Method for detecting thickness and uniformity of plasma spraying coating film

Abstract

The invention discloses a method for detecting the film thickness and uniformity of a plasma spraying coating film. The method comprises the following steps: determining the plasma spraying coating film needing to be detected; detecting the thickness and the uniformity of the plasma spraying coating film; comprehensively evaluating the thickness and uniformity of the film layer; according to the invention, the quality and performance of the coating can be ensured by detecting the thickness and uniformity of the coating. If the film thickness is not uniform, the local performance is possibly reduced, and the overall performance and the service life of the product are influenced; and the detection result can be fed back to the production process, the optimization of the process parameters is facilitated, and the production efficiency and the product quality are improved. For example, the uniformity of the film thickness can be improved by adjusting parameters such as plasma spraying power, gas flow and the like; the situation of excessive spraying or insufficient spraying can be avoided through accurate film thickness and uniformity detection, so that the material waste is reduced, and the cost is reduced; and specific application requirements are met: in some applications.

Description

Technical Field

[0001] The invention relates to the technical field of spray coating, and in particular to a method for detecting the film thickness and uniformity of a plasma spray coating. Background Art

[0002] Plasma spray coating is a surface coating technology that uses plasma spray equipment to deposit materials on the surface of the workpiece in a high-speed spraying manner to form a coating with specific functions or properties. This coating can improve the wear resistance, corrosion resistance, high temperature resistance and other properties of the base material, and improve the service life and performance of the material. The process of plasma spray coating mainly generates plasma through a high-frequency power supply, introduces gas (usually nitrogen, argon or hydrogen) into the plasma chamber, ionizes the gas to form plasma, and sprays the spray material into the plasma in the form of a spray gun. The spray material is heated to a high temperature and melted under the action of the plasma to form a liquid or semi-liquid spray material. The spray material is sprayed onto the surface of the workpiece, and quickly cools and solidifies after contacting the workpiece to form a coating.

[0003] During the plasma spraying process, the sprayed material is subjected to the high temperature of the plasma to form a coating with high high temperature resistance. The plasma sprayed coating has a strong bond with the workpiece material, and the coating is not easy to fall off or peel off. The thickness and uniformity of the film layer are important factors that determine the quality of the coating. By testing the thickness and uniformity of the film layer, it can be ensured that the coating meets the design requirements to meet the use needs and performance requirements of the workpiece. If the film layer thickness is insufficient or uneven, it may lead to problems such as reduced protection performance of the workpiece, poor surface quality or easy peeling of the coating.

[0004] However, during the plasma spray coating process, the coating often forms an uneven thickness distribution at different angles and positions. For irregularly shaped workpiece surfaces, traditional film thickness measurement methods may not be able to cover and detect all areas. In addition, due to the complex shape of the irregular surface, there may be bumps, curves and other features. Especially for non-planar surfaces or workpieces with complex geometric shapes, if the measurement results are inaccurate or incomplete, it will not only reduce the efficiency of film thickness detection, but also reduce the accuracy of coating quality and performance detection. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting the film thickness and uniformity of a plasma spray coating, so as to detect the film thickness and uniformity of the plasma spray coating.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for detecting the thickness and uniformity of a plasma spray coating comprises the following steps: S1: Determine the plasma spray coating to be tested; S2: Detect the thickness and uniformity of plasma spray coating: Laser induced breakdown spectroscopy combined with laser induced fluorescence; Optical simulation software simulates spectral curves; ‌X-ray diffraction; ‌Ultrasonic thickness measurement; Laser scanning measurement method; Magnetic induction method; Infrared thermography; S3: Comprehensively evaluate the film thickness and uniformity.

[0007] Preferably, in S2, an interference image after coating is obtained by a laser interferometer to detect basic data of film thickness and uniformity.

[0008] Preferably, in S2, the reflectivity and extinction coefficient of the film layer are extracted from the interference image by using spectral feature analysis technology, and then the thickness of the film layer is calculated.

