Oral orthodontic correction arch wire friction corrosion test system

Abstract

The invention belongs to the technical field of new material detection, and discloses an orthodontic correction arch wire friction corrosion test system, which comprises a controller, a mechanical excitation device and an electrochemical workstation, and is characterized in that the controller controls the electrochemical workstation to apply polarization pulses to form an ion sheath for neutralizing friction charges; the method comprises the following steps: firstly, carrying out mechanical damage and electrochemical response on the surface of a material, then controlling a mechanical excitation device to apply single instantaneous mechanical scratch, immediately triggering an electrochemical workstation after the scratch is finished, and recording an electrochemical relaxation transient process of spontaneous repassivation of the surface of the material in a static environment without mechanical interference. The technical problem that the dynamic repairing capacity of the material cannot be accurately evaluated due to signal aliasing in an existing continuous friction test is solved, and the obtained data is no longer a fuzzy average value but a clear dynamic fingerprint containing rich physical mechanisms.

Description

TECHNICAL FIELD

[0001] The application relates to an orthodontic correction arch wire friction corrosion test system and belongs to the technical field of new material detection. BACKGROUND

[0002] At present, when evaluating the performance of metal components that simultaneously bear mechanical wear and chemical corrosion, a common technical solution is to jointly use a friction and wear testing machine and an electrochemical workstation to apply continuous friction to the material in a simulated corrosion medium and synchronously monitor the change of electrochemical parameters of the material, the solution provides an effective basis for preliminary screening of the material by obtaining an average index in a long-time, stable wear and corrosion state, however, for orthodontic arch wires and other materials that bear non-continuous and instantaneous external force in actual working conditions, the service behavior of the materials is not uniform material loss, but a dynamic process in which the passivation film on the surface of the materials is broken and re-passivated after being subjected to external force, the performance of the materials is shown in the ability of self-repairing after single breakage of the passivation film, that is, the re-passivation kinetics.

[0003] The existing continuous friction test scheme has a principle limitation in characterizing such a dynamic repair behavior, that is, the physical action of mechanical scratching and the electrochemical reaction of re-passivation of the new interface occur simultaneously and are coupled in time and space, the electrochemical signal collected by the test system is the superposition result of the two processes, and the signal component directly generated by mechanical movement is usually much larger than the pure re-passivation current signal, so that even if high-frequency sampling or signal filtering and other post-processing means are used, the pure information characterizing the repair process itself cannot be accurately separated from the signal, and the direct result is that the test data has poor repeatability and cannot provide key kinetic parameters such as repair rate and repair layer quality, specifically, the existing technology mainly has the following deficiencies: 1, due to the continuous superposition of mechanical disturbance and electrochemical signal, the pure electrochemical repair process information after a single isolated damage event cannot be obtained; 2, the test result is an average value in a long time, which masks the dynamic response characteristics of the material under instantaneous damage, and cannot be used for analysis of the inherent repair mechanism of the material; 3, due to the randomness of the friction process and the superimposed interference of the signal, the dispersion of the test result is large, and it is difficult to make a reliable comparison of different materials or different working conditions.

[0004] The principle limitation is also embodied in some existing specific technical solutions, which is not only limited to the configuration of the test hardware, but also rooted in the test timing and control logic, for example, the Chinese patent for invention with the authorization announcement number CN103202734B discloses an oral orthodontic appliance friction test experimental table, the core of which is to pull the arch wire through the bracket at a constant speed by the motor, and measure the difference of the pulling force at both ends to calculate the macroscopic dynamic and static friction force. This scheme essentially still belongs to a continuous and steady-state measurement mode, and the control logic aims to obtain an average friction coefficient value in a process, and cannot separate the instantaneous mechanical damage event and the subsequent material spontaneous electrochemical repair behavior in time sequence, so it can only evaluate the size of the friction force, but cannot reveal the internal dynamics characteristics of the dynamic process of the rupture and self-repair of the material surface passivation film after the friction damage, and cannot provide direct and effective data support for evaluating the dynamic corrosion resistance and self-repairing ability of the material. Therefore, how to establish a test method which can separate the instantaneous mechanical damage process and the subsequent electrochemical repair process in time sequence, so as to directly and objectively obtain and characterize the passivation dynamics characteristics of the material surface, becomes the technical problem to be solved by the present application. SUMMARY

[0005] The present application provides an oral orthodontic correction arch wire friction corrosion test system, which mainly aims to solve the problem that the existing test method cannot directly and objectively obtain the material surface passivation dynamics characteristics due to the continuous mixing of mechanical disturbance and electrochemical signal.

[0006] To achieve the above-mentioned purpose, the present application provides an oral orthodontic correction arch wire friction corrosion test system, which comprises: An electrochemical cell configured to accommodate an electrolyte and an oral orthodontic correction arch wire sample to be tested; A mechanical excitation device; An electrochemical workstation electrically connected with the oral orthodontic correction arch wire sample as a working electrode; The controller is connected with the mechanical excitation device and the electrochemical workstation, and is configured to: before the mechanical excitation is performed, control the electrochemical workstation to apply a preset cathodic polarization pulse to the orthodontic archwire sample to enrich cations at the interface between the surface of the orthodontic archwire sample and the electrolyte, so as to form an ion sheath for neutralizing the frictional static charge generated in the subsequent mechanical excitation process; then, control the mechanical excitation device to apply a single transient mechanical scratching excitation lasting no more than 500 ms to the surface of the orthodontic archwire sample to form a fresh bare area on the surface; and strictly take the moment when the single transient mechanical scratching excitation is completed as the time zero point, trigger the electrochemical workstation to record an electrochemical relaxation transient current curve generated by the spontaneous repassivation of the fresh bare area in a static electrochemical environment without any mechanical motion interference at a sampling frequency of no less than 1 kHz; and determine the relaxation time constant and the total integral electric quantity characterizing the repassivation kinetics of the orthodontic archwire sample based on the recorded electrochemical relaxation transient current curve.

