Aluminum alloy corrosion degree laser probe quantitative detection method and sampling device

Abstract

The invention belongs to the technical field of laser precision detection, and discloses an aluminum alloy corrosion degree laser probe quantitative detection method and a sampling device.The detection method comprises the steps that microporous filter paper is placed at the sampling position of aluminum alloy and subjected to standing corrosion for preset time so as to transfer out elements to be detected in the aluminum alloy, and the microporous filter paper contains prefabricated corrosion liquid; fixing microporous filter paper on a pure silicon glass slide, and airing to obtain a sample to be detected; scanning the surface of the microporous filter paper of the to-be-detected sample by the laser beam to obtain spectral data of the to-be-detected element; and after optimizing the spectral data, constructing a mapping relation between the laser plasma spectral characteristic signal and the corrosion degree of the aluminum alloy by utilizing a machine learning algorithm so as to obtain a corrosion degree value of the aluminum alloy. The sampling device comprises microporous filter paper and a pure silicon glass slide which can be fixed into a whole, and an anti-corrosion sealing box used for containing the microporous filter paper and the pure silicon glass slide. The detection efficiency, the analysis precision and the result reliability of quantitative detection of the laser probe can be improved.

Description

Technical Field

[0001] The present application belongs to the field of laser precision detection technology, and more specifically, relates to a laser probe quantitative detection method and sampling device for the degree of corrosion of aluminum alloys. Background Art

[0002] Laser probe technology is an in-situ, online, and rapid component analysis technology. It uses a focused high-energy pulsed laser to ablate the surface of a material and a certain depth of the material. The material is instantly vaporized and ionized under the action of the high-energy laser to produce high-temperature plasma, and radiates spectral signals to the surrounding space. By collecting these complex spectral signals, high-wavelength resolution spectral images are formed at different positions on the surface of the imaging device after grating spectroscopy. By recording the position and intensity of these spectral images, the type of material elements represented by different wavelength spectra (or characteristic spectra) can be determined by calibration software. By analyzing the intensity of the characteristic spectrum, the percentage content information of the corresponding elements can be accurately obtained by using quantitative algorithms. Based on the above characteristics, laser probes were first proposed for in-situ quantitative detection of aluminum alloy corrosion, and are expected to exceed EMAT, XRD, ECT and other detection technologies in terms of quantitative accuracy and stability.

[0003] Aluminum alloys can be strengthened by adding major trace elements, among which magnesium is the main added element. Since magnesium exists in the aluminum matrix as a supersaturated solid solution, aluminum alloys are prone to intergranular corrosion. 3 Mg 2) precipitates. These precipitates are prone to chemical reactions with H in the environment or Cl ions in a high-salt environment, causing debonding of the precipitates and inducing the risk of corrosion fracture. In the laser probe system, limited by the optical diffraction limit and the thermodynamic factors of the laser-matter interaction, the ablation pits (ablation resolution) formed on the surface of the laser ablated material often have large lateral dimensions, usually in the range of tens to hundreds of microns, while the grain boundary size of the aluminum alloy is only in the range of 20nm to 100nm, which is much smaller than the laser ablation resolution. Therefore, the laser probe does not have sufficient resolution and is directly used to analyze the precipitates at the grain boundaries of the aluminum alloy. At the same time, other elements in the matrix will also seriously interfere with the magnesium element. In view of this technical difficulty, although narrow pulse width lasers and microscope objectives can be used to improve the spatial resolution of the laser probe technology, it still cannot break through the micron, and a more sensitive detector is required to detect extremely weak spectral signals, which increases the complexity and precision of the system and reduces the applicability of the laser probe in the in-situ detection of aluminum alloys. In addition, high spatial resolution will be affected by the working distance and focal depth of the microscope objective, and the flatness of the sample surface is extremely high. In actual applications, if the grinding accuracy of untrained personnel does not meet the detection requirements of laser probes, it will greatly affect the detection accuracy and reliability, and limit the application of laser probes in high-precision detection of aluminum alloy corrosion degree on site. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide a laser probe quantitative detection method and sampling device for the degree of corrosion of aluminum alloys, aiming to solve the problem of improving the detection efficiency, analysis accuracy and result reliability of laser probe quantitative detection of the degree of corrosion of aluminum alloys.

