Trailer part surface enhanced galvanization treatment process

Abstract

The invention belongs to the technical field of trailer part treatment processes, and particularly relates to a trailer part surface enhanced galvanization treatment process which comprises the following steps: performing laser texturing on a trailer ball base body to form a regular micron-sized pit array; preparing a molybdenum or molybdenum alloy transition layer on the surface by adopting an electric spark deposition technology; in a zincate plating solution containing nano-diamond particles modified by a silane coupling agent, depositing a Zn-nano-diamond composite coating on the transition layer by adopting a bidirectional pulse electroplating method; micro-arc oxidation treatment is carried out in a silicate electrolyte, and a layer of zinc oxide ceramic membrane is generated on the surface; carrying out vacuum impregnation hole sealing treatment on the workpiece subjected to micro-arc oxidation by adopting a hole sealing agent containing a pH response type microcapsule; through multi-technology fusion, a gradient composite coating with excellent bonding strength, limit wear resistance, long-acting corrosion resistance and an intelligent self-repairing function is formed on the surface of the hitch ball, the service life of the hitch ball under the extreme working condition is remarkably prolonged, the reliability of the hitch ball under the extreme working condition is remarkably improved, and the whole process is environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of trailer component processing technology, specifically to a surface-enhancing galvanizing process for trailer components. Background Technology

[0002] Trailer components can be mainly divided into two categories: components on the towing vehicle and components on the towed trailer / trailer. Together, they constitute a towing system. The towing system contains a core component, namely the trailer ball. The spherical design of the trailer ball allows the trailer to rotate freely and flexibly relative to the towing vehicle in the horizontal direction (when turning) and the vertical direction (when traversing undulating roads), thus adapting to various road conditions.

[0003] As a key safety component for towing, trailer balls are exposed to complex and harsh environments for a long time, requiring their surfaces to have extremely high corrosion resistance, wear resistance and fatigue resistance; currently, the mainstream treatment is galvanizing or chrome plating.

[0004] While traditional zinc plating offers good corrosion resistance, it suffers from low hardness, poor wear resistance, and the risk of hydrogen embrittlement. Chromium plating, on the other hand, boasts high hardness, wear resistance, and an attractive appearance, but it is prone to microcracks. Corrosive media can easily seep into these cracks, leading to corrosion of the substrate, and hexavalent chromium pollutes the environment.

[0005] Existing technologies struggle to significantly improve the overall performance of trailer ball surfaces while ensuring environmental friendliness. Therefore, there is a need to develop a green surface treatment technology that combines long-lasting corrosion resistance, ultra-high wear resistance, excellent adhesion, and environmental friendliness; a surface-enhancing galvanizing process for trailer components is proposed here. Summary of the Invention

[0006] Existing technologies struggle to significantly improve the overall performance of trailer ball surfaces while maintaining environmental friendliness. Therefore, there is a need to develop a green surface treatment technology that combines long-lasting corrosion resistance, ultra-high wear resistance, excellent adhesion, and environmental friendliness. To achieve the above objectives, this invention provides the following technical solution: The surface-enhancing galvanizing process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; Step 3: In a zincate plating bath containing nanodiamond particles modified with silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method. Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0007] This invention combines laser texturing with electrical discharge deposition to construct micron-level anchoring points and pre-place an alloy transition layer on the spherical surface, greatly enhancing the adhesion of subsequent coatings. It also employs bidirectional pulse electroplating to co-deposit nanodiamond and zinc, forming a "zinc-diamond" nanocomposite coating as an intermediate layer, combining the sacrificial anode protection of zinc with the superior wear resistance of diamond. Micro-arc oxidation grows a ceramic film primarily composed of zinc oxide on the surface of the composite coating, significantly improving surface hardness and chemical inertness. A silicone resin containing pH-responsive microcapsules is used for pore sealing; when damaged media penetrates the coating, the microcapsules rupture to release a repair agent, automatically repairing microcracks and giving the coating self-healing capabilities. Through the integration of multiple technologies, this invention forms a gradient composite coating on the surface of the trailer ball, possessing excellent bonding strength, extreme wear resistance, long-term corrosion resistance, and intelligent self-healing functions. This completely solves the performance shortcomings of traditional processing methods, significantly improving the service life and reliability of the trailer ball under extreme conditions, and the entire process is green and environmentally friendly.

[0008] Furthermore, in step one, the laser used for laser texturing is a pulsed fiber laser, which produces micro-pits with a diameter of 40-60 μm, a pit depth of 20-40 μm, and a pit center-to-center distance of 80-120 μm.

[0009] Furthermore, step one includes the following steps: 1) The trailer ball base, after undergoing pre-processing including precision turning and grinding, and after cleaning and drying, is fixed on the fixture of the laser processing machine tool; the fixture can be rotated 360 degrees without dead angles in conjunction with the robot; 2) Using CAM software, program the 3D model of the trailer ball; select "hexagonal close-packed" or "square array" as the distribution mode of the pits; this design can achieve the highest surface coverage and the most uniform stress distribution; set the processing parameters, specifically the pit diameter is set to 45-55 μm, the pit depth is 27-33 μm, and the pit center distance is 100 μm; the laser parameters are pulse frequency 50 kHz, single pulse energy 0.5 mJ, scanning speed 800 mm / s, fill line spacing 15 μm, and number of scans 3-5 times; 3) Start the coaxial vision system to identify the preset reference marks on the sphere and automatically correct the origin of the processing coordinates; start the laser and motion system to scan and process the sphere from the top according to the preset program; during the processing, the focus tracking system works in real time to ensure the stability of the laser energy density; 4) After processing, use anhydrous ethanol or acetone to clean the trailer ball in an ultrasonic cleaner to thoroughly remove any micro-molten residues adhering to the surface; then blow the surface dry with high-pressure, dry, and clean nitrogen.

