Method and system for evaluating surface wear of armature

Abstract

Regarding the research field of armature loss, this invention provides a method and system for evaluating armature surface wear. [Solution] The method for evaluating armature surface wear includes: controlling the charging voltage and initial roughness as single variables, conducting armature wear experiments on an electromagnetic rail launch experiment platform, calculating the wear rate for each experiment, measuring the surface roughness after wear, constructing a numerical model of armature wear based on the charging voltage, initial roughness, wear rate, and surface roughness after wear, and inputting the charging voltage and initial roughness into the numerical model of armature wear to predict the wear rate and surface roughness after wear. The present invention makes it possible to quickly obtain the armature wear rate and surface roughness after wear from the charging voltage and initial roughness using the constructed numerical model of armature wear, thereby reducing experimental costs and improving the efficiency of loss evaluation.

Description

Technical Field

[0001] (Cross - reference to Related Applications) This invention claims the priority of a Chinese patent application with an application number of 202411918164.2 and an invention title of "Method and System for Evaluating Armature Surface Wear", which was filed with the China National Intellectual Property Administration on December 25, 2024. All of its contents are incorporated into this invention by reference and constitute a part of this invention and are available for all uses. This invention relates to the research field of armature losses, and particularly to a method and system for evaluating armature surface wear.

Background Art

[0002] The statements in this part only provide information on the background art related to this invention and do not necessarily constitute prior art.

[0003] Electromagnetic emission devices drive a load by a strong magnetic field, achieving high - speed propulsion without the need for conventional fuel, being environmentally friendly, having a high initial velocity, and a long range. They have broad application prospects in aspects such as satellite launch, high - speed train, and cleaning of space stations. The armature is an important component of the electromagnetic emission device. In order to improve the electrical contact performance, a generally C - shaped solid structure is adopted. An inevitable challenge is that when the armature slides relative to the tightened rail, wear is likely to occur, and its wear situation directly affects the electrical contact state between the armature and the rail. Poor contact can cause transition ablation and may seriously affect the service life of the device. Also, wear may reduce the mechanical properties of the armature body and affect the safety of emission.

[0004] Considering performance factors such as strength and conductivity, electromagnetic launchers typically employ aluminum alloy armatures and steel rails. It has been demonstrated that wear during launch primarily occurs on the armature surface, not the steel rails. Because they operate within enclosed tracks, measuring the wear process online in real time is difficult. Therefore, previous research on armature wear mechanisms has relied primarily on post-launch morphological observation and modeling analysis. The Archard wear model shows that defects such as gouging on the armature surface cause material melting and loss, and clearly reveals the deposition of aluminum chips on the steel rails. Measurements have shown that the aluminum deposition layer is approximately 3-10 μm thick, with maximum erosion depths occurring at the top and bottom edges of the armature surface. However, specific wear depths have not been determined, and analysis of armature photographs is limited to simple qualitative evaluations. While quantitative representation of the armature surface contour using image processing algorithms and precision instrument measurements could allow for a more accurate determination of the wear state, this research is currently insufficient.

[0005] In a typical launch, the main heat sources are Joule heating and frictional heating. We analyzed the three-dimensional properties of Joule heating for armatures of different shapes, the damage rules at the contact surface between the armature and the rail due to dry frictional heating, and simulated the internal ballistic dynamic process of armature wear considering the two types of heat sources, but we could not obtain a specific wear mass. Unfortunately, conventional finite element methods are limited in their ability to handle extreme deformations and phase transitions of the armature because they depend on the intrinsic mesh, and as a necessary complement, these models lack an organic relationship with experimental data.

[0006] The actual contact surface between the armature and the rail is composed of multiple minute conductive spots, and the true contact area is only about 1% of the apparent contact area. Friction experiments reveal that the contact area and wear diameter increase with increasing current. (The current can be controlled by adjusting the charging voltage with a pulsed power supply.) Surface roughness is not only an important experimental indicator for evaluating contact quality, but also a crucial experimental condition that affects the contact state between the armature and the rail. Textured surfaces have attracted considerable attention because they possess good tribological properties that alter contact area, blocking, and lubrication. Models have been created with different initial roughness levels on the armature surface, and it has been found that this is closely related to the melting rate and thickness of the material, but this has not been verified experimentally. Much effort is needed to clarify the armature wear characteristics of different currents and initial textured surfaces. In particular, it is urgent to explore the evolution of the macromorphology, microstructure, and structural components of the armature surface, analyze the armature wear mechanism under different operating conditions, and propose a theoretical basis for preventing armature failure and extending the service life of the equipment. [Overview of the project]

[0007] To solve the technical problems present in the background technology described above, the present invention provides a method and system for evaluating armature surface wear. By constructing a numerical model of armature wear, the present invention improves the completeness and accuracy of armature surface wear evaluation.

[0008] To achieve the above objective, the present invention employs the following technical solutions.

[0009] In a first aspect of the present invention, a method for evaluating surface wear of an armature is provided.

[0010] The charging voltage and initial roughness are controlled as single variables, and armature wear experiments are conducted on an electromagnetic rail launch experiment platform. The wear rate for each experiment is calculated, and the surface roughness after wear is measured. To construct a numerical model of armature wear based on charging voltage, initial roughness, wear rate, and surface roughness after wear, The charging voltage and initial roughness are input into a numerical model of armature wear to predict the wear rate and surface roughness after wear, This is a method for evaluating surface wear of an armature, including [specific components].

[0011] Furthermore, the numerical model of armature wear is expressed by the following formula.