[0007] Preferably, a kinetics parameter analysis module is integrated in the controller, and the kinetics parameter analysis module is configured to: calculate the relaxation time constant and the total integral electric quantity by applying an exponential decay function model to the recorded electrochemical relaxation transient current curve for mathematical fitting.

[0008] Preferably, the system further comprises: an acoustic emission sensor configured to synchronously detect and collect an acoustic emission signal generated by the surface of the orthodontic archwire sample due to the rupture of the passivation film in the process in which the mechanical excitation device applies the single transient mechanical scratching excitation; and the controller is further configured to extract a group of acoustic characteristic parameters including the ring count, the peak amplitude and the signal energy from the acoustic emission signal, and perform data correlation analysis on the group of acoustic characteristic parameters, the relaxation time constant and the total integral electric quantity.

[0009] Preferably, the controller is further configured to: synchronously record a scratching period electrochemical current signal output by the electrochemical workstation in the same process in which the single transient mechanical scratching excitation is applied ; and determine a transient coupling coefficient characterizing the strength of the electromechanical coupling at the moment of material damage by calculating the peak amplitude of the cross-correlation function of the acoustic emission signal and the scratching period electrochemical current signal , wherein is the time delay, is the duration of the single transient mechanical scratching excitation.

[0010] Preferably, the controller is further configured to: control the electrochemical workstation to perform an electrochemical impedance spectroscopy measurement on the orthodontic archwire sample before the single transient mechanical scratching excitation is applied, to determine a charge transfer resistance value representing a current interface temperature; and normalize the final determined relaxation time constant and total integrated charge using a function that maps the charge transfer resistance value to a temperature correction coefficient, to output a set of kinetic parameters at a standard reference temperature.

[0011] Preferably, the system further comprises: an optical calibration module including an imaging unit and an image processing unit, the imaging unit is configured to acquire a digital image of the scratch formed by the single transient mechanical scratching excitation after the excitation is completed; the image processing unit is configured to analyze the digital image to calculate an accurate geometric area of the scratch; and the controller is further configured to normalize the total integrated charge to an area-specific charge using the accurate geometric area.

[0012] Preferably, the controller is further configured to: control the mechanical excitation device and the electrochemical workstation to repeat the cycle of applying the single transient mechanical scratching excitation and recording the electrochemical relaxation transient current curve for at least 10 times; and statistically analyze the relaxation time constant and the total integrated charge determined in each cycle to output a standard deviation representing the repeatability stability of the re-passivation behavior of the orthodontic archwire sample.

[0013] Preferably, the mechanical excitation device comprises a scratching needle with a standard geometric shape and a three-axis motion platform for driving the scratching needle; and the controller is configured to precisely reproduce the energy input of each single transient mechanical scratching excitation and the geometric morphology of the scratch by closed-loop controlling the motion speed profile of the three-axis motion platform and the normal contact load applied to the scratching needle.

[0014] Preferably, the controller integrates an acoustic feature analysis module, which is configured to: based on a set of numerical values of acoustic feature parameters, and according to a classification rule that compares the numerical values with a preset threshold, distinguish the microscopic damage mode of the passivation film rupture into a brittle cracking mode with high amplitude and short time or a ductile tearing mode with low amplitude and long time.

[0015] Preferably, the controller is configured to execute the single transient mechanical scratching excitation under an open circuit potential state of the orthodontic archwire sample, and the electrochemical relaxation transient current curve recorded by the controller is a transient current response of the orthodontic archwire sample during a process in which the corrosion potential spontaneously recovers to a stable open circuit potential after the fresh bare area is formed.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1. By recording the electrochemical response under conditions of no mechanical motion interference after applying a single instantaneous mechanical scratching excitation, the physical process of mechanical damage and the electrochemical process of surface repassivation are separated in the time dimension. This reconstruction of the test sequence allows the two processes that were previously mixed and unidentifiable in continuous friction to be presented independently. As a result, what the system records is no longer an unstable average current value, but a relaxation transient process curve that can fully reflect how the bare metal surface reforms the passivation film, providing an objective and clear original data basis for directly obtaining the repassivation kinetic characteristic parameters of the material.

[0017] 2. Before mechanical scratching excitation, a preset electrochemical polarization pulse is applied to the archwire sample using an electrochemical workstation. This action enriches counterions in the solution near the sample surface, forming an ion sheath. When the subsequent scratching action occurs, the physical charge generated by friction is instantly neutralized by this ion sheath. This mechanism utilizes the existing electrochemical control capability of the testing system to remove a non-electrochemical physical interference before recording the core repassivation data, making the initial stage of the relaxation transient process of subsequent measurements purer, thereby improving the accuracy of subsequent kinetic parameter analysis.

