Method for improving surface properties of austenitic stainless steel rocket sled slider

Abstract

The application provides a method for improving surface performance of an austenitic stainless steel rocket sled sliding block, and belongs to the technical field of strengthening and toughening of metal materials and surface modification of metal materials used under high-speed heavy-load extreme working conditions. In the application, a NiTi alloy target with different proportions is used as a source electrode on a textured austenitic stainless steel surface, and an alloy coating is prepared on the austenitic stainless steel surface by using a surface plasma alloying method. The plasma surface alloying is to form an alloy coating with a certain thickness on the workpiece electrode surface by using the sputtering bombardment of argon plasma, so that good combination between the coating and the workpiece electrode can be ensured, and the prepared coating can have high hardness.

Description

Technical Field

[0001] This invention belongs to the field of surface modification of metallic materials, and particularly relates to a method for providing both friction reduction and wear resistance to rocket skid sliders under high-speed and heavy-load conditions. Background Technology

[0002] The dynamic testing process of rocket sleds is a typical high-speed, heavy-load test. The slider component, as a key load-bearing support and guiding motion part, is a crucial bridge connecting the rocket sled and the rail, ensuring the safe and stable operation of the rocket sled system. The 0Cr18Ni9Ti material used for the rocket sled slider is an austenitic stainless steel with low surface hardness and poor wear resistance, seriously threatening the long-term safe service life of the rocket sled system. Therefore, improving the friction and wear performance of the slider, balancing wear resistance and friction reduction, and enhancing its service performance are particularly necessary.

[0003] Significant progress has been made in high-precision measurement technology for rocket skid sliders (Chinese Patent CN109142213B), and Chinese Patent CN204253613U proposes a novel low-resistance slider that allows for timely replacement of worn components. However, the wear problem of the slider cannot be fundamentally solved. While protective coatings (Chinese Patent CN112646454A) can reduce slider thermal erosion and thus slow down wear, abrasive wear caused by coating peeling is difficult to avoid. Appropriate surface morphology design (Chinese Patent CN114676611A), i.e., forming a surface texture, can capture wear debris, thereby reducing wear damage. However, surface textures designed based on fluid dynamics theory are not suitable for the operating environment of rocket skid sliders. Therefore, it is necessary to design a surface texture suitable for the service conditions of rocket skid sliders.

[0004] However, given the high economic and time costs, small sample size, and difficulty in evaluating rocket sled dynamic tests, as well as the inability to fully replicate the tests in the laboratory, it is impossible to reveal the slider wear problem through experimental analysis, nor can it reveal the influence of surface texture on slider wear behavior. Although there are precedents in China for simulating slider wear processes using computers (Chinese Patent CN112580144A), these simulations only use two-dimensional models or only consider local collision deformation. Summary of the Invention

[0005] This invention aims to provide a reasonable and efficient solution to the wear problem of rocket sled sliders, offering a method that combines friction reduction and wear resistance. The continuous groove surface texture obtained by the method provided by this invention results in smaller overall slider deformation, more uniform wear, and effective prevention of abrasive wear. The alloy coating obtained on the textured surface by this invention significantly improves the surface hardness of austenitic stainless steel.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] The first step is to establish a three-dimensional wear-symmetric model based on the actual rocket sled slider / rail friction pair, adopt the Archard wear model and assign a bilinear isotropic strengthening constitutive model to the slider;

[0008] The second step is to design a continuous groove surface texture parallel to the direction of motion;

[0009] The third step is to set boundary conditions for the model based on the actual operating conditions of the rocket sled rail system.

[0010] The fourth step involves importing the model using Solidwork software, taking into account the distortion of the finite element mesh, and then using ANSYS software to complete the constraints of boundary conditions such as symmetry planes, define materials, perform analysis calculations, and analyze the results.

[0011] The fifth step is to use a laser marking machine to design groove textures on the surface of the physical 0Cr18Ni9Ti using the results obtained from ANSYS software.