[0010] By precisely controlling the laser energy and motion path, the macroscopic spherical surface is transformed into a microscopic array of regular "anchor points," which fundamentally solves the problems of poor uniformity and limited adhesion improvement in traditional pretreatment methods such as sandblasting or acid etching, laying a crucial physical foundation for the construction of subsequent high-performance gradient coatings.

[0011] Furthermore, step two includes the following steps: 1) Securely clamp the trailer ball substrate, which has undergone laser texturing pretreatment, onto the worktable of the precision CNC electrical discharge deposition equipment to ensure good conductivity as the positive electrode; install the molybdenum alloy wire electrode on the rotating chuck of the equipment and correct its perpendicularity to the ball surface; seal the processing chamber and purge it with argon gas to reduce the oxygen content in the chamber to no more than 50 ppm. 2) Call the 3D model of the trailer ball and plan the deposition path; the path is staggered from the laser texturing pit array to ensure full coverage and no omissions; set the energy storage capacitor of the precision CNC EDM equipment to 200-300 μF, the discharge voltage to 80-100 V, the discharge frequency to 500-1000 Hz, the electrode rotation speed to 1500-2000 rpm, the scanning speed to 2-4 mm / s, the overlap rate to 40%-50%, and the protective gas flow rate to 15-20 L / min; 3) Start the precision CNC electrical discharge deposition equipment. The servo system drives the rotating molybdenum electrode to move at a constant speed on the spherical surface according to the preset path. Under the servo control, the electrode maintains a constant micro-gap of 0.1-0.3 mm with the workpiece surface, generating continuous and stable high-frequency pulse discharge. Each discharge generates a local high temperature of 8000-10000℃, causing the electrode tip and the micro-area on the surface of the trailer ball substrate to melt instantly. The electrode material is transferred and fused onto the surface of the trailer ball substrate, and then rapidly cooled to form a coating with an ultra-fine crystalline or even amorphous structure. The entire process is carried out under argon protection until the entire spherical surface is completely covered. 4) After deposition, keep the argon gas flowing until the workpiece cools to below 50°C to prevent high-temperature oxidation; remove the trailer ball substrate and gently remove any small amount of sputtered particles that may be attached to the surface using a soft brush or low-pressure airflow.

[0012] By utilizing instantaneous high temperature and pressure, molybdenum and the steel substrate undergo micro-area metallurgical fusion, forming a transition layer with a bonding strength far exceeding that of thermal spraying. The thermal expansion coefficient of molybdenum is between that of the steel substrate and the subsequent Zn-based coating, which can effectively alleviate the internal stress caused by thermal mismatch and prevent the coating from cracking or peeling. The molybdenum alloy layer itself has high hardness, high melting point, low coefficient of friction, and excellent corrosion resistance, providing an additional protective barrier for the substrate. The electrical discharge deposition process has minimal impact on the heat-affected zone of the substrate, and its cladding material can perfectly fill the pits of laser texturing, forming a strong "riveting" structure, which greatly enhances the interfacial bonding force.

[0013] Furthermore, in step three, the nanodiamond particles have a particle size of 10-30 nm and a concentration of 1.0-2.0 g / L in the plating solution; the parameters for bidirectional pulse electroplating are: forward current density of 3-5 A / dm², forward pulse width of 8-12 ms; reverse current density of 0.8-1.2 A / dm², and reverse pulse width of 0.8-1.2 ms.

[0014] Furthermore, step three includes the following steps: 1) Silane-modified pretreatment of nanodiamond KH-550 silane coupling agent was dissolved in a mixed solution of alcohol and water at a volume ratio of 1:10. The pH was adjusted to 4-5 with acetic acid, and the solution was magnetically stirred for 30 min to ensure complete hydrolysis, thus preparing the silane hydrolysate. Nanodiamond powder was weighed at 1.2 times the total required amount according to the plating solution concentration of 1.5 g / L, and slowly added to the hydrolysate. The powder was ultrasonically dispersed for 1 h. The modified nanodiamond was centrifuged to separate the nanodiamond powder, washed three times with anhydrous ethanol to remove the physically adsorbed coupling agent, dried in a vacuum oven at 80℃ for 2 h, and then ground for later use. The Si-OH bonds generated after the hydrolysis of KH-550 combine with the -OH / -COOH bonds on the surface of nanodiamonds. The -NH2 group at the other end is positively charged and can strongly adsorb the negatively charged Zn(OH)4. 2- Complexing ions greatly improve the dispersion stability of nanoparticles in the plating solution and their co-deposition efficiency with zinc ions. 2) Preparation of nano-composite plating solution Prepare a standard zincate plating solution using deionized water, sodium hydroxide at a concentration of 120 g / L, and zinc oxide at a concentration of 15 g / L. Slowly add the modified nanodiamond powder to the zincate plating solution at a concentration of 1.5 g / L while stirring at 500 rpm. Turn on the ultrasonic dispersion system at a power of 600 W and continue to treat the plating solution for 1-2 hours until the nanoparticles are uniformly dispersed. Throughout the electroplating process, maintain mechanical stirring at 200-300 rpm and intermittent ultrasonication with a rhythm of 1 minute pause every 10 minutes.