[0018] 3. While applying mechanical scratching excitation to trigger the repassivation process, the acoustic emission signal generated by the scratching is detected simultaneously. Since mechanical damage and acoustic emission signal are synchronous in time, and repassivation is a follow-up behavior triggered after damage, a correspondence between the cause and effect of the damage process and the healing process under the same physical event is established. By correlating the acoustic emission signal characteristics that characterize the damage mode with the repassivation kinetic parameters that characterize the healing ability, a single test can not only evaluate the repair performance of the material, but also explore the intrinsic relationship between the performance and its microscopic damage mode, providing a richer information dimension for the study of material failure mechanisms.

[0019] 4. By performing cross-correlation analysis on the acoustic emission signal and electrochemical response current during the synchronously recorded scratching process, the acoustic emission signal is used as a time reference to identify the current component in the total electrochemical current that is directly and instantaneously driven by the micro-fracture event. This data processing method transforms the scratching period current signal, which is regarded as background noise and ignored in traditional tests, into effective information that can be used to characterize the electromechanical coupling characteristics of the material at the moment of damage. It does not add new measurement steps, but rather, through in-depth correlation analysis of the two existing data, it uncovers the dynamic response characteristics of the material at the moment of damage, thus deepening the understanding of the material damage behavior.

[0020] 5. Before determining the parameters characterizing the repassivation kinetics, an electrochemical impedance spectroscopy (EIS) measurement is performed on the archwire sample to obtain an impedance parameter directly related to the interface temperature. Since the electrochemical reaction rate and kinetic parameters of the material are both temperature-dependent, this step uses the sample's own interface impedance in the electrolyte as an in-situ temperature indicator. The final calculated kinetic parameters are then normalized based on this impedance parameter. This approach avoids reliance on external temperature measurement and control devices and actively eliminates the influence of ambient temperature changes on the comparability of results by utilizing the testing system's own functions, which helps to establish standardized material performance data. Attached Figure Description

[0021] Fig. 1 This is a schematic diagram of the decoupling measurement excitation relaxation test method of the present invention; Fig. 2 This is a time-domain signal and cross-correlation analysis diagram of acoustic emission and electrochemical current during the scratching process of this invention; Fig. 3 This is a schematic diagram of the hardware structure and signal flow of the multiphysics coupling test system of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. However, those skilled in the art will understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the spirit and scope of this invention, and such modifications and equivalent substitutions should all be covered within the scope of protection claimed by this invention.

[0023] This invention provides a testing system for the frictional corrosion of orthodontic archwires. The system includes: a controller for controlling the testing sequence and data processing; a mechanical excitation device for applying instantaneous mechanical damage to the archwire sample; and an electrochemical workstation for applying electrochemical perturbation and recording the electrochemical response. The system can also integrate an acoustic emission sensor for synchronously acquiring damage signals and an optical calibration module for calibrating the geometric morphology of the scratches. All units are coordinated and scheduled by the controller to achieve a testing method that separates the instantaneous mechanical damage process from the subsequent electrochemical self-healing process in the time dimension, thereby obtaining data characterizing the repassivation kinetics of the archwire sample.

[0024] In one specific implementation, the initial state is defined as follows: a sample of orthodontic archwire to be tested, such as a 0.016-inch × 0.022-inch nickel-titanium alloy archwire, is fixed on the sample holder of the electrochemical cell and immersed in a preset electrolyte, which can be artificial saliva, and its temperature is maintained at 37°C by an external water bath. ±0.5 , pH 6.8; the archwire sample is used as the working electrode in a three-electrode test system with a reference electrode and an auxiliary electrode. The system is first left to stand in this environment until the open circuit potential of the archwire sample drifts less than 1 mV / min within 10 minutes, at which time the system reaches an electrochemical steady state. Before performing a series of tests, the system performs an initial state calibration and excitation parameter verification, which includes the following steps: first, under the static electrochemical environment, a series of cathodic pulses with different potentials (from -0.5 V to -1.5 V vs OCP) and durations (from 5 ms to 50 ms) are applied to the working electrode, and the recovery transient of the open circuit potential after each pulse is recorded. The pulse parameter combination that can restore the potential to a deviation of less than 2 mV from the initial value within the shortest time (e.g., 100 ms) is selected as the charge neutralization pulse input for subsequent tests. Second, a digital image of the stylus tip is obtained using an optical profilometer or a scanning electron microscope, and the tip curvature radius is calculated. The deviation of the radius value from the preset specification (e.g., 200 pm) is less than 5%, which serves as the basis for the mechanical excitation device to perform the test. To address the interference of static charges generated by the stylus and archwire sample friction during subsequent scraping, the system is configured to apply a cathodic polarization pulse of -1.0 V (relative to the open circuit potential) for 10 ms to the archwire sample 20 ms before performing mechanical scraping excitation. This operation enriches cations at the interface between the sample and the electrolyte, forming an ion sheath to neutralize the static charges generated during subsequent friction.

