A method and system for detecting the electrical conductivity of a metal surface coated with silver nanoparticles

Abstract

The present application provides a method and system for detecting the conductive properties of a metal surface coated with a nanosilver coating. The method collects the induced signals of the coated metal sample under alternating electromagnetic fields at different test frequencies; selects a test frequency as a selected test frequency, determines the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample based on the induced signals at the selected test frequency, and identifies the electromagnetic attenuation of the induced eddy current flowing through different depths of the coated metal sample based on the electric field reflection relationship; identifies the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuations; determines the frequency constraint conditions for the conductive properties detection based on the cumulative migration amounts at all test frequencies, and detects the surface conductivity of the coated metal sample according to the frequency constraint conditions. The solution of the present application can avoid the interference of the skin effect while limiting the influence of surface roughness on eddy current detection.

Description

Technical Field

[0001] The present application relates to the field of material detection technology, and more specifically, to a method and system for detecting the conductive properties of a metal surface with a nano-silver coating. Background Art

[0002] Nanosilver-coated metal is a composite material made by uniformly attaching silver particles (typically 1 to 100 nanometers in size) to the surface of a metal substrate (such as stainless steel, copper, and aluminum) using nanotechnology. The nano-sizing of silver imparts unique surface and quantum effects, endowing the coating with excellent antibacterial properties, high electrical conductivity, and catalytic activity. The electrical conductivity of nanosilver-coated metal is particularly critical in the field of electronic components.

[0003] In the prior art, because nanosilver coatings are easily damaged, resulting in changes in surface conductivity, they are usually detected through non-destructive and non-contact means, with eddy current testing being the most commonly used detection method. However, in practical applications, due to the high conductivity of nanosilver coatings, the skin depth inside the sample during low-frequency eddy current testing is usually greater than the thickness of the nanosilver coating. As a result, the collected sensing data does not come from the surface conductivity of the sample, but rather from the mutual coupling of the conductive properties of the coating metal and the base metal. In order to control the skin depth to be less than the thickness of the nanosilver coating (generally by controlling the eddy current testing frequency as high as possible), ultra-high frequency eddy current testing is usually used. However, at ultra-high frequencies, eddy current data is greatly affected by the surface roughness of the nanosilver coating, resulting in a very low signal-to-noise ratio in the collected sensing data. This requires that the eddy current testing frequency be controlled within a minimum range. Therefore, how to avoid interference from the skin effect while limiting the impact of surface roughness on eddy current testing has become a difficult problem facing the industry. Summary of the Invention

[0004] The present application provides a method and system for detecting the conductive properties of a metal surface with a nano-silver coating, which can avoid the interference of the skin effect while limiting the influence of surface roughness on eddy current detection.

[0005] In a first aspect, the present application provides a method for detecting the conductive properties of a metal surface of a nanosilver coating, wherein a coated metal sample is prepared in advance, and the method comprises:

[0006] Applying alternating electromagnetic fields of different test frequencies to the coated metal sample, and collecting induced signals of the coated metal sample under the alternating electromagnetic fields of each test frequency;

[0007] selecting a test frequency as a selected test frequency, determining an electric field reflection relationship at an interface between a coating and a substrate in the coated metal sample based on an induced signal at the selected test frequency, identifying induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship, and then determining an electromagnetic attenuation between adjacent induced eddy currents;

[0008] Identifying the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts, and continuing to determine the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies;

[0009] The frequency constraint conditions for the electrical conductivity test are determined by all the accumulated migration amounts, and the coated metal sample is subjected to non-destructive eddy current testing according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

[0010] In some embodiments, determining the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample according to the induction signal at the selected test frequency specifically includes:

[0011] Decomposing the induced signal into a plurality of standing wave components;

[0012] Determine the energy concentration ratio of each standing wave component;

[0013] screening out the reflected wave component reflected from the interface between the coating and the substrate in the coated metal sample from all standing wave components according to all energy concentration rates;

[0014] The electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined based on all the reflected wave components.