[0005] To achieve the above objectives, the present application provides a laser probe quantitative detection method for aluminum alloy corrosion degree, the detection method comprising:

[0006] S1 placing a microporous filter paper at a sampling position of the aluminum alloy and allowing it to corrode for a preset time to transfer out the element to be tested in the aluminum alloy, wherein the microporous filter paper contains a prefabricated corrosive liquid;

[0007] S2 fixing the microporous filter paper onto a pure silicon glass slide and drying it to obtain a sample to be tested;

[0008] S3: scanning the surface of the microporous filter paper of the sample to be tested with a laser beam to obtain spectrum data of the element to be tested;

[0009] S4 optimizes and processes the spectral data, and uses a machine learning algorithm to construct a mapping relationship between the laser plasma spectral characteristic signal and the corrosion degree of the aluminum alloy to obtain the corrosion degree value of the aluminum alloy.

[0010] This application designs an element corrosion transfer sampling method, and uses this sampling method in the laser probe detection and analysis process to form a fast, non-destructive, safe and high-precision quantitative detection method for the degree of aluminum alloy corrosion. The combination of the two technologies can not only compensate for the shortcomings of laser probe equipment due to the times, but also has broad application prospects in the fields of materials science, environmental monitoring and mineral analysis.

[0011] Furthermore, in step S1, the preset time is less than or equal to 10 minutes.

[0012] Furthermore, in step S1, before placing the microporous filter paper for corrosion, the aluminum alloy sampling location is first polished and sealed for storage.

[0013] Furthermore, in step S2, the corrosion surface of the microporous filter paper contacting the aluminum alloy faces away from the pure silicon glass slide.

[0014] Furthermore, the prefabricated etching solution contains a moisturizer.

[0015] Furthermore, the prefabricated corrosive solution is an ammonium persulfate solution.

[0016] Furthermore, the concentration of the ammonium sulfate solution is 20 wt.%.

[0017] Furthermore, in step S1, the maximum pore size of the microporous filter paper is smaller than the spatial resolution of the laser.

[0018] Furthermore, in step S3, the microporous filter paper on the sample to be tested is first scanned horizontally, and then scanned vertically in a direction perpendicular to the microporous filter paper.

[0019] Furthermore, in step S4, the spectral data is denoised using a wavelet transform method, and the spectral information after denoising is normalized.

[0020] Furthermore, in step S4, a partial least squares regression algorithm is used to construct a mapping relationship between the laser plasma spectrum characteristic signal and the degree of corrosion of the aluminum alloy.

[0021] According to another aspect of the present application, a sampling device is also disclosed, which is used to transfer the element to be measured in the laser probe quantitative detection method for the degree of aluminum alloy corrosion as described in any of the above items, and the transfer device includes microporous filter paper, a pure silicon glass slide and an anti-corrosion sealing box, the microporous filter paper is used to transfer the element to be measured at the aluminum alloy sampling position, and the microporous filter paper contains a prefabricated corrosion liquid; the pure silicon glass slide is used to fix the microporous filter paper containing the element to be measured to obtain the sample to be measured; the anti-corrosion sealing box is used to store the sample to be measured.