[0025] Subsequently, the controller controls the mechanical excitation device to drive a zirconia ceramic stylus with a standard geometric shape to scrape the surface of the archwire sample at a normal contact load of 5 N and a motion speed of 100 mm / s, with a scraping distance of 5 mm. The duration of the scraping action is controlled to be 50 ms to form a fresh exposed area on the sample surface. The moment when the single instantaneous mechanical scraping excitation is completed is taken as the time zero, and all mechanical movements immediately stop, and the electrochemical workstation is immediately triggered to record the electrochemical relaxation transient current curve generated by the spontaneous passivation of the fresh exposed area in the subsequent static electrochemical environment without mechanical motion interference at a sampling frequency of 2 kHz for 2 s. The curve starts from a peak current and decays exponentially with time, eventually returning to the background current level before scraping. This current-time curve is the kinetic fingerprint representing the passivation process. For the processing and parameter extraction of the measurement data, the kinetic parameter analysis module in the controller is configured to perform two core calculation procedures: first, to perform temperature normalization, the module first retrieves a plurality of sets of charge transfer resistance values corresponding to temperatures The data pairs are fitted to the equation using the least squares method. And when the coefficient of determination When the value is greater than 0.99, the equation will be stored for subsequent online measurements. Value to actual temperature The conversion basis; secondly, in order to determine the repassivation kinetic parameters, the module will record the electrochemical relaxation transient current curve data. The double exponential decay function was solved using the Levenberg-Marquardt nonlinear fitting algorithm. The coefficients in the table, among which, For instantaneous current, For time, and The current amplitude coefficient is used as the final output, which is the relaxation time constant characterizing the speed of the repair process. and To extract quantitative kinetic parameters from the fingerprint, the kinetic parameter analysis module integrated in the controller fits the recorded electrochemical relaxation transient current curves using a mathematical model, such as a double exponential decay function model. ,in, For instantaneous current, For time, and This is the current amplitude coefficient. and The relaxation time constant is calculated through fitting to determine the speed of the repair process. and And by examining the curve from arrive By integrating, the total integrated charge required to form a new passivation film is calculated. .

[0026] To investigate the relationship between the damage mode and healing capacity of materials, this system can also be equipped with an acoustic emission sensor. This sensor is configured to simultaneously detect and acquire the acoustic emission signal generated on the surface of the orthodontic archwire sample due to the rupture of the passivation film during a single, instantaneous mechanical scratching excitation lasting 50 ms applied by the mechanical excitation device. The controller extracts a set of acoustic characteristic parameters from the acquired acoustic emission signal, including ring count, peak amplitude, and signal energy, and performs data correlation analysis on this set of acoustic characteristic parameters characterizing the damage mode with the subsequently measured relaxation time constant and total integrated charge characterizing the healing capacity. To utilize the electrochemical signal during the scratching process, the controller is also configured to simultaneously record the electrochemical current signal output by the electrochemical workstation during the scratching period during the same process of applying a single, instantaneous mechanical scratching excitation. And based on synchronously recorded acoustic emission signals the electrochemical current signal during the scratch period by calculating the peak amplitude of the cross-correlation function of the two signals to determine a transient coupling coefficient representing the strength of the electromechanical coupling at the moment of material damage, wherein is the cross-correlation function, is the time delay, is the duration of the single transient mechanical scratch stimulus; in addition, to eliminate the influence of temperature changes in the test environment on the comparability of the results, the system can also be configured to instruct the electrochemical workstation to perform an electrochemical impedance spectroscopy measurement on the archwire sample before applying the single transient mechanical scratch stimulus, for example, by applying a sinusoidal alternating voltage with a frequency of 1 kHz and an amplitude of 5 mV at the open circuit potential, to determine a charge transfer resistance value related to the current interface temperature; the system uses a function relationship between the charge transfer resistance value and the temperature correction coefficient, which is established through a calibration experiment in advance, to normalize the finally determined relaxation time constant and total integrated electric quantity to output a set of kinetic parameters at a standard reference temperature; at the same time, to obtain statistical information of the test results, the controller can also be configured to control the mechanical excitation device and the electrochemical workstation to repeat the cycle of applying a single transient mechanical scratch stimulus and recording the electrochemical relaxation transient current curve at least 10 times at different positions of the same archwire sample, and statistically analyze the relaxation time constant and the total integrated electric quantity determined in each cycle to output a standard deviation representing the repeatability and stability of the re-passivation behavior of the orthodontic archwire sample.

[0027] Example 1: In a new material research and development application, the goal is to develop a novel nickel-titanium alloy orthodontic archwire with higher biocompatibility. A key technical indicator is reducing nickel ion release under frictional corrosion conditions. When evaluating the results using existing continuous friction testing methods, continuous mechanical friction is applied to the sample in simulated saliva while simultaneously recording the average corrosion current. The test results show significant dispersion, and this single average value cannot provide directional guidance for research and development; that is, it cannot distinguish whether the change in material performance stems from a more wear-resistant passivation film or faster repair after passivation film damage. To address this issue, the testing system described in the aforementioned specific implementation method is adopted. The novel nickel-titanium alloy archwire sample and a commercially available standard nickel-titanium alloy archwire sample are placed in the testing system. After reaching an electrochemically stable state, the controller instructs the electrochemical workstation to... A momentary cathodic polarization pulse is applied to the sample surface to form an ion sheath at the interface to neutralize subsequent triboelectric charges. Immediately afterwards, a mechanical excitation device applies a single momentary mechanical scratch excitation to the sample surface lasting no more than 500 ms. In this step, the construction of the preceding ion sheath provides an initial condition free from physical electrostatic charge interference for subsequent electrochemical measurements, while the momentary mechanical excitation creates an isolated and characterizable damage event for the measurement. The timing coordination of the two ensures the validity of the subsequent measurement data. At the instant the scratching action is completed, all mechanical movement stops, and the controller triggers the electrochemical workstation to record the electrochemical relaxation transient current curve generated by the spontaneous repassivation of the freshly exposed area formed by the scratching at a sampling frequency of no less than 1 kHz in a static electrochemical environment free from mechanical movement interference.