[0012] The sixth step is to pre-treat the textured 0Cr18Ni9Ti to obtain pre-treated 0Cr18Ni9Ti;

[0013] Step 7: Pretreated 0Cr18Ni9Ti and NiTi alloy targets with different proportions are subjected to plasma cleaning to obtain cleaned 0Cr18Ni9Ti and cleaned targets.

[0014] In the eighth step, the cleaning target is deposited onto the surface of the 0Cr18Ni9Ti using a plasma surface alloying method to form an alloy coating on the 0Cr18Ni9Ti surface, thereby improving the surface properties of 0Cr18Ni9Ti; the molar ratio of Ni to Ti in the NiTi alloy targets with different proportions is 1:1 to 1:4.

[0015] Specifically, in the first step, given that the wear of the rocket sled slider mainly occurs in the area where the slider interacts with the rail surface, the slider has symmetry along the direction of motion, and the Archard wear model is a classic and widely used model, a three-dimensional wear symmetry model is then established.

[0016] Furthermore, the actual contact area of ​​the slider has geometric dimensions of 284×94×21 mm. Since the thickness of the area with significant thermal fluctuations is only 6 mm, the slider model is scaled down proportionally to have dimensions of 81×13.5×6 mm.

[0017] Specifically, in the second step, when the groove direction is consistent with the sliding direction, the occurrence of stress concentration on the contact surface can be largely avoided. Furthermore, the groove texture parallel to the friction sliding direction can remove abrasive material in time, exhibiting excellent friction reduction effect. Therefore, a groove textured slider is designed.

[0018] Furthermore, 50 and 100 equal parts of the width (13.5 mm) of the slider symmetry model are used as the width and depth of the groove texture, respectively, and the texture density is set at 20% to 35% of the slider contact surface area.

[0019] A V-groove is provided on the surface of the slider, with a width of 0.270 mm and a depth of 0.135 mm. The spacing between adjacent V-grooves is 0.495 mm, 0.648 mm, and 0.878 mm.

[0020] Specifically, in the third step, all components above the slider in the rocket sled rail system are considered as uniform blocks, and the load is assumed to be uniformly distributed on the slider and always perpendicular to the direction of motion.

[0021] Furthermore, in practice, the rocket sled rail is in fixed contact with the ground, thus restricting the degrees of freedom in all directions at the bottom of the rail.

[0022] Furthermore, in practice, the slide rail has extremely high smoothness and a length of several kilometers, and almost no deformation occurs along the running direction. Therefore, the translational degrees of freedom of the front and rear ends of the slide rail along the direction of motion are constrained.

[0023] Specifically, in the fourth step, the finite element method discretizes the geometric model into a series of continuous meshes connected by nodes. Slider wear involves repositioning nodes to simulate material loss, and node changes inevitably cause mesh distortion. Therefore, a geometric mesh update strategy is considered.

[0024] The wear problem is simulated using the classic Archard wear model, with the basic formula being:

[0025]

[0026] In the formula, dh / dt is the change in wear depth per unit time; P is the contact pressure; υ is the sliding speed; H is the hardness of the softer material in the contact pair; and K is the dimensionless wear coefficient.

[0027] Furthermore, based on the designed model, the ANSYS software added the material properties of the slider (0Cr18Ni9Ti stainless steel) and the guide rail (U71Mn steel) and defined the corresponding boundary conditions. Finally, based on the finite element method theory, the wear, stress and contact pressure of the slider contact surface were calculated and simulated to observe the changes under different texture densities.

[0028] Furthermore, based on the analysis and simulation results, the friction reduction effect of the grooved texture was summarized and analyzed, verifying that the grooved texture is beneficial to improving the friction reduction and wear resistance of the rocket sled slider.

[0029] Specifically, in the fifth step, the results obtained from the ANSYS software are used to design groove textures on the surface of the physical 0Cr18Ni9Ti using a laser marking machine, resulting in textured 0Cr18Ni9Ti.

