Semi-quantitative device and method for water immersion ultrasonic detection of coating porosity

Abstract

The invention provides a semi-quantitative device and method for water immersion ultrasonic detection of the porosity of a coating. The device comprises water immersion ultrasonic scanning equipment and an analysis unit, the water immersion ultrasonic scanning equipment is used for determining a corresponding scanning mode according to a to-be-detected surface of the to-be-detected piece, outputting an ultrasonic signal to each to-be-detected surface of the to-be-detected piece by using a water immersion probe of the water immersion ultrasonic scanning equipment based on the scanning mode, receiving a time domain waveform reflected by each to-be-detected surface and sending the time domain waveform to the analysis unit; the analysis unit is used for converting all the time domain waveforms into frequency domain signals and judging whether the coating porosity calculation requirement is met or not according to all the frequency domain signals; and if yes, calculating the coating porosity range of the to-be-detected piece according to the center frequency and the peak frequency in the frequency domain signal. According to the method, the frequency domain processing is performed on the ultrasonic signal of the sealing coating, and the frequency spectrum structure of the frequency domain signal is analyzed to detect the porosity, so that the nondestructive evaluation of the porosity in the material is realized, and the detection accuracy and reliability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and in particular to a semi-quantitative device and method for detecting the porosity of a coating by immersion ultrasonic testing. Background Art

[0002] In the application of coating materials, the quality of the coating directly affects the service life and reliability of the equipment. Among them, the porosity of the coating is an important quality index because pores will reduce the mechanical strength, corrosion resistance, and thermal stability of the coating. Therefore, in order to ensure the coating quality, accurately detecting its porosity is crucial for ensuring the functionality of the coating.

[0003] At present, ultrasonic testing, as a common non-destructive testing technology, has been widely used in the monitoring of coating quality. However, ultrasonic testing still faces certain challenges in the semi-quantitative detection of coating porosity. This is because factors such as coating thickness, density, and hardness affect signal reflection, and the ability to distinguish thin coatings and micro-pores is poor, making it difficult to accurately distinguish internal pores from the interface layer in the coating, thereby affecting the accuracy and reliability of the detection.

[0004] Therefore, how to improve the accuracy and reliability of detecting thin coatings and micro-pores is an urgent problem to be solved at present. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a semi-quantitative device and method for detecting the porosity of a coating by immersion ultrasonic testing to solve the problem of low accuracy and reliability in detecting thin coatings and micro-pores.

[0006] To achieve the above object, embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present invention discloses a semi-quantitative device for detecting the porosity of a coating by immersion ultrasonic testing, the device comprising: an immersion ultrasonic scanning device and an analysis unit;

[0008] The immersion ultrasonic scanning device is configured to determine a corresponding scanning method according to the surface to be inspected of the workpiece to be inspected, and based on the scanning method, output ultrasonic signals to each surface to be inspected of the workpiece to be inspected by using the immersion probe of the immersion ultrasonic scanning device, and receive the time-domain waveforms reflected by each surface to be inspected and send them to the analysis unit;

[0009] The analysis unit is configured to convert all the time-domain waveforms into frequency-domain signals, and determine whether the coating porosity calculation requirements are met according to all the frequency-domain signals; if so, calculate the coating porosity range of the workpiece to be inspected according to the center frequency and peak frequency in the frequency-domain signals.

[0010] Preferably, the immersion ultrasonic scanning device comprises: an excitation interface, an immersion probe, a turntable, and a motion control mechanism;

[0011] The turntable is placed below the horizontal plane after horizontal adjustment, and the turntable is parallel to the horizontal plane;

[0012] The turntable is used to place the part to be inspected;

[0013] The motion control mechanism is respectively connected to the immersion probe and the turntable;

[0014] The motion control mechanism is used to determine the corresponding scanning method according to the surface to be inspected of the part to be inspected, and control the movement of the turntable and the immersion probe based on the scanning method, so that the immersion probe inspects the part to be inspected; it is also used to adjust the excitation signal frequency to be consistent with the nominal frequency of the immersion probe;

[0015] The immersion probe is connected to the excitation interface through a coaxial cable;

[0016] The immersion probe is used to be perpendicular to the surface to be inspected when outputting ultrasonic signals to each surface to be inspected of the part to be inspected; it is also used to receive the time-domain waveform reflected by each surface to be inspected and send it to the analysis unit.

[0017] Preferably, the immersion probe includes: a focusing probe and a receiving probe;

[0018] The focusing probe is used to output ultrasonic signals to each surface to be inspected of the part to be inspected;

[0019] The receiving probe is used to receive the time-domain waveform reflected by each surface to be inspected and send it to the analysis unit.

[0020] Preferably, the motion control mechanism for determining the corresponding scanning method according to the surface to be inspected of the part to be inspected is specifically used for:

[0021] When the surface to be inspected of the part to be inspected is a plane, determining the scanning method of the surface to be inspected as a two-axis motion method;

[0022] When the surface to be inspected of the part to be inspected is a regular curved surface, determining the scanning method of the surface to be inspected as a turntable scanning method;

[0023] When the surface to be inspected of the part to be inspected is an irregular curved surface, determining the scanning method of the surface to be inspected as a laser profiling method.

