Titanium alloy surface modified coating and preparation method thereof

Abstract

The invention relates to the technical field of metal material surface treatment, in particular to a titanium alloy surface modification coating and a preparation method thereof, and the method comprises the following steps: pretreating the titanium alloy surface; the surface of the titanium alloy is subjected to activating treatment through a composite activating solution, and the titanium alloy containing a transition layer is formed; the titanium alloy containing the transition layer is subjected to acid pickling treatment and sand blasting treatment for the first time; plasma immersion ion implantation treatment is adopted, so that the transition metal oxide nanowire is embedded into the titanium alloy containing the transition layer; the Mo element and the like are infiltrated into the transition layer and the titanium alloy through a plasma cementation metallization method; the titanium alloy containing the infiltrated layer is subjected to acid pickling treatment for the second time; the titanium alloy containing the infiltrated layer is subjected to secondary activating treatment, and a titanium alloy matrix is obtained; electroplating the titanium alloy matrix to form a plating layer on the surface of the titanium alloy matrix; carrying out laser shock peening treatment and ultraviolet irradiation treatment on the plating layer; and performing low-temperature annealing treatment to form a modified coating on the surface of the titanium alloy.

Description

Technical Field

[0001] The invention relates to the technical field of metal material surface treatment, and in particular to a titanium alloy surface modified coating and a preparation method thereof. Background Art

[0002] Titanium alloys are widely used in aerospace, medical equipment and other fields due to their advantages such as light weight, high strength and corrosion resistance. However, their surface hardness and wear resistance still need to be improved. Although traditional surface treatment methods such as anodizing and chemical plating can improve certain properties, they have limitations in improving comprehensive performance. Specifically: Insufficient hardness and wear resistance: Titanium alloy itself has low hardness and is prone to adhesive wear and abrasive wear, which limits its scope of application.

[0003] Poor high-temperature oxidation resistance: In a high-temperature environment, the oxide film generated on the surface of the titanium alloy is easy to fall off and cannot effectively protect the substrate, resulting in a decrease in mechanical properties and even causing major accidents.

[0004] Bonding problem: The bonding strength between traditional coatings and titanium alloy substrates is weak, and the coatings are prone to peeling or cracking, affecting service life and reliability.

[0005] Therefore, it is particularly important to develop an efficient and innovative method for titanium alloy surface modification. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a titanium alloy surface modified coating and a preparation method thereof.

[0007] According to a first aspect of the present invention, there is provided a method for preparing a titanium alloy surface modified coating, comprising the following steps: Pre-treating the titanium alloy surface; Using a composite activation solution to activate the surface of the titanium alloy to form a titanium alloy containing a transition layer; Wherein, the composite activation solution is fluorine-containing organic acid, graphite phase carbon nitride nanosheets and rare earth elements; Performing a first pickling treatment and a sandblasting treatment on the titanium alloy containing the transition layer; The titanium alloy containing the transition layer after the first acid pickling treatment and the sandblasting treatment is subjected to plasma immersion ion implantation treatment, and transition metal oxide nanowires are introduced during the process so that the transition metal oxide nanowires are embedded in the titanium alloy containing the transition layer; Using a plasma metallization method to infiltrate Mo, W and other metal elements into the transition layer and the titanium alloy to form a infiltration layer with a thickness of 5-200 μm, wherein the other metal elements are Ni and / or Cr elements; Performing a second pickling treatment on the titanium alloy containing the diffusion layer; Performing a secondary activation treatment on the titanium alloy containing the diffusion layer after the second pickling treatment to obtain a titanium alloy matrix; Electroplating the titanium alloy substrate to form a coating on the surface of the titanium alloy substrate; the electroplating solution used in the electroplating includes: chromic anhydride, sulfuric acid, transition metal oxide nanowires and metal organic framework nanoparticles; wherein the mass fraction of sulfuric acid is 2%-50%, the volume ratio of chromic anhydride to sulfuric acid is 1:4-2:3, the mass fraction of the transition metal oxide nanowires is 0.1%-5% of the electroplating solution, and the mass fraction of the metal organic framework nanoparticles is 0.1%-5% of the electroplating solution; The coating is subjected to laser shock peening treatment and ultraviolet light irradiation treatment; The coating layer after the laser shock strengthening treatment and the ultraviolet light irradiation treatment is subjected to low temperature annealing treatment to form a modified coating layer on the surface of the titanium alloy.