[0030] Furthermore, the pretreatment method described in step six is ​​to remove oil stains, polish, and ultrasonically clean the target material and the textured 0Cr18Ni9Ti in sequence; the solution for removing oil stains is an aqueous solution mixed with metal cleaning agent; the polishing is done using silicon carbide wet sandpaper; and the ultrasonic cleaning is performed using anhydrous ethanol.

[0031] Furthermore, the parameters for plasma cleaning in step seven independently include: the distance from the bottom of the NiTi alloy target to the surface of the pretreated 0Cr18Ni9Ti is 15~20 mm, the working gas pressure is argon, the flow rate of the argon is 18~30 sccm, the working gas pressure is 35±2 Pa, and the cleaning time is 0.5~1 h.

[0032] Specifically, in the seventh step, plasma cleaning is performed in a plasma surface alloying device. The pretreated 0Cr18Ni9Ti is placed on the sample stage of the plasma surface alloying device, and the NiTi alloy target is fixed on the source electrode suspension frame in the plasma surface alloying device by a clamp.

[0033] Furthermore, the parameters for plasma surface alloying deposition in step eight include: the distance from the bottom of the cleaning target to the surface of the cleaned 0Cr18Ni9Ti is 15~20 mm, the working gas is argon, the flow rate of the argon is 18~30 sccm, the working pressure is 35±2 Pa, the temperature is 700~800 ℃, the voltage difference between the cleaned 0Cr18Ni9Ti and the cleaning target is 250~350 V, and the holding time is 3~5 h.

[0034] Specifically, in the eighth step, plasma surface alloying is performed in a plasma surface alloying apparatus, and the cleaning target is fixed on the source suspension frame in the plasma surface alloying apparatus by a clamp.

[0035] By employing the above-described technology, the beneficial effects of the present invention compared to the prior art are as follows:

[0036] (1) This invention is a method for rocket skid sliders with both friction reduction and wear resistance and structural designability under high-speed heavy load conditions. It is a research scheme based on ANSYS finite element software to establish a three-dimensional equivalent model to realize dry friction simulation of two types of contact surfaces, smooth surface and grooved textured surface, and to study the influence of different texture densities on the wear, stress and contact pressure of slider contact surface.

[0037] (2) This invention can not only realize three-dimensional wear simulation under high-speed and heavy-load conditions, but also predict the changing trends of various mechanical properties when wear occurs. It can not only provide a useful reference for solving the wear problem of rocket skid sliders, but also effectively reduce research costs, thus having certain economic significance.

[0038] (3) The continuous groove surface texture designed for the rocket sled slider of the present invention can not only capture abrasive particles and debris in time during the wear process, thereby reducing the wear of the slider surface, but also further ensure the close contact between the slider and the slide rail due to the increase in contact pressure, thus promoting the stable operation of the rocket sled slide rail system to a certain extent.

[0039] (4) In this application, NiTi alloy targets with different proportions are used as source electrodes, and the alloy coating is prepared by plasma surface alloying deposition: ionized argon ions continuously bombard the NiTi alloy target and the surface of 0Cr18Ni9Ti. Bombarding 0Cr18Ni9Ti can raise its temperature, while bombarding the target can sputter the elements in the target. Under the action of gravity and voltage difference, the sputtered elements are deposited on the substrate and undergo thermal diffusion to form an alloy coating. At the same time, the formed alloy coating increases the hardness of the 0Cr18Ni9Ti surface. Attached Figure Description

[0040] Figure 1 A schematic diagram is created for the rocket sled slider model;

[0041] Figure 2 A schematic diagram of the main parameters of a continuous groove surface texture;

[0042] Figure 3 The groove geometry (unit: mm) is given when the texture density is 22%.

[0043] Figure 4 The groove geometry (unit: mm) is given when the texture density is 28%.

[0044] Figure 5 The groove geometry (unit: mm) is given when the texture density is 34%.

[0045] Figure 6 (a) Two-dimensional morphology of the grooves at a texture density of 34%; (b) Three-dimensional morphology.