[0015] Furthermore, the ratio of alcohol to water in the alcohol-water mixture is 9:1.

[0016] Furthermore, step three also includes the following steps: 1) Use the pre-treated trailer ball substrate as the cathode and install it on the hanger of the constant temperature electroplating tank; place the zinc anode symmetrically on both sides of the cathode, adjust the plating solution temperature to 23-27℃, and maintain the pH value at 13-14. 2) Set the electroplating parameters in the constant temperature electroplating bath: the current density of the forward pulse is 4 A / dm² and the pulse width is 10 ms, the current density of the reverse pulse is 1 A / dm² and the pulse width is 1 ms; the pulse frequency is 90 Hz and the electroplating time is 60 min; the constant temperature electroplating bath maintains stirring and temperature control throughout the entire process; the introduction of the reverse pulse can instantly dissolve the dendrites formed at high current density, making the coating more dense and smooth, while promoting the transport and embedding of nanoparticles to the cathode surface.

[0017] Furthermore, in step four, the micro-arc oxidation treatment adopts a DC superimposed pulse power supply mode, with a termination voltage of 400-500V, a current density of 4-6 A / dm², and a treatment time of 5-10 min.

[0018] Furthermore, in step five, the wall material of the pH-responsive microcapsules is urea-formaldehyde resin, and the core material is a mixture of epoxy resin and amine curing agent; the amount of microcapsules added is 3-8% of the total mass of the sealing agent.

[0019] Compared with existing technologies, this invention combines laser texturing with electrical discharge deposition to construct micron-level anchoring points on the spherical surface and pre-place an alloy transition layer, greatly improving the adhesion of subsequent coatings. It also employs bidirectional pulse electroplating to co-deposit nanodiamond and zinc, forming a "zinc-diamond" nanocomposite coating as an intermediate layer, combining the sacrificial anode protection of zinc with the superior wear resistance of diamond. Furthermore, micro-arc oxidation grows a ceramic film primarily composed of zinc oxide on the surface of the composite coating, significantly enhancing surface hardness and chemical inertness. Finally, it uses silicone resin containing pH-responsive microcapsules for pore sealing; when damaged media penetrates the coating, the microcapsules rupture to release a repair agent, automatically repairing microcracks and endowing the coating with self-healing capabilities. This invention integrates multiple technologies to form a gradient composite coating on the surface of trailer balls, which has excellent bonding strength, extreme wear resistance, long-term corrosion resistance and intelligent self-healing function. It completely solves the performance shortcomings of traditional processing technology, significantly improves the service life and reliability of trailer balls under extreme working conditions, and the whole process is green and environmentally friendly. Attached Figure Description

[0020] Figure 1 This is a flowchart of the surface-enhancing galvanizing process for trailer parts according to the present invention. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 like Figure 1 As shown: The surface reinforcement galvanizing treatment process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; Step 3: In a zincate plating bath containing nanodiamond particles modified with silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method. Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0023] This invention combines laser texturing with electrical discharge deposition to construct micron-level anchoring points and pre-place an alloy transition layer on the spherical surface, greatly enhancing the adhesion of subsequent coatings. It also employs bidirectional pulse electroplating to co-deposit nanodiamond and zinc, forming a "zinc-diamond" nanocomposite coating as an intermediate layer, combining the sacrificial anode protection of zinc with the superior wear resistance of diamond. Micro-arc oxidation grows a ceramic film primarily composed of zinc oxide on the surface of the composite coating, significantly improving surface hardness and chemical inertness. A silicone resin containing pH-responsive microcapsules is used for pore sealing; when damaged media penetrates the coating, the microcapsules rupture to release a repair agent, automatically repairing microcracks and giving the coating self-healing capabilities. Through the integration of multiple technologies, this invention forms a gradient composite coating on the surface of the trailer ball, possessing excellent bonding strength, extreme wear resistance, long-term corrosion resistance, and intelligent self-healing functions. This completely solves the performance shortcomings of traditional processing methods, significantly improving the service life and reliability of the trailer ball under extreme conditions, and the entire process is green and environmentally friendly.

[0024] Example 2 This embodiment is based on embodiment 1, with the following additions: In step one, the laser used for laser texturing is a pulsed fiber laser, which produces micro-dimples with a diameter of 40-60 μm, a depth of 20-40 μm, and a center-to-center spacing of 80-120 μm.

[0025] Example 3 The surface-enhancing galvanizing process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; details are as follows: 1) The trailer ball base, after undergoing pre-processing including precision turning and grinding, and after cleaning and drying, is fixed on the fixture of the laser processing machine tool; the fixture can be rotated 360 degrees without dead angles in conjunction with the robot; 2) Using CAM software, program the 3D model of the trailer ball; select "hexagonal close-packed" or "square array" as the distribution mode of the pits; this design can achieve the highest surface coverage and the most uniform stress distribution; set the processing parameters, specifically the pit diameter is set to 45-55 μm, the pit depth is 27-33 μm, and the pit center distance is 100 μm; the laser parameters are pulse frequency 50 kHz, single pulse energy 0.5 mJ, scanning speed 800 mm / s, fill line spacing 15 μm, and number of scans 3-5 times; 3) Start the coaxial vision system to identify the preset reference marks on the sphere and automatically correct the origin of the processing coordinates; start the laser and motion system to scan and process the sphere from the top according to the preset program; during the processing, the focus tracking system works in real time to ensure the stability of the laser energy density; 4) After processing, use anhydrous ethanol or acetone to clean the trailer ball in an ultrasonic cleaner to thoroughly remove any micro-molten residues adhering to the surface; then blow the surface dry with high-pressure, dry, and clean nitrogen.