[0024] Preferably, the motion control mechanism for controlling the movement of the turntable and the immersion probe based on the scanning method is specifically used for:

[0025] When the scanning method is a turntable scanning method, controlling the turntable to rotate;

[0026] Adjust the pulse width of the immersion probe according to the scanning method so that the initial wave width reaches a preset minimum value, and adjust the water distance between the immersion probe and the surface to be inspected of the workpiece to be inspected;

[0027] Control the angles of the A-axis and B-axis of the immersion probe so that the immersion probe is perpendicular to the surface to be inspected of the workpiece to be inspected.

[0028] Preferably, the analysis unit includes: a conversion module, a judgment module, and a calculation module;

[0029] The conversion module is configured to receive all time-domain waveforms. For each time-domain waveform, convert the time-domain waveform into a frequency-domain signal according to the fast Fourier transform algorithm, and extract the center frequency and peak frequency of the frequency-domain signal;

[0030] The judgment module is configured to select the maximum center frequency, the minimum center frequency, the maximum peak frequency, and the minimum peak frequency from all the center frequencies and peak frequencies; calculate a first pore uniformity value according to the maximum center frequency and the minimum center frequency, and calculate a second pore uniformity value according to the maximum peak frequency and the minimum peak frequency; mark the larger value of the first pore uniformity value and the second pore uniformity value as the target pore uniformity value; if the target pore uniformity value is less than the threshold, it is determined that the coating porosity calculation requirements are met;

[0031] The calculation module is configured to, when the coating porosity calculation requirements are met, calculate an average value according to all the center frequencies and peak frequencies and match the average value with a standard specimen to obtain the coating porosity range of the workpiece to be inspected.

[0032] Preferably, the calculation module that calculates an average value according to all the center frequencies and peak frequencies and matches the average value with a standard specimen to obtain the coating porosity range of the workpiece to be inspected is specifically configured to:

[0033] Calculate the average center frequency according to all the center frequencies, and calculate the average peak frequency according to all the peak frequencies;

[0034] Match a plurality of standard specimens corresponding to different coating porosity ranges with the average center frequency and the average peak frequency to obtain the coating porosity range of the workpiece to be inspected.

[0035] Preferably, the analysis unit further includes: an acquisition and display module;

[0036] The acquisition and display module is configured to acquire the time-domain waveforms received by the immersion probe; and is further configured to display the time-domain waveforms and / or the frequency-domain signals.

[0037] Preferably, the acquisition and display module includes an analog-to-digital conversion acquisition card and an oscilloscope.

[0038] The second aspect of the present invention discloses a semi-quantitative method for detecting the porosity of a coating by water immersion ultrasonic testing, which is applied to the semi-quantitative device for detecting the porosity of a coating by water immersion ultrasonic testing disclosed in the first aspect of the present invention, and includes:

[0039] Using a water immersion ultrasonic scanning device to determine a corresponding scanning method according to the surface to be inspected of the workpiece to be inspected;

[0040] Based on the scanning method, using the water immersion probe of the water immersion ultrasonic scanning device to output ultrasonic signals to each surface to be inspected of the workpiece to be inspected, and receiving the time-domain waveforms reflected by each surface to be inspected and sending them to the analysis unit;

[0041] Converting all the time-domain waveforms into frequency-domain signals through the analysis unit;

[0042] Judging whether the requirements for calculating the coating porosity are met according to all the frequency-domain signals;

[0043] If it is satisfied, the coating porosity range of the workpiece to be inspected is calculated according to the center frequency and peak frequency in the frequency-domain signal.

[0044] Based on the above-mentioned semi-quantitative device and method for detecting the porosity of a coating by water immersion ultrasonic testing provided by the embodiments of the present invention, the device includes: a water immersion ultrasonic scanning device and an analysis unit; the water immersion ultrasonic scanning device is used to determine a corresponding scanning method according to the surface to be inspected of the workpiece to be inspected, and based on the scanning method, use the water immersion probe of the water immersion ultrasonic scanning device to output ultrasonic signals to each surface to be inspected of the workpiece to be inspected, and receive the time-domain waveforms reflected by each surface to be inspected and send them to the analysis unit; the analysis unit is used to convert all the time-domain waveforms into frequency-domain signals, and judge whether the requirements for calculating the coating porosity are met according to all the frequency-domain signals; if it is satisfied, the coating porosity range of the workpiece to be inspected is calculated according to the center frequency and peak frequency in the frequency-domain signal. The present invention performs frequency-domain processing on the ultrasonic signals of the sealing coating, analyzes the spectral structure of the frequency-domain signals for porosity detection, thereby realizing non-destructive evaluation of the porosity in the material, and improving the detection accuracy and reliability. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0046] Figure 1Structural diagram of a semi - quantitative device for detecting coating porosity by immersion ultrasonic testing provided by an embodiment of the present invention;

[0047] Figure 2 Placement example diagram of an immersion ultrasonic scanning device and a workpiece to be inspected provided by an embodiment of the present invention;

[0048] Figure 3 Flowchart of a semi - quantitative method for detecting coating porosity by immersion ultrasonic testing provided by an embodiment of the present invention. Specific embodiments

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0050] In this application, the terms "include", "comprise" or any other variant thereof are intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0051] As can be seen from the background technology, since factors such as coating thickness, density, and hardness will affect signal reflection, the current ultrasonic testing has poor resolution for thin coatings and micro - pores, making it difficult to accurately distinguish internal pores in the coating from the interface layer, thereby affecting the accuracy and reliability of the detection.

