Method and system for evaluating armature surface wear

Abstract

This paper provides a method and system for evaluating armature surface wear in the field of armature loss research. [Solution] A method for evaluating armature surface wear includes: 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; 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 constructed numerical model of armature wear allows the armature wear rate and surface roughness after wear to be quickly obtained from the charging voltage and initial roughness, reducing experimental costs and improving the efficiency of loss evaluation.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This invention claims priority to a Chinese patent application bearing application number 202411918164.2 and entitled "Method and system for evaluating armature surface wear," filed with the State Intellectual Property Office of the People's Republic of China on December 25, 2024, the entire contents of which are incorporated herein by reference and constitute a part of the present invention for all purposes. The present invention relates to the field of armature loss research, and in particular to a method and system for assessing armature surface wear. [Background technology]

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Electromagnetic launchers utilize a strong magnetic field to drive a load, achieving high-speed propulsion without the need for conventional fuel. This allows them to achieve environmentally friendly performance, high initial velocity, and long range. These advantages make them suitable for a wide range of applications, including satellite launches, high-speed trains, and space station cleaning. The armature, a key component of an electromagnetic launcher, typically employs a C-shaped solid structure to improve electrical contact performance. An unavoidable challenge is that the armature is prone to wear when sliding relative to the fastened rail, which directly affects the electrical contact between the armature and the rail. Poor contact can lead to transition abrasion, severely impacting the device's service life. Wear can also degrade the mechanical properties of the armature itself, potentially affecting launch safety.

[0004] Considering performance factors such as strength and conductivity, electromagnetic launchers typically use aluminum alloy armatures and steel rails. It has been demonstrated that wear during launch occurs primarily on the armature surface, rather than on the steel rail. Because they operate within a closed track, online, real-time measurement of the wear process is difficult. Previous research into armature wear mechanics has primarily relied on post-launch morphological observation and modeling analysis. The Archard wear model indicates that defects such as gouging on the armature surface cause material melting and loss, and that aluminum chips are clearly visible on the steel rail. Measurements have shown that the thickness of the aluminum deposit layer is approximately 3–10 μm, with the maximum erosion depth appearing at the top and bottom edges of the armature surface. However, no specific wear depth has been reported, and analysis of armature photographs is limited to a simple qualitative assessment. Image processing algorithms and precision instrument measurements could be used to quantitatively represent the curves of the armature surface contour to more accurately determine the wear state, but research into this area remains incomplete.

[0005] In a typical launch, the main heat sources are Joule heating and frictional heating. We analyzed the 3D characteristics of Joule heating in armatures of different shapes and the damage patterns at the armature-rail contact surface due to dry frictional heating. We simulated the internal ballistic dynamics of armature wear by considering these two heat sources, but were unable to obtain specific wear masses. Unfortunately, traditional finite element methods rely on unique meshes, which limits their ability to handle extreme armature deformations and phase transitions. While these models are ideally suited for this purpose, they lack a clear correlation with experimental data.

[0006] The actual contact surface between the armature and the rail is composed of multiple tiny conductive spots, and the true contact area is only about 1% of the apparent contact area. Friction experiments show that the contact area and wear diameter increase with increasing current. (The current can be controlled by adjusting the charging voltage using a pulsed power supply.) Surface roughness is not only an important experimental indicator for evaluating contact quality, but also a crucial experimental condition affecting the contact state between the armature and the rail. Textured surfaces have attracted widespread attention due to their excellent tribological properties, such as varying contact area, blocking, and lubrication. Models have been developed that set different initial roughness levels on the armature surface and found to be closely related to the material melting rate and thickness, but this has not yet been experimentally verified. Much effort is needed to clarify the wear characteristics of armatures with different currents and initially 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 theoretical basis for preventing armature failure and extending the service life of equipment. Summary of the Invention

[0007] In order to solve the technical problems in the background art, the present invention provides a method and system for evaluating armature surface wear, which improves the completeness and accuracy of armature surface wear evaluation by establishing a numerical model of armature wear.

[0008] To achieve the above objectives, the present invention adopts the following technical solutions.

