A method for analyzing micro-morphology and antioxidation performance of refractory stainless steel yarn fiber

Abstract

The application relates to the technical field of physical and chemical property analysis of new materials, and discloses a method for analyzing the micro morphology and oxidation resistance of fire-resistant stainless steel yarn fibers, which comprises the following steps: in-situ oxidation of the fire-resistant stainless steel yarn fibers to be measured at high temperature to generate a chromium trioxide oxidation film; using a 532 nm excitation light source to obtain characteristic fluorescence spectrum of chromium ions of the oxidation film; extracting a first characteristic spectral line center frequency and a bilateral half-height width, calculating an asymmetric factor to remove a broadening component caused by surface geometric curvature, and determining a line width increment reflecting a stress gradient; constructing a dynamic evolution trajectory curve related to stress and distortion within a sampling period, fitting an elliptical envelope to extract an evolution coordination factor and local curvature, and monitoring the change trend of the evolution coordination factor and the local curvature, identifying the internal micro-crack initiation characteristics of the oxidation film, realizing physical isolation of damage signals and geometric noise, and improving the accuracy of the oxidation resistance evaluation of the porous structure fibers.

Description

Technical Field

[0001] This invention relates to a method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers, belonging to the field of new material physicochemical property analysis technology. Background Technology

[0002] Currently, refractory stainless steel yarn is a key component of petrochemical hydrocracking furnaces and high-temperature filtration devices. Its service safety and oxidation resistance integrity under fluctuating thermodynamic environments of 900℃ to 1100℃ are the standards for evaluating the reliability of industrial equipment. Observing the microscopic characteristics of the oxide film on the fiber surface after cooling sampling using scanning electron microscopy or X-ray diffraction is a conventional method for evaluating oxidation resistance. The performance state of the material under extreme working conditions can be inverted through static morphology. Offline testing is prone to analytical bias when dealing with porous and loose single-filament fiber bundles with complex spatial configurations. The diameter of the single filament is 12 to 15 micrometers. During thermal cycling, the stress of oxide film growth and thermal mismatch stress are dynamically intertwined. The morphology obtained by existing cooling sampling is the state after stress release. The cooling process masks the physical characteristics of the oxide film's transformation from dense protection to microcrack initiation at high temperatures, resulting in a lag in early warning of fiber brittle fracture risk.

[0003] While attempts have been made to improve the physical properties of components and extend their service life from the perspective of material formulation, there is a lack of in-situ sensing methods for the dynamic evolution of microscopic damage within components under complex working conditions. For example, Chinese invention patent CN105669227A discloses a high-strength ceramic wear-resistant material, its preparation method, and its application. It improves the material strength and thermal shock stability by introducing stainless steel fibers into the raw materials. However, the technical perspective is limited to static material improvement and enhancement. Under high-temperature cyclic loading, the damage signal of the oxide film on the surface of stainless steel fibers is highly coupled with the geometric background noise generated by the porous structure of the yarn. The comparative solution does not solve the problem of capturing the stress gradient distortion inside the oxide film in the high-temperature in-situ state, and cannot identify the microcrack initiation characteristics through signal decoupling mechanisms. The current technical status quo, which emphasizes static formulation and neglects dynamic analysis, leads to catastrophic spalling of refractory components. Currently, there is a lack of scientific performance criteria. Even with the introduction of high-temperature simulation devices or the construction of cooling correction models to compensate for the effects of thermal shock, it is still difficult to overcome the signal decoupling barrier in porous fiber bundle scenarios. The surface curvature of yarn fibers is variable and the arrangement of monofilaments is uneven, making it impossible to extract the micro-stress field distribution characteristics while maintaining thermal field equilibrium. Existing technologies have the following shortcomings: the detection lacks in-situ capability, and the mechanical stress and temperature drift errors induced by the cooling process cause the observed morphology to deviate from the actual service condition; the indicator dimensions are singular, focusing only on mass gain or thickness, and cannot quantify growth stress and stress gradient distortion; the processing capacity is insufficient, making it difficult to identify local oxide film failure signals in the background noise of porous structures. Oxide film failure is controlled by the evolution trajectory of the internal micro-stress field. Establishing a dynamic evaluation mechanism that reflects the relationship between lattice distortion and failure criticality is the foundation for controlling the life of core components.

[0004] Therefore, how to achieve in-situ monitoring of the micro-stress and morphological stability of oxide film in refractory stainless steel yarn fibers under high temperature environment, and eliminate interference from complex geometric structures to identify the physical critical state of oxide film peeling, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers, comprising the following steps:

[0006] Step 101: Place the refractory stainless steel yarn fiber to be tested in a high-temperature thermodynamic environment within a preset temperature range to perform in-situ oxidation treatment, so that a chromium trioxide oxide film is generated on the surface of the refractory stainless steel yarn fiber to be tested.