[0052] Therefore, an embodiment of the present invention provides a semi - quantitative device and method for detecting coating porosity by immersion ultrasonic testing. The device includes: an immersion ultrasonic scanning device and an analysis unit; the immersion ultrasonic scanning device is used to determine the corresponding scanning method according to the surface to be inspected of the workpiece to be inspected. Based on the scanning method, the immersion ultrasonic probe of the immersion ultrasonic scanning device outputs ultrasonic signals to each surface to be inspected of the workpiece to be inspected, and receives the time - domain waveforms reflected from each surface to be inspected and sends them to the analysis unit; the analysis unit is used to convert all the time - domain waveforms into frequency - domain signals, and judge whether the coating porosity calculation requirements are met according to all the frequency - domain signals; if so, calculate the coating porosity range of the workpiece to be inspected according to the center frequency and peak frequency in the frequency - domain signals. The present invention performs frequency - domain processing on the ultrasonic signals of the sealing coating, analyzes the spectral structure of the frequency - domain signals for porosity detection, thereby realizing non - destructive evaluation of the porosity in the material and improving the detection accuracy and reliability.

[0053] See Figure 1 , which shows the structural diagram of a semi - quantitative device for detecting the porosity of a coating by immersion ultrasonic testing according to an embodiment of the present invention.

[0054] It should be noted that, in the embodiment of the present invention, specifically based on the principle that ultrasonic waves of different frequencies are sensitive to pores in different degrees, high - frequency ultrasonic waves are more sensitive to pores, the high - frequency band of a test block with more porosity attenuates more, and the overall frequency band of the wave frequency will shift towards the low - frequency band, a semi - quantitative detection of the coating porosity is carried out.

[0055] The semi - quantitative device for detecting the porosity of a coating by immersion ultrasonic testing includes an immersion ultrasonic scanning device (i.e., an immersion ultrasonic C - scanning device) and an analysis unit.

[0056] Specifically, the immersion ultrasonic scanning device is used to determine the corresponding scanning method according to the surface to be inspected of the part to be inspected. Based on the scanning method, the immersion ultrasonic probe of the immersion ultrasonic scanning device outputs ultrasonic signals to each surface to be inspected of the part to be inspected, and receives the time - domain waveforms reflected from each surface to be inspected and sends them to the analysis unit.

[0057] It can be understood that the part to be inspected is specifically a device for which the coating porosity needs to be detected.

[0058] In practical applications, the material of the part to be inspected can be a sealing coating, a thermal barrier coating, and a wear - resistant coating, including aluminum - silicon coatings, nickel - graphite coatings, nickel - chromium - iron - aluminum - boron nitride coatings, etc.

[0059] It should be noted that the part to be inspected may include multiple surfaces to be inspected, and these surfaces to be inspected may be flat surfaces, regular curved surfaces, or irregular curved surfaces. Therefore, it is necessary to determine the corresponding scanning method for each surface to be inspected to improve the accuracy and reliability of the detection. The specific determination process is as follows.

[0060] Specifically, the immersion ultrasonic scanning device at least includes: an excitation interface, an immersion ultrasonic probe, a turntable, and a motion control mechanism.

[0061] It can be understood that, combined with Figure 2 the placement example diagram of the immersion ultrasonic scanning device and the part to be inspected shown, the turntable is placed under the horizontal plane after horizontal adjustment, and the turntable is parallel to the horizontal plane.

[0062] Specifically, the turntable is used to place the part to be inspected. The turntable can specifically be a glass plate, and the part to be inspected with a smaller size is placed on the glass plate.

[0063] It should be particularly noted that when the part to be inspected is a rotary part to be inspected, it needs to be fastened from the outside or inside of the part to be inspected with a three - jaw chuck to ensure that the rotary part to be inspected will not fall off or drift during the rotation detection of the rotary part to be inspected.

[0064] It is understandable that the three-jaw chuck on the immersion ultrasonic C-scan device is a precision clamping device designed to ensure the stability of the part to be inspected during the inspection process and enable accurate positioning and clamping.

[0065] It should be noted that before ultrasonic inspection, check whether there are bubbles on the surface of the part to be inspected, especially in the immersion area. Bubbles will hinder the propagation of ultrasonic signals and may cause distortion of the inspection signals. If bubbles are found, they should be removed by gently shaking or using special tools to ensure good contact between the surface of the part to be inspected and the water bath.

[0066] Specifically, the motion control mechanism is respectively connected to the immersion probe and the turntable.

[0067] It is understandable that before inspecting the part to be inspected, the motion control mechanism can be used to adjust the positional relationship between the immersion probe and the part to be inspected and adjust signals, etc. During the inspection of the part to be inspected, the motion control mechanism can be used to control the movement of the immersion probe and the turntable to better inspect the part to be inspected from all angles.

[0068] It should be noted that the motion control mechanism is used to determine the corresponding scanning method according to the surface to be inspected of the part to be inspected, and control the movement of the turntable and the immersion probe based on the scanning method so that the immersion probe can inspect the part to be inspected. The motion control mechanism is also used to adjust the excitation signal frequency to be consistent with the nominal frequency of the immersion probe.

[0069] It is understandable that the specific process of determining the corresponding scanning method according to the surface to be inspected of the part to be inspected is as follows (Process A1 to Process A3):

[0070] Process A1: When the surface to be inspected of the part to be inspected is a plane, determine the scanning method of the surface to be inspected as a two-axis motion method.