[0015] In some embodiments, identifying the induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship specifically includes:

[0016] removing the fluctuation characteristic corresponding to the electric field reflection relationship from the sensing signal to obtain an incident sensing signal;

[0017] determining eddy current signals of different frequency bands according to the incident induced signal;

[0018] Determine the dominant frequency of each eddy current signal;

[0019] All eddy current signals are rearranged into induced eddy currents flowing through different depths of the coated metal sample according to the dominant frequencies of the eddy current signals.

[0020] In some embodiments, determining the electromagnetic attenuation between adjacent induced eddy currents specifically includes:

[0021] Determine the electromagnetic energy of each induced eddy current;

[0022] The electromagnetic attenuation between each two adjacent induced eddy currents is determined according to the electromagnetic energy of each two adjacent induced eddy currents.

[0023] In some embodiments, identifying the cumulative migration amount of the charge skin effect in the coated metal sample at a selected test frequency based on all electromagnetic attenuation amounts specifically includes:

[0024] Performing differential fitting on all electromagnetic attenuation indices to obtain an electromagnetic attenuation curve in the coated metal sample;

[0025] obtaining a nominal thickness of a coating in the coated metal sample;

[0026] The electromagnetic attenuation curve is integrated according to the nominal thickness to obtain the cumulative migration amount of the charge skin effect in the coated metal sample at a selected test frequency.

[0027] In some embodiments, determining the frequency constraint condition for the conductivity test based on all the accumulated migration amounts specifically includes:

[0028] Convert all the cumulative migration amounts into migration amount sequences according to the test frequency;

[0029] determining a migration threshold of the base metal charge in the coating metal sample according to the migration sequence;

[0030] The minimum test frequency that can avoid the skin effect of the base metal is deduced based on all migration thresholds, and the minimum test frequency is used as the frequency constraint condition for the conductive performance detection.

[0031] In some embodiments, an eddy current probe is used to collect the induction signal of the coated metal sample under the alternating electromagnetic field of each test frequency.

[0032] In some embodiments, the coated metal sample includes a coating metal and a base metal.

[0033] In some embodiments, pre-preparing the coated metal sample means cutting a product block of a preset size from the nano-silver coated metal product, and using the cut product block as the coated metal sample.

[0034] In a second aspect, the present application provides a system for detecting the conductive properties of a metal surface with a nano-silver coating, comprising:

[0035] An acquisition module is used to apply alternating electromagnetic fields of different test frequencies to a pre-prepared coated metal sample and to acquire the induction signals of the coated metal sample under the alternating electromagnetic fields of each test frequency;

[0036] a processing module, configured to select a test frequency as a selected test frequency, determine an electric field reflection relationship at an interface between a coating and a substrate in the coated metal sample based on an induced signal at the selected test frequency, identify induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship, and further determine an electromagnetic attenuation between adjacent induced eddy currents;

[0037] The processing module is further configured to identify the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts, and continue to determine the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies;

[0038] The execution module is used to determine the frequency constraint conditions of the conductive performance test through all the cumulative migration amounts, and perform non-destructive eddy current testing on the coated metal sample according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

[0039] The technical solutions provided by the embodiments disclosed in this application have the following beneficial effects:

[0040] The present application provides a method and system for detecting the conductive properties of a metal surface of a nanosilver coating. First, an alternating electromagnetic field of different test frequencies is applied to a pre-prepared coated metal sample, and the induced signals of the coated metal sample under the alternating electromagnetic field of each test frequency are collected; a test frequency is selected as a selected test frequency, and the electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined based on the induced signal at the selected test frequency. Based on the electric field reflection relationship, the induced eddy currents flowing through different depths of the coated metal sample are identified, and then the electromagnetic attenuation between each adjacent induced eddy current is determined; based on all the electromagnetic attenuations, the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency is identified, and the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies is further determined; the frequency constraint conditions for the conductive performance detection are determined based on all the cumulative migration amounts, and the coated metal sample is subjected to non-destructive eddy current testing according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