[0028] For commercially available standard bowwire samples, the recorded relaxation transient current curves exhibited a high peak value in the initial stage and decayed at a relatively slow rate. In contrast, the recorded curves of the novel nickel-titanium alloy bowwire samples showed an initial peak value close to that of the standard sample, but with a faster current decay rate. By mathematically fitting the two curves using the kinetic parameter analysis module integrated in the controller, two sets of repassivation kinetic parameters were calculated. The results show that the relaxation time constant of the novel alloy sample... The value is less than that of the standard sample, and the total integrated charge is less. The values ​​are also lower; this set of highly repeatable kinetic parameters indicates that the performance difference of the new alloy mainly lies in its faster self-repair speed and higher repair layer density after the surface passivation film is damaged instantaneously; the mechanism problem that could not be distinguished due to signal aliasing in the previous continuous friction test method can be transformed into a problem that can be directly quantitatively analyzed by reconstructing the test process into a pulse excitation-relaxation fingerprint event and utilizing the temporal synergy of different functional modules, thus providing an objective basis for the directional optimization design of materials.

[0029] Example 2: To quantitatively characterize the capability of the aforementioned test system to distinguish the different material passivation kinetics and the repeatability of the test results, a comparative test was conducted in this example; the purpose of the test was to quantify the single damage-repair behavior of a commercially available standard nickel-titanium alloy orthodontic archwire (as the control group) and a new type of nickel-titanium alloy archwire treated by surface modification (as the test group) under the same conditions using the system; the test platform used the aforementioned specific embodiment system, in which the functional specifications of the data acquisition module of the electrochemical workstation were: the sampling frequency was not less than 2 kHz, and the current measurement resolution was not less than 1 pA; the three-axis motion platform of the mechanical excitation device, with a speed control accuracy of ±1 mm / s and a normal contact load control accuracy of ±0.1 N, was used to ensure the consistency of each scratch excitation.

[0030] In the test, a key parameter was the sampling frequency of the electrochemical workstation, which needed to be balanced between ensuring signal fidelity and controlling data processing load; since a typical passivation process includes a rapid decay phase with a duration of several milliseconds to several tens of milliseconds, in order to record this process according to the Nyquist sampling theorem, the sampling frequency should be greater than twice the fastest signal change frequency, therefore the sampling frequency was set to 2 kHz in this test to obtain the required time resolution; the test process was as follows: the archwire samples of the control group and the test group were respectively installed in the test system, after reaching the electrochemical steady state in the 37 artificial saliva, the controller executed the steps of applying a cathodic polarization pulse, performing a single transient mechanical scratch excitation, and immediately collecting the electrochemical relaxation transient current curve after the scratch ended in a preset time sequence; in order to obtain statistical data, this cycle was repeated once at 10 different positions of each sample; for the relaxation transient current curve obtained in each measurement, the kinetic parameter analysis module in the system controller processed it, and calculated the corresponding relaxation time constant and the total integral electric quantity ; the results of 10 repeated measurements were statistically analyzed, and the obtained data were summarized in Table 1.

[0031] Table 1: Comparison of passivation kinetic parameters of the control group and the test group.

[0032] As can be seen from the data in Table 1, the average relaxation time constant and the average total integral electric quantity The two groups are lower than the control group, which shows that the surface modification treatment of the arch wire sample has a faster self-repairing speed after damage, and can form a passivation protection layer with less charge consumption; in addition, the standard deviation of the kinetic parameters of the two groups of samples is at a low level, which shows that the test system separates the mechanical disturbance and the electrochemical measurement in time, and can obtain material performance data with high repeatability; the test data confirms that the system can quantify and distinguish the dynamic repair ability of the material, and provides a basis for the comparison of material performance.

[0033] In order to further highlight the technical advantages of the instant excitation-static relaxation test timing adopted in the present application over the continuous friction test mode in the background art, the following comparative example is set.

[0034] Comparative Example 1: This comparative example aims to simulate the existing general technical solution in the background art, that is, the joint use of a friction and wear testing machine and an electrochemical workstation to monitor the change of the electrochemical parameters of the material while applying continuous friction to the material; except for the test timing and control logic, all hardware devices, test samples, electrolyte environment and basic parameters used in this comparative example are strictly the same as those in Example 2, specifically, the test object is a commercially available standard nickel-titanium alloy orthodontic correction arch wire (i.e. the control group in Example 2), the electrolyte is 37 Artificial saliva, the normal contact load applied by the mechanical excitation device is constant at 5.0N, the reciprocating motion speed of the stylus is set to 100mm / s, and the data sampling frequency of the electrochemical workstation is also set to 2kHz; the test process is as follows: install the arch wire sample in the test system, after reaching the electrochemical steady state, the controller instructs the mechanical excitation device to drive the stylus to start continuous reciprocating motion on the same 5mm long area of the arch wire sample, for a total of 60 seconds, during which the electrochemical workstation is configured to record the working current flowing through the arch wire sample synchronously and continuously, and this cycle is also repeated at 10 different sample positions to obtain statistical data.