[0008] In order to further improve the performance of the Mo-infiltrated layer, other metal elements can be introduced while forming the Mo-infiltrated layer to form a composite infiltrated layer. This method can significantly improve the comprehensive properties of the surface modified coating of the titanium alloy through synergistic effects, such as hardness, wear resistance and corrosion resistance. Tungsten has a high melting point and good corrosion resistance, which can significantly improve the high-temperature oxidation resistance and hardness of the Mo-infiltrated layer. Nickel has good toughness and corrosion resistance, which can enhance the bonding strength and toughness of the Mo-infiltrated layer. Chromium has excellent corrosion resistance and wear resistance, which can improve the surface hardness and corrosion resistance of the Mo-infiltrated layer. Since Mo and other metal elements (such as W, Ni or Cr) form a uniform and dense composite infiltrated layer on the surface of the titanium alloy, the synergistic effect between different metals is utilized to significantly improve the comprehensive performance of the surface modified coating, significantly improve the surface hardness, and enhance the wear resistance. The introduction of nanoparticles promotes the diffusion of multiple metal elements, making the composite infiltrated layer more uniform, reducing local stress concentration points, and thus reducing the wear rate. The presence of the composite infiltrated layer effectively blocks the invasion of external corrosive media and improves the corrosion resistance of the titanium alloy. Through the two stages of initial infiltration and deep infiltration, the thickness and structure of the composite infiltration layer are gradually optimized, and the quality and performance of the infiltration layer are improved.

[0009] When Mo and W are infiltrated together, they are able to form a more complex intermetallic compound structure on the surface of the titanium alloy, which not only improves the hardness, but also enhances the fatigue resistance and wear resistance. When Ni is used in combination with other metal elements such as Mo and W, it can act as a bridge to promote the better diffusion of other metal elements into the titanium alloy, while enhancing the mechanical properties and corrosion resistance of the entire composite infiltration layer. When Cr is infiltrated together with other metal elements (such as Mo, W, and Ni), it can form a more complex intermetallic compound, further enhancing the hardness, wear resistance, and corrosion resistance of the material. In addition, the presence of Cr helps to stabilize the distribution of other metal elements in the titanium alloy and ensure the uniformity and consistency of the composite infiltration layer. The microstructure of the multi-metal composite infiltration layer is more complex and uniform, reducing local stress concentration points, thereby reducing the wear rate and extending the service life. The microstructure of the multi-metal composite infiltration layer is more complex and uniform, reducing local stress concentration points, thereby reducing the wear rate and extending the service life.

[0010] According to an embodiment of the present invention, the pretreatment of the titanium alloy surface comprises: Mechanically polishing the titanium alloy may be using fine sandpaper or a polishing wheel to mechanically polish the titanium alloy substrate to make the surface roughness less than 6.4 μm; Using a chemical cleaning agent to remove surface oxides and other contaminants on the surface of the titanium alloy, including: soaking in a 5%-10% hydrochloric acid solution for 5-10 minutes, and then rinsing with deionized water; The titanium alloy is immersed in a citric acid cleaning solution and cleaned by ultrasonic assisted cleaning to ensure that tiny impurities are completely removed. The ultrasonic cleaning time is 10-20 minutes and the temperature is kept at room temperature.

[0011] Mechanical polishing can reduce surface roughness, reduce stress concentration points in subsequent processing, and improve coating adhesion. Chemical cleaning and ultrasonic-assisted cleaning can remove surface oxides and other contaminants to ensure the uniformity and effectiveness of subsequent processing.

[0012] According to an embodiment of the present invention, the method of using a composite activation solution to activate the surface of the titanium alloy to form a titanium alloy containing a transition layer includes: The composite activation solution is prepared by preparing a composite activation solution containing 10% to 80% by mass of perfluorooctanoic acid, 0.1% to 5% by mass of rare earth elements, and 0.1% to 5% by mass of graphite phase carbon nitride nanosheets, and the rest is water, wherein the rare earth elements include lanthanum or cerium; Activation treatment: immerse the pretreated titanium alloy in the composite activation solution for 5-15 minutes at room temperature to promote the formation of a more stable oxide layer on the surface of the titanium alloy and enhance the adhesion of subsequent coatings.