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

[0010] Controlling the charging voltage and initial roughness as single variables, respectively, and conducting armature wear experiments on an electromagnetic rail launching experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear; Building a numerical model of armature wear based on the charging voltage, initial roughness, wear rate, and surface roughness after wear; Inputting the charging voltage and initial roughness into a numerical model of armature wear to predict the wear rate and surface roughness after wear; The method for evaluating the surface wear of an armature includes:

[0011] Furthermore, the numerical model of the armature wear is expressed by the following equation:

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[0012] Further, the electromagnetic rail launch test platform includes a charging circuit, a launcher, and a detection device; The charging circuit includes a charger, a power supply module, a variable inductor L, and a diode D2. The charger is connected to a step-up transformer and charges the pulse power supply module after rectification by a silicon stack. The power supply module generates a large pulse current through a capacitor and discharges it to the launcher through a semiconductor switch assembly D1. The semiconductor switch assembly D1 is equipped with 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 so as to expand the waveform and mitigate the impact of the large current. After discharging, the energy is released through the freewheeling diode D2. The launcher is designed to be rectangular in caliber and includes a rail 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, an energy dispersive spectrometer, and a laser spectrum confocal microscope. The current sensor CT and high-voltage probe detect the rail current and muzzle voltage, respectively, and send 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 micro-morphology and local micro-area components of the armature surface after firing, and the laser spectrum confocal microscope is used to perform 3D contour measurement and obtain data on the height and roughness of the armature wear scars.

[0013] Furthermore, the method of 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 obtaining an image of the surface wear morphology of the armature after each experiment to locate the worn area, and employing a laser spectrum confocal microscope to measure the worn area and obtain the surface roughness after wear.

[0015] Furthermore, the method for acquiring the surface wear morphology image of the armature and locating the wear area includes collecting the surface wear morphology image of the armature by a camera, performing Gaussian noise removal, spatial domain enhancement and threshold division processing on the surface wear morphology image of the armature, and marking the connected area as the wear area.

[0016] Furthermore, after each experiment, the wear area is analyzed by energy dispersive spectroscopy to obtain the changes in elemental content in the wear area.

[0017] Furthermore, 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 to verify the numerical model of armature wear.

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

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

[0020] An experimental module for controlling the 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 building 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 initial roughness into a numerical model of armature wear and predicting the wear rate and surface roughness after wear; The present invention relates to an evaluation system for armature surface wear, including:

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

[0022] The present invention mainly aims to obtain the evolution rules of armature wear under operating conditions with different charging voltages and initial surface roughness through quantitative detection, and fundamentally suppress the occurrence of material breakdown. By constructing a numerical model of armature wear, the completeness and accuracy of armature surface wear evaluation are improved.

[0023] The present invention uses a numerical model of armature wear that can quickly obtain the armature wear rate and surface roughness after wear from the charging voltage and initial roughness, thereby reducing experimental costs and improving the efficiency of loss evaluation.

[0024] The drawings in the specification that form a part of this invention are intended to provide a further understanding of the invention, and the illustrative embodiments of the invention and their descriptions are intended to interpret the invention and are not intended to unduly limit the invention. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a circuit diagram of the electromagnetic rail launch experimental platform of the present embodiment. [Figure 2] 10 shows surface wear morphology images of the armature in the experiment of different charging voltages in this example (the material indicated by the arrow is a conductive adhesive applied during the SEM test and can be ignored). [Figure 3] 10A and 10B are images of surface wear morphology of an armature in an experiment with different initial roughnesses in this embodiment. [Figure 4] 10 is a schematic diagram showing the results of image processing of the armature and counting of the communication area at 1900 V in this embodiment. [Figure 5] FIG. 1 is a schematic diagram of wear results at different charging voltages in this example. [Figure 6] FIG. 10 is a schematic diagram of the wear results for different initial roughnesses in this example. [Figure 7] FIG. 10 is a schematic diagram showing changes in the height of a straight line profile peak in this embodiment. [Figure 8] FIG. 2 is a schematic diagram showing the change in the degree of wear at different charging voltages in this embodiment. [Figure 9] FIG. 10 is a schematic diagram showing the change in the degree of wear at different initial roughnesses in this embodiment. [Figure 10] 3A and 3B are schematic diagrams of the micro-morphology of the surface of the armature at different charging voltages in this embodiment. [Figure 11] 11 is a schematic diagram of element distribution in the wear region at 1900 V in this example. In Fig. 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] FIG. 2 is a schematic diagram showing the change in element content in the worn region at different charging voltages in this embodiment. [Figure 13] 1A and 1B are schematic diagrams of the micro-morphology of the surface of the armature at different initial roughnesses in this embodiment. [Figure 14] FIG. 10 is a schematic diagram showing the change in element content in the wear region at different initial roughnesses in this embodiment. [Figure 15] FIG. 10 is a schematic diagram showing the change in heat flux density over time in this embodiment. [Figure 16(a)] FIG. 1 is a schematic diagram showing the change in heat flux density with the charging voltage in this embodiment. [Figure 16(b)] FIG. 10 is a schematic diagram showing the change in heat flux density with the initial roughness in this embodiment. [Figure 17] 3 is a schematic diagram of the dynamic wear process of the armature with increasing charging voltage in this embodiment. FIG. [Figure 18] 1 is a schematic diagram of the dynamic wear process of the armature in which the initial roughness is reduced in this embodiment; FIG. [Figure 19] 4 is a flowchart of a method for evaluating surface wear of an armature according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] The invention will now be further described with reference to the following figures and examples.