[0022] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0023] (1) The present application designs an element corrosion transfer sampling method and applies the sampling method to the laser probe detection and analysis process. Its significant advantages are: first, in terms of detection sensitivity, the corrosion transfer sampling method can effectively separate and concentrate the elements to be tested, avoiding the introduction of matrix elements to interfere with subsequent detection and analysis, thereby improving the sensitivity of subsequent laser probe detection and analysis; and the laser probe detection technology can quickly obtain the spectral information of the elements. This combination can increase the analysis accuracy from the ppm level to the ppb level, which is 2 to 3 orders of magnitude higher than the traditional laser probe analysis; second, in terms of multi-element analysis, laser probe technology can detect multiple elements at the same time. After combining with the corrosion transfer sampling method, it can realize the simultaneous and rapid analysis of other elements while detecting the separated specific elements, thereby increasing the richness of sample analysis; finally, in terms of data processing, the corrosion transfer sampling method provides quantitative information, while the laser probe detection provides qualitative and quantitative analysis of the elements. The combination of the two methods further enhances the reliability of the detection and analysis results in terms of data processing.

[0024] (2) The detection method of this application has extremely high quantitative accuracy. 3 Mg 2 The two phases are highly similar, so the traditional laser probe method cannot distinguish them. The corrosion transfer sampling method uses the difference in their corrosion potential (the electrochemical corrosion potential of the magnesium-rich phase of aluminum alloy is lower than that of the matrix element) to precipitate the magnesium-rich phase (Al2O3) at the grain boundary of the aluminum alloy. 3 Mg 2 ) without transferring its matrix elements. Through the above characteristics, the corrosion transfer sampling method greatly reduces the interference caused by the matrix elements, thereby improving the stability of the plasma characteristic spectrum and greatly improving the quantitative detection accuracy of the corrosion degree of aluminum alloys.

[0025] (3) The prefabricated corrosion solution of the present application improves the corrosion efficiency during the element transfer process by using strongly oxidizing ammonium persulfate, and can also compensate for the impact of insufficient surface flatness of the sample. There is no need to pre-polish the aluminum alloy sample, thereby greatly improving the sampling efficiency during the quantitative detection process and controlling the time of the entire detection and analysis process to within about 10 minutes, meeting the industrial demand for quantitative detection of aluminum alloy corrosion.

[0026] (4) This application introduces the least squares regression algorithm (PLS algorithm) into data analysis. Since the quantitative results of the traditional single variable calibration method are R 2Around 0.1, there is no correlation at all, which is not suitable for data analysis in this application. However, after the introduction of the PLS algorithm, its R 2 It can reach above 0.95, and the quantitative accuracy is improved by about 10 times, which can fully meet actual industrial needs.

[0027] (5) The present application also provides a sampling device, which is compact and portable and can realize on-site sampling. The sampling process is safe, fast and time-saving, which greatly improves the efficiency of sampling and subsequent testing. The corrosion solution contained in the sampling device can stimulate a stronger spectrum, and because the surface flatness of the pure silicon slide is high, the stability of the spectrum can be improved, and the sample to be tested can be sealed and stored for a long time after sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic flow chart of a method for quantitatively detecting the corrosion degree of aluminum alloy using a laser probe provided in an embodiment of the present application;

[0029] Figure 2 is a schematic diagram of the structure of the laser induced breakdown spectroscopy analysis system used in the embodiments of the present application;

[0030] Figure 3 It is a schematic diagram of the structure of a sampling device used in a laser probe quantitative detection method for aluminum alloy corrosion degree provided in an embodiment of the present application.

[0031] In all the drawings, the same figure marks are used to represent the same elements or structures, among which: 1-laser, 2-laser beam, 3-reflector, 4-reflected laser beam, 5-focusing objective lens, 6-focused laser beam, 7-plasma, 8-analyzed substance, 81 microporous filter paper, 82-pure silicon slide, 83-corrosion-resistant sealing box, 9-X-axis motion unit, 10-Y-axis motion unit, 11-Z-axis motion unit, 12-spectral signal, 13-spectral collector, 14-transmission optical fiber, 15-spectrometer, 16-enhanced coupling device ICCD, 17-first signal trigger line, 18-power line, 19-USB cable, 20-second signal trigger line, 21-computer. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0034] The terms "first" and "second" in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects. For example, a first response message and a second response message are used to distinguish different response messages rather than to describe a specific order of the response messages.