[0013] Contains fluorinated organic acid, graphite carbon nitride nanosheets and rare earth elements. The fluorinated organic acid can promote the formation of a more stable oxide layer on the surface of the titanium alloy, the rare earth elements help to improve the activation effect, and the graphite carbon nitride nanosheets can enhance the conductivity and mechanical properties of the coating.

[0014] Perfluorooctanoic acid is a powerful surfactant that can significantly reduce the surface tension of the solution, thereby promoting its uniform spreading on the surface of the titanium alloy. This property helps to improve the efficiency of chemical reactions in subsequent processing steps. The fluorinated groups in perfluorooctanoic acid can react chemically with the surface of the titanium alloy to form a dense and stable oxide protective film, which can serve as a good foundation for subsequent coatings and enhance the bonding strength between the coating and the substrate.

[0015] Rare earth elements (such as lanthanum or cerium) can form stable oxides on the surface of titanium alloys (such as La 2 O 3 or CeO 2 ), these oxides have high chemical and thermal stability, can effectively prevent further oxidation of the substrate, and provide better adhesion for subsequent coatings. The presence of rare earth elements can refine the grain structure on the surface of titanium alloys, reduce microscopic defects, and thus improve the overall performance of the material.

[0016] Graphite-phase carbon nitride nanosheets have excellent electrical conductivity and can significantly improve the electrical conductivity of the titanium alloy surface, which is very important for subsequent electroplating processes because it can ensure uniform current distribution and avoid local overheating or uneven current density. Graphite-phase carbon nitride nanosheets have good mechanical strength and toughness and can form a tough protective layer on the surface of titanium alloy, enhancing the surface's wear resistance and impact resistance.

[0017] The oxide protective film formed by perfluorooctanoic acid, the stable oxide layer generated by rare earth elements, and the physical barrier provided by graphite phase carbon nitride nanosheets work together to form a multi-layer protection system, which greatly improves the corrosion resistance of the titanium alloy surface. The low surface tension characteristics of perfluorooctanoic acid make it easier for rare earth elements to disperse and deposit evenly on the surface of titanium alloys, thereby forming a denser and more uniform oxide protective film. This synergistic effect not only improves the surface activity, but also enhances the quality and stability of the oxide layer. The low surface tension characteristics of perfluorooctanoic acid make it easier for rare earth elements to disperse and deposit evenly on the surface of titanium alloys, thereby forming a denser and more uniform oxide protective film. This synergistic effect not only improves the surface activity, but also enhances the quality and stability of the oxide layer.

[0018] The low surface tension of PFOA enables the graphite carbon nitride nanosheets to be more evenly distributed on the titanium alloy surface, ensuring that the current is evenly distributed during the electroplating process and avoiding local overheating or uneven current density. In addition, PFOA can also help the nanosheets adhere better to the titanium alloy surface, allowing the graphite carbon nitride nanosheets to form a uniform micro-nano structure on the titanium alloy surface, which not only maintains the smoothness of the surface, but also enhances the mechanical properties of the surface and enhances its stability.

[0019] Rare earth oxides and graphite carbon nitride nanosheets work together to form a multi-layer protection system. Rare earth oxides provide chemical and thermal stability, while graphite carbon nitride nanosheets provide a physical barrier. The two complement each other and significantly enhance the corrosion resistance of the titanium alloy surface. The self-healing function of rare earth oxides is combined with the photocatalytic activity of graphite carbon nitride nanosheets to form a dynamic self-cleaning system. When the surface is contaminated or damaged, rare earth oxides can quickly repair the damaged area, while graphite carbon nitride nanosheets can decompose pollutants through photocatalysis to maintain the clean state of the surface. By improving the hardness, wear resistance and corrosion resistance of the titanium alloy surface, the composite activation solution can significantly extend the service life of the product, reduce the frequency of maintenance and replacement, and bring long-term economic benefits.

[0020] According to an embodiment of the present invention, the titanium alloy containing the transition layer after the first acid pickling treatment and the sandblasting treatment is subjected to plasma immersion ion implantation treatment, and transition metal oxide nanowires are introduced during the process so that the transition metal oxide nanowires are embedded in the titanium alloy containing the transition layer, comprising: Using glow discharge plasma equipment, set the voltage to 500V-1000V, the current density to 1mA / cm²-10mA / cm², and the treatment time to 5-15 minutes. Synchronously introduce transition metal oxide nanowires (TMONWs), and embed TMONWs into the surface of titanium alloy by ion implantation to improve surface conductivity and mechanical properties.