[0026] By precisely controlling the laser energy and motion path, the macroscopic spherical surface is transformed into a microscopic array of regular "anchor points," which fundamentally solves the problems of poor uniformity and limited adhesion improvement in traditional pretreatment methods such as sandblasting or acid etching, laying a crucial physical foundation for the construction of subsequent high-performance gradient coatings. Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; Step 3: In a zincate plating bath containing nanodiamond particles modified with silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method. Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0027] Example 4 The surface-enhancing galvanizing process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; details are as follows: 1) Securely clamp the trailer ball substrate, which has undergone laser texturing pretreatment, onto the worktable of the precision CNC electrical discharge deposition equipment to ensure good conductivity as the positive electrode; install the molybdenum alloy wire electrode on the rotating chuck of the equipment and correct its perpendicularity to the ball surface; seal the processing chamber and purge it with argon gas to reduce the oxygen content in the chamber to no more than 50 ppm. 2) Call the 3D model of the trailer ball and plan the deposition path; the path is staggered from the laser texturing pit array to ensure full coverage and no omissions; set the energy storage capacitor of the precision CNC EDM equipment to 200-300 μF, the discharge voltage to 80-100 V, the discharge frequency to 500-1000 Hz, the electrode rotation speed to 1500-2000 rpm, the scanning speed to 2-4 mm / s, the overlap rate to 40%-50%, and the protective gas flow rate to 15-20 L / min; 3) Start the precision CNC electrical discharge deposition equipment. The servo system drives the rotating molybdenum electrode to move at a constant speed on the spherical surface according to the preset path. Under the servo control, the electrode maintains a constant micro-gap of 0.1-0.3 mm with the workpiece surface, generating continuous and stable high-frequency pulse discharge. Each discharge generates a local high temperature of 8000-10000℃, causing the electrode tip and the micro-area on the surface of the trailer ball substrate to melt instantly. The electrode material is transferred and fused onto the surface of the trailer ball substrate, and then rapidly cooled to form a coating with an ultra-fine crystalline or even amorphous structure. The entire process is carried out under argon protection until the entire spherical surface is completely covered. 4) After deposition, keep the argon gas flowing until the workpiece cools to below 50°C to prevent high-temperature oxidation; remove the trailer ball substrate and gently remove any small amount of sputtered particles that may be attached to the surface using a soft brush or low-pressure airflow.

[0028] By utilizing instantaneous high temperature and pressure, molybdenum and the steel substrate undergo micro-area metallurgical fusion, forming a transition layer with a bonding strength far exceeding that of thermal spraying. The thermal expansion coefficient of molybdenum is between that of the steel substrate and the subsequent Zn-based coating, which can effectively alleviate the internal stress caused by thermal mismatch and prevent the coating from cracking or peeling. The molybdenum alloy layer itself has high hardness, high melting point, low coefficient of friction, and excellent corrosion resistance, providing an additional protective barrier for the substrate. The electrical discharge deposition process has minimal impact on the heat-affected zone of the substrate, and its cladding material can perfectly fill the pits of laser roughening, forming a strong "riveting" structure, which greatly enhances the interfacial bonding force. Step 3: In a zincate plating bath containing nanodiamond particles modified with silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method. Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0029] Example 5 The surface-enhancing galvanizing process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; Step 3: In a zincate plating bath containing nanodiamond particles modified with a silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method; details are as follows: 1) Silane-modified pretreatment of nanodiamond KH-550 silane coupling agent was dissolved in a mixed solution of alcohol and water at a volume ratio of 1:10 (the ratio of alcohol to water in the mixed solution was 9:1). The pH was adjusted to 4-5 with acetic acid, and the solution was magnetically stirred for 30 min to ensure complete hydrolysis, thus preparing the silane hydrolysate. Nanodiamond powder was weighed at 1.2 times the total required amount according to the plating solution concentration of 1.5 g / L, and slowly added to the hydrolysate. The powder was ultrasonically dispersed for 1 h. The modified nanodiamond was centrifuged to separate the nanodiamond powder, washed three times with anhydrous ethanol to remove the physically adsorbed coupling agent, dried in a vacuum oven at 80℃ for 2 h, and then ground for later use. The Si-OH bonds generated after the hydrolysis of KH-550 combine with the -OH / -COOH bonds on the surface of nanodiamonds. The -NH2 group at the other end is positively charged and can strongly adsorb the negatively charged Zn(OH)4. 2-Complexing ions greatly improve the dispersion stability of nanoparticles in the plating solution and their co-deposition efficiency with zinc ions. 2) Preparation of nano-composite plating solution Prepare a standard zincate plating solution using deionized water, sodium hydroxide at a concentration of 120 g / L, and zinc oxide at a concentration of 15 g / L. Slowly add the modified nanodiamond powder to the zincate plating solution at a concentration of 1.5 g / L while stirring at 500 rpm. Turn on the ultrasonic dispersion system at a power of 600 W and continue to treat the plating solution for 1-2 hours until the nanoparticles are uniformly dispersed. Maintain mechanical stirring at 200-300 rpm and intermittent ultrasonication with a rhythm of 1 minute pause every 10 minutes throughout the electroplating process. 3) Use the pre-treated trailer ball substrate as the cathode and install it on the hanger of the constant temperature electroplating tank; place the zinc anode symmetrically on both sides of the cathode, adjust the plating solution temperature to 23-27℃, and maintain the pH value at 13-14. 4) Set the electroplating parameters for the constant temperature electroplating bath: the current density of the forward pulse is 4 A / dm² and the pulse width is 10 ms; the current density of the reverse pulse is 1 A / dm² and the pulse width is 1 ms; the pulse frequency is 90 Hz and the electroplating time is 60 min; the constant temperature electroplating bath maintains stirring and temperature control throughout the entire process; the introduction of the reverse pulse can instantly dissolve the dendrites formed at high current density, making the coating more dense and smooth, while promoting the transport and embedding of nanoparticles to the cathode surface.