[0007] Step 102: Irradiate the surface of the chromium trioxide oxide film with an excitation light source of 532 nm through a co-directional confocal optical path system to obtain the characteristic fluorescence spectrum of chromium ions in the chromium trioxide oxide film.

[0008] Step 103: Extract the center frequency of the first characteristic spectral line in the characteristic fluorescence spectrum, and determine the frequency drift by comparing the center frequency with the frequency of the stress-free reference state; simultaneously extract the left half-width and right half-width of the first characteristic spectral line, calculate the ratio of the left half-width to the right half-width to determine the asymmetry factor, and based on the deviation of the asymmetry factor in the range of 0.95 to 1.05, remove the symmetry broadening component caused by the surface geometric curvature of the refractory stainless steel yarn fiber to be tested, thereby determining the linewidth increment reflecting the internal stress gradient of the chromium trioxide oxide film;

[0009] Step 104: Within the preset total number of continuous sampling periods, construct a dynamic evolution trajectory curve reflecting the relationship between stress and distortion by using the frequency drift obtained at each sampling time as the abscissa and the synchronously extracted linewidth increment as the ordinate; use the least squares fitting algorithm to fit the elliptical envelope of the dynamic evolution trajectory curve, calculate the ratio of the minor axis to the major axis of the envelope circle as the evolution co-factor, and calculate the local curvature of the dynamic evolution trajectory curve at each sampling point.

[0010] Step 105: Monitor the changing trends of evolution co-factor and local curvature; if, within the current sampling window, the rate of decrease of evolution co-factor exceeds the preset imbalance threshold, and the root mean square deviation of local curvature shows a sudden jump of more than 20%, it is determined that microcracks have started inside the chromium trioxide oxide film.

[0011] Preferably, in step 103, the instantaneous temperature of the chromium trioxide oxide film surface is calculated using the relative intensity ratio of the first characteristic spectral line and the second characteristic spectral line in the characteristic fluorescence spectrum. And perform thermal compensation correction on the frequency drift based on the linear temperature drift coefficient; instantaneous temperature It conforms to the functional relationship with the relative intensity ratio: ,in, The instantaneous temperature of the measuring area. The energy level difference between the first and second characteristic spectral lines. Boltzmann's constant, and These represent the integrated intensity of the first and second characteristic spectral lines, respectively.

[0012] Preferably, in step 104, the total number of sampling periods is set to an integer between 10 and 30, and the sampling frequency is set to 2Hz to 5Hz, so that the dynamic evolution trajectory curve covers the complete thermal expansion response period within the current sampling window.

[0013] Preferably, in step 102, the diameter of the laser beam generated by the excitation source after beam expansion and focusing is matched with the diameter of the single filament of the refractory stainless steel yarn fiber to be tested, and the power of the excitation source on the surface of the chromium trioxide oxide film is controlled between 15mW and 20mW.

[0014] Preferably, the process of extracting spectral parameters in step 103 includes the following steps: Step 501, using the double Lorentz function to perform nonlinear least squares fitting on the collected characteristic fluorescence spectrum to analyze the peak position coordinates, peak intensity and full width at half maximum of the first characteristic spectral line; Step 502, constraining the peak position difference between the first characteristic spectral line and the second characteristic spectral line to conform to the preset temperature mapping relationship, and determining the signal validity of the characteristic fluorescence spectrum by calculating the fitting residual.

[0015] Preferably, in step 104, the dynamic evolution trajectory curve is normalized, and the frequency drift and linewidth increment in the coordinate system are projected to a numerical range of zero to one, respectively, in order to extract the evolution co-factor.

[0016] Preferably, in step 105, the determination of the initiation of microcracks inside the chromium trioxide oxide film is performed by identifying the trajectory loss characteristics of the dynamic evolution trajectory curve when the chromium trioxide oxide film undergoes local peeling. The trajectory loss characteristics are characterized by the transformation of the dynamic evolution trajectory curve from a closed loop to an open trajectory.

[0017] Preferably, in step 101, the temperature of the high-temperature thermodynamic environment is set to 900°C to 1100°C, and the duration of the in-situ oxidation treatment is determined according to the preset service life cycle of the refractory stainless steel yarn fiber to be tested.

[0018] Preferably, in step 103, when the relative intensity ratio deviates from the theoretical value at the corresponding instantaneous temperature by more than 10%, it is determined that the characteristic fluorescence spectrum is interfered with by background infrared radiation, and the signal smoothing process is initiated to correct the frequency drift.

[0019] Preferably, in step 105, the initial reference value of the evolution synergy factor is set to be no less than 0.85. When the evolution synergy factor continuously decreases to below 0.6, an early warning signal is output indicating that the chromium trioxide oxide film has entered a critical failure state.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. In the microstructure of stainless steel yarn fibers, the asymmetric evolution of characteristic fluorescence spectral peaks is utilized to decouple the symmetric broadening component caused by the geometric curvature of the fiber surface from the stress gradient broadening component caused by internal damage of the oxide film at the physical mechanism level. This solves the problem of measurement artifact interference caused by the bending of the single filament surface when analyzing porous and loose structure yarn fibers. By identifying the skew features of the left half height and width and the right half height and width of the spectral line, pathological damage signals are extracted. The system maintains analytical accuracy and signal-to-noise ratio when dealing with complex microstructures with single filament diameters of 12 to 15 micrometers.