[0021] Infiltration layer According to an embodiment of the present invention, the plasma metallization method is used to infiltrate Mo, W and other metal elements into the transition layer and the titanium alloy to form a diffusion layer with a thickness of 5-200 μm, and the other metal elements are Ni and / or Cr elements including: The titanium alloy containing the transition layer is placed in a glow plasma metal ion infiltration device, and Mo nanoparticles and W nanoparticles with a particle size of 50-200 nm and other metal element particles are used, an alternating electromagnetic field is applied, the magnetic field strength is 30-40mT, and the alloy is heated to 650-750°C for 1-3 hours at a pressure of 5-15Pa for preliminary infiltration; Continue to apply alternating electromagnetic field with a magnetic field strength of 50-60mT, heat to 950-1050℃, keep warm for 4-6 hours, and keep the air pressure at 20-30Pa for deep penetration; During the initial penetration and the deep penetration, a nitrogen and argon mixed gas is used as the atmosphere to form a penetration layer with a thickness of 5-200 μm. More surface active sites are activated by high-energy ion bombardment, and transition metal oxide nanowires are introduced simultaneously to enhance surface conductivity and mechanical properties.

[0022] According to an embodiment of the present invention, the second pickling treatment of the titanium alloy containing the diffusion layer includes: using a mixed solution of hydrofluoric acid and nitric acid with a mass fraction of 5%-70% (volume ratio of 1:(3-7)), soaking time is 1-5 minutes, and then rinsing with deionized water.

[0023] According to an embodiment of the present invention, performing a secondary activation treatment on the titanium alloy containing the infiltration layer after the second pickling treatment to obtain a titanium alloy matrix comprises: The titanium alloy containing the diffusion layer after the second pickling treatment is sequentially immersed in a mixed solution consisting of a 10%-80% by mass sodium dichromate aqueous solution, a 10%-80% by mass hydrofluoric acid, and a 10%-80% by mass polyethylene glycol, and treated at 20-100° C. for 10-60 minutes.

[0024] Wherein, the volume ratio of the sodium dichromate aqueous solution, hydrofluoric acid and polyethylene glycol is 8:1:1; The mixed solution also includes 0.1%-5% of graphite phase carbon nitride nanosheets by mass fraction of the mixed solution. Adding an appropriate amount of graphite phase carbon nitride nanosheets can further activate the surface of the titanium alloy and ensure uniformity and density in the subsequent electroplating process.

[0025] According to an embodiment of the present invention, electroplating the titanium alloy substrate to form a coating on the surface of the titanium alloy substrate comprises: Prepare electroplating solution; The titanium alloy substrate is placed in an electroplating tank containing an electroplating solution and electroplated at a temperature of 50-55°C, wherein the cathode current density is 1-100A / dm² and the power-on time is 1-10 hours, thereby obtaining a wear-resistant coating with a thickness of 0.01-0.1mm. Pulse current assisted technology is used to ensure that the coating is more delicate and flat, reduce porosity, and increase coating density. Contains chromic anhydride, sulfuric acid, transition metal oxide nanowires and metal organic framework nanoparticles. The ratio of chromic anhydride and sulfuric acid optimizes the hardness and wear resistance of the coating; the transition metal oxide nanowires enhance the conductivity and mechanical strength; and the MOFs nanoparticles give the coating additional functional properties, such as photocatalytic activity and self-cleaning ability.

[0026] According to an embodiment of the present invention, the metal organic framework (MOFs) nanoparticles may be ZIF-8 or UiO-66.

[0027] According to an embodiment of the present invention, after the electroplating is completed, the sample is quickly placed in a cold trap for rapid cooling to prevent cracks caused by thermal stress.

[0028] According to an embodiment of the present invention, the laser shock peening treatment and ultraviolet light irradiation treatment on the coating include: The laser power of laser shock peening treatment is 500W-1kW, and the scanning speed is 500mm / s-1000mm / s, which fully covers the surface of the coating and further improves the surface hardness and fatigue life of the coating; The light source for the UV irradiation treatment is high-intensity UV light, and the irradiation time is 30 minutes to 2 hours, which activates the photosensitive functional groups in the MOFs nanoparticles and gives the coating additional photocatalytic activity and self-cleaning ability.