[0030] Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0031] Example 6 This embodiment is based on embodiment 1, with the following additions: In step three, the nanodiamond particles have a particle size of 10-30 nm and a concentration of 1.0-2.0 g / L in the plating solution; the parameters for bidirectional pulse electroplating are: forward current density of 3-5 A / dm², forward pulse width of 8-12 ms; reverse current density of 0.8-1.2 A / dm², and reverse pulse width of 0.8-1.2 ms.

[0032] Example 7 The surface-enhancing galvanizing process for trailer parts includes the following steps: Step 1: Perform laser texturing pretreatment on the trailer ball substrate to form a regular array of micron-sized pits; the specific steps are as follows: 1) The trailer ball base, after undergoing pre-processing including precision turning and grinding, and after cleaning and drying, is fixed on the fixture of the laser processing machine tool; the fixture can be rotated 360 degrees without dead angles in conjunction with the robot; 2) Using CAM software, program the 3D model of the trailer ball; select "hexagonal close-packed" or "square array" as the distribution mode of the pits; this design can achieve the highest surface coverage and the most uniform stress distribution; set the processing parameters, specifically the pit diameter is set to 45-55 μm, the pit depth is 27-33 μm, and the pit center distance is 100 μm; the laser parameters are pulse frequency 50 kHz, single pulse energy 0.5 mJ, scanning speed 800 mm / s, fill line spacing 15 μm, and number of scans 3-5 times; 3) Start the coaxial vision system to identify the preset reference marks on the sphere and automatically correct the origin of the processing coordinates; start the laser and motion system to scan and process the sphere from the top according to the preset program; during the processing, the focus tracking system works in real time to ensure the stability of the laser energy density; 4) After processing, use anhydrous ethanol or acetone to clean the trailer ball in an ultrasonic cleaner to thoroughly remove any micro-molten residues adhering to the surface; then blow the surface dry with high-pressure, dry, and clean nitrogen.

[0033] By precisely controlling the laser energy and motion path, the macroscopic spherical surface is transformed into a microscopic array of regular "anchor points," which fundamentally solves the problems of poor uniformity and limited adhesion improvement in traditional pretreatment methods such as sandblasting or acid etching, laying a crucial physical foundation for the construction of subsequent high-performance gradient coatings. Step 2: A molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball substrate after laser texturing pretreatment using electrical discharge deposition technology; details are as follows: 1) Securely clamp the trailer ball substrate, which has undergone laser texturing pretreatment, onto the worktable of the precision CNC electrical discharge deposition equipment to ensure good conductivity as the positive electrode; install the molybdenum alloy wire electrode on the rotating chuck of the equipment and correct its perpendicularity to the ball surface; seal the processing chamber and purge it with argon gas to reduce the oxygen content in the chamber to no more than 50 ppm. 2) Call the 3D model of the trailer ball and plan the deposition path; the path is staggered from the laser texturing pit array to ensure full coverage and no omissions; set the energy storage capacitor of the precision CNC EDM equipment to 200-300 μF, the discharge voltage to 80-100 V, the discharge frequency to 500-1000 Hz, the electrode rotation speed to 1500-2000 rpm, the scanning speed to 2-4 mm / s, the overlap rate to 40%-50%, and the protective gas flow rate to 15-20 L / min; 3) Start the precision CNC electrical discharge deposition equipment. The servo system drives the rotating molybdenum electrode to move at a constant speed on the spherical surface according to the preset path. Under the servo control, the electrode maintains a constant micro-gap of 0.1-0.3 mm with the workpiece surface, generating continuous and stable high-frequency pulse discharge. Each discharge generates a local high temperature of 8000-10000℃, causing the electrode tip and the micro-area on the surface of the trailer ball substrate to melt instantly. The electrode material is transferred and fused onto the surface of the trailer ball substrate, and then rapidly cooled to form a coating with an ultra-fine crystalline or even amorphous structure. The entire process is carried out under argon protection until the entire spherical surface is completely covered. 4) After deposition, keep the argon gas flowing until the workpiece cools to below 50°C to prevent high-temperature oxidation; remove the trailer ball substrate and gently remove any small amount of sputtered particles that may be attached to the surface using a soft brush or low-pressure airflow.