[0071] It should be noted that when scanning (i.e., inspecting) the planar surface to be inspected, the motion control mechanism needs to always keep the immersion probe perpendicular to the part to be inspected.

[0072] Process A2: When the surface to be inspected of the part to be inspected is a regular curved surface, determine the scanning method of the surface to be inspected as a turntable scanning method.

[0073] It is understandable that when performing turntable scanning (i.e., inspecting) on the regular curved surface to be inspected, the motion control mechanism also needs to always keep the immersion probe perpendicular to the part to be inspected.

[0074] It should be noted that the turntable scanning method controls the rotation of the turntable through the motion control mechanism to achieve a full-range scan of the surface or interior of the part to be inspected, enabling the ultrasonic probe to scan the part to be inspected from multiple angles and improving the comprehensiveness and accuracy of the inspection.

[0075] Process A3: When the surface to be inspected of the part to be inspected is an irregular curved surface, determine the scanning method of the surface to be inspected as the laser profiling method.

[0076] It can be understood that when scanning (i.e., detecting) the surface to be inspected of an irregular curved surface, the motion control mechanism also needs to always keep the immersion probe perpendicular to the part to be inspected.

[0077] It should be noted that for the ultrasonic inspection of irregular curved surfaces, the laser profiling method uses a laser scanning device to obtain the three-dimensional shape data of the surface of the part to be inspected in real time and generates an accurate surface contour. Then, based on these contour data, an accurate scanning trajectory can be formulated for the ultrasonic probe, enabling the immersion probe to scan according to the true shape of the part to be inspected.

[0078] This method can overcome the limitations brought by irregular curved surfaces to traditional scanning methods, ensure that the ultrasonic probe can collect accurate detection data from multiple angles and directions, thereby improving the detection accuracy, which is particularly significant in the inspection of objects with complex shapes (such as aerospace components, automotive parts, etc.).

[0079] Specifically, before the inspection, the motion control mechanism adjusts the excitation signal frequency of the immersion ultrasonic C-scan device to make it consistent with the nominal frequency of the immersion probe. Then, adjust the pulse width of the immersion probe to make the initial wave width reach the preset minimum value, and adjust the water distance between the immersion probe and the surface to be inspected of the part to be inspected.

[0080] It should be noted that during the entire inspection process, the motion control mechanism always keeps the water distance between the immersion probe and the surface to be inspected of the part to be inspected consistent.

[0081] It can be understood that during ultrasonic inspection, the smaller the wave width, the higher the resolution of the system, and smaller defects can be detected. The purpose of pulse width adjustment is to ensure that the width of the initial wave is as small as possible, which can improve the time resolution of the system, that is, it can distinguish closer defects.

[0082] It should be noted that the minimum wave width means that by adjusting the pulse width of the signal source, the generated ultrasonic signal is made as short as possible in time, which can more accurately capture the reflection and propagation of the signal during inspection, thereby improving the detection accuracy.

[0083] Specifically, before the inspection, when the distance between the immersion probe and the surface to be inspected is greater than the focal length, the motion control mechanism controls the angles of the A-axis and B-axis of the immersion probe to make the immersion probe perpendicular to the surface to be inspected of the part to be inspected. At this time, it helps to make the interface wave amplitude reach the highest, which is helpful for detecting more subtle defects.

[0084] It is understandable that after the motion control mechanism adjusts the immersion probe to a preset water distance from the part to be inspected, it is necessary to adjust the gain of the device to amplify or reduce the signal intensity so that the signal amplitude reaches about 80% of the maximum measurement range of the instrument.

[0085] It should be noted that adjusting the gain can help improve the signal clarity, making the echo signal easier to detect. When adjusting the gain, it is necessary to ensure that the signal intensity (i.e., amplitude) is close to 80% of the full scale displayed by the instrument. This is to ensure that the signal is strong enough for detection but not too strong to cause signal saturation and lose details. In short, it is to keep the signal intensity within a moderate range.

[0086] Specifically, the immersion probe is connected through a coaxial cable and an excitation interface, and the immersion probe is set at a preset water distance from the part to be inspected.

[0087] It is understandable that coaxial cables are usually used to transmit signals, ensuring that the signals reach the immersion probe from the device without interference to generate ultrasonic waves.

[0088] It should be noted that an ultrasonic immersion probe with a suitable frequency, focal length, and wafer diameter is pre-selected according to ultrasonic C-scan and connected to the device interface of the ultrasonic immersion scanning device. When connecting and installing, it should be ensured that there is no water residue at the interface, and the sealing strip should be tightened after installation.

[0089] It is understandable that when the immersion probe outputs ultrasonic signals to each surface to be inspected of the part to be inspected, it is perpendicular to the surface to be inspected. The immersion probe is also used to receive the time-domain waveforms reflected by each surface to be inspected and send them to the analysis unit.

[0090] It should be noted that the frequency of the immersion probe can be 1 MHz, 2 MHz, 5 MHz, 10 MHz, 15 MHz, 25 MHz, or a value between 1 MHz and 25 MHz. The diameter of the immersion probe can be 3 mm, 6 mm, 9 mm, 15 mm, 19 mm, 25 mm, or a value between 3 mm and 25 mm. The focal length of the ultrasonic immersion probe can be 25 mm, 50 mm, 75 mm, or a value between 25 mm and 75 mm. The above values are only used for example explanations and do not specifically limit the relevant parameters of the actual immersion probe.