[0035] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0036] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0037] The present application provides a laser probe quantitative detection method for the corrosion degree of aluminum alloys, such as Figure 1 As shown, the detection method includes:

[0038] S1: placing a microporous filter paper at a sampling position of the aluminum alloy and allowing it to corrode for a preset time to transfer out the element to be tested in the aluminum alloy, wherein the microporous filter paper contains a prefabricated corrosive liquid;

[0039] S2 fixes the microporous filter paper onto a pure silicon glass slide and allows it to dry to obtain the sample to be tested;

[0040] S3 enables the laser beam to scan the surface of the microporous filter paper of the sample to be tested to obtain the spectrum data of the element to be tested;

[0041] After optimizing the spectral data, S4 uses a machine learning algorithm to construct a mapping relationship between the laser plasma spectral characteristic signal and the degree of corrosion of the aluminum alloy to obtain the corrosion degree value of the aluminum alloy.

[0042] In one embodiment, the steps from pre-configuring a prefabricated etching solution to using the prefabricated etching solution for corrosion extraction according to steps S1-S2 mainly include: sample grinding (a), solution configuration (b), ultrasonic oscillation (c), chemical etching (d), and static corrosion sampling (e).

[0043] (a) Sample grinding: To ensure the accuracy and repeatability of the test results, before corroding the sample surface, the sample after high temperature treatment needs to be placed on a grinding machine and polished with 400-mesh and 1000-mesh sandpaper to remove surface dirt. After grinding, the sample surface to be corroded is sealed with anti-oxidation tape to prevent oxidation caused by long-term exposure to air.

[0044] (b) Preparation of prefabricated etching solution: 20g of ammonium persulfate reagent and 100g of deionized water are measured on a weighing table, and the weighed ammonium persulfate powder is placed in a beaker containing deionized water using a weighing paper. In order to mix them evenly, a glass rod is used to stir for about 5 minutes. Specifically, in other preferred embodiments, the prefabricated etching solution can also be selected from other etching reagents with similar chemical properties to ammonium persulfate, and the concentration is also 20wt.%.

[0045] (c) Ultrasonic oscillation: In order to improve the uniformity of fine particles in the solution, the beaker was placed in an ultrasonic oscillator and oscillated for 10 seconds to break up the particle aggregation in the liquid and disperse the particles into smaller sizes, thereby ensuring a consistent concentration of the corrosive agent acting on the aluminum alloy sample.

[0046] (d) Chemical etching: During the corrosion transfer process, the spectral intensity of the characteristic spectrum radiated by the plasma will be affected by the amount of transferred elements. Therefore, in order to improve the stability of the aluminum alloy transfer spectrum at the same corrosion time, 7 μl of the corrosion solution is sucked by a pipette and dripped into the microporous filter paper to ensure that no corrosion solution remains on the sample surface after the corrosion transfer, thereby improving the stability of the extracted spectrum. Specifically, in order to keep the prefabricated corrosion solution moist, a moisturizer such as glycerol or propylene glycol can be added, and the microporous filter paper with the prefabricated corrosion solution dripped on it is sealed and packaged, so that it can excite a stronger spectrum intensity after the spectral elements are extracted.

[0047] (e) Static corrosion sampling: Place the microporous filter paper obtained in the previous step at the sampling position of the aluminum alloy to be tested. After 10 minutes of corrosion at room temperature, use tweezers to transfer the microporous filter paper to a pure silicon glass slide (which does not contain aluminum and magnesium elements). In order to improve the signal-to-noise ratio, the corrosion surface of the filter paper is turned away from the pure silicon glass slide, and corrosion-resistant acrylic glue is selected as the adhesive to fix the microporous filter paper on the pure silicon glass slide. Finally, after the filter paper is placed in a constant temperature box for natural drying, the preparation of the sample to be tested is completed.

[0048] In one of the embodiments, in step S1, microporous filter paper with good corrosion resistance is preferably used as the element transfer medium, and the maximum pore size of the microporous filter paper is less than or equal to 10 μm, which is much smaller than the spatial resolution of the laser used in this embodiment, to ensure effective ablation.