[0022] 2. Construct a dual-dimensional correlation trajectory curve between frequency displacement and linewidth evolution, transforming static stress numerical monitoring into phase space trajectory topological feature identification. When the absolute value of oxide film stress does not reach the preset damage threshold, capture the metastable critical characteristics of oxide film transformation from elastic strain accumulation to microcrack initiation, identify the difference between synergistic spectral line drift caused by overall temperature field fluctuations and stress concentration effect caused by local cracking of oxide film, and realize the prediction of refractory fiber service life and oxidation resistance integrity.

[0023] 3. By combining the synergy factor and the dynamic monitoring of the local curvature of the trajectory curve, a self-compensating analysis logic for the ultra-high temperature thermodynamic fluctuation environment is constructed. This eliminates background noise interference caused by uneven spatial arrangement of yarn fiber bundles and differences in thermal field distribution. Under continuous thermal cycling conditions from 900℃ to 1100℃, the trajectory phase tearing phenomenon is identified, rather than relying on isolated transient sampling data. This establishes the physical criteria for the transformation of the oxide film from a dense protective state to a failure state, making the analysis results stable in actual industrial scenarios such as petrochemical high-temperature furnaces. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the main process steps of the method for analyzing the antioxidant properties of refractory stainless steel yarn fibers according to the present invention.

[0025] Figure 2 This is a schematic diagram of the double Lorentz fitting analysis of the characteristic fluorescence spectrum of the oxide film of the present invention;

[0026] Figure 3This is a schematic diagram of the dynamic evolution trajectory and elliptical envelope fitting of the stress-distortion relationship in this invention.

[0027] Figure 4 This is a schematic diagram of the overall logical architecture and functional module division of the analysis method of the present invention. Detailed Implementation

[0028] The following disclosure is used to elaborate on the technical solutions provided by the present invention in order to explain the technical concept of the present invention, but is not intended to limit the scope of protection of the present invention. Any equivalent substitutions or improvements made by those skilled in the art to the following technical features without departing from the essential spirit of the present invention shall fall within the scope of protection of the present invention.

[0029] This invention provides a method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers. Through high-temperature in-situ detection, energy dispersive spectroscopy (EDS) characteristic evolution analysis, and phase space trajectory identification, a non-contact quantitative evaluation of the damage state of the oxide film on the surface of stainless steel fibers is achieved. The system induces the formation of a chromium trioxide oxide film on the fiber surface in a controlled thermodynamic environment. Characteristic fluorescence spectra containing stress information are acquired using a specific wavelength excitation light source. Background noise introduced by the local surface curvature of the fiber is eliminated through peak shape asymmetry correction logic, and the linewidth increment reflecting the internal stress gradient is determined. Finally, by constructing a dynamic evolution trajectory curve relating stress and distortion, the initiation state of microcracks within the oxide film is determined using topological characteristic parameters, thus completing the evaluation of the fiber's antioxidant properties. This method is applicable to stainless steel yarns. When analyzing typical service scenarios such as hydrocracking furnaces or high-temperature filtration devices, refractory stainless steel yarn fibers are in a fluctuating thermal field of 900°C to 1100°C. Since the yarn is a porous and loose body spun from thousands of monofilaments with a diameter of 12μm to 15μm, the growth stress and thermal mismatch stress of the oxide film are highly intertwined during the dynamic oxidation process. The release of thermal stress generated during the cooling process can cause artifacts in the observed morphology. The present invention adopts an in-situ oxidation process, placing the refractory stainless steel yarn fiber to be tested in a high-temperature thermodynamic environment within a preset temperature range, so that a chromium trioxide oxide film is generated on the surface of the refractory stainless steel yarn fiber to be tested. The temperature of this environment is set in the range of 900°C to 1100°C according to the preset service life cycle of the fiber.

[0030] To obtain local stress data of the oxide film without disrupting the high-temperature field, the system utilizes a 532nm excitation light source. This light source, irradiated with a co-directional confocal optical path system, excites chromium ions in the oxide film to produce characteristic fluorescence spectra. A continuous-wave solid-state laser is used as the excitation light source, with its output power controlled within the range of 15mW to 20mW. Furthermore, the diameter of the laser beam after beam expansion and focusing matches the diameter of a single filament of the refractory stainless steel yarn being tested, thus locking the detection area onto the surface of a single fiber and obtaining data containing... Spectral lines and The spectral signal; due to the micron-level local curvature of the stainless steel yarn fiber surface, when the light beam is incident on the cylindrical surface of the fiber, physical broadening occurs due to the difference in reflection path. This broadening is not caused by oxide film damage. To address this obstacle, a parameter extraction procedure is established, and the acquired characteristic fluorescence spectra are fitted nonlinearly using the double Lorentz function. The function expression is as follows: ,in, Spectral intensity; For background base site; and They are respectively Peak and Peak intensity coefficient; Frequency coordinates; and They are respectively Peak and The coordinates of the peak position; and They are respectively Peak and Half the height and width of the peak.