[0046] Figure 7 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 2;

[0047] Figure 8 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 3;

[0048] Figure 9 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 4;

[0049] Figure 10 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 5;

[0050] Figure 11 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 6;

[0051] Figure 12 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 7;

[0052] Figure 13 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 8;

[0053] Figure 14 This is a cross-sectional view of the coating after surface alloying of the sample obtained in Example 9. Detailed Implementation

[0054] This invention provides a method for improving the surface properties of austenitic stainless steel rocket sled sliders. An equivalent three-dimensional wear model is established by simplifying the rocket sled slider / rail friction pair through symmetry analysis. The finite element method is used in conjunction with the Archard wear model, elastoplastic deformation theory, and a geometric update strategy, with boundary conditions constrained according to actual working conditions. Dry friction simulations of two types of contact surfaces—smooth surfaces and grooved textured surfaces—are performed using ANSYS finite element software to study the influence of different texture densities on wear, stress, and contact pressure of the slider contact surface.

[0055] Furthermore, in order to provide the public with a better understanding of the present invention, certain specific details are described in detail in the following detailed description of the present invention.

[0056] Please see Figure 1 ~ Figure 5 A method for combining friction reduction and wear resistance with structural designability for rocket skid sliders includes the following steps:

[0057] S1. Establish a three-dimensional wear-symmetric model based on the actual rocket sled slider / rail friction pair, adopt the Archard wear model and assign a bilinear isotropic reinforcement constitutive model to the slider;

[0058] S2. Based on the characteristics of the rocket sled slider being high-speed, heavy-load, dry friction, and a large amount of frictional heat, analyze and select a surface texture suitable for the rocket sled slider, and design a continuous groove surface texture parallel to the direction of motion.

[0059] S3. Set boundary conditions for the model based on the actual operating conditions of the rocket sled rail system;

[0060] S4. Based on the finite element method and considering the distortion of the finite element mesh, the model is imported using Solidworks software, and the boundary conditions such as symmetry planes, material definitions, analysis calculations, and results are completed using ANSYS software.

[0061] Example 1:

[0062] A method for achieving both friction reduction and wear resistance in rocket sled sliders is proposed. First, a three-dimensional wear-symmetric model is established based on the actual rocket sled slider / rail friction pair. Second, based on the established model, the pre-designed surface texture type, size range, and arrangement are determined. Considering wear issues, the surface-textured slider is further simulated and analyzed using the finite element method, thus completing the surface texture design of the rocket sled slider contact interface that achieves both friction reduction and wear resistance.

[0063] The specific process is as follows:

[0064] 1. Establish a three-dimensional wear-symmetric model of the slider;

[0065] Please see Figure 1 A schematic diagram is created for the rocket sled slider model.

[0066] Specifically, wear on the rocket sled slider mainly occurs in the area where the slider interacts with the rail surface, and the slider exhibits symmetry along the direction of motion. Assuming all components above the slider in the rocket sled rail system are equivalent to a uniform block, and that the load is uniformly distributed on the slider and always perpendicular to the direction of motion.

[0067] Furthermore, the actual contact area of ​​the slider has geometric dimensions of 284×94×21 mm. Since the thickness of the area with significant thermal fluctuations is only 6 mm, the slider model is scaled down proportionally to have dimensions of 81×13.5×6 mm.

[0068] 2. Main parameters and selection of continuous groove surface texture;

[0069] Please see Figure 2 , which are the main parameters of grooved surface texture.

[0070] Specifically, compared to single, independent, discontinuous, and non-continuous surface textures, continuous groove surface textures are more conducive to the timely removal of abrasive particles and debris by the rocket sled slider.

[0071] Furthermore, when the groove direction is consistent with the sliding direction, the stress concentration phenomenon on the contact surface can be avoided to a large extent. Moreover, the groove texture parallel to the friction sliding direction can remove the abrasive in time, showing excellent friction reduction effect.

[0072] Furthermore, 50 and 100 equal parts of the width (13.5 mm) of the slider symmetry model are used as the width and depth of the groove texture, respectively, that is, the width of the V-groove is 0.270 mm and the depth is 0.135 mm.