[0049] In one of the embodiments, corrosion-resistant and stable acrylic adhesive is further preferably used as an adhesive to fix the microporous filter paper on the transfer carrier to ensure a high surface flatness and improve the stability of the spectrum.

[0050] In one embodiment, a pure silicon glass slide is further preferred as the transfer carrier. The pure silicon glass slide has extremely high corrosion resistance and hardly reacts chemically with other acids. Its acid resistance is 30 times that of ceramics and 150 times that of stainless steel. It also has good thermal stability and can withstand laser energy of about 50 mJ. In addition, the pure silicon glass slide selected in this embodiment is extremely small in size, with a volume of only 3 cm 3 The prepared sample to be tested is small and portable.

[0051] In one embodiment, the quantitative detection device used in the aforementioned step S3 is as follows Figure 2 The laser induced breakdown spectroscopy analysis system shown includes a plasma characteristic spectrum imaging unit and a laser scanning unit.

[0052] The aforementioned plasma characteristic spectrum imaging unit mainly includes: a laser 1, a laser beam 2, a reflector 3, a reflected laser beam 4, a focusing objective lens 5, a focused laser beam 6, an analyzed substance 8, a plasma 7, a spectral signal 12, a spectral collector 13, a transmission optical fiber 14, a spectrometer 15, an ICCD 16, a first signal trigger line 17, a power line 18, a USB cable 19, a second signal trigger line 20 and a computer 21 arranged in sequence along the propagation direction of the light beam.

[0053] Laser 1 is used to emit a laser beam of a specific wavelength, beam diameter and pulse width. In this application, Nd:YAG laser is used. In order to achieve high power output of the laser, a wavelength of 1064nm with a high energy level matching degree is selected as the emission wavelength. In this embodiment, the laser ablation object is a microporous filter paper, and its surface pore size can reach tens of microns. In order to prevent the laser beam from passing through the pore size due to its small diameter, resulting in ineffective ablation, and thus inability to obtain a stable plasma characteristic spectrum, the pulse width of the laser is in the order of nm, and the diameter of the laser beam 2 is 1mm to 2mm.

[0054] The laser beam 2 emitted by the laser 1 is reflected by the reflector 3 and then the reflected laser beam 4 reaches the focusing objective lens 5. The angle between the reflector 3 and the laser beam 2 is 45 degrees, which can deflect the transmission direction of the laser beam 2 by 90 degrees. The reflected laser beam 4 is transmitted to the focusing objective lens 5, and under the focusing action of the focusing objective lens 5, a focused laser beam 6 is formed. The focusing objective lens can be divided into a low-power objective lens, a medium-power objective lens and a high-power objective lens due to its different magnifications. The magnification of the focusing objective lens 5 in this embodiment is usually 10 times, which is used to improve the resolution of the beam tip of the focused laser beam 6, so that the laser pulse can better ablate the surface of the microporous filter paper and obtain a stable plasma characteristic spectrum signal. At this magnification, the spatial resolution of the laser ablation pit is hundreds of microns, which is higher than the maximum aperture of the microporous filter paper. At the same time, the larger ablation size is conducive to improving the sampling efficiency and shortening the detection time.

[0055] The beam tip of the focused laser beam 6 interacts with the surface of the analyzed substance 8 and the material at a certain depth. The beam tip of the focused laser beam 6 will penetrate into the sample surface by several microns to tens of microns to achieve the best ablation effect. The material is instantly melted, vaporized and ionized. This process is extremely rapid and will form plasma 7, which radiates spectral signals to the surrounding space.

[0056] The spectrum signal 12 of a certain angle range emitted by the plasma 7 is collected by the spectrum collector 13. Under the action of the spectrum collector 13, the collected spectrum signal 12 is coupled into the transmission optical fiber 14. Under the transmission action of the transmission optical fiber 14, the spectrum signal 12 is transmitted to the spectrometer 15 and the gain-coupled charge-coupled device ICCD16 respectively. After the spectrum signal is split by the grating of the spectrometer 15, a spectrum image with high wavelength resolution is formed at different positions on the surface of the imaging device ICCD16.