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[0012] Furthermore, the electromagnetic rail launch experiment platform includes a charging circuit, a launcher, and a detection device. The charging circuit includes a charger, a power module, a variable inductor L, and a diode D2. The charger is connected to a boost transformer and charges the pulse power module after rectification by a silicon stack. The power module generates a pulsed high current using a capacitor and discharges it to the emitter using a semiconductor switch assembly D1. The semiconductor switch assembly D1 contains a dynamic pulse absorption circuit and a pulse trigger circuit. The variable inductor L is used to adjust the pulse width and peak value output from the capacitor to amplify the waveform and mitigate the shock of the high current. After discharge, the energy is released by the freewheeling diode D2. The launcher is designed to have a rectangular caliber and includes rails and an armature. The detection system includes a current sensor CT, a high-voltage probe, a digital oscilloscope, a voltage divider, a digital instrument, a thermal field emission scanning electron microscope and an energy-dispersive spectrometer, and a laser spectral confocal microscope. The current sensor CT and high-voltage probe detect the rail current and muzzle voltage, respectively, and transmit the measured waveforms to the digital oscilloscope. The voltage divider and digital instrument measure the charging voltage. The thermal field emission scanning electron microscope is used together with the energy-dispersive spectrometer to detect the micromorphology and local micro-region components of the armature surface after firing. The laser spectral confocal microscope performs 3D contour measurements to obtain data on the height and roughness of armature wear marks.

[0013] Furthermore, the method for calculating the wear rate for each experiment includes measuring the mass of the armature before and after each launch, calculating the mass loss from the difference between the mass of the armature before launch and the mass of the armature after launch, and obtaining the wear rate from the ratio of the mass loss to the mass of the armature before launch.

[0014] Furthermore, the method for measuring the surface roughness after wear includes, after each experiment, acquiring an image of the armature's surface wear pattern to locate the wear region, and using a laser spectral confocal microscope to measure the wear region and obtain the surface roughness after wear.

[0015] Furthermore, a method for acquiring surface wear morphology images of the armature and positioning the wear region includes collecting surface wear morphology images of the armature using a camera, performing Gaussian noise reduction, spatial region enhancement, and threshold segmentation processing on the surface wear morphology images of the armature, and marking the communication region as the wear region.

[0016] Furthermore, after each experiment, the wear region is analyzed using an energy-dispersive spectrometer to obtain changes in elemental content within the wear region.

[0017] Furthermore, after each experiment, the temporal change in the peak value of the heat flux density of Joule heat and the temporal change in the peak value of the heat flux density of frictional heat during the launch process are calculated to verify the numerical model of armature wear.

[0018] Furthermore, the initial roughness is determined by polishing the surface of the armature with sandpaper having different mesh numbers.

[0019] A second aspect of the present invention provides an evaluation system for surface wear of an armature.

[0020] An experimental module for controlling the charging voltage and the initial roughness as single variables respectively, performing an armature wear experiment on an electromagnetic rail launch experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear, A model construction module for constructing a numerical model of armature wear based on the charging voltage, the initial roughness, the wear rate, and the surface roughness after wear, An output module for inputting the charging voltage and the initial roughness into the numerical model of armature wear and predicting the wear rate and the surface roughness after wear, which is an evaluation system for surface wear of an armature including these components.

[0021] Compared with the prior art, the present invention has the following beneficial effects.

[0022] The main object of the present invention is to obtain, by quantitative detection, the evolution rule of armature wear in operating states with different charging voltages and initial surface roughnesses, and to fundamentally suppress the occurrence of material fracture. By constructing a numerical model of armature wear, the completeness and accuracy of the surface wear evaluation of the armature are improved.

[0023] With the constructed numerical model of armature wear, the present invention can quickly obtain the wear rate and the surface roughness after wear of the armature from the charging voltage and the initial roughness, reducing the experimental cost and improving the efficiency of loss evaluation.

[0024] The drawings in the specification, which constitute part of the present invention, are for further understanding of the present invention, and the exemplary embodiments and descriptions thereof are for interpretation purposes only and are not intended to improperly limit the present invention. [Brief explanation of the drawing]

[0025] [Figure 1] This is a circuit diagram illustrating the principle of the electromagnetic rail launch experimental platform in this embodiment. [Figure 2] These are images of the armature surface wear morphology in experiments with different charging voltages in this embodiment (the substance indicated by the arrow is conductive adhesive applied during the SEM test and is negligible). [Figure 3] These are images of the surface wear morphology of the armature in experiments with different initial roughness levels in this embodiment. [Figure 4] This is a schematic diagram of the armature image processing and communication region counting results at 1900V in this embodiment. [Figure 5] This is a schematic diagram of the wear results at different charging voltages in this embodiment. [Figure 6] This is a schematic diagram of the wear results at different initial roughness levels in this embodiment. [Figure 7] This is a schematic diagram illustrating the change in the peak height of the straight-line contour in this embodiment. [Figure 8] This is a schematic diagram illustrating the change in the degree of wear at different charging voltages in this embodiment. [Figure 9] This is a schematic diagram illustrating the change in the degree of wear at different initial roughness levels in this embodiment. [Figure 10] This is a schematic diagram of the micromorphology of the armature surface at different charging voltages in this embodiment. [Figure 11] This is a schematic diagram of the elemental distribution in the wear region at 1900V in this embodiment. Figure 11(a) shows the distribution of each element, (b) shows a schematic diagram of the energy and signal intensity of each element, (c) shows the distribution of C, (d) shows the distribution of O, (e) shows the distribution of Al, (f) shows the distribution of Fe, (g) shows the distribution of Cu, and (h) shows the distribution of Si. [Figure 12] This is a schematic diagram illustrating the change in elemental content in the wear region at different charging voltages in this embodiment. [Figure 13] This is a schematic diagram of the micromorphology of the armature surface at different initial roughness levels in this embodiment. [Figure 14] This is a schematic diagram illustrating the change in elemental content in the wear region at different initial roughness levels in this embodiment. [Figure 15] This is a schematic diagram illustrating the change in heat flux density over time in this embodiment. [Figure 16(a)] This is a schematic diagram illustrating the change in heat flux density with respect to the charging voltage in this embodiment. [Figure 16(b)] This is a schematic diagram illustrating the change in heat flux density with respect to the initial roughness of this embodiment. [Figure 17] This is a schematic diagram of the dynamic wear process of the armature as the charging voltage increases in this embodiment. [Figure 18] This is a schematic diagram of the dynamic wear process of the armature in which the initial roughness of this embodiment is reduced. [Figure 19] This is a flowchart illustrating the method for evaluating surface wear of the armature in this embodiment. [Modes for carrying out the invention]