[0073] Please see Figure 3 ~ Figure 5 The spacing between adjacent V-grooves is 0.495 mm, 0.648 mm, and 0.878 mm, which are the groove geometric dimensions (all in mm) when the texture density is 22%, 28%, and 34%, respectively.

[0074] 3. The wear of the grooved textured slider was simulated and analyzed using the finite element method;

[0075] Specifically, the three-dimensional wear symmetry model created using Solidworks is imported into ANSYS Workbench of the ANSYS finite element software for symmetry plane constraints and mesh generation.

[0076] The wear problem is simulated using the classic Archard wear model, with the basic formula being:

[0077]

[0078] In the formula, dh / dt is the change in wear depth per unit time;

[0079] P—Contact pressure;

[0080] υ — Sliding speed;

[0081] H – Hardness of the softer material in the contact pair;

[0082] K – Dimensionless wear coefficient.

[0083] Furthermore, wear simulation analysis was performed using the transient structural physics module in ANSYS Workbench.

[0084] 4. Determine the optimal grooved surface texture and verify the model;

[0085] Specifically, a three-dimensional wear model was used to simulate and analyze the influence of texture density on contact surface wear, Von-mises stress, and contact pressure, among other contact characteristics.

[0086] Furthermore, the simulation analysis combined with relevant literature to evaluate the friction reduction and wear resistance performance of the grooved textured slider, and determined the texture density to be 34%.

[0087] Furthermore, the results obtained from ANSYS software were used to design grooved textures on the surface of physical 0Cr18Ni9Ti using a laser marking machine, resulting in textured 0Cr18Ni9Ti.

[0088] The following is a detailed implementation process to illustrate the method of using a plasma surface alloying device, taking a textured 0Cr18Ni9Ti sample and NiTi alloy targets with different proportions as examples.

[0089] Example 2:

[0090] The plasma surface alloying process specifically includes the following steps:

[0091] (1) Pretreatment of textured 0Cr18Ni9Ti samples: The wire-cut 0Cr18Ni9Ti samples were placed in an aqueous solution containing metal cleaning agent for degreasing treatment, and then polished step by step with 180~2000# silicon carbide wet sandpaper; the polished 0Cr18Ni9Ti samples were ultrasonically cleaned with anhydrous ethanol and dried with cold air for later use.

[0092] (2) Cleaning of the plasma surface alloying device: While waiting for ultrasonic cleaning, open the vent valve of the plasma surface alloying device until the air pressure inside the plasma surface alloying device is equal to the atmospheric pressure, raise the bell jar, polish and clean the inside of the bell jar with sandpaper, and then wipe the inside of the bell jar, the sample stage and the base clean with alcohol.

[0093] (3) Arrangement of the pretreated 0Cr18Ni9Ti sample: Place the pretreated 0Cr18Ni9Ti sample horizontally on the sample stage connected to the workpiece. Then adjust the distance (target-substrate distance) from the bottom of the NiTi alloy target (the molar ratio of Ni to Ti in the NiTi alloy target described in Example 1 is 1:1) to the surface of the pretreated 0Cr18Ni9Ti sample to 17 mm. Before lowering the bell jar, ensure that all objects can be observed from the temperature measurement window of the bell jar itself. After the positions of the pretreated 0Cr18Ni9Ti and the NiTi alloy target are adjusted, lower the bell jar. Close the vent valve; turn on the cooling water.

[0094] (4) Vacuuming inside the bell jar: Start the mechanical pump and evacuate through the evacuation pipe. When the vacuum level inside the bell jar is <4.5 Pa, open the inflation valve and the flow indicator cleaning valve. Introduce high-purity argon gas into the bell jar through the inflation pipe for 5 minutes to ensure that the chamber is filled with argon gas. After cleaning, close the cleaning valve and the inflation valve to reduce the vacuum level inside the bell jar to <4.5 Pa.