[0009] Preferably, the key step in S2 is to construct a polarized light scattering model to analyze the roughness characteristics of the film layer and evaluate the surface uniformity of the film layer.

[0010] Preferably, in S2, the uniformity of the film layer is fully understood by comprehensively evaluating the roughness characteristics and texture characteristics of the film layer.

[0011] Preferably, in S2, a damage analysis model is established to evaluate the damage and stress state inside the coating to ensure the quality of the coating.

[0012] Preferably, the three-dimensional reconstruction technology in S2 can more intuitively understand the flow field changes during the spraying process and optimize the spraying process.

[0013] In summary, due to the adoption of the above technology, the beneficial effects of the present invention are: 1. Ensure product quality and performance: By testing the thickness and uniformity of the coating, the quality and performance of the coating can be ensured. If the film thickness is uneven, it may cause local performance degradation, affecting the overall performance and service life of the product.

[0014] 2. Optimize process parameters: The test results can be fed back into the production process to help optimize process parameters and improve production efficiency and product quality. For example, by adjusting the power, gas flow rate and other parameters of plasma spraying, the uniformity of film thickness can be improved.

[0015] 3. Reduce material waste: Accurate film thickness and uniformity detection can avoid over-spraying or under-spraying, thereby reducing material waste and reducing costs.

[0016] 4. Meeting specific application requirements: In some applications, such as aerospace, electronic devices, etc., there are strict requirements for precise control and uniformity of film thickness. The test results can ensure that these requirements are met and improve the reliability and safety of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, so that other features, purposes and advantages of the present invention become more obvious. The accompanying drawings of the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0019] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances of the specification.

[0021] The present invention provides Figure 1 A method for detecting the thickness and uniformity of a plasma spray coating is shown, comprising the following steps: S1: Determine the plasma spray coating to be tested; S2: Detect the thickness and uniformity of plasma spray coating: Laser induced breakdown spectroscopy combined with laser induced fluorescence technology: The interference image after coating is obtained through laser interferometer to detect the basic data of film thickness and uniformity; This method is based on laser-induced breakdown spectroscopy combined with laser-induced fluorescence technology, and can measure the film thickness of the coating sample at the order of 10nm, and can distinguish the surface uniformity of the coating at the order of μm. This method is a micro-destructive and nearly non-destructive detection method, which can be measured in real time, in situ, online, contactless and actively, and will not interfere with the coating process. It is easy to operate and can be analyzed in real time. Optical simulation software simulates the spectrum curve: through the spectrum feature analysis technology, the reflectivity and extinction coefficient of the film layer are extracted from the interference image, and then the thickness of the film layer is calculated; This method includes selecting multiple test points on the sample to be tested, obtaining the reflectance or transmittance spectra of the multiple test points, selecting the reference wavelength, reference spectrum and wavelength point, simulating the spectrum curve and the film thickness corresponding to the spectrum curve through optical simulation software, and obtaining the calculation formula between the film thickness and the reflectance or transmittance corresponding to the selected wavelength point, and finally calculating the film thickness of all test points under the selected wavelength point according to the calculation formula. This method overcomes the problems of long film thickness testing of large batches or large-size samples and sample destructiveness, and can quickly obtain the film thickness of all test points; ‌X-ray diffraction method: By constructing a polarized light scattering model, the roughness characteristics of the film layer are analyzed. This is a key step in evaluating the surface uniformity of the film layer. The coating thickness is determined by analyzing the position and intensity of the diffraction peak. It is suitable for metal or ceramic coatings: X-ray diffraction uses the diffraction phenomenon produced when X-rays interact with matter to analyze the crystal structure of the material. When X-rays are irradiated to the coating surface, they interact with the crystal structure in the coating to produce a specific diffraction pattern. By measuring the position and intensity of these diffraction peaks, the thickness of the coating can be deduced. This method is suitable for thickness measurement of metal coatings and ceramic coatings with high accuracy and reliability; Application scenarios of X-ray diffraction: X-ray diffraction has a wide range of applications in materials science and engineering, especially in studying the microstructure and chemical composition of metals, alloys, steels, ceramics, etc. By analyzing the position and intensity of diffraction peaks, phase diagrams and phase transitions, diffusion interfaces, inclusion and precipitation analysis, failure analysis, oxidation, corrosion and segregation phenomena can be determined; Ultrasonic thickness measurement: It uses the propagation time and reflection signal of ultrasonic waves to measure thickness. It is suitable for metal and some ceramic coatings. It comprehensively evaluates the roughness and texture characteristics of the film layer to fully understand the uniformity of the film layer. The basic principle of ultrasonic thickness measurement is to use the time it takes for ultrasonic waves to propagate in a material to calculate the thickness. When an ultrasonic probe emits a high-frequency sound wave pulse, the pulse propagates in the material and encounters the interface of the material, part of the sound wave will be reflected back to the probe. By accurately measuring the time it takes for ultrasonic waves to propagate in the material and combining it with the known speed of sound, the thickness of the material can be calculated.