[0057] The spectrum collector 13 contains a piece of ultraviolet fused quartz lens inside, and the transmission optical fiber 14 is installed on the imaging surface of the ultraviolet fused quartz lens. The spectrum signal 12 is on the object plane of the spectrum collector 13. The object plane and the imaging plane form an optical conjugate structure. Therefore, the spectrum collector 13 can couple the spectrum signal 12 into the transmission optical fiber 14.

[0058] The transmission optical fiber 14 is connected to the light receiving end of the spectrometer 15. The light collected by the spectrometer 15 passes through a dispersion device, usually a prism or a grating, to separate light of different wavelengths according to the wavelength or frequency of the light to form a spectrum. The colors or spectral lines of the spectrum represent different wavelengths. The spectrum of each element or compound has specific wavelength characteristics, which can be used to identify their components. Since the characteristic spectral intensity of the plasma of the element to be measured after the transfer is weak, the present application adopts an enhanced coupling device ICCD16 combined with a spectrometer to detect the spectral signal 12, and through the photoelectron multiplication method, even very weak fluorescence or plasma emission signals can be clearly captured. In addition, ICCD has time resolution, and the time window technology is used to control the timing of light collection, that is, the energy enhancement effect of ICCD is turned on within a certain time window, which enables it to capture signals within a specific time period, suppress background noise, and achieve higher time resolution, which helps to improve the signal quality in laser probe measurement.

[0059] The first signal trigger line 7 and the second signal trigger line 0 are used to synchronize the trigger signals among the laser, ICCD and computer.

[0060] The power cord 18 is used to power the laser. The USB cable 19 is used to transmit and control the ICCD to adjust the time resolution and the grid width of the spectrometer. The position and intensity of these spectral images are recorded by the computer 21. The calibration software can be used to determine the type of material element represented by different wavelength spectra or characteristic spectra.

[0061] The above optical path structure is only a preferred embodiment of the present invention. According to functional requirements, the required optical system can be added to the optical path system, which is within the protection scope of the present invention.

[0062] The aforementioned laser scanning unit mainly includes: an X-axis motion unit 9, a Y-axis motion unit 10 and a Z-axis motion unit 11. Among them: the X-axis motion unit 9 and the Y-axis motion unit 10 constitute a lateral scanning unit, which can perform laser scanning on a certain area of ​​the surface of the analyzed substance 8 (i.e., the sample to be tested). Laser scanning is usually performed in a certain scanning mode, mainly including continuous scanning or line-by-line scanning. The Z-axis motion unit 11 is mainly used to control the relative height between the surface of the analyzed substance 8 and the tip of the focused laser beam 6 to achieve the best laser ablation effect.

[0063] In the laser probe experiment, the laser beam needs to be focused on a specific area of ​​the sample to induce breakdown of the plasma and generate a measurable spectral signal. The three-dimensional displacement platform can accurately control the position of the sample to be tested on the horizontal plane and the height in the vertical direction, that is, the position of the sample to be tested on the horizontal plane is controlled by the X-axis motion unit 9 and the Y-axis motion unit 10, and its height in the vertical direction is controlled by the Z-axis motion unit 11, ensuring that the laser beam can always be aimed at the target area of ​​the sample. This is crucial for high-precision elemental analysis, analysis of small areas, and compensation for uneven sample surfaces.

[0064] The three-dimensional displacement platform allows the sample to be laser irradiated at multiple points, thereby achieving spatial scanning. When scanning the sample surface, the laser beam can irradiate different positions point by point to analyze the spectral information of different areas. This can be used to analyze the uniformity of the sample surface or analyze the elemental composition of a specific area, which is particularly suitable for heterogeneous samples or multi-level analysis.