[0095] (5) Plasma cleaning: After the bell jar is evacuated, open the inflation valve, turn on the flow display valve control, and adjust the gas flow meter (argon flow rate is 19~25 sccm) to ensure that the working gas pressure reaches 35± After maintaining a pressure of 2 Pa for 5 min, the unipolar pulse bias power supply and the DC bias power supply are turned on respectively, generating glow discharge phenomena on the pretreated 0Cr18Ni9Ti sample and the NiTi alloy target. At this time, argon gas is ionized into argon plasma, which bombards the surface of the 0Cr18Ni9Ti sample and the pretreated NiTi alloy target, respectively. This bombardment removes impurities such as deposits and oxide layers from the surface of the pretreated 0Cr18Ni9Ti sample and the NiTi alloy target, thus cleaning the pretreated 0Cr18Ni9Ti sample and the NiTi alloy target separately.

[0096] (6) Plasma surface alloying deposition: After the pretreatment of the 0Cr18Ni9Ti sample and the cleaning of the NiTi alloy target are completed, the unipolar pulse bias power supply and the DC bias power supply are simultaneously turned on again, so that glow discharge is generated on both the cleaned 0Cr18Ni9Ti sample and the cleaned target. The 0Cr18Ni9Ti sample is heated by bombardment with argon plasma. When adjusting the voltage of the unipolar pulse bias power supply and the DC bias power supply, the voltage difference between the workpiece electrode and the source electrode must be 300 V. When the temperature of the cleaned 0Cr18Ni9Ti sample reaches 750 ℃, the heat preservation is started for 4 h, and the NiTi alloy coating preparation begins.

[0097] (7) Sample cooling: After holding at 750 ℃ ​​for 4 h, slowly reduce the voltage of the single-pole pulse bias power supply and the DC bias power supply until 0 V, and then turn off the two power cabinets; wait 1 h and then stop introducing argon gas, wait for the sample device to cool to room temperature, then turn off the vacuum system and the circulating water system, and take out the 0Cr18Ni9Ti sample that has completed plasma surface alloying.

[0098] Example 3

[0099] The difference between this embodiment and embodiment 2 is that the temperature for cleaning the 0Cr18Ni9Ti sample in step (6) is 800 ℃, the holding time is 5 h, and the voltage difference is 350 V. Other steps and parameters are the same as in embodiment 1.

[0100] Example 4

[0101] The difference between this embodiment and embodiment 2 is that in step (6), the temperature for cleaning the 0Cr18Ni9Ti sample is 700 ℃, the holding time is 4 h, the voltage difference is 350 V, and the target material ratio is 1:2. Other steps and parameters are the same as in embodiment 1.

[0102] Example 5

[0103] The difference between this embodiment and embodiment 2 is that the heat preservation time for cleaning the 0Cr18Ni9Ti sample in step (6) is 5 h, the voltage difference is 250 V, and the target material ratio is 1:2. Other steps and parameters are the same as in embodiment 1.

[0104] Example 6

[0105] The difference between this embodiment and embodiment 2 is that in step (6), the temperature for cleaning the 0Cr18Ni9Ti sample is 700 ℃, the holding time is 3 h, the voltage difference is 350V, and the target material ratio is 1:2. Other steps and parameters are the same as in embodiment 1.

[0106] Example 7

[0107] The difference between this embodiment and embodiment 2 is that the temperature for cleaning the 0Cr18Ni9Ti sample in step (6) is 700 ℃, the holding time is 5 h, and the target material ratio is 1:4. Other steps and parameters are the same as in embodiment 1.

[0108] Example 8

[0109] The difference between this embodiment and embodiment 2 is that the heat preservation time for cleaning the 0Cr18Ni9Ti sample in step (6) is 3 h, the voltage difference is 350 V, and the target material ratio is 1:4. Other steps and parameters are the same as in embodiment 1.

[0110] Example 9

[0111] The difference between this embodiment and embodiment 2 is that in step (6), the temperature for cleaning the 0Cr18Ni9Ti sample is 800 ℃, the holding time is 4 h, the voltage difference is 250V, and the target material ratio is 1:4. Other steps and parameters are the same as in embodiment 1.