[0026] The present invention will be further described below with reference to the drawings and embodiments.

[0027] It should be noted that the following detailed descriptions are all illustrative and intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art.

[0028] It should be noted that the terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. For example, unless otherwise specified in the context, the singular form used herein is intended to include plural forms, and it should also be understood that when the terms “contains” and / or “includes” are used herein, it indicates the presence of features, processes, operations, devices, assemblies and / or combinations thereof.

[0029] Example 1 As shown in Figure 19, this embodiment is The charging voltage and initial roughness are controlled as single variables, and armature wear experiments are conducted on an electromagnetic rail launch experiment platform. The wear rate for each experiment is calculated, and the surface roughness after wear is measured. To construct a numerical model of armature wear based on charging voltage, initial roughness, wear rate, and surface roughness after wear, This invention provides a method for evaluating armature surface wear, which includes inputting the charging voltage and initial roughness into a numerical model of armature wear to predict the wear rate and the surface roughness after wear.

[0030] The present invention is experimentally verified in the following aspects: (1) An experimental platform and detection means are described, along with the operating procedure for electromagnetic emission experiments. These experiments target different charging voltages and initial surface roughness. (2) Surface wear characteristics of the armature are quantitatively analyzed by image processing algorithms and confocal contour measurement. (3) Dynamic wear behavior of the armature under different operating conditions is analyzed by microstructure and component detection. In particular, the evolutionary changes of the armature wear mode are shown. (4) The experimental conclusions are verified by calculating the heat flux density of Joule heat and frictional heat, a numerical model of armature wear is constructed, and basic solutions to guide the design of the apparatus are proposed.

[0031] Step 1: Experimental platform and detection means The electromagnetic rail launch system operates in a short-time pulsed discharge state, and the widely applied energy drive device to achieve the current amplitude and energy intensity required for launch is a capacitor energy storage type pulsed power supply. To reduce the parasitic mass of the launch assembly and increase the payload ratio, the launch chamber should be designed to be approximately rectangular. Based on this, an electromagnetic rail launch experimental platform was constructed, and its circuit principle is shown in Figure 1.

[0032] The experimental platform in Figure 1 mainly includes a charging circuit, a launcher, and a detection device. Related components include a voltage divider, a high-voltage digital meter, a boost transformer, a silicon stack for rectification, a resistor R1, a switch K, a resistor R2, a capacitor C, a resistor R'1, a switch K', a resistor R'2, a high-capacity semiconductor switch assembly D1, a variable inductor L, a freewheeling diode D2, and a launcher. In the charging circuit, a 10kVA charger is connected to a boost transformer and charges the pulse power module after rectification by the silicon stack, with a maximum charging voltage of 100kV and a charging current of 100mA. The power module generates pulsed high currents through two sets of 4mF-5kV capacitors and discharges them to the launcher via the high-capacity semiconductor switch assembly D1. The switch contains the necessary dynamic pulse absorption and pulse trigger circuits. The variable inductor L is used to adjust the pulse width and peak value output from the capacitors to amplify the waveform and mitigate the shock of the high current. After discharge, energy is released by the freewheeling diode D2. The launcher is designed with a rectangular bore of 15mm x 20mm. The rails are made of two parallel 1200mm x 23mm x 2mm 45# medium carbon structural steel plates, and the stability of the chamber is maintained by polytetrafluoroethylene insulating supports and pretension bolts. The armature is made of 6063-T6 aluminum alloy material, adopts a typical C-shaped solid structure, and weighs approximately 15.667g.

[0033] Before the main experiment, a no-load experiment is first conducted to check whether the circuit connections are good and to ensure that the capacitor can be charged effectively. The charging voltage is measured using a voltage divider (with a voltage division ratio of 1000:1) and its associated digital instrument. During the experiment, the rail current and muzzle voltage are detected using a current sensor CT and a high-voltage probe (with an attenuation ratio of 1000:1), respectively, and the measured waveforms are transmitted to a digital oscilloscope. After the experiment is completed, a KathMatic laser spectral confocal microscope (LSCM) is used to perform 3D contour measurements and obtain data on the height and roughness of armature wear marks. A GeminiSEM 300 thermal field emission scanning electron microscope (SEM) is used to detect the micro-morphology of the armature surface, and its minute regional components are analyzed in combination with an energy dispersive spectrometer (EDS).

[0034] 2. Surface wear characteristics of the armature To investigate the effects of charging voltage and initial roughness on armature wear performance, two sets of experiments were conducted with a single variable controlled.