[0029] According to an embodiment of the present invention, the step of performing low temperature annealing on the coating after laser shock peening and ultraviolet irradiation to form a modified coating on the surface of the titanium alloy comprises: The annealing temperature is 800-1000°C, the annealing time is 10-30 minutes, and nitrogen or argon is used as the pressure medium to release the internal stress and optimize the microstructure of the coating.

[0030] According to a second aspect of the present invention, a titanium alloy surface modified coating prepared by a method for preparing a titanium alloy surface modified coating is provided.

[0031] The titanium alloy surface modified coating and preparation method thereof provided by the present invention work together with a composite activation solution and ion implantation treatment to activate more surface active sites, so that Mo elements, W elements and other metal elements penetrate more evenly and deeply, thereby improving the bonding strength between the coating and the substrate.

[0032] Other metal elements can be introduced while forming the Mo infiltration layer to form a composite infiltration layer. The transition layer formed by the infiltration of Mo, W and other metal elements combined with the secondary activation treatment ensures the uniformity and density in the subsequent electroplating process and reduces porosity and defects.

[0033] The reasonable ratio of chromic anhydride, sulfuric acid, transition metal oxide nanowires and MOFs nanoparticles not only improves the hardness and wear resistance of the coating, but also gives the coating additional functional properties such as photocatalytic activity and self-cleaning ability.

[0034] Laser shock peening improves the surface hardness and fatigue life of the coating, while ultraviolet light irradiation treatment activates the photosensitive functional groups in the MOFs nanoparticles, giving the coating additional photocatalytic activity and self-cleaning ability. The two work together to improve the overall performance of the coating.

[0035] The low temperature annealing treatment not only releases internal stress and optimizes the coating microstructure, but also enhances the effects of other processing steps and improves the overall stability and service life of the coating. DETAILED DESCRIPTION

[0036] The present application provides a titanium alloy surface modified coating and a preparation method thereof.

[0037] Example 1 Pretreatment: Mechanical polishing to a surface roughness of <6.4μm; soaking in a 5% hydrochloric acid solution for 5 minutes, then rinsing with deionized water; ultrasonic assisted cleaning, cleaning in a citric acid cleaning solution for 15 minutes.

[0038] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, lanthanum), soak at room temperature for 10 minutes.

[0039] The first pickling treatment: immersion in a mixed solution of 50% hydrofluoric acid and nitric acid (volume ratio 1:4) for 3 minutes.

[0040] Sandblasting: Conventional sandblasting.

[0041] PIII treatment: voltage 800 V, current density 5 mA / cm², treatment time 10 min, introduction of transition metal oxide nanowires.

[0042] Mo, W, Ni infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation for 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation for 5 hours, air pressure is 25Pa.

[0043] Second pickling treatment: same as the first pickling treatment.

[0044] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 60°C for 30 minutes, and 2% graphite phase carbon nitride nanosheets were added.

[0045] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 52°C, cathode current density 50A / dm², power-on time 5 hours.

[0046] Laser shock peening treatment: laser power 800W, scanning speed 800mm / s.

[0047] Ultraviolet irradiation treatment: UV-A light source, irradiation time 1 hour.

[0048] Low temperature annealing treatment: 900°C, 20 minutes, argon protection.

[0049] Example 2 Pretreatment: Same as Example 1.

[0050] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, cerium), soaking at room temperature for 12 minutes.

[0051] First pickling treatment: same as Example 1.

[0052] PIII treatment: voltage 900V, current density 7mA / cm², treatment time 12 minutes.

[0053] Mo, W, Cr infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation time is 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation time is 5 hours, air pressure is 25Pa.

[0054] Second pickling treatment: same as the first pickling treatment.

[0055] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 70°C for 40 minutes, and 3% graphite phase carbon nitride nanosheets were added.

[0056] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 55°C, cathode current density 60A / dm², power-on time 6 hours.

[0057] Laser shock peening treatment: laser power 900W, scanning speed 900mm / s.

[0058] Ultraviolet light irradiation treatment: UV-B light source, irradiation time 1.5 hours.

[0059] Low temperature annealing treatment: 950°C, 25 minutes, argon protection.