[0041] It can be seen that the present application applies alternating electromagnetic fields of different test frequencies and collects induced signals, selects a selected test frequency to determine the electric field reflection relationship between the coating and the substrate interface, thereby identifying the induced eddy currents at different sample depths and determining the electromagnetic attenuation in the sample (i.e., the amount of electromagnetic attenuation), and then obtains the cumulative migration amount of charge caused by the skin effect at each frequency. Finally, the constraint conditions (i.e., frequency constraints) when the base metal does not have a skin effect are defined by the cumulative migration amount, and finally eddy current detection is performed according to the constraints. This solves the contradiction that the surface roughness has a large influence at high frequencies in the background and the skin depth exceeds the coating thickness at low frequencies. While avoiding the interference of the skin effect, the influence of the surface roughness on the eddy current detection is limited, and the purpose of accurately detecting the conductive properties of the nano-silver coated metal surface is achieved. In summary, the solution of the present application can limit the influence of the surface roughness on the eddy current detection while avoiding the interference of the skin effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is an exemplary flow chart of a method for detecting the conductive properties of a metal surface of a nanosilver coating according to some embodiments of the present application;

[0043] Figure 2 is an exemplary flow chart of determining an electric field reflection relationship according to some embodiments of the present application;

[0044] Figure 3 is a schematic diagram of the principle of electric field reflection according to some embodiments of the present application;

[0045] Figure 4 Schematic diagram of the structure of the metal surface conductivity detection system of the nanosilver coating according to some embodiments of the present application;

[0046] Figure 5 It is a structural schematic diagram of a computer device for implementing a method for detecting the conductive properties of a metal surface of a nanosilver coating according to some embodiments of the present application. DETAILED DESCRIPTION

[0047] In order to better understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0048] refer to Figure 1 , which is an exemplary flow chart of a method for detecting the conductive properties of a metal surface of a nano-silver coating according to some embodiments of the present application. The method 100 for detecting the conductive properties of a metal surface of a nano-silver coating mainly includes the following steps:

[0049] In step 101, alternating electromagnetic fields of different test frequencies are applied to a pre-prepared coated metal sample, and induction signals of the coated metal sample under the alternating electromagnetic fields of each test frequency are collected.

[0050] In some embodiments, the pre-preparation of the coated metal sample can be achieved in the following manner, namely: preparing the coated metal sample means cutting a product block of a preset size from the nanosilver-coated metal product, and using the cut product block as the coated metal sample, wherein the preset size can be preset according to actual needs. For example, the present application sets the preset size to 10×10 mm².

[0051] In specific implementation, the application of alternating electromagnetic fields of different test frequencies to the pre-prepared coated metal sample can be achieved in the following manner, namely: using a signal generator to generate alternating signals of different test frequencies, inputting the signals into the excitation coil of the eddy current detection probe through a power amplifier, bringing the probe 1 cm close to the surface of the coated metal sample, and switching the preset frequencies in sequence through the control system. Those skilled in the art know that the preset frequencies can be randomly selected from the range of 1 MHz to 10 GHz, and the total number of preset frequencies can be set according to actual needs, which will not be repeated here.

[0052] In specific implementation, the collection of the induced signals of the coated metal sample under the alternating electromagnetic field of each test frequency can be achieved in the following manner, namely: the detection coil of the eddy current detection probe is used to synchronously collect the magnetic field signals generated by the induced eddy currents on the sample surface under the alternating electromagnetic field of each test frequency, and each analog signal is converted into a digital signal through a data acquisition card, and the converted digital signals are used as the induced signals of the coated metal sample under the alternating electromagnetic field of each test frequency.

[0053] In step 102, a test frequency is selected as a selected test frequency, and the electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined based on the induced signal at the selected test frequency. Based on the electric field reflection relationship, the induced eddy currents flowing through the coated metal sample at different depths are identified, and then the electromagnetic attenuation between each adjacent induced eddy current is determined.

[0054] In some embodiments, reference Figure 2 This figure is an exemplary flow chart of determining an electric field reflection relationship according to some embodiments of the present application. In the present application, determining the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample based on the induced signal at a selected test frequency can be achieved by using the following steps:

[0055] In step 1021, the sensing signal is decomposed into a plurality of standing wave components;

[0056] In step 1022, the energy concentration ratio of each standing wave component is determined;

[0057] In step 1023, the reflected wave component reflected from the interface between the coating and the substrate in the coated metal sample is screened out from all standing wave components according to all energy concentration rates;

[0058] In step 1024, the electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined based on all the reflected wave components.