[0065] The X-axis motion unit 9, the Y-axis motion unit 10 and the Z-axis motion unit 11 all have high single-step motion accuracy, repeat positioning accuracy and motion speed. The single-step accuracy is usually similar to the laser ablation line width, and is generally controlled in the range of 1μm. The repeat positioning accuracy determines the image frame accuracy, that is, whether there is image distortion or deformation, which is generally controlled in the range of 1μm or even lower. The motion speed determines the frame rate of the image, that is, how long it takes to completely draw an image, which is generally controlled in the speed range of 0.1mm / s to 100mm / s, such as 0.5mm / s, 1mm / s, 15mm / s, 25mm / s, 35mm / s, 45mm / s, 55mm / s, 65mm / s, 75mm / s, 85mm / s, 90mm / s, 100mm / s, or any speed value between any two of the aforementioned speed values.

[0066] In one of the embodiments, in step S3, the microporous filter paper on the sample to be tested is first scanned horizontally to compensate for the spectral fluctuation caused by the uneven distribution of the transferred elements, while avoiding the focus asymmetry caused by the uneven surface of the sample, and optimizing the interaction effect between the laser and the sample; then a vertical scan is performed in the direction perpendicular to the microporous filter paper, wherein the vertical direction (Z-axis motion unit 11) is used to control the laser focus to perform depth profile analysis on the surface and deep layers of the microporous filter paper, and scan layer by layer to obtain element distribution information at different depths.

[0067] The aforementioned computer 21 is equipped with analysis software, which integrates background removal, median filtering, wavelet transform and edge detection algorithms. In this embodiment, wavelet transform is mainly used to denoise the spectrum by decomposing the signal into components of multiple scales. Unlike Fourier transform, wavelet transform can provide information in both time domain and frequency domain, and is suitable for the analysis of non-stationary signals.

[0068] The key step of denoising is to judge which coefficients represent the main part of the signal and which coefficients are noise according to the size of the wavelet coefficients. The threshold method is used for judgment, that is, a threshold is set to compare the size of each wavelet coefficient. If the coefficient is less than the threshold, it is considered to be noise and removed; otherwise, the coefficient is retained. Wavelet changes can effectively improve the signal-to-noise ratio of spectral data and optimize the quality of spectral lines. At the same time, the spectral signal after denoising is further normalized to improve the data analysis process.

[0069] Based on the above steps, this embodiment uses the machine learning algorithm PLS to construct a mapping relationship between the laser plasma spectrum characteristic signal and the degree of corrosion of the aluminum alloy, and obtains the value of the degree of corrosion of the aluminum alloy to convert the coefficient R 2 , root mean square error RMSE, and average relative error ARE are used as evaluation indicators in the quantitative analysis process.

[0070] More specifically, the optimized spectral data is divided into a training set and a prediction set according to a certain ratio. The PCA (principal component analysis) method is used to extract the effective characteristic variables of the aluminum alloy spectrum to complete the data dimension reduction. According to the relationship between RMSE and the number of principal components, the number of principal components under the lowest RMSE is selected to complete the data dimension reduction. After extracting the optimal number of characteristic information and completing the model training, the obtained PLS model is used to analyze the prediction set data. DFA (discriminant factor analysis) is introduced to convert the probability matrix of the output result into a certain prediction value, and the data is evaluated based on ACC (accuracy).

[0071] In a more preferred embodiment, according to the theory of optical diffraction and laser-matter interaction, the spatial resolution of laser ablation pits is often related to the pulse width of the laser. If the optical system remains unchanged, the narrower the pulse width, the higher the spatial resolution of the ablation pits. Since the maximum pore size of the preferred microporous filter paper of the present invention is no more than 30 μm, in order to make the spatial resolution of the laser higher than the maximum pore size of the microporous filter paper to ensure effective ablation, the preferred laser pulse width of this embodiment is 6 ns and the wavelength is 1064 nm (higher matching with the energy level of the Nd:YAG laser).