[0035] a) Using an unpolished armature, the charging voltages were set to 1900V, 2000V, 2100V, 2200V, 2300V, and 2400V, respectively.

[0036] b) The charging voltage was set to 2000V, and the armature surface was pre-polished with sandpaper of mesh counts of 120cw, 180cw, 240cw, 600cw, 800cw, 1000cw, 1500cw, and 2000cw before firing. LSCM measurements yielded textured surfaces with initial roughness of 2.65μm, 2.15μm, 1.65μm, 1.05μm, 0.55μm, 0.25μm, 0.15μm, and 0.05μm, respectively. In other words, the smaller the mesh count of the sandpaper, the rougher the polished armature surface.

[0037] Step 2.1: Macro images of the armature after firing were taken to preliminarily evaluate the degree of armature surface wear and to determine the area to be observed by subsequent SEM. The armature surface wear patterns in experiments with different charging voltages are shown in Figure 2.

[0038] As can be seen in Figure 2, as the voltage increases, the recessed wear craters and strip-like grooves on the armature surface after firing gradually change into fine dimples, fine scratches, and conductive adhesive. Of these, the white areas are exposed aluminum alloy matrix, while the black metal oxides appear from the edges of the tail fins and diffuse towards the armature head, being most widely distributed at 2100V and 2200V. Above 2300V, the black areas tend to decrease and are accompanied by tumor-like morphological tissue.

[0039] Figure 3 shows the surface wear morphology of the armature in experiments with different initial roughness levels. In Figure 3, in the range above 1.05 μm, as the initial roughness decreases, the wear craters and scratches on the armature surface gradually become shallower after firing, and polished texture is still visible in localized areas. Below 0.55 μm, the black oxide diffuses more widely forward and is accompanied by complex impact grooves, tumor-like, and fluid-like morphologies.

[0040] To quantitatively extract armature wear information, an image processing algorithm is used to perform Gaussian noise reduction, spatial region enhancement, and threshold segmentation on the photographs in Figures 2 and 3, and to mark the communication regions. Using an armature emitting at 1900V as an example, the image processing and the counting results of the communication regions are shown in Figure 4.

[0041] As can be seen in Figure 4, oxides in the image appear black due to binarization, while shallow wear craters, scratches, and other depressions appear white. White depressions with the same gradation value are identified as independent interconnected regions and enclosed in rectangular frames. The centroid position of each interconnected region is indicated by a vertical line, and based on this, they are counted and displayed numerically in the figure. A total of 183 interconnected regions are identified at 1900V. All armature images are 1064 × 1890 pixels, and the proportion of white areas and the number of interconnected regions within them are statistically analyzed. At the same time, the ratio of mass loss after firing to mass before firing is calculated to analyze the change in wear rate. The wear results at different charging voltages are shown in Figure 5.

[0042] As can be seen from Figure 5, as the charging voltage increases, the proportion of white areas and the wear rate decrease and then increase, but the trend in the number of interconnected areas is the opposite. This is because, as the voltage increases, the number of pits decreases, the wear craters that are concentrated over a large area change into shallow dimples over a larger area, and in the relative friction process, the damage changes from localized severe damage to more uniform minor damage, which is consistent with the morphology shown in Figure 2. However, above 2100V, the oxide layer coating becomes wider, the aluminum alloy matrix peels off over a large area, the interconnected areas become concentrated again, and the wear rate increases.

[0043] As shown in Figure 6, similar wear results are calculated for different initial roughnesses. As can be seen from Figure 6, as the initial roughness decreases, the proportion of the white area decreases, then slightly increases, and then decreases significantly. The wear rate decreases and then slightly increases. The number of interconnected areas changes irregularly but increases overall. This indicates that as the initial surface becomes smoother, the number of wear craters decreases and their distribution becomes more dispersed. Oxidative wear becomes more severe after the roughness becomes less than 0.25 μm, but unlike the delamination of the material in an unpolished, operating state, the armature forms a complex erosion morphology due to the deformation and deposition of the metal and its oxides, and therefore the increase in the wear rate is not apparent as the white aluminum alloy area decreases.

[0044] Step 2.2: Wear contour and surface roughness To accurately analyze the wear characteristics of the armature, LSCM (Laser-Surface Compression Molding) is used to obtain data on the armature's surface contour and roughness. An armature still operating at 1900V is used as an example.

[0045] By scanning the point cloud data of the height diagram, accurate information on the surface contour relief of the armature can be obtained. To compare the degree of damage at the front and rear ends of the armature, four horizontal lines x1 to x4 were drawn on the surface of the armature and contour measurements were performed, and the changes in peak height are shown in Figure 7.

[0046] Figure 7 shows that all four lines tend to have a more pronounced undulation in the leading edge and a flatter trailing edge. The presence of wear craters and grooves indicates a clear depression in the armature head. The highest peak in region A1 is 322.77 μm above the original reference plane, with a maximum valley depth of 203.55 μm. The trailing edge of the armature consists mainly of folds formed by the deposition of a fluid structure and oxides after the aluminum was heated and melted. The trailing edge of the contour is small and finely undulated, with maximum peak heights and valley depths of only 181.83 μm and 86.92 μm, respectively. While the surface roughness of region A2 is significantly reduced, its broader fold distribution results in a larger interface area.

[0047] To compare the changes in armature wear at different charging voltages, surface roughness Sa, maximum peak height Sp, and maximum valley depth Sv were statistically analyzed, and the results are shown in Figure 8.