[0059] In a specific implementation, the decomposition of the induced signal into multiple standing wave components can be achieved in the following manner, that is, as a preferred embodiment, the induced signal can be decomposed into multiple eigenmode functions by the empirical mode decomposition method in the prior art, and each eigenmode function obtained by the decomposition is used as a standing wave component.

[0060] It should be noted that the standing wave component in the present application is a fluctuation signal with standing wave characteristics of a specific frequency in the induction signal.

[0061] In specific implementation, the energy concentration rate of each standing wave component can be determined by calculating the kurtosis of each standing wave component and using the kurtosis of each standing wave component as the energy concentration rate of each standing wave component.

[0062] It should be noted that the energy concentration rate in this application is a parameter value that measures the degree of energy concentration of a component.

[0063] In specific implementation, the following method can be used to screen out the reflected wave component reflected at the interface between the coating and the substrate in the coated metal sample from all standing wave components based on all energy concentration rates, namely: first, calculate the average value of all energy concentration rates, and then use twice the average value as the energy threshold, and use all standing wave components with energy concentration rates greater than the energy threshold as the reflected wave component reflected at the interface between the coating and the substrate in the coated metal sample. Since there is an air interface between the coating and the substrate in the coated metal sample, the electric field will be reflected on the air interface to generate a reflected wave. Due to the interference effect, the reflected wave can also be set with an energy threshold by other methods to screen out the reflected wave with obviously concentrated energy, which will not be repeated here.

[0064] In specific implementation, determining the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample based on all reflected wave components can be achieved in the following manner, namely: the signal obtained by adding all reflected wave components is used as characterization data describing the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample.

[0065] It should be noted that the electric field reflection relationship in this application refers to the fluctuation characteristics of the electric field at the interface between the coating and the substrate in the coated metal sample caused by reflection.

[0066] In some embodiments, reference Figure 3This figure is a schematic diagram of the principle of electric field reflection shown in some embodiments of the present application. After the electric field is emitted from the coated metal and passes through the interface between the coating and the substrate, part of the electric field is transmitted into the base metal, causing a skin effect on the base metal, and the other part of the electric field is reflected by the interface between the coating and the substrate and then emitted from the coated metal to the surface of the coated metal sample.

[0067] In some embodiments, identifying the induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship can be achieved by using the following steps:

[0068] removing the fluctuation characteristic corresponding to the electric field reflection relationship from the sensing signal to obtain an incident sensing signal;

[0069] determining eddy current signals of different frequency bands according to the incident induced signal;

[0070] Determine the dominant frequency of each eddy current signal;

[0071] All eddy current signals are rearranged into induced eddy currents flowing through different depths of the coated metal sample according to the dominant frequencies of the eddy current signals.

[0072] In a specific implementation, removing the fluctuation characteristics corresponding to the electric field reflection relationship from the sensing signal to obtain the incident sensing signal can be achieved in the following manner, namely: subtracting the characterization data corresponding to the electric field reflection relationship from the sensing signal, the characterization data being data characterizing the fluctuation characteristics corresponding to the electric field reflection relationship, and then using the signal obtained after the subtraction as the incident sensing signal.

[0073] It should be noted that the incident sensing signal in this application refers to the sensing signal after removing the signal reflected from the interface between the coating and the substrate.

[0074] In a specific implementation, the eddy current signals of different frequency bands can be determined based on the incident induced signal in the following manner, namely, the incident induced signal is decomposed into multiple wavelet components by wavelet decomposition in the prior art, and each of the decomposed wavelet components is used as the eddy current signal of different frequency bands, wherein the wavelet decomposition is performed using a Haar wavelet basis.

[0075] It should be noted that the eddy current signal in this application is a fluctuation signal of the induced current within a specific frequency range.

[0076] In specific implementation, the dominant frequency of each eddy current signal can be determined in the following manner: first, each eddy current signal is subjected to a short-time Fourier transform, and the frequency with the largest amplitude in each transformed data is used as the dominant frequency of each eddy current signal.

[0077] It should be noted that the dominant frequency in this application is the frequency component with the largest amplitude in the eddy current signal.