[0091] Specifically, the immersion probe includes: a focusing probe and a receiving probe.

[0092] It should be noted that the focusing probe is used to output ultrasonic signals to each surface to be inspected of the part to be inspected. The receiving probe is used to receive the time-domain waveforms reflected by each surface to be inspected and send them to the analysis unit.

[0093] It is understandable that during the actual detection process, the focusing probe maintains a perpendicular relationship with the surface to be inspected of the workpiece to be inspected, but the distance between the focusing probe and the surface to be inspected can be the focal length of the focusing probe or less than the focal length.

[0094] Specifically, the analysis unit is used to convert all time-domain waveforms into frequency-domain signals, and determine whether the coating porosity calculation requirements are met according to all the frequency-domain signals; if so, the coating porosity range of the workpiece to be inspected is calculated based on the center frequency and peak frequency in the frequency-domain signals.

[0095] It is understandable that the analysis unit includes a conversion module, a judgment module, and a calculation module.

[0096] Among them, the conversion module is used to receive all time-domain waveforms. For each time-domain waveform, according to the Fast Fourier Transform (FFT) algorithm, the time-domain waveform is converted into a frequency-domain signal, and the center frequency X i and peak frequency Y i of the frequency-domain signal are extracted.

[0097] The judgment module is used to select the maximum center frequency X imax , the minimum center frequency X imin , the maximum peak frequency Y imax and the minimum peak frequency Y imin from all the center frequencies and peak frequencies; calculate the first pore uniformity value Z1 according to the maximum center frequency X imax and the minimum center frequency X imin , and calculate the second pore uniformity value Z2 according to the maximum peak frequency Y imax and the minimum peak frequency Y imin ; mark the larger value of the first pore uniformity value Z1 and the second pore uniformity value Z2 as the target pore uniformity value Z; if the target pore uniformity value is less than the threshold, it is determined that the coating porosity calculation requirements are met.

[0098] It is understandable that the first pore uniformity value Z1 is calculated according to the maximum center frequency X imax and the minimum center frequency X imin , as shown in formula (1) specifically.

[0099] Z1 = (X imax - X imin ) / X imax × 100% (1)

[0100] The second pore uniformity value Z2 is calculated according to the maximum peak frequency Y imax and the minimum peak frequency Y imin , as shown in formula (2) specifically.

[0101] Z2 = (Y imax - Y imin ) / Y imax × 100% (2)

[0102] It should be noted that if Z1 is greater than Z2, then Z1 is marked as the target pore uniformity value Z; if Z2 is greater than Z1, then Z2 is marked as the target pore uniformity value Z.

[0103] It can be understood that if the target pore uniformity value is less than the threshold value, it is determined that the coating porosity calculation requirements are met. If the target pore uniformity value is not less than the threshold value, it is determined that the coating porosity calculation requirements are not met, and the overall porosity value of the coating cannot be calculated. For example, if the target pore uniformity value Z is less than 20%, it is determined that the coating porosity calculation requirements are met.

[0104] A calculation module, configured to, when the coating porosity calculation requirements are met, calculate an average value based on all center frequencies and peak frequencies and match the average value with a standard test block to obtain the coating porosity range of the workpiece to be inspected.

[0105] It can be understood that the calculation module is specifically configured to calculate the average center frequency based on all center frequencies, and calculate the average peak frequency based on all peak frequencies; match multiple standard test blocks corresponding to different coating porosity ranges with the average center frequency and the average peak frequency to obtain the coating porosity range of the workpiece to be inspected.

[0106] It should be noted that in each standard test block, the center frequency corresponds to a value range, and the peak frequency corresponds to a value range. When the average center frequency and the average peak frequency respectively correspond to the center frequency value range and the peak frequency value range of the same standard test block, it is determined that the workpiece to be inspected matches the current standard test block. Therefore, the coating porosity range corresponding to the current standard test block is the coating porosity range of the workpiece to be inspected.

[0107] It should be particularly noted that the standard test block is a test block with the same coating as the workpiece to be inspected, and each standard test block corresponds to a coating porosity range, such as 0 - 20%, 20% - 40%, 40% - 60%, 60% - 80%, etc.

[0108] In practical applications, the analysis unit further includes: an acquisition and display module.

[0109] Among them, the acquisition and display module is configured to acquire the time-domain waveform received by the immersion probe; the acquisition and display module is further configured to display the time-domain waveform, and / or, the frequency-domain signal.

[0110] It should be noted that the acquisition and display module includes an analog-to-digital conversion acquisition card (AD acquisition card) and an oscilloscope.

[0111] It is understandable that the sampling frequency of the acquisition and display module is at least 10 times the nominal frequency of the probe, and the sampling length should at least include a complete waveform.

[0112] In the embodiment of the present invention, by utilizing the difference in the sensitivity of ultrasonic waves with different frequencies to pores, that is, the characteristic that high-frequency ultrasonic waves are more sensitive to micro-pores, the semi-quantitative detection of the porosity of the coating is realized by observing the change of the wave frequency. Compared with the traditional ultrasonic detection method, this method has higher accuracy and convenience, and is particularly suitable for the detection of the porosity of thermal spray coatings with a thickness range of 0.8 - 2.5 mm.