[0112] The surface hardness of the samples obtained in Examples 1-8 and the untreated 0Cr18Ni9Ti sample was measured, and the results are shown in Table 1.

[0113] Table 1 Surface hardness of Examples 2-9 and untreated samples

[0114]

[0115] As shown in Table 1, the surface hardness of the 0Cr18Ni9Ti sample increased by 893.36 HV compared to the untreated sample after treatment with the parameters shown in Example 2; by 419.01 HV after treatment with the parameters shown in Example 3; by 832.22 HV after treatment with the parameters shown in Example 4; by 1002.56 HV after treatment with the parameters shown in Example 5; by 748.32 HV after treatment with the parameters shown in Example 6; and by 828.83 HV after treatment with the parameters shown in Example 7. The surface hardness of the 0Cr18Ni9Ti sample treated with the parameters shown in Example 8 increased by 864.97 HV compared to the untreated 0Cr18Ni9Ti sample; the surface hardness of the 0Cr18Ni9Ti sample treated with the parameters shown in Example 9 increased by 443.52 HV compared to the untreated 0Cr18Ni9Ti sample. These results indicate that the NiTi alloy coating prepared on the surface of 0Cr18Ni9Ti using this invention significantly improves the surface hardness of 0Cr18Ni9Ti. The infiltration of target elements into the 0Cr18Ni9Ti surface alters the microstructure and induces solid solution strengthening, which in turn enhances the surface hardness of 0Cr18Ni9Ti.

[0116] Figure 7 This is a cross-sectional view of the coating on the sample obtained in Example 2. Figure 7 It can be seen that the coating thickness obtained under the conditions of target material 1:1, 750 ℃, 4 h, 300 V is 0.0298 mm.

[0117] Figure 8 This is a cross-sectional view of the coating on the sample obtained in Example 3. Figure 8 It can be seen that the coating thickness obtained under the conditions of target 1:1, 800 ℃, 5 h, and 350 V is 0.0719 mm.

[0118] Figure 9 This is a cross-sectional view of the coating on the sample obtained in Example 4. Figure 9 It can be seen that the coating thickness obtained under the conditions of target ratio 1:2, 700 ℃, 4 h, and 350 V is 0.0282 mm.

[0119] Figure 10 This is a cross-sectional view of the coating on the sample obtained in Example 5. Figure 10 It can be seen that the coating thickness obtained under the conditions of target ratio 1:2, 750 ℃, 5h, and 250V is 0.0170 mm.

[0120] Figure 11 This is a cross-sectional view of the coating on the sample obtained in Example 6. Figure 11 It can be seen that the coating thickness obtained under the conditions of target ratio 1:2, 800 ℃, 3h, and 300 V is 0.0217 mm.

[0121] Figure 12 This is a cross-sectional view of the coating on the sample obtained in Example 7. Figure 12 It can be seen that the coating thickness obtained under the conditions of target material ratio 1:4, 700 ℃, 5h, and 300 V is 0.0266 mm.

[0122] Figure 13 This is a cross-sectional view of the coating on the sample obtained in Example 8. Figure 13 It can be seen that the coating thickness obtained under the conditions of target ratio 1:4, 800 ℃, 5h, and 350 V is 0.0193 mm.

[0123] Figure 14 This is a cross-sectional view of the coating on the sample obtained in Example 9. Figure 14 It can be seen that the coating thickness obtained under the conditions of target material ratio 1:4, 800 ℃, 4h, and 250 V is 0.0554 mm.