[0048] As can be seen from Figure 8, as the charging voltage increases, Sa decreases, then slightly increases, and then decreases again. At 1900V, the armature surface has noticeable depressions and protrusions, and the surface roughness is very high. As the voltage increases, the degree of wear is reduced. When the voltage increases to 2100V, the depth of localized wear craters decreases, but the degree of heat generation and oxidation becomes more intense, and a fluid melting morphology appears on the surface, so the roughness actually increases. As the voltage continues to increase, the armature surface becomes flatter due to erosive expansion that tends to become more uniform, and a large amount of surface metal peeling, and the roughness gradually decreases again.

[0049] The change in armature wear at different initial roughness levels is shown in Figure 9. In Figure 9, as the initial roughness decreases, Sa decreases and then increases. When the initial roughness is 2.65 μm, the armature surface after firing is uneven, with large peak heights, valley depths, and roughness. As the initial roughness decreases, the surface tends to become flatter. However, below 1.05 μm, severe high-temperature oxidation and molten ablation occur between the armature and the rail, leading to the deposition of a large oxide layer and a significant increase in roughness as corrosion pits, cracks, and ultimately grooves are formed.

[0050] Step 3: Analysis of Dynamic Wear Behavior To investigate the microstructure and structural components of the armature's wear surface and clarify the essence of its damage formation process and phenomena, we will select a typical wear region with the highest surface roughness based on macroscopic observations, set the sampling size to 2 mm × 2 mm, and perform SEM micromorphology and EDS component analysis on the armature surface under different operating conditions to explore its dynamic wear behavior.

[0051] Step 3.1: Wear behavior at different charging voltages The micromorphology of the armature surface at different charging voltages is shown in Figure 10. According to Figure 10, as the charging voltage increases, the wear debris becomes finer, pores and microcracks degrade into deeper cracks, and eventually flake-like delamination marks appear. At 1900V, large, irregularly shaped wear debris is formed and fragmented. This is because, under the action of high-speed carrier friction, the harder steel rails rub against the softer aluminum alloy armature surface, generating wear debris, which macroscopically appears as independently dispersed wear craters in Figure 2. As the voltage increases, on the one hand, the armature's movement speed increases, and the duration of shear force action decreases. On the other hand, the normal component of the Lorentz force increases, and the wear debris becomes finer and sharper under the action of compression, which helps to cut the armature surface, thereby forming elongated scratches in Figure 2 and reducing roughness. As the voltage continues to rise, the circuit current increases, and the accumulated Joule heat accelerates the oxidation reaction, heating and softening the metal, causing particulate molten pores to appear on the armature surface. Small fatigue cracks appear at stress concentration points at the bottom or edges of the pores, leading to more severe degradation and increased surface roughness. This indicates that after 2100V and 2200V, the wear mode begins to shift from abrasive wear to oxidative wear and fatigue wear. The cracks continue to spread and connect with each other along the direction of armature movement, eventually causing the metallic material to delaminate or deposit, and at 2300V, the armature surface shows traces of flaky delamination and ripple-like deposits. The deposited layer effectively fills the depressions in the aluminum matrix, and the erosive expansion tends to become more uniform, making the armature surface flatter and reducing roughness again. At 2400V, the delamination layer changes from grayish-black to silvery-gray, meaning that the surface metal and brittle oxide layer largely detach, exposing the underlying aluminum matrix.

[0052] Furthermore, elemental information of the wear interface was detected using EDS, and the elemental distribution in the wear region at 1900V is shown in Figure 11.

[0053] As can be seen from Figures 11(a) and (b), the wear region mainly contains elements such as C, O, Al, Fe, Cu, and Si. Of these, Al accounts for more than 58.34%, forming the matrix of the armature of the initial 6063-T6 aluminum alloy, and its main components further include Fe, Si, Cu, etc. As can be seen from Figures 11(c), (d), and (f), small amounts of dispersed Fe, O, and C also cover the Al layer in Figure 11(e), which are scattered steel rail chips in the friction. The changes in elemental content of the wear region at different charging voltages were statistically analyzed, and the results are shown in Figure 12.

[0054] As can be seen from Figure 12, the changes in the content of Al, Si, and Cu elements are basically consistent, decreasing and then increasing, representing a change in the proportion of aluminum alloy material in the wear region, while the change in the O element is the opposite. Below 2100V, as the voltage increases, on the one hand, abrasive wear is reduced, and the large area of ​​pits on the armature surface decreases, while on the other hand, oxidative wear becomes more severe, the area covered by the oxide layer increases, and therefore the proportion of Al decreases and the O increases. Above 2100V, due to the severe oxidation reaction and uneven heat distribution, cracks at localized stress concentration points expand and even penetrate. The oxide is more brittle and easily broken than aluminum metal, and under the action of cutting through sharp wear debris, it detaches in layered flakes, re-exposing the aluminum alloy matrix and increasing the content of Al element. The trend for the Fe element does not perfectly match that of Al, and when combined with the change for the C element, it is shown that there is bidirectional movement of the metallic material during the relative friction process between the armature and the rail, and the filling of steel rail wear debris reduces the surface roughness of the armature at 2000V in Figure 8 to a certain extent.