[0031] Parse The center frequency and full width at half maximum (FWHM) of the peak are determined, and constraints are imposed. Peak and The peak position difference conforms to the preset temperature mapping relationship. The validity of the signal is determined by calculating the fitting residual. A zero-stress benchmark calibration procedure is established, and the purity is selected. of Standard powder is placed in a high-temperature environment for synchronous thermal equilibrium treatment, and the center wavelength drift of the excitation light source is locked using a wavelength monitoring unit. 66. Extract the R1 spectral line frequency of the powder under thermal equilibrium state as the temperature-controlled zero-point wave value. The correction function is defined as ,in The room temperature reference frequency, The instrument temperature drift compensation coefficient is determined by periodically acquiring standard powder energy dispersive spectroscopy signals to calibrate the spectrometer grating rotation angle deviation in real time. This eliminates the impact of non-isothermal disturbances on the accuracy of micro-stress analysis and ensures the frequency drift compensation coefficient. The calculation results have physical traceability and can be extracted. The center frequency of the spectral line is compared with the frequency of the stress-free reference state to determine the frequency shift. Synchronous extraction left half height and width of the spectral line and the height and width of the right half Calculate their ratio as the asymmetric factor. Based on the deviation of this factor within the range of 0.95 to 1.05, the symmetric broadening component caused by the surface geometric curvature of the refractory stainless steel yarn fiber under test is identified and eliminated, thereby determining the linewidth increment reflecting the internal stress gradient of the chromium trioxide oxide film. This procedure eliminates measurement bias caused by surface curvature through decoupling at the physical mechanism level. In extremely high-temperature environments, strong infrared background radiation interferes with the frequency localization of spectral lines; therefore, self-compensation logic is introduced, utilizing characteristic fluorescence spectra... Spectral lines and The integrated intensity ratio of spectral lines is used to calculate the instantaneous temperature of the chromium trioxide oxide film surface. Its functional relationship conforms to: ,in, The instantaneous temperature of the measuring area; The energy level difference between the first characteristic spectral line and the second characteristic spectral line; Boltzmann's constant; and The integrated intensities of the first and second characteristic spectral lines are respectively; based on the obtained instantaneous temperature and the effect of linear temperature drift coefficient on frequency drift Perform thermal compensation correction. When the intensity ratio deviates from the theoretical value at the corresponding temperature by more than 10%, it is determined that the signal is affected by background radiation interference. Initiate the signal smoothing process to correct the data and ensure that the analysis results are not affected by non-isothermal disturbances.

[0032] To capture the metastable critical characteristics of the oxide film transitioning from elastic accumulation to brittle fracture, the system sets the sampling frequency to 2Hz to 5Hz within a preset 10 to 30 consecutive sampling periods, and uses the frequency drift obtained at each sampling time. The x-axis represents the line width increment extracted synchronously. Using the vertical axis as the ordinate, a dynamic evolution trajectory curve reflecting the relationship between stress and distortion is constructed. This curve is then normalized, and the numerical values ​​within the coordinate system are projected to the 0-1 interval. Dynamic trajectory topology analysis is then performed to determine the frequency drift obtained within the sampling period. With line width increment Mapped to state observation vector Construct the covariance matrix Calculate the matrix Maximum eigenvalue with minimum eigenvalue Define evolutionary co-factors ,in Indicator stress principal axis evolution strength, Indicator of local distortion dispersion, and setting of failure critical threshold based on statistical distribution of material interface bonding energy. If within 3 consecutive sampling periods Converging toward the threshold and local curvature Root mean square deviation sudden jump The stress field was determined to be transforming from isotropic elastic accumulation to non-uniform microcrack initiation. An elliptical envelope was fitted using a least-squares fitting algorithm, and the ratio of the minor axis to the major axis of the envelope circle was calculated as an evolution co-factor. And calculate the local curvature of the trajectory curve at each sampling point. By monitoring evolutionary co-factors With local curvature Damage is identified by the changing trend of the evolution co-factor. The rate of change of the decrease exceeds the preset threshold, and the local curvature When the root mean square deviation increases by more than 20%, it is determined that microcracks have started inside the chromium trioxide oxide film. At this time, the trajectory shows the characteristic of changing from a closed loop to an open trajectory. Based on this, the system outputs an early warning signal of the critical failure state. For specific engineering deployments, the system is equipped with an optical fiber transmission unit to introduce the excitation light into the window of the high-temperature reactor. The reflected signal is captured by the co-directional confocal optical path and transmitted to a spectrometer with a focal length of not less than 500 mm. Its spectroscopic system adopts a holographic grating of 1800 lines / mm to ensure that the spectral resolution is better than 0.1 cm⁻¹.