[0113] Specifically, the present invention performs frequency-domain processing on the ultrasonic signals of the sealing coating and analyzes the spectral structure to realize the non-destructive evaluation of the porosity. This method is not only applicable to the semi-quantitative detection of the porosity of the sealing coating, but also can be used for the detection of thermal barrier coatings and wear-resistant coatings. Through frequency-domain signal analysis, the range of the porosity inside the coating can be obtained, and more information about the material inside can be further acquired. This has important application value in aspects such as the research of coating materials, material selection, optimization of thermal spray processes, and defect control.

[0114] Generally speaking, the present invention can accurately and conveniently evaluate the porosity of the coating, providing strong technical support for the research and production in related fields.

[0115] Corresponding to the semi-quantitative device for detecting the porosity of a coating by water immersion ultrasonic provided in the above embodiment of the present invention, refer to Figure 3 , which shows the flowchart of a semi-quantitative method for detecting the porosity of a coating by water immersion ultrasonic provided in the embodiment of the present invention.

[0116] It is understandable that this semi-quantitative method for detecting the porosity of a coating by water immersion ultrasonic is applied to the semi-quantitative device for detecting the porosity of a coating by water immersion ultrasonic shown above, and includes: Figure 1 Step S301: Use the water immersion ultrasonic scanning device to determine the corresponding scanning method according to the surface to be inspected of the workpiece to be inspected.

[0117] Step S302: Based on the scanning method, use the water immersion probe of the water immersion ultrasonic scanning device to output ultrasonic signals to each surface to be inspected of the workpiece to be inspected, and receive the time-domain waveforms reflected by each surface to be inspected and send them to the analysis unit.

[0118] Step S303: The analysis unit converts all the time-domain waveforms into frequency-domain signals.

[0119] Step S304: Judge whether the requirements for calculating the porosity of the coating are met according to all the frequency-domain signals.

[0120] Step S304: Determine whether the requirements for calculating the coating porosity are met based on all the frequency-domain signals.

[0121] Step S305: If the condition is satisfied, calculate the coating porosity range of the workpiece to be inspected based on the center frequency and peak frequency in the frequency-domain signal.

[0122] It should be noted that the specific implementation manners of steps S301 to S305 can be found in the above Figure 1 and Figure 2 content shown, which will not be elaborated here.

[0123] In the embodiment of the present invention, this method utilizes the difference in the sensitivity of ultrasonic waves with different frequencies to pores, that is, the characteristic that high-frequency ultrasonic waves are more sensitive to minute pores. By observing the change in wave frequency, semi-quantitative detection of the coating porosity is achieved. This method can be widely applied to sealing coatings, thermal barrier coatings, and wear-resistant coatings, providing porosity range information, with high accuracy and convenience, and supporting coating material research and process optimization.

[0124] To better explain a semi-quantitative method for detecting coating porosity by immersion ultrasonic testing proposed in the embodiment of the present invention, see the following examples for a detailed illustration of this method.

[0125] Example 1, the process of immersion ultrasonic testing the porosity of an aluminum-silicon coating planar square is as follows:

[0126] (1) Place the workpiece to be inspected and install the probe

[0127] Install an immersion ultrasonic focused probe with a nominal frequency of 10 MHz, a focusing depth of 76 mm, and a wafer diameter of 9.5 mm on the immersion ultrasonic C-scan device, ensure that the connection between the probe and the device is dry and sealed, place the workpiece to be inspected on a horizontal glass plate (i.e., a turntable), and remove the bubbles on the surface of the coating square.

[0128] (2) Adjust the device

[0129] Connect the excitation interface of the immersion ultrasonic C-scan device to the probe respectively using coaxial cables, control the movement of the probe and the turntable using the motion control mechanism, adjust the excitation signal frequency of the immersion ultrasonic C-scan device to 10 MHz, adjust the pulse width, and at a distance greater than the focal length between the probe and the surface to be inspected, adjust the angles of the A-axis and B-axis of the probe to make the amplitude of the interface wave the highest, and adjust the water distance to 70 mm for gain adjustment to make the signal amplitude reach 81% of the total scale.

[0130] (3) Signal processing and recording

[0131] Record the time-domain waveform received by the receiving probe, convert this waveform into a frequency-domain signal through fast Fourier transform (FFT), and record the center frequency X i and peak frequency Y i .

[0132] (4)Scanning

[0133] The immersion probe scans the part to be inspected point by point under the drive of the mechanical system, records the X i and Y i at each scanning position, and the maximum values obtained are X imax and Y imax respectively, and the minimum values obtained are X imin and Y imin .

[0134] (5)Judging the porosity uniformity

[0135] According to the formulas Z1 = (X imax - X imin ) / X imax × 100%; Z2 = (Y imax - Y imin ) / Y imax × 100% to calculate the values of Z1 and Z2, select the larger number of Z1 and Z2 as the Z value. If the Z value is greater than 20%, the porosity uniformity of the coating does not meet the requirements, and the overall porosity value of the coating cannot be calculated; if the Z value is less than 20%, the calculation of the finishing porosity of the coating can be carried out.

[0136] (6)Semi - quantitative calculation of porosity

[0137] For the coating with qualified porosity uniformity, take the average values of X i and Y i at different scanned positions, and compare them with the standard test block to obtain the porosity range.