[0055] Step 3.2: Wear behavior at different initial roughness levels The micromorphology of the armature surface at different initial roughness levels is shown in Figure 13. According to Figure 13, as the initial roughness decreases, the wear debris becomes smaller, and the armature surface becomes temporarily relatively flat, leading to more severe material loss or deposition. As can be seen from the comparison with Figure 10, the wear debris from firing after sanding has rounder and blunter edges, reducing cutting ability, and slightly improving the armature wear rate (comparison between Figures 5 and 6) and surface roughness (comparison between Figures 8 and 9). When the initial roughness is 2.65 μm, the micropeaks scattered during firing polish the aluminum alloy at a constant angle of attack, leaving depressions or flanges on the armature surface. As the initial roughness decreases, the surface becomes flatter, abrasive wear is reduced, and at 1.65 μm, traces of polishing are still visible in localized areas after firing. However, if the thickness is reduced to less than 1.05 μm, the polished surface becomes too smooth, which actually reduces the conductive spots on the armature-rail contact surface, shrinking the effective current transmission path and increasing contact resistance. Due to heat accumulation, the armature continuously heats up and softens, and the aluminum matrix undergoes plastic deformation under the cutting action of wear debris, but without completely delaminating, it is extruded and deposited on the surface, forming a folded and fluid structure. At the same time, localized high temperatures and compressive stress can cause a molten metal liquid film to instantaneously induce cold welding, accelerating the formation of a dark oxide layer. The brittle oxide layer is prone to fracture and, after being detached as wear debris, adheres to the armature surface, further melting and depositing, leaving ablation pits and ridges. Furthermore, the adhesive oxide transforms the original steel-aluminum contact into a contact of more compatible homogeneous materials, increasing the strength of the joint and aiding in adhesive wear. On the other hand, it reduces the conductive area, causing more energy to be converted into heat when current flows through the armature, further intensifying wear and degradation. A bright white light region was observed at 0.05 μm, indicating the low conductivity of the sample, which results in a charging effect under the SEM lens.

[0056] Similarly, changes in elemental content in the wear region at different initial roughness levels were detected, and the results are shown in Figure 14. According to Figure 14, as the initial roughness decreases, the elements Al, Si, and Cu decrease, then slightly increase, and then decrease again, while the element O does the opposite, and the elements Fe and C fluctuate slightly. Above 1.65 μm, as the flatness of the armature surface improves, abrasive wear is reduced and the proportion of exposed aluminum matrix decreases. The fluctuations in Fe and C elements indicate that steel rail chips remain on the armature surface. As the initial roughness decreases, heat accumulates due to the increased contact resistance, and the wear mode between the armature and rail shifts from abrasive wear to oxidative wear, which is almost balanced at 1.65–1.05 μm, with a slight improvement in roughness (Figure 9). Subsequently, the heat-affected area continues to expand, and the oxide layer accumulates on the armature surface without severely delaminating as would occur with increasing charging voltage. Under repeated digging and cutting behavior, a fluid-like structure and tumor-like defects develop, the components of the oxide layer such as Fe, C, and O continue to increase, and the proportion of elements in the aluminum matrix decreases. In addition, small amounts of sulfur are detected at 0.25-0.05 μm, which may be due to the reaction of the metal with sulfides in the air under high-speed, high-temperature friction, which also further intensifies armature ablation.

[0057] 4. Consideration To clarify the damage mechanism at the armature-rail contact interface, the time-dependent changes in the peak heat flux densities of Joule heat QJ and frictional heat QF during firing are calculated, as shown in Figure 15. As can be seen from Figure 15, the trend in the change of heat flux density of Joule heat is consistent with the pulsed current source, rising and then falling, while the heat flux density of frictional heat increases steadily. Throughout the firing process, although the initial movement speed of the armature is low, the current rapidly reaches the pulsed peak value, and Joule heat, as the main heat source, causes dot-like pit-type ablation on the surface, especially the front end, due to its non-uniform distribution. After 3.05 ms, the movement speed of the armature increases, and the frictional heat rises to exceed the Joule heat, forming a flake-like high-temperature region on the tail fin and leading to an expanding erosion phenomenon. Previous studies have pointed out that Joule heat is concentrated in the head of the armature, and the frictional heat accumulated in the rear is detrimental to the armature, and this conclusion is consistent with the present invention, and the validity of the results will be further verified. As shown in Figures 16(a) and 16(b), the changes in the peak values ​​of two types of heat flux densities at different charging voltages and initial roughnesses are calculated.

[0058] As can be seen from Figures 16(a) and 16(b), the heat flux densities of both Joule heat and frictional heat continue to increase as the charging voltage increases and the initial roughness decreases. Although the initial peak of Joule heat is low, the rate of increase is faster, and at 2100V and 0.55μm, it even exceeds that of frictional heat. This is consistent with the conclusion obtained in previous studies that "frictional heat mainly acts when the armature is moving at low speeds." Furthermore, the increase in Joule heat due to the increase in charging voltage is more pronounced than in the case of roughness reduction. Summarizing the wear morphology and changes in heat flux density, the dynamic wear process of the armature as the charging voltage increases is as shown in Figure 17.

[0059] As can be seen from Figure 17, under low voltage, abrasive wear first occurs in the armature, forming wear craters and grooves extending in the direction of movement on the surface. As the voltage increases, the abrasive grains become thinner under normal pressure, reducing abrasive wear. The accumulation of heat also catalyzes oxidative wear, forming a black, brittle oxide layer on the surface of the armature. Above 2100V, Joule heating increases rapidly, and the rapidly moving armature is constantly in contact with a new, room-temperature orbit ahead, and the heat is also rapidly carried away by a high cooling gradient. Under the action of alternating forces generated in a strong alternating temperature field, cracks develop and spread in the armature, and eventually the surface metal, especially the brittle oxide, flakes off, and the wear is converted into fatigue wear.