[0078] In specific implementation, all eddy current signals are rearranged into induced eddy currents flowing through different depths of the coated metal sample according to the dominant frequency of each eddy current signal. This can be achieved in the following manner: according to the principle of skin effect, the frequency of the eddy current signal is inversely proportional to the penetration depth, so all eddy current signals can be arranged in descending order according to the dominant frequency of each eddy current signal. The arranged eddy current signals are the induced eddy currents flowing through different depths of the coated metal sample arranged in ascending order of depth.

[0079] It should be noted that, in this application, each induced eddy current is a plurality of signals describing the distribution of induced current from the surface layer to the deep layer in the coated metal sample.

[0080] In some embodiments, determining the electromagnetic attenuation between adjacent induced eddy currents may be achieved by using the following steps:

[0081] Determine the electromagnetic energy of each induced eddy current;

[0082] The electromagnetic attenuation between each two adjacent induced eddy currents is determined according to the electromagnetic energy of each two adjacent induced eddy currents.

[0083] In a specific implementation, the electromagnetic energy of each induced eddy current can be determined in the following manner: for each induced eddy current, each induced eddy current is squared and then summed, and each summed value is used as the electromagnetic energy of each induced eddy current.

[0084] It should be noted that the electromagnetic energy in this application is a parameter value that quantifies the energy of the induced eddy current.

[0085] In a specific implementation, determining the electromagnetic attenuation between each two adjacent induced eddy currents based on the electromagnetic energy of each two adjacent induced eddy currents can be achieved in the following manner, namely: subtracting the electromagnetic energy between each two adjacent induced eddy currents, and using the obtained difference as the electromagnetic attenuation between each two adjacent induced eddy currents, wherein subtracting the electromagnetic energy between each two adjacent induced eddy currents means subtracting the electromagnetic attenuation of two induced eddy currents adjacent in depth.

[0086] It should be noted that the electromagnetic attenuation in this application is a parameter value that measures the degree of electromagnetic energy attenuation between two induced eddy currents at adjacent depths.

[0087] In step 103, the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency is identified based on all electromagnetic attenuation amounts, and the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies is continuously determined.

[0088] In some embodiments, identifying the cumulative migration amount of the charge skin effect in the coated metal sample at a selected test frequency based on all electromagnetic attenuation amounts can be achieved by using the following steps:

[0089] Performing differential fitting on all electromagnetic attenuation indices to obtain an electromagnetic attenuation curve in the coated metal sample;

[0090] obtaining a nominal thickness of a coating in the coated metal sample;

[0091] The electromagnetic attenuation curve is integrated according to the nominal thickness to obtain the cumulative migration amount of the charge skin effect in the coated metal sample at a selected test frequency.

[0092] In specific implementation, all electromagnetic attenuation indices are differentially fitted to obtain the electromagnetic attenuation curve in the coated metal sample in the following manner, namely, the discrete data points of each adjacent electromagnetic attenuation are combined by spline interpolation in the prior art, and the fitted curve is used as the electromagnetic attenuation curve.

[0093] It should be noted that the electromagnetic attenuation curve in this application is a curve that describes the attenuation of electromagnetic energy in a coated metal sample at a specific test frequency.

[0094] It should be noted that the nominal thickness in this application can be obtained directly from the metal manufacturer of the nanosilver coating, for example, the nominal thickness of the coating set can be obtained directly from the device used by the manufacturer when performing the coating.

[0095] In a specific implementation, the electromagnetic attenuation curve is integrated according to the nominal thickness, and the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency is obtained by the following method: first, the nominal thickness is converted into a frequency value f according to the formula of the skin effect principle, wherein the magnetic permeability and electrical conductivity in the formula are taken as the magnetic permeability and electrical conductivity of pure metal silver; then, the electromagnetic attenuation curve is definite integrated, and the definite integral range is f to positive infinity. The value obtained by the integration is used as the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency.

[0096] It should be noted that the cumulative migration amount in this application is a parameter value that measures the total amount of charge in the coated metal sample migrating toward the sample surface at a specific test frequency.