[0027] It should be noted that the following detailed description is for illustrative purposes only and is intended to further explain the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art.

[0028] It should be noted that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the exemplary embodiments according to the present invention. For example, unless the context clearly dictates otherwise, the singular forms used herein are intended to include the plural forms, and it should also be understood that the use of the terms "comprises" and / or "includes" herein indicates the presence of features, steps, operations, devices, assemblies, and / or combinations thereof.

[0029] Example 1 As shown in FIG. 19, this embodiment Controlling the charging voltage and initial roughness as single variables, respectively, and conducting armature wear experiments on an electromagnetic rail launching experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear; Building a numerical model of armature wear based on the charging voltage, initial roughness, wear rate, and surface roughness after wear; A method for evaluating the surface wear of an armature is provided, 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] This invention is experimentally and verified through several aspects: (1) The experimental platform and detection means, along with the operating procedures for the electromagnetic launch experiment, are described. The experiment covers different charging voltages and initial surface roughness. (2) The surface wear characteristics of the armature are quantitatively analyzed using image processing algorithms and confocal contour measurement. (3) The dynamic wear behavior of the armature under different operating conditions is analyzed using microstructure and component detection. In particular, the evolution of the armature wear mode is demonstrated. (4) The heat flux density of Joule heat and friction heat is calculated to verify the experimental conclusions, and a numerical model of armature wear is constructed, providing a basic solution for guiding the design of the equipment.

[0031] Step 1: Experimental platform and detection means The electromagnetic rail launch system operates in a short-duration pulse discharge mode. To achieve the required current amplitude and energy intensity for launch, a commonly used energy drive is a capacitor-energy storage pulse power supply. To reduce the parasitic mass of the launch assembly and increase the payload ratio, the launch chamber should be designed as a roughly rectangular shape. Based on this, an electromagnetic rail launch experimental platform was constructed, the circuit principle of which is shown in Figure 1.

[0032] The experimental platform in Figure 1 primarily includes a charging circuit, a launcher, and a detection device. Related components include a voltage divider, a high-voltage digital meter, a step-up transformer, a rectifying silicon stack, resistor R1, switch K, resistor R2, capacitor C, resistor R'1, switch K', resistor R'2, a high-capacity semiconductor switch assembly D1, a variable inductor L, a freewheeling diode D2, and the launcher. In the charging circuit, a 10-kVA charger is connected to the step-up transformer and, after rectification by the silicon stack, charges the pulse power module. The maximum charging voltage can reach 100 kV, and the charging current is 100 mA. The power module generates a high-pulse current through two 4 mF-5 kV capacitors and discharges it to the launcher via the high-capacity semiconductor switch assembly D1. The switches are equipped with the necessary dynamic pulse absorption and pulse trigger circuits. Variable inductor L is used to adjust the pulse width and peak value output from the capacitors to expand the waveform and mitigate the impact 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 rail is made of two parallel 1200mm x 23mm x 2mm 45# medium carbon structural steel plates, with polytetrafluoroethylene insulating supports and pretension bolts to maintain chamber stability. The armature is made of 6063-T6 aluminum alloy and adopts a typical C-shaped solid structure, weighing approximately 15.667g.

[0033] Prior to the experiment, a no-load test was first conducted to check whether the circuit connections were good and ensure the capacitors could be charged effectively. The charging voltage was measured using a voltage divider (with a 1000:1 voltage division ratio) and its associated digital instrument. During the experiment, a current sensor CT and a high-voltage probe (with a 1000:1 attenuation ratio) were used to detect the rail current and muzzle voltage, respectively, and the measured waveforms were transmitted to a digital oscilloscope. After the experiment, a KathMatic laser spectral confocal microscope (LSCM) was used to perform 3D contour measurements and obtain data such as the height and roughness of the armature wear scar. A GeminiSEM 300 thermal field emission scanning electron microscope (SEM) was used to detect the micro-morphology of the armature surface, and its micro-area components were analyzed in combination with an energy dispersive spectrometry (EDS).

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

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

[0036] b) The charging voltage was set to 2000V. Before firing, the armature surface was pre-polished with sandpaper of mesh numbers 120cw, 180cw, 240cw, 600cw, 800cw, 1000cw, 1500cw, and 2000cw. LSCM measurements revealed textured surfaces with initial roughnesses 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 number of the sandpaper, the rougher the polished armature surface.