[0035] During the test, the recorded electrochemical current signal presents a high-amplitude, high-noise and non-decaying characteristic fluctuation signal, because the mechanical disturbance signal generated by the continuous reciprocating motion of the stylus is completely mixed with the electrochemical signal generated by the continuous rupture and repair of the passivation film in time, and since there is no static relaxation phase without mechanical disturbance, the exponential decay curve representing the spontaneous repassivation process after single damage cannot be identified and separated from the mixed signal. Therefore, the relaxation time constant representing the speed of the repair process cannot be calculated by applying an exponential decay function model for mathematical fitting. ; as an alternative, only the total current signal recorded in 60 seconds can be integrated and divided by the scratch area and time, to obtain an average corrosion charge density representing the average corrosion rate in the test period. The results of 10 repeated measurements are statistically analyzed, and the data obtained are summarized in Table 2.

[0036] Table 2: Table of electrochemical parameters obtained by using the existing continuous friction test method.

[0037] Analyzing the data in Table 2, it can be seen that, by using the existing continuous friction test method, due to the limitations of its test principle, firstly, the relaxation time constant cannot be obtained at all This core kinetic parameter, thus the speed of the material's dynamic repair ability, cannot be quantitatively evaluated; secondly, the standard deviation of the average corrosion charge density measured is as high as 2.5, which is nearly two orders of magnitude higher than the standard deviation of the total integrated charge measured in Table 1 (0.03-0.05), which objectively confirms the technical defects of the prior art in the background art, i.e. the large dispersion and poor repeatability of the test results. The test results of the present comparative example show that, under the condition of continuous mixing of mechanical disturbance and electrochemical response signals, the dynamic characteristics of the material surface repassivation are indeed objectively obtained and characterized, thereby inversely proving the necessity and non-obviousness of the core technical concept of the present application, which decouples the two in the time dimension.

[0038] Example 3: This example combines Figs. 1 to 3 to illustrate an oral orthodontic correction arch wire friction corrosion test system, as shown in Fig. 1 , starting from the test preparation phase, the sample to be tested is placed in the electrolyte until the system reaches a stable state, then a cathodic polarization pulse is applied to form an ion sheath, and the friction static charge interference is removed in advance, then a single instantaneous mechanical scratching lasting no more than 500 ms is performed to form a fresh bare area on the sample surface. This scratching action will simultaneously trigger the acoustic emission signal synchronous acquisition module to detect the acoustic emission signal generated by the rupture of the passivation film, and provide a basis for subsequent data correlation analysis. At the moment when the scratching is completed, the system enters the static electrochemical relaxation measurement phase, and the spontaneous repassivation transient current curve is recorded by high-frequency sampling. The recorded curve is fitted by the kinetic parameter analysis module to calculate the relaxation time constant and the total integrated charge. At the same time, an optical calibration module can calibrate the accurate geometric area of the scratch after measurement, and the result can be used for normalization correction of the kinetic parameter analysis, and finally the repassivation kinetic parameters representing the material's dynamic repair ability are output.

[0039] As shown in Fig. 2 , the test system is composed of a mechanical scratching module, an acoustic emission signal synchronous acquisition module, a high-frequency sampling module, a kinetic parameter analysis module, and an optical calibration module. Typical curves of the simultaneously recorded acoustic emission signal, the electrochemical current signal during the scratch period and the cross-correlation function of the two signals as a function of time during a single transient mechanical scratch excitation process, where the abscissa is time in milliseconds ms, the left ordinate is the amplitude of the acoustic emission signal in millivolts mV, which is also the ordinate axis of the cross-correlation function, and the right ordinate is the electrochemical current in microamperes µA, the solid curve in the figure represents the acoustic emission signal which exhibits two transient high-amplitude pulses due to the rupture of the passivation film, the dashed curve represents the electrochemical current signal during the scratch period recorded synchronously during the scratch process and the dotted curve represents the cross-correlation function of the two signals calculated as described above The resulting peak amplitude of the cross-correlation function is used to determine a transient coupling coefficient that characterizes the strength of the electromechanical coupling at the moment of material damage.

[0040] As Fig. 3 shown, the figure shows the overall structure of the test system of the present application, the core of which is a controller that integrates timing control, data processing and analysis modules, which is connected to an electrochemical workstation through control and acquisition signals, connected to a mechanical excitation device containing a three-axis motion platform and a standard stylus through motion control signals, and receives data acquisition signals from an acoustic emission sensor and an optical calibration module. At the physical level, the mechanical excitation device applies physical scratching to the test wire sample and the electrolyte in the electrochemical cell, the electrochemical workstation is connected to the electrochemical cell to transmit electrochemical signals, the acoustic emission sensor monitors the sample state through acoustic sensing, and the optical calibration module observes the sample through optical imaging.