[0034] By utilizing instantaneous high temperature and pressure, molybdenum and the steel substrate undergo micro-area metallurgical fusion, forming a transition layer with a bonding strength far exceeding that of thermal spraying. The thermal expansion coefficient of molybdenum is between that of the steel substrate and the subsequent Zn-based coating, which can effectively alleviate the internal stress caused by thermal mismatch and prevent the coating from cracking or peeling. The molybdenum alloy layer itself has high hardness, high melting point, low coefficient of friction, and excellent corrosion resistance, providing an additional protective barrier for the substrate. The electrical discharge deposition process has minimal impact on the heat-affected zone of the substrate, and its cladding material can perfectly fill the pits of laser roughening, forming a strong "riveting" structure, which greatly enhances the interfacial bonding force. Step 3: In a zincate plating bath containing nanodiamond particles modified with a silane coupling agent, a Zn-nanodiamond composite coating is deposited on the transition layer using a bidirectional pulse electroplating method; details are as follows: 1) Silane-modified pretreatment of nanodiamond KH-550 silane coupling agent was dissolved in a mixed solution of alcohol and water at a volume ratio of 1:10 (the ratio of alcohol to water in the mixed solution was 9:1). The pH was adjusted to 4-5 with acetic acid, and the solution was magnetically stirred for 30 min to ensure complete hydrolysis, thus preparing the silane hydrolysate. Nanodiamond powder was weighed at 1.2 times the total required amount according to the plating solution concentration of 1.5 g / L, and slowly added to the hydrolysate. The powder was ultrasonically dispersed for 1 h. The modified nanodiamond was centrifuged to separate the nanodiamond powder, washed three times with anhydrous ethanol to remove the physically adsorbed coupling agent, dried in a vacuum oven at 80℃ for 2 h, and then ground for later use. The Si-OH bonds generated after the hydrolysis of KH-550 combine with the -OH / -COOH bonds on the surface of nanodiamonds. The -NH2 group at the other end is positively charged and can strongly adsorb the negatively charged Zn(OH)4. 2- Complexing ions greatly improve the dispersion stability of nanoparticles in the plating solution and their co-deposition efficiency with zinc ions. 2) Preparation of nano-composite plating solution Prepare a standard zincate plating solution using deionized water, sodium hydroxide at a concentration of 120 g / L, and zinc oxide at a concentration of 15 g / L. Slowly add the modified nanodiamond powder to the zincate plating solution at a concentration of 1.5 g / L while stirring at 500 rpm. Turn on the ultrasonic dispersion system at a power of 600 W and continue to treat the plating solution for 1-2 hours until the nanoparticles are uniformly dispersed. Maintain mechanical stirring at 200-300 rpm and intermittent ultrasonication with a rhythm of 1 minute pause every 10 minutes throughout the electroplating process. 3) Use the pre-treated trailer ball substrate as the cathode and install it on the hanger of the constant temperature electroplating tank; place the zinc anode symmetrically on both sides of the cathode, adjust the plating solution temperature to 23-27℃, and maintain the pH value at 13-14. 4) Set the electroplating parameters for the constant temperature electroplating bath: the current density of the forward pulse is 4 A / dm² and the pulse width is 10 ms; the current density of the reverse pulse is 1 A / dm² and the pulse width is 1 ms; the pulse frequency is 90 Hz and the electroplating time is 60 min; the constant temperature electroplating bath maintains stirring and temperature control throughout the entire process; the introduction of the reverse pulse can instantly dissolve the dendrites formed at high current density, making the coating more dense and smooth, while promoting the transport and embedding of nanoparticles to the cathode surface.

[0035] Step 4: Using the workpiece obtained in Step 3 as the anode, perform micro-arc oxidation treatment in a silicate electrolyte to generate a zinc oxide ceramic film on the surface. Step 5: Vacuum impregnation and sealing treatment is performed on the workpiece after micro-arc oxidation using a sealing agent containing pH-responsive microcapsules, followed by curing.

[0036] Furthermore, in step four, the micro-arc oxidation treatment adopts a DC superimposed pulse power supply mode, with a termination voltage of 400-500V, a current density of 4-6 A / dm², and a treatment time of 5-10 min.

[0037] In step five, the wall material of the pH-responsive microcapsules is urea-formaldehyde resin, and the core material is a mixture of epoxy resin and amine curing agent; the amount of microcapsules added is 3-8% of the total mass of the sealing agent.

[0038] I. Experimental Objective By comparing and testing traditional zinc plating, traditional chrome plating, and your innovative gradient composite coating process, the superiority and innovation of the new process are quantitatively demonstrated by data on key performance indicators such as strength, wear resistance, corrosion resistance, hardness, and environmental friendliness.

[0039] II. Sample Preparation Prepare four sets of trailer ball samples with identical material and size (e.g., Φ50 mm spheres with a 40Cr steel matrix): Control group A was conventional zinc plating, which was performed according to GB / T 9799-2011 "Metallic and other inorganic coatings - treated zinc electroplating on steel" using conventional cyanide or alkaline zincate plating. Control group B was conventional zinc plating, with hard chrome plating performed according to GB / T 11379-2008 "Chromium electroplating for engineering use in metal coatings".

[0040] Control group C was a blank control group, which underwent only polishing treatment without any coating. Experimental group D strictly followed the process steps described in Example 7.

[0041] III. Experimental Content and Testing Methods (See Table 1 for details) Table 1

[0042] IV. Experimental Results and Data Analysis The following results were obtained from the experiments and tests mentioned in Table 1: 1. Bond strength Experimental group D will achieve the highest grade 0 (no peeling) in the cross-cut test. Its bond strength in the pull-out test will be significantly higher than that of control groups A and B, and the failure mode should be cohesive failure (i.e., failure within the adhesive or coating, rather than detachment from the coating interface with the substrate).

