 2 is a schematic diagram of the thermal wave imaging detection principle;
FIG. 3 is a three-dimensional schematic view of an apparatus of the present invention;
FIG. 4 is a schematic view of a thermal imager field of view and a reference test strip;
FIG. 5 is a schematic diagram of system drift detection calibration using a reference strip;
FIG. 6 is a schematic diagram of a plurality of reference test strips for detecting the coating thickness of a test piece.
Detailed Description
In order that the features of the invention may be better understood, the invention will now be further described with reference to the following specific drawings and examples.
First, the basic principle of thermal wave imaging is described, and as shown in FIG. 2, a thermal excitation source 11 heats the surface of a test piece 14, which may be in the form of high energy short pulses, or intensity modulated so-called phase lock. The generated thermal wave 21 propagates towards the interior of the tested piece, when meeting the interface 23 between the coating 15 and the substrate, a part of the transmitted thermal wave 24 continues to propagate towards the interior of the sample, another part of the reflected thermal wave 22 will be reflected back to the surface of the sample, and the time, intensity, etc. of the reflected thermal wave are related to the thickness of the coating and the physical properties of the coating and the base material. By detecting the time-varying relation of the thermal wave signal, the information such as the thickness of the coating can be obtained.
In the detection process of thermal wave imaging, the temperature of the surface of the tested piece is determined by thermal excitation energy, surface light energy absorptivity, material heat capacity, density, thermal diffusion coefficient, ambient temperature and the like. The surface temperature and the thermal excitation energy are in a direct proportion relation and are in a linear relation with the system drift, so that the data can be normalized by a method for simultaneously detecting the reference test piece and the tested piece, and the influence generated by the thermal excitation energy and the system drift can be eliminated.
Fig. 1 is a schematic diagram of the system of the present invention, which is composed of a thermal imager 10, a thermal excitation source 11, a support frame 12, a reference test piece 13, a signal acquisition and processing module 16, a thermal excitation driver 17, and the like. The thermal imager 10 is fixed on the upper end of the support frame 12, and the reference test block is fixed on the lower portion of the support frame 12 near one side of the tested piece and within the field of view of the thermal imager 10. The reference strip may be one or more, and has two functions, namely, it is used to correct the system drift, such as the intensity variation of the excitation source, or the aging of the components used in the apparatus, and the change of the ambient temperature and humidity. The material of the reference strip may be different from that of the test piece, but preferably has similar physical properties. Another function of the reference strip is to calibrate the coating thickness, and the reference strip should be as similar as possible to the substrate and coating materials of the tested piece, so as to obtain reliable measurement results.
Fig. 3 is a schematic perspective view of the device of the present invention, wherein a test piece holder 18 for holding a reference test piece 13 is disposed at the bottom of the supporting frame 12, and the test piece holder 18 is in the field of view, so as to fix the reference test piece 13 and protect and conceal the reference test piece 13. Fig. 4 shows the spatial relationship between the test piece holder 18, the reference test piece 13, the outer frame 25 of the support frame 12, and the field of view 24 of the thermal imager 10, where the reference test piece 13 is located at the edge of the field of view 24 of the thermal imager 10, and when the detection result is displayed, the holder area in the field of view is hidden, so that the reference test piece 13 is not visible in the image of the detection result.
Usually, when the system drifts, including the change of environmental conditions, the same ratio of the influence is generated on the reference test strip 13 and the tested object 14, as shown in fig. 5, since various parameters of the reference test strip 13 are known, when the measurement result changes, usually caused by the change of external conditions, the same influence is generated on the tested object 14. The measured value of the tested object 14 is corrected by using the measured value of the reference test piece 13, so as to obtain the correct value of the tested object 14.
When coating thickness measurements are made, the measurements and the coating are related to a number of physical parameters of the substrate material, which are often not accurately known. In addition, various factors cannot be sufficiently considered, and therefore, it is difficult to directly measure the thickness of the coating layer. For this purpose, a calibration curve can be used, as shown in fig. 6, several reference test pieces 13 with different thicknesses are used, the thermal wave signal values of these reference test pieces 13 with different thicknesses are measured, and numerical fitting is performed on the coordinates of the thermal wave signal corresponding to the thickness of the coating layer, so as to obtain a calibration curve. When the tested piece 14 is detected, the obtained thermal wave signals are compared to obtain the coating thickness of the tested piece 14. Usually, the reference test piece 13 is made of the same or similar material as the tested object 14, and the coating thickness of the reference test piece 13 is distributed around the coating thickness of the tested object 14, so as to obtain better detection accuracy.
The invention is mainly applied to the measurement of the thickness of a coating, and comprises a single-layer or multi-layer structure, but can also be applied to the detection of other physical parameters of the coating, such as the thermal characteristics, the mechanical parameters, the bonding quality and the like of the coating and a substrate material.
The foregoing description of the invention is illustrative, but not limiting, and it is intended that the invention be modified, varied and equivalents within the scope of the claims appended hereto as fall within the scope of the invention.
Claims (5)
1. A thermal wave imaging coating thickness measuring system is characterized by comprising:
the thermal excitation source is used for exciting thermal waves on the surface of the tested piece;
the thermal imager is used for acquiring a thermal wave signal of the surface of the tested piece;
the data processing device is used for analyzing and processing the acquired thermal wave image;
the supporting frame is used for bearing the thermal imager and keeping the working distance between the thermal imager and the tested piece;
and the reference test piece is arranged on the supporting frame and close to the part of the tested piece, is positioned in the field of view of the thermal imaging instrument and is used for providing a correction basis for the detection result of the tested piece.
2. The system of claim 1, comprising a plurality of reference strips distributed over different areas of the field of view of the thermal imager.
3. The system of claim 1, wherein the reference strip comprises a coating and a base material having the same or similar thermal and mechanical properties as the test object.
4. The system of claim 1, wherein the plurality of reference test strips have different coating thicknesses, and the thickness ranges are distributed in the areas adjacent to the coating thickness of the test strip.
5. The system of claim 1, wherein the bottom of the support frame has a specimen holder parallel to the detection plane for receiving the reference specimen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121508711.1U CN217005751U (en) | 2021-07-04 | 2021-07-04 | Thermal wave imaging coating thickness measuring system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121508711.1U CN217005751U (en) | 2021-07-04 | 2021-07-04 | Thermal wave imaging coating thickness measuring system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217005751U true CN217005751U (en) | 2022-07-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202121508711.1U Active CN217005751U (en) | 2021-07-04 | 2021-07-04 | Thermal wave imaging coating thickness measuring system |
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| Country | Link |
|---|---|
| CN (1) | CN217005751U (en) |
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2021
- 2021-07-04 CN CN202121508711.1U patent/CN217005751U/en active Active
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