[0097] In step 104, the frequency constraint conditions for the conductivity test are determined by all the accumulated migration amounts, and non-destructive eddy current testing is performed on the coated metal sample according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

[0098] In some embodiments, determining the frequency constraint condition for the conductivity test based on all the accumulated migration amounts can be achieved by using the following steps:

[0099] Convert all the cumulative migration amounts into migration amount sequences according to the test frequency;

[0100] determining a migration threshold of the base metal charge in the coating metal sample according to the migration sequence;

[0101] The minimum test frequency that can avoid the skin effect of the base metal is deduced based on all migration thresholds, and the minimum test frequency is used as the frequency constraint condition for the conductive performance detection.

[0102] In specific implementation, converting all the accumulated migration amounts into a migration amount sequence according to the test frequency can be achieved in the following way: ie, arranging all the accumulated migration amounts in ascending order according to the test frequency, and using the arranged sequence as the migration amount sequence.

[0103] In a specific implementation, determining the migration threshold of the base metal charge in the coated metal sample based on the migration sequence can be achieved in the following manner: first, calculating the Pearson autocorrelation coefficient of the migration sequence at different lag orders, then arranging all the Pearson autocorrelation coefficients in ascending order according to the size of the lag order, and subtracting a preset correlation threshold from each Pearson autocorrelation coefficient in the order of arrangement, recording the lag order corresponding to the first Pearson correlation coefficient whose subtraction result is less than zero, and using this lag order as the migration threshold of the base metal charge in the coated metal sample.

[0104] It should be noted that the migration threshold in this application is a parameter value that quantifies the critical state of charge migration of the base metal in the coated metal sample.

[0105] In specific implementation, the minimum test frequency that can avoid the skin effect of the base metal can be inferred based on all migration thresholds in the following way: first, the first N cumulative migration amounts are selected from the migration amount sequence, and the first N cumulative migration amounts are fitted into an exponential curve. Subsequently, the remaining cumulative migration amounts in the migration amount sequence are fitted into another exponential curve, and the horizontal coordinate of the intersection of the two exponential curves is used as the minimum test frequency that can avoid the skin effect of the base metal. The fitting can be performed by the least squares method in the prior art, and the dependent variables of the two curves are both cumulative migration amounts, and the independent variables are both test frequencies, and N is the migration threshold.

[0106] It should be noted that the frequency constraint in this application is the minimum frequency that limits the occurrence of skin effect on the base metal.

[0107] In a specific implementation, nondestructive eddy current testing of the coated metal sample is performed according to the frequency constraints. Obtaining the surface conductivity of the coated metal sample can be achieved by using the following method: starting at the minimum frequency within the frequency constraints, testing the conductivity of the coated metal sample according to the experimental procedure described in "Research on Conductivity Testing Methods for Thin Metal Materials Based on Multi-Frequency Eddy Currents," and using the measured conductivity as the surface conductivity of the coated metal sample.

[0108] In addition, in another aspect of the present application, in some embodiments, the present application provides a metal surface conductivity detection system of a nano silver coating, referring to Figure 4 , which is a schematic structural diagram of a system for detecting the conductive properties of a metal surface with a nano-silver coating according to some embodiments of the present application. The system 400 for detecting the conductive properties of a metal surface with a nano-silver coating includes: an acquisition module 401, a processing module 402, and an execution module 403, which are described as follows:

[0109] Acquisition module 401, in this application, acquisition module 401 is mainly used to apply alternating electromagnetic fields of different test frequencies to the pre-prepared coated metal sample, and collect the induced signals of the coated metal sample under the alternating electromagnetic fields of each test frequency;

[0110] Processing module 402, in the present application, is primarily configured to select a test frequency as a selected test frequency, determine an electric field reflection relationship at an interface between a coating and a substrate in the coated metal sample based on an induced signal at the selected test frequency, identify induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship, and further determine an electromagnetic attenuation between adjacent induced eddy currents;

[0111] It should be noted that the processing module 402 in the present application is further configured to identify the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts, and continue to determine the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies;

[0112] Execution module 403. In this application, execution module 403 is mainly used to determine the frequency constraint conditions for conductive performance detection through all cumulative migration amounts, perform non-destructive eddy current detection on the coated metal sample according to the frequency constraint conditions, and obtain the surface conductivity of the coated metal sample.