[0033] Example 1: Online analysis of the antioxidant properties of refractory stainless steel yarn with a single filament diameter of 12μm to 15μm was performed in a petrochemical hydrocracking furnace with an operating temperature maintained at 900℃ to 1100℃. Under this condition, the yarn consists of thousands of single filaments with different surface curvatures. Due to the difference in thermal field distribution during thermodynamic cycling, each single filament generates a complex background stress signal, making it difficult for traditional single-frequency displacement detection methods to distinguish between pathological damage signals caused by stress gradients within the oxide film and geometric broadening noise caused by fiber bundle arrangement. The system uses an excitation light source with a wavelength of 532nm and an irradiation power of 18mW to act on the yarn surface. The characteristic fluorescence spectrum of the chromium trioxide oxide film is captured through a co-directional confocal optical path, and extracted... left half height and width of the spectral line With right half height and width Calculate the asymmetric factor To characterize the deformation features of spectral lines, among which It is an asymmetric factor. The left half-width of the spectral line. The half-width at half-maximum (FWHM) of the spectral line is shown by comparison. For deviations outside the 0.95 to 1.05 range, the system directly eliminates the symmetric geometric broadening component caused by the fiber cylindrical surface during the signal processing stage, thereby obtaining the linewidth increment reflecting the internal distortion of the oxide film. .

[0034] During online monitoring, the system simultaneously extracts the frequency drift. Compared with the above line width increment A dynamic evolution trajectory curve reflecting the relationship between stress and distortion is constructed in a two-dimensional phase space, and the least squares method is used to fit the elliptical envelope, and the evolution synergy factor is calculated in real time. ,in The ratio of the minor axis to the major axis of the envelope circle, when the oxide film maintains its morphology intact, The value remains at At the above levels, with increasing service time, when microcracks with a growth rate of less than 1 μm begin to germinate inside the oxide film, the non-uniform stress field at the crack tip causes phase tearing of the spectral lines, leading to... The value rapidly decreased to below 0.6 within the continuous sampling period, and the root mean square deviation of the locally calculated curvature C showed a sudden change of more than 20%, indicating the initiation of microcracks inside the oxide film; the system utilizes Spectral lines and The integrated intensity ratio of spectral lines Real-time calculation of instantaneous temperature in the measuring area Based on the linear temperature drift coefficient Perform thermal compensation correction on the frequency drift.

[0035] Example 2: In a physical testing platform used to evaluate the oxidation resistance of refractory stainless steel yarn fibers, the test object was selected as refractory stainless steel fiber with a single filament diameter of 15 μm. This physical testing platform is equipped with a heating device with a temperature control accuracy better than ±1°C and a spectrophotometric analysis system with a focal length of 500 mm and a spectral resolution better than 0.1 cm⁻¹. The test data came from real-time acquisition of oxidation products on the fiber surface under a thermal cycling environment of 900°C to 1100°C. To simulate the industrial environment, Gaussian white noise with a signal-to-noise ratio of 20 dB was superimposed on the signal input of the spectrophotometric analysis system to evaluate the system's signal resolution capability under electronic thermal noise interference. The sampling frequency was set based on the balance between capturing the transient characteristics of oxide film stress redistribution and the computational load of the data processing module. When the oxide film growth rate was... To obtain the complete thermal response trajectory within the 2s thermal expansion driving cycle, the sampling frequency was set to 5Hz. The system used a continuous wave solid-state laser with a wavelength of 532nm and an irradiation power of 18mW to obtain the characteristic fluorescence spectrum of chromium ions in the chromium trioxide oxide film through a co-directional confocal optical path. See Table 1 for the comparison of characteristic parameters of the sample group and the control group of the present invention at different oxidation stages.

[0036] Table 1: Online Detection Test Data of Damage to Fiber Oxide Film in Refractory Stainless Steel

[0037]

[0038] According to Table 1, during the stable period of the sample group of this invention, the asymmetry factor... Maintaining a level of 0.98, the system, based on this symmetrical distribution characteristic, eliminates the geometric broadening component caused by the curvature of the fiber surface, thus reducing the linewidth increment reflecting the stress gradient within the oxide film. The linewidth increment stabilized at 1.86 cm⁻¹; when the sample group entered the germination stage after oxidation for 85% of the preset service life, the linewidth increment... It suddenly increased to 4.32cm⁻¹ and Deviation to 1.18, evolution co-factor Decreased to 0.58, local curvature The root mean square deviation jumped to 22.4%, and the system determined, based on the aforementioned topological characteristic changes, that microcracks had begun to initiate within the oxide film. In the out-of-range control group at 1200°C, which exceeded the preset operating window, the oxide film underwent an irreversible phase transformation, resulting in an abnormally widened linewidth increment of 15.42 cm⁻¹, and the evolution synergy factor... It dropped to an extremely low coordination state of 0.12.