[0138] Example 2, the process of immersion ultrasonic testing the porosity of the compressor casing coating is as follows:

[0139] (1)Placing the part to be inspected and installing the probe

[0140] Install the immersion ultrasonic focused probe with a nominal frequency of 15 MHz, a focusing depth of 1 inch, and a wafer diameter of 0.375 inch on the immersion ultrasonic C - scan device, ensure that the connection between the probe and the device is dry and sealed, fasten the compressor casing with a three - jaw chuck on the immersion ultrasonic C - scan device from the inside, and remove the bubbles on the surface of the compressor casing coating.

[0141] (2)Adjusting the equipment

[0142] Connect the excitation interface of the immersion ultrasonic C-scan device to the probe using coaxial cables respectively. Control the movement of the probe and the turntable using the motion control mechanism. Adjust the excitation signal frequency of the immersion ultrasonic C-scan device to 15 MHz, adjust the pulse width. At a distance greater than the focal length between the probe and the surface to be inspected, adjust the angles of the A-axis and B-axis of the probe to make the amplitude of the interface wave the highest. Adjust the water distance to 25 mm and adjust the gain so that the signal amplitude reaches 78% of the total scale.

[0143] (3) Signal processing and recording

[0144] Record the amplitude A1 of the time-domain waveform received by the receiving probe i , convert this waveform into a frequency-domain signal through fast Fourier transform (FFT), and record the amplitude A2 of the second harmonic signal of the nominal frequency of the probe i .

[0145] (4) Scanning

[0146] The immersion probe scans the part to be inspected point by point driven by the mechanical system, and record the X i and Y i at each scanning position. The maximum values obtained are X imax and Y imax respectively, and the minimum values obtained are X imin and Y imin .

[0147] (5) Judging the porosity uniformity

[0148] Calculate the values of Z1 and Z2 according to the formulas Z1 = (X imax - X imin ) / X imax × 100%; Z2 = (Y imax - Y imin ) / Y imax × 100%. Select the larger number of Z1 and Z2 as the Z value. If the Z value is greater than 20%, the porosity uniformity of the coating does not meet the requirements and the overall porosity value of the coating cannot be calculated; if the Z value is less than 20%, the calculation of the finishing porosity of the coating can be carried out.

[0149] (6) Semi-quantitative calculation of porosity

[0150] For the coating with qualified coating air uniformity, take the average values of X i and Y i at different scanned positions, compare it with the standard test block, and the porosity range can be obtained.

[0151] Example 3, the process of detecting the porosity of the air coating of the three-dimensional curved surface structure blade by immersion ultrasonic is as follows:

[0152] (1) Place the part to be inspected and install the probe

[0153] Install a water-immersion ultrasonic focusing probe with a nominal frequency of 25 MHz, a focusing depth of 2 inches, and a wafer diameter of 0.25 inches on the water-immersion ultrasonic C-scan device, ensuring that the connection between the probe and the device is dry and sealed. Place the three-dimensional curved surface structure blade on a horizontal glass plate (i.e., the turntable), and remove the air bubbles on the surface of the blade coating.

[0154] (2) Adjust the device

[0155] Connect the excitation interface of the water-immersion ultrasonic C-scan device to the probe using coaxial cables respectively. Use the motion control mechanism to control the movement of the probe and the turntable. Adjust the excitation signal frequency of the water-immersion ultrasonic C-scan device to 25 MHz, adjust the pulse width. When the distance between the probe and the surface to be inspected is greater than the focal length, adjust the angles of the A-axis and B-axis of the probe to make the amplitude of the interface wave the highest. Adjust the water distance to 50 mm to adjust the gain so that the signal amplitude reaches 80% of the total scale.

[0156] (3) Signal processing and recording

[0157] Record the time-domain waveform received by the receiving probe, convert this waveform into a frequency-domain signal through fast Fourier transform (FFT), and record the center frequency X i and the peak frequency Y i .

[0158] (4) Scanning

[0159] The water-immersion probe scans the part to be inspected point by point under the drive of the mechanical system, and records X i and Y i at each scanning position. The maximum values obtained are X imax and Y imax respectively, and the minimum values obtained are X imin and Y imin .

[0160] (5) Judge the porosity uniformity

[0161] Calculate the values of Z1 and Z2 according to the formulas Z1 = (X imax - X imin ) / X imax × 100%; Z2 = (Y imax - Y imin ) / Y imax × 100%. Select the larger number among Z1 and Z2 as the Z value. If the Z value is greater than 20%, the porosity uniformity of the coating does not meet the requirements, and the overall porosity value of the coating cannot be calculated; if the Z value is less than 20%, the calculation of the overall porosity of the coating can be carried out.

[0162] (6)Semi - quantitative calculation of porosity

[0163] For a coating with a compliant coating air void uniformity, take the average value of X i and Y i at different scanned positions, and compare it with a standard test block to obtain the porosity range.

[0164] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for a system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For related parts, reference can be made to the partial description of the method embodiment. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0165] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0166] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A semi-quantitative device for detecting the porosity of a coating by water immersion ultrasonic testing, characterized in that: The device comprises: a water immersion ultrasonic scanning device and an analysis unit; The water immersion ultrasonic scanning device is used to determine a corresponding scanning mode according to the surface to be inspected of the object to be inspected, and based on the scanning mode, use the water immersion probe of the water immersion ultrasonic scanning device to output an ultrasonic signal to each surface to be inspected of the object to be inspected, and receive a time domain waveform reflected by each surface to be inspected to send to the analysis unit; The analysis unit is used to convert all time domain waveforms into frequency domain signals, and determine whether the coating porosity calculation requirements are met based on all frequency domain signals; if met, the coating porosity range of the test piece is calculated based on the center frequency and peak frequency in the frequency domain signals.