[0041] Example 4: In an application that requires high-throughput, long-term stability quality monitoring, the test system is used to continuously test wire samples of the same batch. Under such repeated working conditions, the zirconia ceramic stylus in the mechanical excitation device will gradually change its geometry due to physical wear, its tip radius of curvature will increase, and the scratch width formed under the same scratch parameters will also increase. This physical drift in scratch geometry will cause the total integrated electric quantity Systematic deviations in the original electrochemical parameters can affect the accuracy of comparisons between different batches or long-term test results. To address this foreseeable situation in engineering practice, this system integrates and executes a standardized online calibration and parameter normalization procedure for scratch geometry area during each independent test cycle. After the controller triggers and completes the acquisition of an electrochemical relaxation transient current curve, the sample stage remains stationary, and the controller then activates the optical calibration module. The imaging unit in this module is configured as a digital microscope with a resolution of no less than 5 million pixels and a coaxial illumination source to acquire images of the formed scratches, obtaining a digital image. This image is then transmitted to the image processing unit in the controller.

[0042] The image processing unit executes an algorithm to calculate the scratch area. First, the acquired digital image is converted to grayscale, and the Canny edge detection operator is applied to identify the scratch boundaries. Second, perpendicular sampling is performed along the scratch length at 50-micrometer intervals, measuring and recording the pixel distance between two boundary points on each sampling line. For a 5mm long scratch, this step yields 100 independent width measurements. Third, the arithmetic mean of these 100 width measurements is calculated, and this average pixel width value is converted to the physical width using a conversion factor of 0.5 micrometers / pixel pre-calibrated using a standard micrometer scale. Ultimately, the controller will determine the physical width. With the scratch length preset by the mechanical excitation device Multiply by the product to obtain the geometric area of ​​the exposed region resulting from this excitation. The controller then uses the real-time measured geometric area. The raw total integrated charge obtained from this measurement Perform normalized calculations per unit area and output a normalized total integral charge. By equipping each electrochemical measurement with an instant physical morphology calibration, this procedure eliminates measurement uncertainties introduced by physical factors such as scriber wear, thereby ensuring the comparability of the output kinetic parameters of the test system under long-term continuous operation.

[0043] Example 5: In a material screening application where different archwire samples need to be classified by their damage modes and the correlation between damage modes and healing behavior needs to be established, the acoustic emission signals collected by the system have waveform features related to the fracture mode of the material, where brittle cracking usually produces high amplitude short duration acoustic signals, while ductile tearing produces low amplitude long duration signals; to enable automated and repeatable classification between different test batches, an engineering procedure is needed to convert this qualitative description into quantitative classification rules; to establish this procedure, the system performs an offline classifier calibration procedure before deployment; this procedure selects two reference materials with defined damage modes, one is a hard ceramic rod with brittle cracking damage mode, and the other is a polymer rod with ductile tearing damage mode; the system performs 20 single transient mechanical scratching excitations on each of these two reference materials, and synchronously collects the acoustic emission signals during all 40 excitations; the acoustic feature analysis module in the controller extracts the peak amplitude and signal energy two acoustic feature parameters from each of the collected acoustic emission signal waveforms, where the signal energy is obtained by integrating the square of the signal voltage over the duration of the excitation; subsequently, the module calculates the average peak amplitude and average signal energy of the brittle cracking group and the ductile tearing group, and takes the midpoint of the two group averages as the discrimination threshold for online classification.

[0044] During online testing of unknown archwire samples, the controller synchronously collects their acoustic emission signals and extracts the same peak amplitude and signal energy parameters during the execution of single transient mechanical scratching excitations; the controller compares the extracted parameters with the discrimination thresholds determined in the aforementioned calibration procedure, if both the peak amplitude and the signal energy are greater than their respective thresholds, then the microscopic damage mode of this damage event is classified as brittle cracking mode, otherwise it is classified as ductile tearing mode; through this pre-emptive calibration procedure, the system can perform automated classification based on objective data and deterministic algorithms, thereby providing stable and reproducible data input for subsequent correlation analysis between damage modes and re-passivation kinetic parameters; in other words, after online testing of unknown archwire samples and classification of their microscopic damage modes, the controller can also be configured to perform in-depth analysis on the two signals recorded synchronously during the scratching process; the controller retrieves the time series data of the acoustic emission signals and the scratching period electrochemical current signals stored in it corresponding to this scratching event, and performs cross-correlation function calculation on these two sets of data; by finding the time delay The peak amplitude close to zero position, the system can quantify the coupling strength between the mechanical fracture event and the transient electrochemical reaction in this damage event, which is finally output as a dimensionless transient coupling coefficient, which provides a new dimension for evaluating the intrinsic mechanical and electrical response characteristics of the material at the moment of damage occurrence, independent of the re-passivation kinetics parameters.

[0045] Embodiment 6: The electrochemical reaction rate has a dependence on temperature, and slight temperature fluctuations in the environment will cause the measured re-passivation kinetics parameters to deviate, thereby affecting the accuracy of data comparison when standardization comparison of test data of different laboratories or different time batches is required; to eliminate this influence, the system is built-in with a set of engineering procedures for temperature normalization of kinetics parameters; before the system performs the test, an offline parameter calibration is performed to establish a function relationship between the charge transfer resistance value and the temperature; the calibration process is as follows: a standard archwire sample is placed in the electrolytic cell, and the electrolyte temperature is set at multiple temperature points, i.e. 35.0 , 36.0 , 37.0 and 38.0 , after stabilization at each temperature point, the sample is measured by the electrochemical workstation for an electrochemical impedance spectroscopy, and the charge transfer resistance value corresponding to the temperature point is recorded , thereby obtaining a set of temperature data pairs, and a function model for subsequent query is established based on the set of data.