[0113] In addition, the present application also provides a computer device, which includes a memory and a processor, wherein the memory stores a code, and the processor is configured to obtain the code and execute the above-mentioned method for detecting the conductive properties of the metal surface of the nanosilver coating.

[0114] In some embodiments, reference Figure 5 , which is a schematic diagram of the structure of a computer device for implementing a method for detecting the conductive properties of a metal surface of a nano-silver coating according to some embodiments of the present application. The method for detecting the conductive properties of a metal surface of a nano-silver coating in the above embodiment can be performed by Figure 5 The computer device 500 shown in FIG. 5 is implemented as shown in FIG. 5 . The computer device 500 includes at least one processor 501 , a communication bus 502 , a memory 503 , and at least one communication interface 504 .

[0115] The processor 501 may be a general-purpose central processing unit (CPU) or an application-specific integrated circuit (ASIC).

[0116] The communication bus 502 may be used to transmit information between the aforementioned components.

[0117] The memory 503 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, a random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), a magnetic disk or other magnetic storage device, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto. The memory 503 may be independent and connected to the processor 501 via the communication bus 502. The memory 503 may also be integrated with the processor 501.

[0118] The memory 503 is used to store the program code for executing the solution of the present application, and is controlled by the processor 501 for execution. The processor 501 is used to execute the program code stored in the memory 503. The program code may include one or more software modules. The method for detecting the conductive properties of the metal surface of the nanosilver coating in the above embodiment can be implemented by the processor 501 and one or more software modules in the program code in the memory 503.

[0119] The communication interface 504 uses any device such as a transceiver to communicate with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area network (WLAN), etc.

[0120] In a specific implementation, as an example, a computer device may include multiple processors, each of which may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0121] The aforementioned computer device can be a general-purpose computer device or a dedicated computer device. In a specific implementation, the computer device can be a desktop computer, a portable computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, or an embedded device. The embodiments of this application do not limit the type of computer device.

[0122] In addition, the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for detecting the conductive properties of the metal surface of the nanosilver coating.

[0123] In summary, in the method and system for detecting the conductive properties of the metal surface of the nanosilver coating disclosed in the embodiment of the present application, first, an alternating electromagnetic field of different test frequencies is applied to a pre-prepared coated metal sample, and the induced signals of the coated metal sample under the alternating electromagnetic field of each test frequency are collected; a test frequency is selected as the selected test frequency, and the electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined according to the induced signal at the selected test frequency, and the induced eddy currents flowing through the coated metal sample at different depths are identified based on the electric field reflection relationship, and then the electromagnetic attenuation between each adjacent induced eddy current is determined; the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency is identified according to all the electromagnetic attenuations, and the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies is further determined; the frequency constraint conditions for the conductive performance detection are determined by all the cumulative migration amounts, and the coated metal sample is subjected to non-destructive eddy current testing according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

[0124] It can be seen that the present application applies alternating electromagnetic fields of different test frequencies and collects induced signals, selects a selected test frequency to determine the electric field reflection relationship between the coating and the substrate interface, thereby identifying the induced eddy currents at different sample depths and determining the electromagnetic attenuation in the sample (i.e., the amount of electromagnetic attenuation), and then obtains the cumulative migration amount of charge caused by the skin effect at each frequency. Finally, the constraint conditions (i.e., frequency constraints) when the base metal does not have a skin effect are defined by the cumulative migration amount, and finally eddy current detection is performed according to the constraints. This solves the contradiction that the surface roughness has a large influence at high frequencies in the background and the skin depth exceeds the coating thickness at low frequencies. While avoiding the interference of the skin effect, the influence of the surface roughness on the eddy current detection is limited, and the purpose of accurately detecting the conductive properties of the nano-silver coated metal surface is achieved. In summary, the solution of the present application can limit the influence of the surface roughness on the eddy current detection while avoiding the interference of the skin effect.