[0037] Step 2.1: To initially evaluate the degree of armature surface wear and determine the area to be observed by SEM, macroscopic images of the armature were taken after firing. The armature surface wear morphology in different charging voltage experiments is shown in Figure 2.

[0038] As can be seen from Figure 2, with increasing voltage, the concave wear craters and grooves on the armature surface after firing gradually transformed into fine dimples, fine scratches, and conductive adhesive. The white areas represent the exposed aluminum alloy matrix, while the black metal oxides appear from the tail edge and diffuse toward the armature head, being most prevalent at 2100V and 2200V. Above 2300V, the black areas tend to decrease and become tumor-like.

[0039] Figure 3 shows the surface wear morphology of the armature in experiments with different initial roughnesses. In Figure 3, as the initial roughness decreases, within the range of 1.05 μm or higher, the wear craters and scratches on the armature surface after firing gradually become shallower, with localized areas still exhibiting polished textures. When the initial roughness decreases below 0.55 μm, the black oxide spreads more widely and is accompanied by complex impact grooves, tumors, waterfalls, and other morphologies.

[0040] To quantitatively extract the wear information of the armature, an image processing algorithm was used to remove Gaussian noise, enhance the spatial domain, and segment the images in Figures 2 and 3, and mark the open areas. Taking an armature firing at 1900V as an example, the image processing and open area counting results are shown in Figure 4.

[0041] As can be seen in Figure 4, oxides in the image are displayed in black through binarization, while shallow wear craters, scratches, and other depressions are displayed in white. White depressions with the same grayscale value are identified as independent connected regions and enclosed in a rectangular frame. The centroid position of each connected region is indicated by a vertical line, and the region is counted based on this and displayed numerically in the image. A total of 183 connected regions were identified at 1900V. Each armature image is 1064 x 1890 pixels, and statistics are collected on the percentage of white regions and the number of connected regions. The ratio of mass loss after firing to mass before firing is also calculated to analyze the change in wear rate. 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 number of interconnected areas changes in the opposite direction. This is because as the voltage increases, the number of pits decreases, and the large, concentrated wear craters change into more small, shallow dimples, and the relative friction process 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 becomes more widespread, the aluminum alloy matrix peels off over a large area, the interconnected areas become concentrated again, and the wear rate increases.

[0043] Similarly, the wear results for different initial roughnesses were calculated, as shown in Figure 6. As can be seen from Figure 6, as the initial roughness decreases, the proportion of white areas decreases, then increases slightly, and then decreases significantly. The wear rate decreases and then increases slightly. The number of interconnected areas varies irregularly, but generally increases. This indicates that as the initial surface becomes smoother, the number of wear craters decreases and their distribution becomes more dispersed. After the roughness falls below 0.25 μm, oxidation wear becomes severe. However, unlike the material peeling that occurs during unpolished operation, the armature experiences a complex corrosion morphology due to the deformation and deposition of metal and its oxides. Therefore, as the white aluminum alloy area decreases, the increase in the wear rate is not obvious.

[0044] Step 2.2: Wear contour and surface roughness In order to accurately analyze the wear characteristics of the armature, the surface contour and roughness data of the armature are obtained by LSCM. Take the armature still firing at 1900V as an example.

[0045] By scanning the point cloud data of the height map, accurate information on the surface contour undulations of the armature can be obtained. To compare the damage level 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. The changes in peak height are shown in Figure 7.

[0046] Figure 7 shows that all four lines tend to be highly undulating in the front and flat in the rear. Due to the presence of wear craters and grooves, there are obvious depressions in the head of the armature. The highest peak in region A1 exceeds the original reference surface by 322.77 μm, with a maximum valley depth of 203.55 μm. The rear end of the armature is primarily folds formed by the flowing structure and oxide deposition of the aluminum after it is heated and melted. The rear of the contour line is small and finely undulating, with a maximum peak height and valley depth of only 181.83 μm and 86.92 μm, respectively. The surface roughness in region A2 is significantly reduced, but the fold distribution is wider, resulting in a larger interface spreading area.

[0047] In order to compare the change in the degree of armature wear at different charging voltages, the 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 increases slightly, and then decreases again. At 1900V, the armature surface exhibits significant pits and protrusions, resulting in very high surface roughness. As the voltage increases, the degree of wear decreases. When the voltage increases to 2100V, the depth of localized wear craters decreases, but heat generation and oxidation become more intense, resulting in a flowing molten form on the surface, which actually increases the roughness. As the voltage continues to increase, the armature surface becomes flatter, and the roughness gradually decreases again, due to the more uniform corrosion expansion and the large amount of surface metal spalling.