[0060] Example 3 Pretreatment: Same as Example 1.

[0061] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, lanthanum), soak at room temperature for 15 minutes.

[0062] First pickling treatment: same as Example 1.

[0063] PIII treatment: voltage 1000V, current density 10mA / cm², treatment time 15 minutes.

[0064] Mo, W, Ni, Cr infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation for 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation for 5 hours, air pressure is 25Pa.

[0065] Second pickling treatment: same as the first pickling treatment.

[0066] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 80°C for 50 minutes, and 4% graphite phase carbon nitride nanosheets were added.

[0067] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 58°C, cathode current density 80A / dm², power-on time 7 hours.

[0068] Laser shock peening treatment: laser power 1000W, scanning speed 1000mm / s.

[0069] Ultraviolet irradiation treatment: UV-C light source, irradiation time 2 hours.

[0070] Low temperature annealing treatment: 1000℃, 30 minutes, argon protection.

[0071] Example 4 Pretreatment: Same as Example 1.

[0072] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, lanthanum), soaking at room temperature for 8 minutes.

[0073] First pickling treatment: same as Example 1.

[0074] PIII treatment: voltage 700V, current density 6mA / cm², treatment time 8 minutes.

[0075] Mo and W infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation time is 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation time is 5 hours, air pressure is 25Pa.

[0076] Second pickling treatment: same as the first pickling treatment.

[0077] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 50°C for 20 minutes, and 1.5% graphite phase carbon nitride nanosheets were added.

[0078] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 50°C, cathode current density 40A / dm², power-on time 4 hours.

[0079] Laser shock peening treatment: laser power 700W, scanning speed 700mm / s.

[0080] Ultraviolet irradiation treatment: UV-A light source, irradiation time 0.5 hours.

[0081] Low temperature annealing treatment: 850°C, 15 minutes, argon protection.

[0082] Example 5 Pretreatment: Same as Example 1.

[0083] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, cerium), soaking at room temperature for 11 minutes.

[0084] First pickling treatment: same as Example 1.

[0085] PIII treatment: voltage 850V, current density 8mA / cm², treatment time 11 minutes.

[0086] Mo, W, Ni infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation for 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation for 5 hours, air pressure is 25Pa.

[0087] Second pickling treatment: same as the first pickling treatment.

[0088] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 65°C for 35 minutes, and 2.5% graphite phase carbon nitride nanosheets were added.

[0089] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 53°C, cathode current density 55A / dm², power-on time 5.5 hours.

[0090] Laser shock peening treatment: laser power 850W, scanning speed 850mm / s.

[0091] Ultraviolet irradiation treatment: UV-B light source, irradiation time 1.25 hours.

[0092] Low temperature annealing treatment: 925°C, 22.5 minutes, argon protection.

[0093] Example 6 Pretreatment: Same as Example 1.

[0094] Activation treatment: composite activation solution (fluorinated organic acid, graphite phase carbon nitride nanosheets, lanthanum), soaking at room temperature for 14 minutes.

[0095] First pickling treatment: same as Example 1.

[0096] PIII treatment: voltage 950V, current density 9mA / cm², treatment time 14 minutes.

[0097] Mo, W, Cr infiltration: initial infiltration temperature is 700℃, magnetic field intensity is 35mT, insulation time is 2 hours, air pressure is 10Pa; deep infiltration temperature is 1000℃, magnetic field intensity is 55mT, insulation time is 5 hours, air pressure is 25Pa.

[0098] Second pickling treatment: same as the first pickling treatment.

[0099] Secondary activation treatment: mixed solution (sodium dichromate aqueous solution, hydrofluoric acid, polyethylene glycol, volume ratio 8:1:1), treated at 75°C for 45 minutes, and 3.5% graphite phase carbon nitride nanosheets were added.

[0100] Electroplating: electroplating solution (sulfuric acid, chromic anhydride, transition metal oxide nanowires, MOFs nanoparticles), temperature 57°C, cathode current density 75A / dm², power-on time 6.5 hours.

[0101] Laser shock peening treatment: laser power 950W, scanning speed 950mm / s.

[0102] Ultraviolet irradiation treatment: UV-C light source, irradiation time 1.75 hours.

[0103] Low temperature annealing treatment: 975°C, 27.5 minutes, argon protection.