Claims

1. A method for improving the surface properties of austenitic stainless steel rocket sled sliders, characterized in that... Includes the following steps: The first step is to establish a three-dimensional wear-symmetric model based on the actual rocket sled slider / rail friction pair, adopt the Archard wear model and assign a bilinear isotropic strengthening constitutive model to the slider; The second step is to design a continuous groove surface texture parallel to the direction of motion. The groove textured slider is set as follows: 50 and 100 equal parts of the slider symmetry model width of 13.5 mm are used as the width and depth of the groove texture, respectively, and the texture density is 20% to 35% of the slider contact surface area. The third step is to set boundary conditions for the model based on the actual operating conditions of the rocket sled rail system. The fourth step involves importing the model using Solidwork software, taking into account the distortion of the finite element mesh, and then using ANSYS software to complete the constraint of the boundary conditions of the symmetry plane, material definition, analysis calculation, and result analysis. The fifth step is to use a laser marking machine to design groove textures on the surface of the physical 0Cr18Ni9Ti using the results obtained from ANSYS software. The sixth step is to pre-treat the textured 0Cr18Ni9Ti to obtain pre-treated 0Cr18Ni9Ti; Step 7: Pretreated 0Cr18Ni9Ti and NiTi alloy targets of different proportions are subjected to plasma cleaning to obtain cleaned 0Cr18Ni9Ti and cleaned targets. The parameters of plasma cleaning include: the distance from the bottom of the NiTi alloy target to the surface of the pretreated 0Cr18Ni9Ti is 15~20 mm, the working gas is argon, the flow rate of the argon is 18~30 sccm, the working pressure is 35±2 Pa, and the cleaning time is 30 min~1 h. In the eighth step, the cleaning target is deposited onto the surface of the 0Cr18Ni9Ti using a plasma surface alloying method to form an alloy coating on the 0Cr18Ni9Ti surface, thereby improving the surface properties of 0Cr18Ni9Ti; the molar ratio of Ni to Ti in the NiTi alloy targets with different proportions is 1:1 to 1:

4.

2. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In the first step, the wear of the rocket sled slider mainly occurs in the area where the slider interacts with the rail surface. The slider is symmetrical along the direction of movement. The geometric dimensions of the actual contact area of ​​the slider are 284×94×21 mm. Based on the fact that the thickness of the area with significant thermal fluctuations is only 6 mm, the slider model size is established as 81×13.5×6 mm by scaling down the size proportionally.

3. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In the third step, all components above the slider in the rocket sled rail system are considered as uniform blocks, and the load is assumed to be uniformly distributed on the slider and always perpendicular to the direction of motion.

4. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In the fourth step, based on the designed model, the ANSYS software adds the material properties of the 0Cr18Ni9Ti stainless steel slider and the U71Mn steel slide rail, and defines the corresponding boundary conditions. Finally, based on the finite element method, the wear, stress, and contact pressure of the slider contact surface are calculated and simulated to observe the changes under different texture densities. According to the analysis and simulation results, the friction reduction effect of the grooved texture is summarized and analyzed to verify that the grooved texture is beneficial to improving the friction reduction and wear resistance of the rocket sled slider.

5. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In the sixth step, the pretreatment methods are as follows: removing oil stains, polishing, and ultrasonic cleaning are performed on the target material and the textured 0Cr18Ni9Ti. The solution for removing oil stains is an aqueous solution mixed with metal cleaning agent. The polishing is performed using silicon carbide wet sandpaper. Anhydrous ethanol is selected for ultrasonic cleaning.

6. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In the seventh step, plasma cleaning is performed in a plasma surface alloying device. The pretreated 0Cr18Ni9Ti is placed on the sample stage of the plasma surface alloying device, and the NiTi alloy target is fixed on the source electrode suspension frame in the plasma surface alloying device by a clamp.

7. The method for improving the surface properties of austenitic stainless steel rocket sled sliders according to claim 1, characterized in that: In step eight, the parameters for plasma surface alloying deposition include: the distance from the bottom of the cleaning target to the surface of the cleaned 0Cr18Ni9Ti is 15~20 mm, the working gas is argon, the flow rate of the argon is 18~30 sccm, the working pressure is 35±2 Pa, the temperature is 700~800 ℃, the voltage difference between the cleaned 0Cr18Ni9Ti and the cleaning target is 250~350 V, and the holding time is 3~5 h.

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