[0043] The reason is that the micron-level anchoring points created by laser texturing in experimental group D and the metallurgical bonding transition layer formed by electrical spark deposition are incomparable to the purely physical bonding of traditional zinc plating and chromium plating.

[0044] 2. Abrasion resistance analysis The wear rate in experimental group D will be significantly lower than that in control groups A and B. It is expected to reduce wear by more than 80% compared to traditional galvanizing and by more than 50% compared to chromium plating.

[0045] The reason is that the ultra-high hardness of the nanodiamonds in experimental group D, combined with the micro-arc oxidation ceramic layer, creates an extremely wear-resistant surface. While chrome plating is hard, it is brittle, whereas the composite coating combines both hardness and toughness.

[0046] 3. Corrosion Resistance Analysis The time it takes for red rust to appear in experimental group D will be much longer than in control groups A and B. It is expected that no red rust will appear after more than 2000 hours of neutral salt spray testing.

[0047] The reason is that the micro-arc oxidation ceramic layer in experimental group D provides an excellent physical barrier, and the cathodic protection effect of the Zn layer as a sacrificial anode still exists. The self-healing sealing layer can effectively prevent the penetration of corrosive media.

[0048] 4. Hardness Analysis The surface hardness (micro-arc oxidation layer) of experimental group D will be much higher than that of the traditional zinc-plated control group A, and also higher than that of the chromium-plated control group B. The cross-sectional hardness increases in a gradient from the substrate to the surface.

[0049] The reason is that the micro-arc oxidation ceramic layer and nano-diamond reinforcement phase in experimental group D greatly improved the hardness.

[0050] 5. Self-healing performance analysis In the scratch test, only the scratch edge corrosion spread width of experimental group D was the smallest, and signs of sealant flowing out and covering the scratch could be observed under a microscope.

[0051] The reason is the unique characteristics of the process in experimental group D: the pH-responsive microcapsules rupture and repair at the scratches, thus slowing down the corrosion process.

[0052] 6. Environmental impact analysis The hexavalent chromium content in experimental group D and control group A was 0. However, a large amount of hexavalent chromium was detected in the coating of control group B.

[0053] Through the above series of standardized experimental comparisons, it is expected that sufficient data will be obtained to prove the following: The D process in this experimental group comprehensively surpasses traditional zinc and chromium plating processes in key performance indicators such as combined strength, wear resistance, corrosion resistance life, and hardness. Furthermore, its unique intelligent self-healing function and chromium-free environmental protection throughout the entire process address the fundamental shortcomings of traditional processes in terms of long-term reliability and environmental friendliness.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A surface enhanced galvanizing process for trailer parts, characterized in that, The method comprises the following steps: Step one, laser texturing pretreatment is performed on the trailer ball base body to form a regular micron-level pit array; Step two, a molybdenum or molybdenum alloy transition layer is prepared on the surface of the trailer ball base body after laser texturing pretreatment by using electric spark deposition technology; Step three, a Zn-nano diamond composite plating layer is deposited on the transition layer by using a bidirectional pulse plating method in a zincate plating solution containing nano diamond particles modified by a silane coupling agent; Step four, the workpiece obtained in step three is used as an anode, and a zinc oxide ceramic film is generated on the surface by micro-arc oxidation treatment in a silicate electrolyte; Step five, a vacuum immersion sealing treatment is performed on the workpiece after micro-arc oxidation by using a pore sealing agent containing pH-responsive microcapsules, and then solidification is performed.

2. The surface enhanced galvanizing process for trailer parts according to claim 1, characterized in that, The laser used in the laser texturing is a pulsed fiber laser, the micro-pits generated have a diameter of 40-60 μm, a pit depth of 20-40 μm, and a pit center distance of 80-120 μm.

3. The surface enhanced galvanizing process for trailer parts of claim 1 wherein, In the step one, the following steps are included: 1) After the trailer ball base body is cleaned and dried after the pre-processes including finish machining and grinding, it is fixed on the clamp of the laser processing machine; the clamp can be rotated by 360 degrees without dead angle in cooperation with the robot; 2) The CAM software is used to program according to the 3D model of the trailer ball; "hexagonal close packing" or "square array" is selected as the distribution mode of the pits; this design can achieve the highest surface coverage and the most uniform stress distribution; the processing parameters are set, specifically the pit diameter is set to 45-55 μm, the pit depth is set to 27-33 μm, and the pit center distance is set to 100 μm; the laser parameters are pulse frequency 50 kHz, single pulse energy 0.5 mJ, scanning speed 800 mm / s, filling line distance 15 μm, and scanning times 3-5 times; 3) The coaxial vision system is started, the preset reference mark on the ball is recognized, and the processing coordinate origin is automatically corrected; the laser and the motion system are started, and the scanning processing is performed from the top end of the ball according to the preset program; during the processing, the focal point tracking system works in real time to ensure the stability of the laser energy density; 4) After the processing is completed, the trailer ball is cleaned in the ultrasonic cleaning machine using anhydrous ethanol or acetone to completely remove the micro-melted residues attached to the surface; the surface is dried with high-pressure, dry, and clean nitrogen gas.