[0039] Example 3: This example combines Figures 1 to 4 This paper describes the analytical method for the microstructure and antioxidant properties of a refractory stainless steel yarn fiber, such as... Figure 1 As shown, in step 101, the refractory stainless steel yarn fiber to be tested is placed in a high-temperature thermodynamic environment to perform high-temperature in-situ oxidation treatment, so that a chromium trioxide oxide film is formed on the fiber surface. In step 102, the oxide film is irradiated using a 532 nm excitation light source through a co-directional confocal optical path system to obtain the characteristic fluorescence spectrum of chromium ions in the oxide film. Then, steps 103-A and 103-B are performed in parallel. In step 103-A, the center frequency of the first characteristic spectral line is extracted and compared with the frequency of the stress-free reference state to determine the frequency shift. In step 103-B, the asymmetry factor is calculated. The broadening component caused by surface geometric curvature is removed to determine the linewidth increment reflecting the stress gradient. Based on this, step 104-A is performed to construct a dynamic evolution trajectory curve of stress and distortion correlation within the sampling period, with the frequency drift as the abscissa and the linewidth increment as the ordinate. Then, step 104-B uses the least squares fitting algorithm to fit the trajectory curve to an ellipse envelope to extract the evolution co-factor and local curvature. Finally, step 105 is performed to identify the microcrack initiation characteristics inside the oxide film by monitoring the changing trends of the evolution co-factor and local curvature.

[0040] like Figure 2As shown, the horizontal axis represents wavelength in nanometers (nm), and the vertical axis represents intensity in arbitrary units (au). The solid line in the figure represents the acquired measured spectrum, which exhibits a distinct bimodal characteristic in the wavelength range of 690 nm to 694 nm. The dashed line represents the R1 spectral line fitting curve obtained by fitting with a double Lorentz function, and the dotted line represents the R2 spectral line fitting curve obtained by fitting with a double Lorentz function. The peak position coordinates, peak intensities, and full width at half maximum (FWHM) of the R1 and R2 spectral lines are obtained by nonlinear least-squares fitting of the measured spectrum, and spectral characteristic parameters for subsequent stress analysis are extracted based on these parameters. Figure 3 As shown, the horizontal axis represents the frequency drift. The unit is wavenumber (cm⁻¹), and the vertical axis represents the line width increment. The unit is wavenumber (cm⁻¹). The solid line with data points in the figure constitutes the dynamic evolution trajectory, showing the coordinated change path of frequency drift and linewidth increment within a continuous sampling period. The dashed line in the figure is the elliptical envelope fitting curve performed on this dynamic evolution trajectory. The evolution coordination factor is extracted by calculating the ratio of the minor axis to the major axis of this envelope circle, which is used to characterize the topological features and stability of the stress field inside the oxide film. Figure 4 As shown in the figure, this diagram illustrates the overall logical architecture of the analysis method for the microstructure and antioxidant properties of refractory stainless steel yarn fibers. It includes six main functional modules: the oxidation environment construction module covers high-temperature environments from 900℃ to 1100℃, in-situ oxidation treatment, and the formation of chromium trioxide oxide film; the optical signal acquisition module covers a 532 nm excitation light source, a co-directional confocal optical path, and 15 mW to 20 mW power control; the signal decoupling processing module is responsible for extracting the center frequency of characteristic spectral lines, calculating asymmetry factors, eliminating geometric curvature broadening, and determining linewidth increments; the temperature self-compensation module uses the intensity ratio of the double peaks of characteristic spectral lines to calculate the instantaneous temperature T and correct the frequency drift; the dynamic evolution analysis module performs stress distortion trajectory construction, elliptical envelope fitting, and extraction of evolution synergy factors; and the state determination logic module monitors the decreasing trend of synergy factors and sudden jumps in local curvature to identify microcrack initiation characteristics, ultimately outputting the microcrack initiation determination and antioxidant performance evaluation results.

[0041] Example 4: In the calibration procedure for analyzing the antioxidant properties of refractory stainless steel yarn fibers, a stress-free reference state establishment procedure was performed. Chromium trioxide standard powder with a purity of not less than 99.9% and a median particle size between 1 μm and 2 μm was selected as a physical reference. This powder sample was placed in the same high-temperature thermodynamic environment (900°C to 1100°C) as the yarn fiber to be tested for sufficient thermal equilibrium treatment. The surface of the powder sample was irradiated with an excitation light source with a wavelength of 532 nm, and its characteristic fluorescence spectrum was collected to extract... The center frequency of the spectral line is used as the reference value for the zero-stress wave at that temperature. The unit is cm⁻¹, which eliminates measurement deviations introduced by the slight wavelength drift of the excitation source or the thermal expansion of the grating in the beam splitter system, and provides a basis for subsequent frequency shift measurements. The calculation provides a zero-point reference; after acquiring the dynamic energy spectrum data of the surface of the refractory stainless steel yarn fiber under test, the system performs geometric deconstruction of the dynamic evolution trajectory curve reflecting the correlation between stress and distortion, and calculates the frequency drift acquired at each moment within a preset continuous 20 sampling periods. With line width increment This constitutes the observation vector sequence.