[0046] When an unknown sample is tested online, the controller instructs the electrochemical workstation to perform a same electrochemical impedance spectroscopy on the archwire sample at a time point before a single transient mechanical scratching excitation is performed, to determine a real-time charge transfer resistance value characterizing the current interface temperature; after the scratching excitation is completed and the original relaxation time constant and the total integral electric quantity are calculated, the controller uses the function model established by the aforementioned calibration process to inversely calculate the interface temperature of the current test according to the measured value, and according to the difference between the interface temperature and the standard reference temperature, the original calculated kinetics parameters are normalized by using a preset physical model, and finally a set of kinetics parameters at the standard reference temperature 37.0 are output.

[0047] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application.

[0048] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A test system for frictional corrosion of orthodontic archwires, characterized in that, The system includes: An electrochemical cell was configured to contain electrolytes and the orthodontic archwire sample to be tested. Mechanical excitation device; An electrochemical workstation is used to form a working electrode with an orthodontic archwire sample and is electrically connected to it. A controller, connected to a mechanical excitation device and an electrochemical workstation, is configured to: before performing mechanical excitation, control the electrochemical workstation to apply a preset cathodic polarization pulse to the orthodontic archwire sample to enrich cations at the interface between the orthodontic archwire sample surface and the electrolyte, thereby forming an ion sheath to neutralize the triboelectric charge generated during subsequent mechanical excitation; subsequently, control the mechanical excitation device to apply a single, transient mechanical scratch excitation lasting no more than 500 ms to the surface of the orthodontic archwire sample to form a fresh exposed area on the surface; and strictly using the instantaneous completion of the single transient mechanical scratch excitation as the time zero point, under a static electrochemical environment without any subsequent mechanical motion interference, trigger the electrochemical workstation to record the electrochemical relaxation transient current curve generated by the spontaneous repassivation of the fresh exposed area at a sampling frequency of no less than 1 kHz; based on the recorded electrochemical relaxation transient current curve, determine the relaxation time constant and total integrated charge characterizing the repassivation kinetics of the orthodontic archwire sample.

2. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The controller integrates a kinetic parameter analysis module, which is configured to calculate the relaxation time constant and the total integral charge by applying an exponential decay function model to the recorded electrochemical relaxation transient current curve.

3. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The system also includes: an acoustic emission sensor configured to simultaneously detect and acquire acoustic emission signals generated by the rupture of the passivation film on the surface of the orthodontic archwire sample during the application of a single instantaneous mechanical scratching excitation by the mechanical excitation device; and a controller configured to extract a set of acoustic characteristic parameters, including ring count, peak amplitude and signal energy, from the acoustic emission signal, and to perform data correlation analysis on the set of acoustic characteristic parameters with the relaxation time constant and the total integrated charge.

4. The orthodontic archwire friction corrosion testing system according to claim 3, characterized in that, The controller is also configured to simultaneously record the electrochemical current signal during the scratching period output by the electrochemical workstation during the same process of applying a single instantaneous mechanical scratching excitation. Based on synchronously recorded acoustic emission signals; Electrochemical current signal during the scratching period By calculating the cross-correlation function of the two The peak amplitude is used to determine an instantaneous coupling coefficient characterizing the electromechanical coupling strength at the moment of material damage, where, For time delay, The duration of a single instantaneous mechanical scratching excitation.

5. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The controller is also configured to: before applying a single instantaneous mechanical scratching excitation, control the electrochemical workstation to perform an electrochemical impedance spectroscopy measurement on the orthodontic archwire sample to determine a charge transfer resistance value characterizing the current interface temperature; and normalize the finally determined relaxation time constant and total integrated charge using a function that maps the charge transfer resistance value to a temperature correction coefficient to output a set of kinetic parameters at a standard reference temperature.

6. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The system also includes: an optical calibration module, comprising an imaging unit and an image processing unit, wherein the imaging unit is configured to acquire a digital image of the scratch formed by a single instantaneous mechanical scratch excitation after the excitation is completed; the image processing unit is configured to analyze the digital image to calculate the precise geometric area of ​​the scratch; and the controller is further configured to normalize the total integrated charge per unit area using the precise geometric area.

7. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The controller is also configured to control the mechanical excitation device and the electrochemical workstation to repeatedly perform a cycle of applying a single instantaneous mechanical scratch excitation and recording the electrochemical relaxation transient current curve at least 10 times; and to perform statistical analysis on the relaxation time constant and total integrated charge determined in each cycle to output a standard deviation characterizing the repeatability stability of the repassivation behavior of the orthodontic archwire sample.

8. The orthodontic archwire friction corrosion testing system according to claim 1, characterized in that, The mechanical excitation device includes a scriber with a standard geometry and a three-axis motion platform for driving the scriber; the controller is configured to control the motion velocity profile of the three-axis motion platform and the normal contact load applied to the scriber via a closed loop.

9. The orthodontic archwire friction corrosion testing system according to claim 3, characterized in that, The controller integrates an acoustic feature analysis module, which is configured to classify the microscopic damage mode of passivation film rupture into a high-amplitude, short-duration brittle cracking mode or a low-amplitude, long-duration ductile tearing mode based on a set of acoustic feature parameters and a classification rule that compares the values ​​with a preset threshold.

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