[0049] Figure 9 shows the change in the degree of armature wear for different initial roughnesses. As shown in Figure 9, Sa decreases and then increases as the initial roughness decreases. 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, when the initial roughness is less than 1.05 μm, severe high-temperature oxidation and fusion abrasion occur between the armature and the rail, resulting in the accumulation of a large oxide layer. As erosion pits, cracks, and even grooves form, the roughness increases significantly.

[0050] Step 3: Analysis of dynamic wear behavior In order to investigate the microstructure and structural components of the worn surface of the armature and clarify the nature of the damage formation process and phenomenon, a typical wear area with the highest surface roughness of the armature was selected based on macroscopic observation, and the sampling size was set to 2mm x 2mm. SEM micromorphology and EDS component analysis were performed 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. As shown in Figure 10, as the charging voltage increases, the wear debris becomes thinner, and the small pits and microcracks deteriorate into deeper cracks, eventually resulting in the appearance of flake-like peeling marks. At 1900 V, large, irregularly shaped wear debris forms and breaks apart. This is because, under the action of high-speed carrier friction, the harder steel rail rubs against the softer aluminum alloy armature surface, generating wear debris, which macroscopically appears as the independently dispersed wear craters shown in Figure 2. As the voltage increases, on the one hand, the armature's moving speed increases, and the duration of the shear force is shortened. 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 the elongated scratches shown in Figure 2 and reducing roughness. As the voltage continues to increase, the circuit current increases, and the accumulated Joule heat accelerates the oxidation reaction, heating and softening the metal, resulting in the appearance of granular molten pits on the armature surface. Small fatigue cracks appear at the stress concentration areas at the bottom or edges of the pits, causing severe degradation and increasing surface roughness. This indicates that at 2100V and 2200V, the wear mode begins to transition from abrasive wear to oxidation and fatigue wear. The cracks continue to propagate along the direction of armature movement and connect with each other, eventually resulting in spalling and deposition of metal material. At 2300V, flake-like traces of the spalled layer and ripple-like deposits are visible on the armature surface. The deposit effectively fills the depressions in the aluminum matrix, tending to uniformly expand due to corrosion, making the armature surface flatter and reducing roughness again. At 2400V, the spalled layer changes color from gray-black to silver-gray, meaning that the surface metal and brittle oxide layer have largely shed, exposing the underlying aluminum matrix.

[0052] Furthermore, elemental information of the wear interface was detected by EDS, and the element distribution status is shown in Figure 11, taking the wear area at 1900V as an example.

[0053] As can be seen from Figure 11(a) and (b), the wear zone contains mainly C, O, Al, Fe, Cu, and Si. Al accounts for over 58.34% of the total, which is the matrix of the original 6063-T6 aluminum alloy armature. Its main components include Fe, Si, and Cu. As can be seen from Figure 11(c), (d), and (f), small amounts of dispersed Fe, O, and C also cover the Al layer in Figure 11(e), which represents the steel rail chips scattered during rubbing. The changes in element content in the wear zone 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 contents of Al, Si, and Cu are essentially consistent, decreasing and then increasing, representing the change in the proportion of aluminum alloy material in the wear zone, while the change in O is opposite. Below 2100V, as the voltage increases, on the one hand, abrasive wear is reduced, reducing the large-area pits on the armature surface, and on the other hand, oxidative wear becomes more severe, increasing the oxide layer coverage area, resulting in a decrease in the proportion of Al and an increase in O. Above 2100V, intense oxidation and uneven heat distribution cause cracks at local stress concentrations to expand and penetrate further. Oxides are more brittle and brittle than aluminum metal. Under the action of sharp wear debris, they fall off in layers, re-exposing the aluminum alloy matrix and increasing the Al content. The trend of the Fe element does not completely coincide with that of Al, and when combined with the change in the C element, it indicates that there is bidirectional movement of metal material during the relative friction process between the armature and the rail. The filling of steel rail wear debris also reduces the surface roughness of the armature to a certain extent at 2000V in Figure 8.