[0042] By calculating the covariance matrix of the sequence and solving its characteristic equation, the eigenvalues ​​representing the principal axis directions of the data distribution are obtained. and , The largest eigenvalue represents the intensity of the evolution of the principal stress axes. The minimum eigenvalue represents the intensity of trajectory discrepancy caused by distortion perturbation, and is the evolution co-factor. Defined as: ,in, As an evolutionary co-factor, The largest eigenvalue of the covariance matrix. The smallest eigenvalue of the covariance matrix; this evolutionary cooperativity factor The initial reference value of 0.85 is anchored to the energy level splitting symmetry of the chromium trioxide single crystal lattice under purely elastic strain, representing a highly isotropic stress field distribution. When micropores initiate within the oxide film, the localization and divergence of the strain field leads to... Rapid growth, The value converges towards its failure critical threshold of 0.6, which is set based on the statistical distribution of the interfacial bonding energy of the refractory stainless steel oxide layer. When the value is below 0.6 for three consecutive sampling periods, it is determined that the dispersion of the local stress gradient exceeds the safety envelope of the grain boundary cohesion, and the system outputs an early warning signal that the oxide film has entered the critical failure state.

[0043] Example 5: In the field deployment procedure for the analysis method of oxidation resistance of refractory stainless steel yarn fibers, a baseline setting procedure based on environmental background signal suppression was executed. The spectroscopic analysis system continuously acquired 50 cycles of environmental energy spectrum data with the excitation light source off, and calculated the average background intensity of the detector in the 690nm to 710nm band. The excitation light source is turned on and irradiated onto the surface of the fiber under test at room temperature to obtain the initial integration strength ratio. ,in The initial integration strength ratio, At room temperature The integrated intensity of spectral lines At room temperature The integrated intensity of the spectral lines is normalized by calculating the ratio of the real-time integrated intensity ratio to the initial integrated intensity ratio. This eliminates deviations introduced by fiber transmission loss and detector responsivity differences, thus providing a basis for subsequent instantaneous temperature measurements. The inversion provides an input baseline.

[0044] When the system encounters a situation where the energy spectrum signal is momentarily discontinuous due to airflow disturbances within the petrochemical hydrocracking furnace, the system initiates a signal purification procedure based on sliding median filtering. Within a preset window consisting of 20 consecutive sampling periods, the system analyzes the acquired frequency drift. The sequence is sorted in descending order, and the middle value is selected as the valid input parameter for the current moment. The sum of the integrated intensities of the characteristic spectral lines detected in real time is considered. Below background intensity The value is 1.5 times higher, which is determined to be due to optical path obstruction causing signal validity loss. The system automatically maintains the evolution of the effective sampling period as a cooperating factor. The signal recovery and identification logic is then activated until the subsequent integration strength recovers to above the aforementioned threshold, at which point the eigenvalue solving program for the covariance matrix is ​​reactivated.

[0045] Example 6: In the adaptation procedure for field deployment of refractory stainless steel yarn fibers from different production batches, a piezomagnetic coefficient calibration procedure based on load energy spectrum response was performed. A static elastic load ranging from 0 MPa to 500 MPa was applied to the fiber bundles of the test batch using a tensile loading stage with displacement monitoring function. The fiber surface was then irradiated with an excitation light source of 532 nm to obtain the characteristic fluorescence spectrum of the chromium trioxide oxide film. The data processing module analyzed the data. The center frequency coordinates of the spectral lines were calculated, and the frequency shift at each load level was determined. Linear regression fitting was performed on the obtained frequency drift sequence and the corresponding static elastic load sequence to determine the piezomagnetic coefficient of the fiber batch. Its unit is cm⁻¹ / MPa. This specification eliminates the deviation of stress conversion coefficient caused by fluctuations in raw material composition, and provides a physically traceable input parameter for the dynamic evolution trajectory analysis of stress and distortion.

[0046] In the online monitoring scenario of a petrochemical hydrocracking furnace accompanied by mechanical vibration and high temperature fluctuations, to correct the measurement error caused by the shift of the probe spot, the system executes a dynamic focusing compensation program based on spatial signal intensity before dynamic monitoring. A three-dimensional displacement control mechanism performs a step-by-step energy spectrum scan within a 100μm diameter spatial region containing the fiber filament under test, recording the values ​​at each spatial coordinate point. The peak intensity of the spectral line is determined, and its global maximum value is locked as the physical focusing origin for the current monitoring period. If obtained during online monitoring Instantaneous integrated intensity of spectral lines The intensity was below 40% of the intensity corresponding to the physical focusing origin for five consecutive sampling cycles, and the ambient background intensity was measured simultaneously. If the fluctuation amplitude is less than 5%, the data processing module determines that the optical path has undergone geometric offset and controls the receiving optical path to perform an optimization adjustment program until the signal strength recovers to the preset threshold. This procedure achieves physical isolation between environmental vibration noise and material damage signals, enabling the evolution synergy factor to maintain a stable output state under complex working conditions.