[0104] Comparative Example 1 Only traditional anodizing treatment is performed, no other special treatment is performed.

[0105] Comparative Example 2 Only chemical nickel plating is performed, no other special treatment is performed.

[0106] Experimental data: Comparative Example 3 Only plasma immersion ion implantation treatment was performed, and no other special treatment was performed.

[0107] Comparative Example 4 Only Mo element infiltration treatment was performed, and no other special treatment was performed.

[0108] Experimental example Mechanical performance test: Hardness test and wear resistance test were carried out according to the standard. Corrosion resistance test: The salt spray resistance time of the coating was measured, and the results are shown in Table 1.

[0109] Table 1. Performance test results of Examples 1-6 and Comparative Examples 1-4 Data Analysis and Conclusion Hardness: The hardness of the examples is generally higher than that of the comparative examples, especially in Examples 3 and 6, whose hardness reaches HV 950 and HV 930, which are significantly better than all the comparative examples.

[0110] Wear resistance: The wear resistance of the embodiments is significantly better than that of the comparative examples. For example, the wear rate of embodiment 3 is the lowest, which is only 0.0008 mm³ / Nm, while the highest in the comparative examples is 0.015 mm³ / Nm (Comparative Example 1).

[0111] Corrosion resistance: The corrosion resistance of the examples far exceeds that of the comparative examples. The salt spray resistance test time of Examples 3 and 6 exceeds 2500 hours and 2300 hours, while the highest time of the comparative examples is only 800 hours (Comparative Example 4).

[0112] in conclusion By comparing the experimental data of different embodiments and comparative examples, it can be clearly seen that the method for preparing the titanium alloy surface modified coating provided by the present invention can significantly improve the hardness, wear resistance and corrosion resistance of the titanium alloy surface. In particular, the synergistic effect in the embodiment makes the coating perform well in multiple performance indicators, which is far superior to the traditional single treatment method. This shows that the present invention has high practical value and application prospects.

[0113] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0114] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a titanium alloy surface modified coating, characterized in that: The following steps are involved: Pre-treating the titanium alloy surface; The titanium alloy surface is activated by using a composite activation solution to form a titanium alloy containing a transition layer; wherein the composite activation solution is a fluorine-containing organic acid, graphite-phase carbon nitride nanosheets and rare earth elements; Performing a first pickling treatment and a sandblasting treatment on the titanium alloy containing the transition layer; The titanium alloy containing the transition layer after the first pickling treatment and the sandblasting treatment is subjected to plasma immersion ion implantation treatment, and transition metal oxide nanowires are introduced during the process so that the transition metal oxide nanowires are embedded in the titanium alloy containing the transition layer; Using a plasma metallization method to infiltrate Mo, W and other metal elements into the transition layer and the titanium alloy to form a infiltration layer with a thickness of 5-200 μm, wherein the other metal elements are Ni and / or Cr; Performing a second pickling treatment on the titanium alloy containing the diffusion layer; Performing a secondary activation treatment on the titanium alloy containing the diffusion layer after the second pickling treatment to obtain a titanium alloy matrix; Electroplating the titanium alloy substrate to form a coating on the surface of the titanium alloy substrate; the electroplating solution used in the electroplating includes: chromic anhydride, sulfuric acid, transition metal oxide nanowires and metal organic framework nanoparticles; wherein the mass fraction of sulfuric acid is 2%-50%, the volume ratio of chromic anhydride to sulfuric acid is 1:4-2:3, the mass fraction of the transition metal oxide nanowires is 0.1%-5% of the electroplating solution, and the mass fraction of the metal organic framework nanoparticles is 0.1%-5% of the electroplating solution; The coating is subjected to laser shock peening treatment and ultraviolet light irradiation treatment; The coating layer after the laser shock strengthening treatment and the ultraviolet light irradiation treatment is subjected to low temperature annealing treatment to form a modified coating layer on the surface of the titanium alloy.

2. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The pretreatment of the titanium alloy surface comprises: Mechanically polishing the titanium alloy to make the surface roughness less than 6.4 μm; Using a chemical cleaning agent to remove surface oxides and other contaminants on the surface of the titanium alloy, including: soaking in a 5%-10% hydrochloric acid solution for 5-10 minutes, and then rinsing with deionized water; The titanium alloy is immersed in a citric acid cleaning solution and cleaned by ultrasonic assisted cleaning to ensure that tiny impurities are completely removed. The ultrasonic cleaning time is 10-20 minutes and the temperature is kept at room temperature.

3. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The method of using a composite activation solution to activate the surface of the titanium alloy to form a titanium alloy containing a transition layer includes: The composite activation solution is prepared by preparing a composite activation solution containing 10% to 80% by mass of perfluorooctanoic acid, 0.1% to 5% by mass of rare earth elements, and 0.1% to 5% by mass of graphite phase carbon nitride nanosheets, and the rest is water, wherein the rare earth elements include lanthanum or cerium; Activation treatment: immerse the pretreated titanium alloy in the composite activation solution for 5-15 minutes at room temperature to promote the formation of a more stable oxide layer on the surface of the titanium alloy and enhance the adhesion of subsequent coatings.

4. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The titanium alloy containing the transition layer after the first acid pickling treatment and the sandblasting treatment is subjected to plasma immersion ion implantation treatment, and transition metal oxide nanowires are introduced during the process so that the transition metal oxide nanowires are embedded in the titanium alloy containing the transition layer, comprising: Use a glow discharge plasma device, set the voltage to 500V-1000V, the current density to 1mA / cm²-10mA / cm², and the treatment time to 5-15 minutes.

5. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The plasma metallization method is used to infiltrate Mo, W and other metal elements into the transition layer and the titanium alloy to form a infiltration layer with a thickness of 5-200 μm, and the other metal elements are Ni and / or Cr elements including: The titanium alloy containing the transition layer is placed in a glow plasma metal ion infiltration device, and Mo nanoparticles and W nanoparticles with a particle size of 50-200 nm and other metal element particles are used, an alternating electromagnetic field is applied, the magnetic field strength is 30-40mT, and the alloy is heated to 650-750°C for 1-3 hours at a pressure of 5-15Pa for preliminary infiltration; Continue to apply alternating electromagnetic field with a magnetic field strength of 50-60mT, heat to 950-1050℃, keep warm for 4-6 hours, and keep the air pressure at 20-30Pa for deep penetration; During the initial penetration and the deep penetration, a mixed gas of nitrogen and argon is used as the atmosphere to form a penetration layer with a thickness of 5-200 μm.

6. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The step of performing a secondary activation treatment on the titanium alloy containing the diffusion layer after the second pickling treatment to obtain a titanium alloy matrix comprises: The titanium alloy containing the diffusion layer after the second pickling treatment is sequentially immersed in a mixed solution consisting of a sodium dichromate aqueous solution with a mass fraction of 10%-80%, a hydrofluoric acid with a mass fraction of 10%-80%, and a polyethylene glycol with a mass fraction of 10%-80%, and treated at 20-100° C. for 10-60 minutes; Wherein, the volume ratio of the sodium dichromate aqueous solution, hydrofluoric acid and polyethylene glycol is 8:1:1; The mixed liquid also includes graphite phase carbon nitride nanosheets in an amount of 0.1% to 5% by mass of the mixed liquid.

7. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The electroplating of the titanium alloy substrate to form a coating on the surface of the titanium alloy substrate comprises: Prepare electroplating solution; The titanium alloy substrate is placed in an electroplating tank containing an electroplating solution and electroplated at a temperature of 50-55°C, wherein the cathode current density is 1-100A / dm² and the power-on time is 1-10 hours, thereby obtaining a wear-resistant coating with a thickness of 0.01-0.1mm.

8. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The laser shock peening treatment and ultraviolet light irradiation treatment of the coating include: The laser power of laser shock peening treatment is 500W-1kW, and the scanning speed is 500mm / s-1000mm / s; The light source of the ultraviolet irradiation treatment is high-intensity ultraviolet light, and the irradiation time is 30 minutes to 2 hours.

9. The method for preparing a titanium alloy surface modified coating according to claim 1, characterized in that: The step of performing low temperature annealing on the coating after laser shock peening and ultraviolet irradiation to form a modified coating on the surface of the titanium alloy comprises: The annealing temperature is 800-1000° C., the annealing time is 10-30 minutes, and nitrogen or argon is used as the pressure medium.

10. A titanium alloy surface modified coating prepared according to the method for preparing a titanium alloy surface modified coating according to any one of claims 1 to 9.

Images