[0055] Step 3.2: Wear behavior at different initial roughnesses The micromorphology of the armature surface with different initial roughness values ​​is shown in Figure 13. Figure 13 shows that as the initial roughness decreases, the wear debris becomes smaller, and the armature surface temporarily becomes relatively flat, resulting in more severe material loss or deposition. As can be seen from a comparison with Figure 10, the wear debris generated by firing after sandpaper grinding becomes rounder and duller, reducing cutting ability. This results in a slight improvement in the armature wear rate (Figure 5 vs. Figure 6) and surface roughness (Figure 8 vs. Figure 9). When the initial roughness is 2.65 μm, the micropeaks broken up during firing abrade the aluminum alloy at a certain angle of attack, leaving pits or flanges on the armature surface. As the initial roughness decreases, the surface becomes flatter and abrasive wear is reduced. When the initial roughness is 1.65 μm, grinding marks are still visible in localized areas after firing. However, if the polishing thickness is reduced to less than 1.05 μm, the surface becomes too smooth after polishing, reducing the number of conductive spots on the armature-rail contact surface, reducing the effective current transmission path and increasing contact resistance. Due to heat accumulation, the armature continues to heat up and soften. The aluminum matrix undergoes plastic deformation under the cutting action of wear debris, but does not completely peel off. Instead, it is extruded and deposited on the surface, forming a folded and flowing structure. At the same time, the localized high temperature and compressive stress can cause a molten metal film to form an instantaneous cold weld, accelerating the formation of a dark oxide layer. The brittle oxide layer is prone to fracture, and after falling off as wear debris, it adheres to the armature surface, where it further melts and deposits, leaving ablation pits and bumps. The adhered oxide also transforms the original steel-aluminum contact into a more compatible homogeneous material contact, which on the one hand makes the joint stronger and helps with adhesive wear, and on the other hand reduces the conductive area, which converts more energy into heat when current flows through the armature, further intensifying wear and degradation. A bright white light area was observed at 0.05 μm, indicating the poor conductive performance of the sample, which causes a charging effect under the SEM lens.

[0056] Similarly, the elemental content of the wear zone was examined for different initial roughness values. The results are shown in Figure 14. Figure 14 shows that as the initial roughness decreases, Al, Si, and Cu decrease, then increase slightly, and then decrease again. O exhibits the opposite effect, while Fe and C show slight variations. For values ​​above 1.65 μm, abrasive wear is reduced as the armature surface becomes more even, reducing the proportion of exposed aluminum matrix. The variations in Fe and C indicate that steel rail chips remain on the armature surface. As the initial roughness decreases, heat builds up due to increased contact resistance, and the wear mode between the armature and rail shifts from abrasive wear to oxidation wear. For values ​​between 1.65 and 1.05 μm, the balance is nearly achieved, with slight improvements in roughness (Figure 9). The heat-affected area then continues to expand, and the oxide layer accumulates on the armature surface without the violent peeling that occurs when the charging voltage increases. Repeated cutting with repeated penetrations results in the formation of flowing structures and tumor-like defects. The oxide layer contains increasing amounts of Fe, C, O, and other elements, while the proportion of elements in the aluminum matrix decreases. Small amounts of S were also detected in the 0.25-0.05 μm range, which may be due to a reaction between the metal and sulfides in the air under high-speed, high-temperature friction, further exacerbating abrasion of the armature.

[0057] 4. Consideration To clarify the damage mechanism at the armature-rail contact interface, we calculated the time-dependent changes in the peak values ​​of the heat flux density of Joule heat QJ and friction heat QF during firing, as shown in Figure 15. As can be seen from Figure 15, the change trend of the heat flux density of Joule heat coincides with the pulse current source, rising and then falling, while the heat flux density of friction heat continues to increase. During the entire firing process, the armature's initial moving speed is low, but the current quickly reaches the pulse peak value. Joule heat is the main heat source, and its uneven distribution causes dot-like pit-like ablation on the surface, especially at the front end. After 3.05 ms, the armature's moving speed increases, and the frictional heat exceeds the Joule heat, forming a flank-like high-temperature area on the tail and leading to extensive corrosion. Previous studies have suggested that Joule heat is concentrated at the head of the armature, while frictional heat accumulated at the rear is harmful to the armature. This conclusion is consistent with the present invention, further validating the validity of our results. As shown in Fig. 16(a) and Fig. 16(b), the changes in the peak values ​​of the two types of heat flux density 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 Joule heating and frictional heating both continue to increase as the charging voltage increases and the initial roughness decreases. Although the initial peak of Joule heating is lower, the rate of increase is faster, exceeding the frictional heating at 2100 V and 0.55 μm. This is consistent with the conclusion reached in previous research that "frictional heating mainly occurs when the armature moves at low speeds." Furthermore, the effect of increasing Joule heating with increasing charging voltage is more pronounced than with decreasing roughness. Summarizing the changes in wear morphology and heat flux density, the dynamic wear process of the armature with increasing charging voltage is shown in Figure 17.

[0059] As can be seen from Figure 17, at low voltages, the armature first undergoes abrasive wear, forming wear craters and grooves extending in the direction of movement. 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 armature surface. Above 2100V, Joule heating increases rapidly, and the fast-moving armature constantly encounters new, room-temperature tracks ahead. The heat is rapidly removed by the high temperature gradient. Under the action of the alternating forces generated by the strong alternating temperature field, cracks form and propagate in the armature. Eventually, the surface metal, especially the brittle oxide, flakes off, and the wear transforms into fatigue wear.