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

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers, characterized in that, Includes the following steps: Step 101: Place the refractory stainless steel yarn fiber to be tested in a high-temperature thermodynamic environment within a preset temperature range to perform in-situ oxidation treatment, so that a chromium trioxide oxide film is generated on the surface of the refractory stainless steel yarn fiber to be tested. Step 102: Irradiate the surface of the chromium trioxide oxide film with an excitation light source of 532 nm through a co-directional confocal optical path system to obtain the characteristic fluorescence spectrum of chromium ions in the chromium trioxide oxide film. Step 103: Extract the center frequency of the first characteristic spectral line in the characteristic fluorescence spectrum, and determine the frequency drift by comparing the center frequency with the frequency of the stress-free reference state; simultaneously extract the left half-width and right half-width of the first characteristic spectral line, calculate the ratio of the left half-width to the right half-width to determine the asymmetry factor, and based on the deviation of the asymmetry factor in the range of 0.95 to 1.05, remove the symmetry broadening component caused by the surface geometric curvature of the refractory stainless steel yarn fiber to be tested, thereby determining the linewidth increment reflecting the internal stress gradient of the chromium trioxide oxide film; Step 104: Within the preset total number of continuous sampling periods, construct a dynamic evolution trajectory curve reflecting the relationship between stress and distortion by using the frequency drift obtained at each sampling time as the abscissa and the synchronously extracted linewidth increment as the ordinate; use the least squares fitting algorithm to fit the elliptical envelope of the dynamic evolution trajectory curve, calculate the ratio of the minor axis to the major axis of the envelope circle as the evolution co-factor, and calculate the local curvature of the dynamic evolution trajectory curve at each sampling point. Step 105: Monitor the changing trends of evolution co-factor and local curvature; if, within the current sampling window, the rate of decrease of evolution co-factor exceeds the preset imbalance threshold, and the root mean square deviation of local curvature shows a sudden jump of more than 20%, it is determined that microcracks have started inside the chromium trioxide oxide film.

2. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 103, the instantaneous temperature of the chromium trioxide oxide film surface is calculated using the relative intensity ratio of the first characteristic spectral line and the second characteristic spectral line in the characteristic fluorescence spectrum. And perform thermal compensation correction on the frequency drift based on the linear temperature drift coefficient; instantaneous temperature It conforms to the functional relationship with the relative intensity ratio: ,in, The instantaneous temperature of the measuring area. The energy level difference between the first and second characteristic spectral lines. Boltzmann's constant, and These represent the integrated intensity of the first and second characteristic spectral lines, respectively.

3. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 104, the total number of sampling periods is set to an integer between 10 and 30, and the sampling frequency is set to 2Hz to 5Hz, so that the dynamic evolution trajectory curve covers the complete thermal expansion response period within the current sampling window.

4. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 102, the diameter of the laser beam generated by the excitation source after beam expansion and focusing is matched with the diameter of the single filament of the refractory stainless steel yarn fiber to be tested, and the power of the excitation source on the surface of the chromium trioxide oxide film is controlled between 15mW and 20mW.

5. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, Step 103 involves extracting spectral parameters, including the following steps: Step 501, using the double Lorentz function to perform nonlinear least squares fitting on the acquired characteristic fluorescence spectrum to analyze the peak position coordinates, peak intensity, and full width at half maximum (FWHM) of the first characteristic spectral line; Step 502, constraining the peak position difference between the first and second characteristic spectral lines to conform to a preset temperature mapping relationship, and determining the signal validity of the characteristic fluorescence spectrum by calculating the fitting residual.

6. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 104, the dynamic evolution trajectory curve is normalized, and the frequency drift and linewidth increment in the coordinate system are projected to the numerical range of zero to one, respectively, in order to extract the evolution co-factor.

7. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 105, the determination of the initiation of microcracks inside the chromium trioxide oxide film is performed by identifying the trajectory loss characteristics of the dynamic evolution trajectory curve when the chromium trioxide oxide film undergoes local peeling. The trajectory loss characteristics are characterized by the transformation of the dynamic evolution trajectory curve from a closed loop to an open trajectory.

8. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 1, characterized in that, In step 101, the temperature of the high-temperature thermodynamic environment is set to 900℃ to 1100℃, and the duration of the in-situ oxidation treatment is determined according to the preset service life cycle of the refractory stainless steel yarn fiber to be tested.

9. The method for analyzing the microstructure and antioxidant properties of refractory stainless steel yarn fibers according to claim 2, characterized in that, In step 103, when the relative intensity ratio deviates from the theoretical value at the corresponding instantaneous temperature by more than 10%, it is determined that the characteristic fluorescence spectrum is interfered with by background infrared radiation, and the signal smoothing process is initiated to correct the frequency drift.

Images