[0072] In another embodiment, a sampling device is provided for detecting the element to be detected by corrosion transfer in the laser probe quantitative detection method for the degree of corrosion of aluminum alloy provided in any of the above embodiments. Figure 3As shown, the transfer device includes a microporous filter paper 81, a pure silicon glass slide 82 and an anti-corrosion sealing box 83. The microporous filter paper 81 is used to transfer the element to be measured at the sampling position of the aluminum alloy, and the microporous filter paper 81 contains a prefabricated corrosive liquid; the pure silicon glass slide 82 is used to fix the microporous filter paper 81 containing the element to be measured to obtain the sample to be measured; the anti-corrosion sealing box 83 is used to store the sample to be measured. Specifically, corrosion-resistant and stable acrylic adhesive is selected as an adhesive to fix the microporous filter paper 81 on the pure silicon glass slide 82 to ensure that its surface flatness is high and the stability of the spectrum is improved. More specifically, the anti-corrosion sealing box 83 is a sealing box formed by one-piece molding or split combination of silicon dioxide or similar materials. There are multiple accommodating cavities in the sealing box body, and each accommodating cavity is equipped with a cover body that can be opened and closed separately, which is used to seal and accommodate multiple samples to be measured. The sampling device provided in this embodiment is small and convenient, and can realize in-situ sampling and real-time "online detection", meeting the actual on-site detection needs.

[0073] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0074] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A laser probe quantitative detection method for aluminum alloy corrosion degree, characterized in that: The detection method comprises: S1 placing a microporous filter paper at a sampling position of the aluminum alloy and allowing it to corrode for a preset time to transfer out the element to be tested in the aluminum alloy, wherein the microporous filter paper contains a prefabricated corrosive liquid; S2 fixing the microporous filter paper onto a pure silicon glass slide and drying it to obtain a sample to be tested; S3 uses a laser beam to scan the surface of the microporous filter paper of the sample to be tested to obtain spectrum data of the element to be tested; S4 optimizes and processes the spectral data, and uses a machine learning algorithm to construct a mapping relationship between the laser plasma spectral characteristic signal and the corrosion degree of the aluminum alloy to obtain the corrosion degree value of the aluminum alloy.

2. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S1, the preset time is less than or equal to 10 minutes.

3. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S1, before placing the microporous filter paper for corrosion, the sampling location of the aluminum alloy is first polished and sealed for storage.

4. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S2, the corrosion surface of the microporous filter paper contacting the aluminum alloy faces away from the pure silicon glass slide.

5. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: The prefabricated etching solution contains a moisturizer; preferably, the prefabricated etching solution is an ammonium persulfate solution; preferably, the configuration concentration of the prefabricated etching solution is 20wt.%.

6. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S1, the maximum pore size of the microporous filter paper is smaller than the spatial resolution of the laser.

7. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S3, the microporous filter paper on the sample to be tested is firstly scanned horizontally, and then vertically scanned in a direction perpendicular to the microporous filter paper.

8. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S4, the spectral data is denoised using a wavelet transform method, and the spectral information after denoising is normalized.

9. The laser probe quantitative detection method for aluminum alloy corrosion degree according to claim 1, characterized in that: In step S4, a partial least squares regression algorithm is used to construct a mapping relationship between the laser plasma spectrum characteristic signal and the degree of corrosion of the aluminum alloy.

10. A sampling device, characterized in that: Used to transfer the element to be measured in the laser probe quantitative detection method for the degree of aluminum alloy corrosion as described in any one of claims 1 to 9, the transfer device includes a microporous filter paper (81), a pure silicon glass slide (82) and an anti-corrosion sealing box (83), the microporous filter paper (81) is used to transfer the element to be measured at the aluminum alloy sampling position, and the microporous filter paper contains a prefabricated corrosion liquid; the pure silicon glass slide (82) is used to fix the microporous filter paper (81) containing the element to be measured to obtain a sample to be measured; the anti-corrosion sealing box (83) is used to store the sample to be measured.

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