[0060] The dynamic wear process of an armature with reduced initial roughness is shown in Figure 18. As can be seen from Figure 18, the armature first experiences abrasive wear. As the initial roughness decreases, the abrasive grains become rounder and duller, weakening the cutting action and reducing abrasive wear. At the same time, the conductive spots decrease and contact resistance increases. Under high temperatures, the aluminum alloy surface undergoes an oxidation reaction with the gas medium, producing an oxide film that adheres to the surface. The oxide film is pressed and migrates, and the newly exposed surface is re-oxidized and deposited, ultimately forming a complex molten morphology. Under the effects of oxidation and adhesive wear, material does not shed in large quantities, but conductivity decreases.

[0061] From the above research, it is clear that the relationship between the charging voltage and initial roughness and the degree of material wear is complex. In order to comprehensively consider the influence of these two factors on the armature wear performance, the wear rate w r and the surface roughness Sa of the armature after wear and the relationship between them are established respectively.

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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 the 1.2m long track in this experimental platform, the optimal charging voltage is 2100V.

[0063] 2) Set the 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 should be paid to conductivity.

[0064] 3) For the C-shaped solid armature, the head needs to be improved in heat resistance and the tail needs to be improved in wear resistance, and an appropriate plating layer or paint is expected.

[0065] 5. Conclusion The primary objective of this invention is to quantitatively determine the evolution of armature wear under operating conditions with different charging voltages and initial surface roughnesses, thereby fundamentally preventing material damage. Firing experiments were conducted with charging voltages ranging from 1900V to 2400V and initial roughnesses ranging from 0.05μm to 2.65μm. Image processing analysis, LSCM contour measurement, SEM morphology detection, EDS component analysis, and heat flux density calculation were performed on the armature surface after firing. The following statements apply to the work presented:

[0066] 1) As the charging voltage increases, the wear rate of the armature decreases and then increases, the wear roughness decreases, then increases slightly, and then decreases again. The abrasive wear transforms into oxidation wear and fatigue wear, causing large amounts of material loss.

[0067] 2) With the reduction of the initial roughness, the wear rate of the armature decreases and then increases slightly, the wear roughness increases overall, the abrasive wear transforms into oxidative wear and adhesive wear, and the conductivity is seriously impaired.

[0068] 3) The head of the C-shaped solid armature is mainly subject to dot-like pit-type abrasion caused by Joule heat, while the tail is mainly subject to expansive corrosion caused by frictional heat, so there are different requirements for the heat resistance and wear resistance of the material.

[0069] In this study, an electromagnetic orbital launch experimental platform was constructed, and morphological analysis, contour measurement, and component detection were performed on the armature surface after launch. The results showed that as the charging voltage increased, the armature transitioned from abrasive wear to oxidation and fatigue wear. As the initial surface roughness decreased, abrasive wear, oxidation wear, and adhesive wear occurred sequentially. This is because the rate of increase in Joule heat was higher than that of frictional heat, gradually becoming the dominant wear mode. For this platform, the optimal charging voltage and initial surface roughness were 2100 V and 0.55-1.05 μm, respectively. Finally, a numerical model of armature wear and an optimization direction for armature design were proposed.

[0070] Example 2 In this embodiment, An experimental module for controlling the 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 building a numerical model of armature wear based on the charging voltage, the initial roughness, the wear rate, and the surface roughness after wear; A system for evaluating the surface wear of an armature is provided, which includes: an output module for inputting the charging voltage and the initial roughness into a numerical model of armature wear and predicting the wear rate and the surface roughness after wear.

[0071] In some embodiments, the numerical model of armature wear is expressed as:

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[0072] In some embodiments, the electromagnetic rail launch test platform includes a charging circuit, a launcher, and a detection device; The charging circuit includes a charger, a power supply module, a variable inductor L, and a diode D2. The charger is connected to a step-up transformer and charges the pulse power supply module after rectification by a silicon stack. The power supply module generates a large pulse current through a capacitor and discharges it to the launcher through a semiconductor switch assembly D1. The semiconductor switch assembly D1 is equipped with 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 so as to expand the waveform and mitigate the impact of the large current. After discharging, the energy is released through the freewheeling diode D2. The launcher is designed to be rectangular in caliber and includes a rail 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, an energy dispersive spectrometer, and a laser spectrum confocal microscope. The current sensor CT and high-voltage probe detect the rail current and muzzle voltage, respectively, and send 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 micro-morphology and local micro-area components of the armature surface after firing, and the laser spectrum confocal microscope is used to perform 3D contour measurement and obtain data on the height and roughness of the armature wear scars.