[0060] The dynamic wear process of the armature as the initial roughness is reduced is shown in Figure 18. As can be seen from Figure 18, abrasive wear occurs first in the armature, and as the initial roughness is reduced, the abrasive grains become rounder and duller, the cutting action weakens, and abrasive wear is reduced. At the same time, the number of conductive spots decreases and the contact resistance increases, so under high temperature conditions, the aluminum alloy surface undergoes an oxidation reaction with the gas medium, forming an oxide film that adheres to the surface. The oxide film is pressed and moved, and the newly exposed surface is oxidized and deposited again, ultimately forming a complex molten form. Under the action of oxidative wear and adhesive wear, the material does not fall off in large quantities, but its conductivity decreases.

[0061] The above research revealed that the relationship between charging voltage, initial roughness, and the degree of material wear is complex. Therefore, in order to comprehensively consider the influence of the two types of factors on the wear performance of the armature, the wear rate w r Furthermore, the surface roughness Sa of the armature after wear and its relationship to each of these will be established.

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[0062] 1) Apply an appropriate charging voltage. It is not wise to blindly increase the charging voltage in pursuit of acceleration. For a 1.2m long track on this experimental platform, the optimal charging voltage is 2100V.

[0063] 2) Set an appropriate level of surface roughness. For this platform, the optimal initial roughness is 0.55 to 1.05 μm, which can be achieved by polishing with 600 cw to 800 cw sandpaper. For rough materials, attention must be paid to conductivity.

[0064] 3) For C-shaped solid armatures, the head portion needs improved heat resistance, and the tail portion needs enhanced wear resistance; therefore, an appropriate plating layer or paint is expected.

[0065] 5. Conclusion The main objective of this invention is to fundamentally suppress the occurrence of material fracture by quantitatively detecting the evolutionary rules of armature wear under different charging voltages and initial surface roughness operating conditions. Launch experiments were conducted with charging voltages of 1900V to 2400V and initial roughness of 0.05μm to 2.65μm. Image processing analysis, LSCM contour measurement, SEM morphological detection, EDS component analysis, and heat flux density calculation were performed on the armature surface after launch. The following statements hold true regarding the work provided.

[0066] 1) As the charging voltage increases, the armature wear rate decreases and then increases, the wear roughness decreases, then slightly increases, and then decreases further. Abrasive wear is converted to oxidative wear and fatigue wear, and a large amount of material is shed.

[0067] 2) As the initial roughness decreases, the armature wear rate decreases and then slightly increases, the overall wear roughness increases, and the wear changes from abrasive wear to oxidative wear and adhesive wear, severely impairing conductivity.

[0068] 3) In the head of a C-shaped solid armature, dot-shaped pit abrasion mainly occurs due to Joule heating, while in the tail fin, expansive erosion dominated by frictional heat occurs, thus presenting different requirements for the material's heat resistance and wear resistance.

[0069] In this invention, an electromagnetic orbital launch experimental platform is constructed, and morphological analysis, contour measurement, and component detection are performed on the surface of the armature after launch. The results show that as the charging voltage increases, the armature wear changes from abrasive wear to oxidative wear and fatigue wear. As the initial surface roughness decreases, abrasive wear, oxidative wear, and adhesive wear occur sequentially. This is because the rate of increase of Joule heat is higher than that of frictional heat, and it gradually becomes dominant in the wear mode. For this platform, the optimal charging voltage and initial surface roughness are 2100V and 0.55~1.05μm, respectively. Finally, a numerical model of armature wear and directions for optimizing armature design are proposed.

[0070] Example 2 This embodiment is, An experimental module for controlling charging voltage and initial roughness as single variables, conducting armature wear experiments on an electromagnetic rail launch experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear, A model building module for constructing a numerical model of armature wear based on charging voltage, initial roughness, wear rate, and surface roughness after wear, The present invention provides an armature surface wear evaluation system that includes an output module for inputting charging voltage and initial roughness into a numerical model of armature wear and predicting the wear rate and surface roughness after wear.

[0071] In some embodiments, the numerical model of armature wear is expressed by the following formula.

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[0072] In some embodiments, the electromagnetic rail launch experimental platform includes a charging circuit, a launcher and a detection device, The charging circuit includes a charger, a power module, a variable inductor L, and a diode D2. The charger is connected to a boost transformer and charges the pulse power module after rectification by a silicon stack. The power module generates a pulsed high current using a capacitor and discharges it to the emitter using a semiconductor switch assembly D1. The semiconductor switch assembly D1 contains a dynamic pulse absorption circuit and a pulse trigger circuit. The variable inductor L is used to adjust the pulse width and peak value output from the capacitor to amplify the waveform and mitigate the shock of the high current. After discharge, the energy is released by the freewheeling diode D2. The launcher is designed to have a rectangular caliber and includes rails and an armature. The detection system includes a current sensor CT, a high-voltage probe, a digital oscilloscope, a voltage divider, a digital instrument, a thermal field emission scanning electron microscope and an energy-dispersive spectrometer, and a laser spectral confocal microscope. The current sensor CT and high-voltage probe detect the rail current and muzzle voltage, respectively, and transmit the measured waveforms to the digital oscilloscope. The voltage divider and digital instrument measure the charging voltage. The thermal field emission scanning electron microscope is used together with the energy-dispersive spectrometer to detect the micromorphology and local micro-region components of the armature surface after firing. The laser spectral confocal microscope performs 3D contour measurements to obtain data on the height and roughness of armature wear marks.

[0073] In some embodiments, the method for calculating the wear rate for each experiment includes measuring the mass of the armature before and after each launch, calculating the mass loss from the difference between the mass of the armature before launch and the mass of the armature after launch, and obtaining the wear rate from the ratio of the mass loss to the mass of the armature before launch.