4. The surface-enhanced galvanizing process for trailer parts according to claim 1 or 2 or 3, characterized in that, In the step two, the following steps are included: 1) The trailer ball base body after laser texturing pretreatment is firmly clamped on the workbench of the precise numerical control electric spark deposition equipment as the positive electrode to ensure good conductivity; the molybdenum alloy wire electrode is installed on the rotating chuck of the equipment and its perpendicularity to the ball surface is corrected; the sealed processing cabin is washed with argon gas to reduce the oxygen content in the cabin to not higher than 50 ppm; 2) Call the 3D model of the trailer ball, plan the deposition path; the path is staggered with the laser etched pit array to ensure full coverage and no omission; set the energy storage capacitor of the precision NC electric spark deposition equipment to 200-300 μF, the discharge voltage to 80-100 V, the discharge frequency to 500-1000 Hz, the electrode rotation speed to 1500-2000 rpm, the scanning speed to 2-4 mm / s, the overlap rate to 40%-50%, and the protective gas flow to 15-20 L / min; 3) Start the precision NC electric spark deposition equipment, and the servo system drives the rotating molybdenum electrode to move uniformly on the spherical surface according to the preset path; the electrode keeps a constant micro gap of 0.1-0.3 mm with the workpiece surface under the servo control, and generates continuous and stable high-frequency pulse discharge; the local high temperature of 8000-10000 °C is generated in each discharge moment, so that the electrode tip and the surface micro area of the trailer ball substrate are instantaneously melted, the electrode material is transferred and cladded to the surface of the trailer ball substrate, and then is rapidly cooled to form a coating with ultra-fine crystal or amorphous structure; the whole process is carried out under argon protection until the whole spherical surface is completely covered; 4) After deposition, keep the argon flow until the workpiece is cooled to below 50 °C to prevent high-temperature oxidation; take out the trailer ball substrate, and gently remove the small amount of sputtering particles that may be attached to the surface using a soft brush or low-pressure gas flow.

5. The surface enhanced galvanizing process for trailer parts of claim 1 wherein, In the step three, the particle size of the nanodiamond particles is 10-30 nm, and the concentration in the plating solution is 1.0-2.0 g / L; the parameters of the bidirectional pulse plating are as follows: forward current density 3-5 A / dm², forward pulse width 8-12 ms; reverse current density 0.8-1.2 A / dm², reverse pulse width 0.8-1.2 ms.

6. The surface enhanced galvanizing process for trailer parts of claim 1 wherein, In the step three, the following steps are included: 1) Silane modification pretreatment of nanodiamond Dissolve the KH-550 silane coupling agent in a mixed solution of alcohol and water at a volume ratio of 1:10, adjust the pH to 4-5 with acetic acid, and magnetically stir for 30 min to fully hydrolyze, complete the preparation of the silane hydrolysis solution; weigh the nanodiamond powder, which is 1.2 times the total required amount of 1.5 g / L plating solution concentration, slowly add it to the hydrolysis solution, and ultrasonic dispersion for 1 h; centrifugal separation of modified nanodiamond, washed with absolute ethanol three times to remove physically adsorbed coupling agent, dried in a vacuum oven at 80 °C for 2 h, and ground for use; 2) Configuration of nanocomposite plating solution Prepare a standard zincate plating solution with deionized water, 120 g / L sodium hydroxide and 15 g / L zinc oxide; slowly add the modified nanodiamond powder to the zincate plating solution at a concentration of 1.5 g / L under stirring at a speed of 500 rpm; turn on the ultrasonic dispersion system, power 600 W, continuously treat the plating solution for 1-2 h, until the nanoparticles are uniformly dispersed, and maintain mechanical stirring at 200-300 rpm and intermittent ultrasonic at a rhythm of 1 min of ultrasonic stop every 10 min during the whole electroplating process.

7. The surface enhanced galvanizing process for trailer parts according to claim 6, characterized in that, The ratio of alcohol to water in the mixed solution of alcohol and water is 9:

1.

8. The surface enhanced galvanizing process for trailer parts as claimed in claim 6 wherein, In the third step, the following step is further included: 1) The trailer ball body after the pre-treatment is installed on the hanger of the constant temperature electroplating tank as a cathode, and zinc anodes are symmetrically placed on both sides of the cathode, the temperature of the plating solution is adjusted to 23-27 DEG C, and the pH value is maintained at 13-14; 2) The electroplating parameters of the constant temperature electroplating tank are set, the current density of the forward pulse is 4 A / dm2 and the pulse width is 10 ms, the current density of the reverse pulse is 1 A / dm2 and the pulse width is 1 ms; the pulse frequency is 90 Hz, and the electroplating time is 60 min; the constant temperature electroplating tank keeps stirring and temperature control during the whole working process; the introduction of the reverse pulse can instantaneously dissolve the dendrites formed at high current density, so that the coating is more dense and flat, and the transmission and embedding of the nanoparticles to the cathode surface are promoted.

9. The surface enhanced galvanizing process for trailer parts of claim 1 wherein, In the fourth step, the micro-arc oxidation treatment adopts a direct current superimposed pulse power mode, the terminal voltage is 400-500 V, the current density is 4-6 A / dm2, and the treatment time is 5-10 min.

10. The surface enhanced galvanizing process for trailer parts of claim 1 wherein, In the fifth step, the wall material of the pH-responsive microcapsule is urea-formaldehyde resin, and the core material is a mixture of epoxy resin and amine curing agent; the adding amount of the microcapsule is 3-8% of the total mass of the pore sealing agent.

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