[0073] In some embodiments, the method of 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: acquiring a surface wear morphology image of the armature after each experiment to locate the worn area; and employing a laser spectrum confocal microscope to measure the worn area to obtain the surface roughness after wear.

[0075] In some embodiments, the method of acquiring an armature surface wear morphology image and locating a wear area includes collecting an armature surface wear morphology image by a camera, performing Gaussian noise removal, spatial domain enhancement and threshold segmentation processes on the armature surface wear morphology image, and marking connected areas as wear areas.

[0076] In some examples, after each experiment, the wear area is analyzed by energy dispersive spectroscopy to obtain the changes in elemental content in the wear area.

[0077] In some embodiments, after each experiment, the change over time in the peak value of the heat flux density of Joule heat and the change over time in the peak value of the 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 sanding the surface of the armature with sandpaper of different mesh numbers.

[0079] The above description is merely a preferred embodiment of the present invention, and is not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the present invention. All modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Controlling the charging voltage and initial roughness as single variables, respectively, and conducting armature wear experiments on an electromagnetic rail launching experimental platform, calculating the wear rate for each experiment, and measuring the surface roughness after wear; Building a numerical model of armature wear based on the charging voltage, initial roughness, wear rate, and surface roughness after wear; inputting the charging voltage and the 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, where the charging voltage is 1900V to 2400V and the initial roughness is 0.05μm to 2.65μm: [Equation 7] [Equation 8] However, w ｒ is the wear rate (%), Sa is the surface roughness of the armature after wear (μm), U is the charging voltage (V), Sa ０ A method for evaluating surface wear of an armature, characterized in that: represents the initial roughness (μm).

2. The electromagnetic rail launch test platform includes a charging circuit, a launcher, and a detection device; The charging circuit includes a charger, a power supply 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 a large pulse current by a capacitor. The semiconductor switch assembly D １ Discharge to the emitter by semiconductor switch assembly D １ A dynamic pulse absorption circuit and a pulse trigger circuit are arranged in the capacitor. The variable inductor L is used to adjust the pulse width and peak value output from the capacitor so as to expand the waveform and mitigate the impact of large current. After discharge, the freewheeling diode D ２ It releases energy by The launcher is designed to be rectangular in caliber and includes a rail and an armature.

2. The method for evaluating the surface wear of an armature according to claim 1, wherein 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 current sensor CT and the high-voltage probe detect the rail current and the muzzle voltage respectively, and the measured waveforms are transmitted to the digital oscilloscope; the voltage divider and the digital instrument measure the charging voltage; the thermal field emission scanning electron microscope together with the energy dispersive spectrometer are used to detect the micro-morphology and local micro-area components of the armature surface after firing; and the laser spectrum confocal microscope is used to perform three-dimensional contour measurement and obtain data on the height and roughness of the armature wear scar.

3. 2. The method for evaluating armature surface wear according to claim 1, wherein 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.

4. 2. The method for evaluating the surface wear of an armature according to claim 1, characterized in that the method for measuring the surface roughness after wear includes: obtaining an image of the surface wear morphology of the armature after each experiment to locate the worn area; and employing a laser spectrum confocal microscope to measure the worn area and obtain the surface roughness after wear.

5. 5. The method for evaluating the surface wear of an armature according to claim 4, wherein the method for acquiring the surface wear morphology image of the armature and locating the wear area includes collecting the surface wear morphology image of the armature by a camera, performing Gaussian noise removal, spatial domain enhancement and threshold division processing on the surface wear morphology image of the armature, and marking the connected area as the wear area.

6. 5. The method for evaluating the surface wear of an armature according to claim 4, wherein after each experiment, the worn area is analyzed by an energy dispersive spectroscope to obtain the change in element content in the worn area.

7. 2. The method for evaluating the surface wear of an armature according to claim 1, characterized in that after each experiment, the change over time in the peak value of the heat flux density of Joule heat and the change over time in the peak value of the heat flux density of frictional heat during the firing process are calculated to verify the numerical model of armature wear.

8. 8. The method for evaluating the surface wear of an armature according to claim 1, wherein the initial roughness is determined by polishing the surface of the armature with sandpaper of different mesh numbers.

9. An experimental module for controlling the 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 building 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 a numerical model of armature wear and predicting the wear rate and the surface roughness after wear; The numerical model of the armature wear is expressed by the following equation, where the charging voltage is 1900V to 2400V and the initial roughness is 0.05μm to 2.65μm: [Equation 9] [Equation 10] However, w ｒ is the wear rate (%), Sa is the surface roughness of the armature after wear (μm), U is the charging voltage (V), Sa ０ 10 is an evaluation system for the surface wear of an armature, characterized in that: represents the initial roughness (μm).

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