[0125] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0126] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for detecting the conductive properties of a metal surface of a nanosilver coating, wherein: The coated metal sample is prepared in advance, characterized in that the method comprises: Applying alternating electromagnetic fields of different test frequencies to the coated metal sample, and collecting induced signals of the coated metal sample under the alternating electromagnetic fields of each test frequency; selecting a test frequency as a selected test frequency, determining an electric field reflection relationship at an interface between a coating and a substrate in the coated metal sample based on an induced signal at the selected test frequency, identifying induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship, and then determining an electromagnetic attenuation between adjacent induced eddy currents; Identifying the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts, and continuing to determine the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies; The frequency constraint conditions for the electrical conductivity test are determined by all the accumulated migration amounts, and the coated metal sample is subjected to non-destructive eddy current testing according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

2. The method according to claim 1, wherein Determining the electric field reflection relationship at the interface between the coating and the substrate in the coated metal sample according to the induced signal at the selected test frequency specifically includes: Decomposing the induced signal into a plurality of standing wave components; Determine the energy concentration ratio of each standing wave component; screening out the reflected wave component reflected from the interface between the coating and the substrate in the coated metal sample from all standing wave components according to all energy concentration rates; The electric field reflection relationship of the interface between the coating and the substrate in the coated metal sample is determined based on all the reflected wave components.

3. The method according to claim 1, wherein Identifying the induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship specifically includes: removing the fluctuation characteristic corresponding to the electric field reflection relationship from the sensing signal to obtain an incident sensing signal; determining eddy current signals of different frequency bands according to the incident induced signal; Determine the dominant frequency of each eddy current signal; All eddy current signals are rearranged into induced eddy currents flowing through different depths of the coated metal sample according to the dominant frequencies of the eddy current signals.

4. The method according to claim 1, wherein Determining the electromagnetic attenuation between adjacent induced eddy currents specifically includes: Determine the electromagnetic energy of each induced eddy current; The electromagnetic attenuation between each two adjacent induced eddy currents is determined according to the electromagnetic energy of each two adjacent induced eddy currents.

5. The method according to claim 1, wherein Identifying the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts specifically includes: Performing differential fitting on all electromagnetic attenuation indices to obtain an electromagnetic attenuation curve in the coated metal sample; obtaining a nominal thickness of a coating in the coated metal sample; The electromagnetic attenuation curve is integrated according to the nominal thickness to obtain the cumulative migration amount of the charge skin effect in the coated metal sample at a selected test frequency.

6. The method according to claim 1, wherein The frequency constraints for determining the conductivity test based on all the cumulative migration values include: Convert all the cumulative migration amounts into migration amount sequences according to the test frequency; determining a migration threshold of the base metal charge in the coating metal sample according to the migration sequence; The minimum test frequency that can avoid the skin effect of the base metal is deduced based on all migration thresholds, and the minimum test frequency is used as the frequency constraint condition for the conductive performance detection.

7. The method according to claim 1, wherein The eddy current probe is used to collect the induction signal of the coated metal sample under the alternating electromagnetic field of each test frequency.

8. The method according to claim 1, wherein The coated metal sample includes a coating metal and a base metal.

9. The method according to claim 1, wherein Pre-preparing the coated metal sample refers to cutting a product block of a preset size from the nano-silver coated metal product, and using the cut product block as the coated metal sample.

10. A system for detecting the conductive properties of metal surfaces coated with nano-silver, characterized in that: The system includes: An acquisition module is used to apply alternating electromagnetic fields of different test frequencies to a pre-prepared coated metal sample and to acquire the induction signals of the coated metal sample under the alternating electromagnetic fields of each test frequency; a processing module, configured to select a test frequency as a selected test frequency, determine an electric field reflection relationship at an interface between a coating and a substrate in the coated metal sample based on an induced signal at the selected test frequency, identify induced eddy currents flowing through the coated metal sample at different depths based on the electric field reflection relationship, and further determine an electromagnetic attenuation between adjacent induced eddy currents; The processing module is further configured to identify the cumulative migration amount of the charge skin effect in the coated metal sample at the selected test frequency based on all electromagnetic attenuation amounts, and continue to determine the cumulative migration amount of the charge skin effect in the coated metal sample at the remaining test frequencies; The execution module is used to determine the frequency constraint conditions of the conductive performance test through all the cumulative migration amounts, and perform non-destructive eddy current testing on the coated metal sample according to the frequency constraint conditions to obtain the surface conductivity of the coated metal sample.

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