[0022] Scope of application and advantages: 1. Non-destructive: Measurement can be performed without destroying the material.

[0023] 2. Wide range of applications: suitable for materials of various thicknesses and shapes.

[0024] 3. High precision: The measurement accuracy is high, suitable for occasions with high precision requirements; Laser scanning measurement method: The thickness is calculated by the distance between the laser and the coating surface. It is suitable for thinner coatings and flat surfaces. By establishing a damage analysis model, the damage and stress state inside the coating are evaluated to ensure the quality of the coating. ‌Laser scanning measurement method‌ is to scan the coating surface with a laser scanner or laser rangefinder, measure the distance between the laser and the coating, and calculate the coating thickness based on the scanning results. This method is suitable for thinner coatings and flat surfaces; The laser scanning measurement method is based on the principle of triangulation. The laser beam forms a small light spot on the surface of the object to be measured. The imaging objective lens images the light spot onto the photosensitive surface of the photosensitive receiver, generating an electrical signal to detect the position of the light spot on its sensitive surface. When the object to be measured moves, the position of the light spot relative to the imaging objective lens changes, and the position of its image point on the photosensitive device also changes accordingly. The actual moving distance of the object to be measured can be calculated, thereby determining the thickness of the coating.

[0025] Laser scanning measurement is suitable for thinner coatings and flat surfaces. Since the laser beam reflects more evenly on a flat surface, it can provide more accurate measurement results. In addition, this method is more sensitive to thinner coating measurements and can provide higher measurement accuracy; advantage: 1. High precision: Laser scanning measurement method can provide higher measurement accuracy and is suitable for occasions requiring high-precision measurement; 2. Wide range of applications: Suitable for thinner coatings and flat surfaces, and can meet a variety of measurement needs.

[0026] Magnetic induction method: ‌The thickness of the magnetic coating is deduced by measuring the magnetic field strength, which is often used to measure the magnetic coating. ‌ This method mainly uses the principle of magnetic induction to determine the thickness of the coating by measuring the change in the magnetic field. Specifically, the magnetic method is a commonly used coating thickness measurement method, which uses the principle of magnetic induction to measure the thickness of the surface coating on iron-based metals. This method is suitable for measuring the thickness of non-magnetic coatings on magnetic substrates, such as paint, coatings, plating, etc. on metal surfaces; How the magnetic method works 1. The magnetic method determines the thickness of the coating by applying a magnetic field at the interface between the coating and the substrate and then measuring the change in the magnetic field. The specific steps are as follows: 2. Apply a magnetic field: Apply a magnetic field at the interface between the coating and the substrate.

[0027] 3. Measure changes in magnetic field: Use a magnetic induction measuring instrument to measure changes in the magnetic field.

[0028] 4. Calculate coating thickness: Calculate the coating thickness by analyzing the changes in the magnetic field.

[0029] Scope of application and advantages: ‌Scope of application‌: Suitable for measuring surface coatings on ferrous metals, such as paint, coating, plating, etc.

[0030] ‌Advantages‌: Simple operation, fast measurement speed, suitable for on-site detection.