2. The device according to claim 1, characterized in that The water immersion ultrasonic scanning device comprises: an excitation interface, a water immersion probe, a turntable and a motion control mechanism; The turntable is placed under a horizontal plane after horizontal adjustment, and the turntable is parallel to the horizontal plane; The turntable is used to place the object to be inspected; The motion control mechanism is connected to the immersion probe and the turntable respectively; The motion control mechanism is used to determine a corresponding scanning mode according to the surface to be inspected of the object to be inspected, and control the movement of the turntable and the immersion probe based on the scanning mode so that the immersion probe can detect the object to be inspected; and is also used to adjust the frequency of the excitation signal to be consistent with the nominal frequency of the immersion probe; The immersion probe is connected to the excitation interface via a coaxial cable; The immersion probe is used to maintain perpendicularity to each surface to be inspected when outputting ultrasonic signals to each surface to be inspected of the object to be inspected; and is also used to receive the time domain waveform reflected by each surface to be inspected and send it to the analysis unit.

3. The device according to claim 1, characterized in that The immersion probe comprises: a focusing probe and a receiving probe; The focusing probe is used to output an ultrasonic signal to each surface to be inspected of the object to be inspected; The receiving probe is used to receive the time domain waveform reflected by each of the to-be-tested surfaces and send it to the analyzing unit.

4. The device according to claim 2, characterized in that The motion control mechanism that determines the corresponding scanning mode according to the surface to be inspected of the object to be inspected is specifically used for: When the surface to be inspected of the object to be inspected is a plane, determining that the scanning mode of the surface to be inspected is a two-axis motion mode; When the surface to be inspected of the object to be inspected is a regular curved surface, determining that the scanning method of the surface to be inspected is a turntable scanning method; When the surface to be inspected of the object to be inspected is an irregular curved surface, the scanning method of the surface to be inspected is determined to be a laser profiling method.

5. The device according to claim 2, characterized in that The motion control mechanism for controlling the turntable and the immersion probe to move based on the scanning mode is specifically used for: When the scanning mode is a turntable scanning mode, controlling the turntable to rotate; According to the scanning mode, the pulse width of the immersion probe is adjusted so that the initial wave width reaches a preset minimum value, and the water distance between the immersion probe and the inspection surface of the inspection object is adjusted; The angles of the A axis and the B axis of the immersion probe are controlled so that the immersion probe and the surface to be inspected of the object to be inspected are perpendicular to each other.

6. The device according to claim 1, characterized in that The analysis unit includes: a conversion module, a judgment module and a calculation module; The conversion module is used to receive all time domain waveforms, convert each of the time domain waveforms into a frequency domain signal according to a fast Fourier transform algorithm, and extract the center frequency and peak frequency of the frequency domain signal; The judgment module is used to select the maximum center frequency, the minimum center frequency, the maximum peak frequency and the minimum peak frequency from all center frequencies and peak frequencies; calculate a first pore uniform value according to the maximum center frequency and the minimum center frequency, and calculate a second pore uniform value according to the maximum peak frequency and the minimum peak frequency; mark the larger value of the first pore uniform value and the second pore uniform value as a target pore uniform value; if the target pore uniform value is less than a threshold value, it is determined that the coating porosity calculation requirement is met; The calculation module is used to calculate an average value according to all center frequencies and peak frequencies and match the average value with a standard test block to obtain the coating porosity range of the test piece when the coating porosity calculation requirements are met.

7. The device according to claim 6, characterized in that The calculation module for obtaining the coating porosity range of the test piece by calculating the average value according to all center frequencies and peak frequencies and matching the average value with a standard test block is specifically used for: Calculating the average of center frequencies from all center frequencies and calculating the average of peak frequencies from all peak frequencies; A plurality of standard test blocks corresponding to different coating porosity ranges are matched with the center frequency average value and the peak frequency average value to obtain the coating porosity range of the test piece.

8. The device according to claim 1, characterized in that The analysis unit also includes: an acquisition and display module; The acquisition and display module is used to acquire the time domain waveform received by the immersion probe; and is also used to display the time domain waveform and / or the frequency domain signal.

9. The device according to claim 8, characterized in that The acquisition and display module includes an analog-to-digital conversion acquisition card and an oscilloscope.

10. A semi-quantitative method for detecting the porosity of a coating by water immersion ultrasonic testing, characterized in that: A semi-quantitative device for detecting the porosity of a coating by water immersion ultrasonic testing as claimed in any one of claims 1 to 9, comprising: Using water immersion ultrasonic scanning equipment to determine the corresponding scanning method according to the surface to be inspected of the object to be inspected; Based on the scanning method, the water immersion probe of the water immersion ultrasonic scanning device is used to output an ultrasonic signal to each surface to be inspected of the inspected object, and a time domain waveform reflected by each surface to be inspected is received and sent to an analysis unit; Convert all time domain waveforms into frequency domain signals by the analysis unit; Determine whether the coating porosity calculation requirements are met based on all frequency domain signals; If satisfied, the coating porosity range of the test piece is calculated based on the center frequency and peak frequency in the frequency domain signal.

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