[0074] In some embodiments, the method for measuring the surface roughness after wear includes, after each experiment, acquiring an image of the armature's surface wear pattern to locate the wear region, and using a laser spectral confocal microscope to measure the wear region and obtain the surface roughness after wear.

[0075] In some embodiments, the method for acquiring surface wear morphology images of the armature and positioning the wear region includes collecting surface wear morphology images of the armature using a camera, performing Gaussian noise reduction, spatial region enhancement, and threshold segmentation processing on the surface wear morphology images of the armature, and marking the communication region as the wear region.

[0076] In some examples, after each experiment, the wear region was analyzed using an energy-dispersive spectrometer to obtain the changes in elemental content in the wear region.

[0077] In several examples, after each experiment, the time-dependent changes in the peak heat flux density of Joule heat and the time-dependent changes in the peak heat flux density of frictional heat during the firing process are calculated to verify the numerical model of armature wear.

[0078] In some embodiments, the initial roughness is determined by polishing the surface of the armature with sandpaper of different mesh counts.

[0079] The above description is merely a preferred embodiment of the present invention and does not limit it; those skilled in the art will know that the present invention can be modified and altered in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are all included within the scope of protection of the present invention.

Claims

1. The charging voltage and initial roughness are controlled as single variables, and armature wear experiments are conducted on an electromagnetic rail launch experiment platform. The wear rate for each experiment is calculated, and the surface roughness after wear is measured. To construct a numerical model of armature wear based on charging voltage, initial roughness, wear rate, and surface roughness after wear, This includes inputting the charging voltage and initial roughness into a numerical model of armature wear to predict the wear rate and the surface roughness after wear, The numerical model of the armature wear is expressed by the following equation: [Number 7] [Number 8] However, lol ｒ is the wear rate, Sa is the surface roughness of the armature after wear, U is the charging voltage, Sa ０ A method for evaluating surface wear of an armature, characterized by representing the initial roughness.

2. The electromagnetic rail launch experiment platform includes a charging circuit, a launcher, and a detection device. The charging circuit consists of a charger, a power module, a variable inductor L, and a diode D. ２ The charger is connected to a step-up transformer and charges the pulse power module after rectification by a silicon stack. The power module generates pulse high current through a capacitor and semiconductor switch assembly D １ This discharges to the launcher, and semiconductor switch assembly D １ A dynamic pulse absorption circuit and a pulse trigger circuit are arranged there, and a variable inductor L is used to adjust the pulse width and peak value output from the capacitor to amplify the waveform and mitigate the shock of large currents, and after discharge, a freewheeling diode D ２ By releasing energy, The launcher is designed to have a rectangular caliber and includes rails and an armature. The detection device includes a current sensor CT, a high-voltage probe, a digital oscilloscope, a voltage divider, a digital instrument, a thermal field emission scanning electron microscope and an energy-dispersive spectrometer, and a laser spectrum confocal microscope. The detection device is characterized by detecting the rail current and muzzle voltage using the current sensor CT and high-voltage probe, transmitting the measured waveforms to the digital oscilloscope, measuring the charging voltage using the voltage divider and digital instrument, using the thermal field emission scanning electron microscope together with the energy-dispersive spectrometer to detect the micromorphology and local micro-region components of the armature surface after firing, and performing three-dimensional contour measurement using the laser spectrum confocal microscope to obtain data on the height and roughness of the armature wear marks. This is the method for evaluating armature surface wear according to claim 1.

3. The method for calculating the wear rate for each experiment is characterized by comprising: measuring the mass of the armature before and after each launch; calculating the mass loss from the difference between the mass of the armature before launch and the mass of the armature after launch; and obtaining the wear rate from the ratio of the mass loss to the mass of the armature before launch, as described in claim 1.

4. The method for measuring surface roughness after wear is characterized by comprising: acquiring a surface wear morphology image of the armature after each experiment to position the wear region; and using a laser spectral confocal microscope to measure the wear region and obtain the surface roughness after wear, as described in claim 1.

5. The method for acquiring an image of the surface wear morphology of the armature and positioning the wear region is characterized by comprising: collecting an image of the surface wear morphology of the armature using a camera; performing Gaussian noise reduction, spatial region enhancement, and threshold division processing on the image of the surface wear morphology of the armature; and marking the communication region as the wear region, as described in claim 4.

6. The method for evaluating surface wear of an armature according to claim 4, characterized in that, after each experiment, the wear region is analyzed using an energy-dispersive spectrometer to obtain the change in elemental content in the wear region.

7. The method for evaluating armature surface wear according to claim 1, characterized in that, after each experiment, the time-dependent changes in the peak value of the heat flux density of Joule heat and the time-dependent changes in the peak value of the heat flux density of frictional heat during the firing process are calculated, and a numerical model of armature wear is verified.

8. The method for evaluating surface wear of an armature according to any one of claims 1 to 7, characterized in that the initial roughness is determined by polishing the surface of the armature with sandpaper of different mesh counts.

9. An experimental module for controlling charging voltage and initial roughness as single variables, conducting armature wear experiments on an electromagnetic rail launch experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear, A model building module for constructing a numerical model of armature wear based on charging voltage, initial roughness, wear rate, and surface roughness after wear, It includes an output module for inputting the charging voltage and initial roughness into a numerical model of armature wear and predicting the wear rate and surface roughness after wear, The numerical model of the armature wear is expressed by the following equation: [Number 9] [Number 10] However, lol ｒ is the wear rate, Sa is the surface roughness of the armature after wear, U is the charging voltage, Sa ０ An armature surface wear evaluation system characterized by representing the initial roughness.

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