[0031] Infrared thermography: The method of estimating coating thickness by recording thermal distribution images is applicable to coatings with thermal resistance effect. This method is called infrared thermography. Infrared thermography uses an infrared thermal imager to record the thermal distribution image of the coating surface, and then infers the coating thickness by analyzing the changes in thermal distribution. This method is suitable for coatings with thermal resistance effects, such as thermal barrier coatings. The basic principle of infrared thermography is to use infrared radiation to measure the temperature distribution on the surface of an object. Since the thermal resistance effect of the coating will cause changes in the temperature distribution, the coating thickness can be inferred from these changes. Application scenarios and applicable conditions of infrared thermal imaging: Infrared thermography is suitable for coatings with thermal resistance effects, such as thermal barrier coatings. This method does not require contact with the coating surface, so it will not damage the coating and is suitable for measuring coating thickness of various materials. In addition, infrared thermography can also be used to detect the uniformity and integrity of the coating, helping to evaluate the overall quality of the coating; Infrared thermography operation steps and precautions: 1. Prepare the test instrument: Make sure the infrared thermal imager is in good working condition and calibrate the instrument to ensure the accuracy of the measurement.

[0032] 2. Record thermal distribution image: Aim the infrared thermal imager at the coating surface and record its thermal distribution image.

[0033] 3. Analyze the image: The thickness of the coating can be derived by analyzing the temperature changes in the thermal distribution image.

[0034] 4. Calibration and verification: Calibration and verification should be performed when necessary to ensure the reliability of the measurement results; S3: Comprehensively evaluate the film thickness and uniformity.

[0035] The above steps have the following benefits for evaluating the film thickness and uniformity: 1. Ensure product quality and performance: By testing the thickness and uniformity of the coating, the quality and performance of the coating can be ensured. If the film thickness is uneven, it may cause local performance degradation, affecting the overall performance and service life of the product.

[0036] 2. Optimize process parameters: The test results can be fed back into the production process to help optimize process parameters and improve production efficiency and product quality. For example, by adjusting the power, gas flow rate and other parameters of plasma spraying, the uniformity of film thickness can be improved.

[0037] 3. Reduce material waste: Accurate film thickness and uniformity detection can avoid over-spraying or under-spraying, thereby reducing material waste and reducing costs.

[0038] 4. Meeting specific application requirements: In some applications, such as aerospace, electronic devices, etc., there are strict requirements for precise control and uniformity of film thickness. The test results can ensure that these requirements are met and improve the reliability and safety of the product.

Claims

1. A method for detecting the thickness and uniformity of a plasma spray coating, characterized in that: The following steps are involved: S1: Determine the plasma spray coating to be tested; S2: Detect the thickness and uniformity of plasma spray coating: Laser induced breakdown spectroscopy combined with laser induced fluorescence; Optical simulation software simulates spectral curves; ‌X-ray diffraction; ‌Ultrasonic thickness measurement; Laser scanning measurement method; Magnetic induction method; Infrared thermography; S3: Comprehensively evaluate the film thickness and uniformity.

2. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: In S2, the interference image after coating is obtained by a laser interferometer to detect basic data of film thickness and uniformity.

3. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: In S2, the reflectivity and extinction coefficient of the film layer are extracted from the interference image by using spectral feature analysis technology, and then the thickness of the film layer is calculated.

4. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: The key step in S2 is to construct a polarized light scattering model, analyze the roughness characteristics of the film layer, and evaluate the surface uniformity of the film layer.

5. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: In S2, the uniformity of the film layer is fully understood by comprehensively evaluating the roughness characteristics and texture characteristics of the film layer.

6. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: In S2, a damage analysis model is established to evaluate the damage and stress state inside the coating to ensure the quality of the coating.

7. The method for detecting the thickness and uniformity of a plasma spray coating according to claim 1, characterized in that: The three-dimensional reconstruction technology in S2 can more intuitively understand the flow field changes during the spraying process and optimize the spraying process.

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