Surface treatment process of titanium-aluminum alloy for nano-injection molding and application

Abstract

The application relates to the technical field of material surface treatment, in particular to a surface treatment process of titanium-aluminum alloy for nano injection molding parts and application. The application comprises the following steps: step one: after polishing, alkali washing and oil removal and acid washing treatment, titanium-aluminum alloy is obtained; step two: after the pretreated titanium-aluminum alloy is subjected to primary anodic oxidation, an oxide film is removed, secondary anodic oxidation is carried out, and finally sealing treatment is carried out, the surface-treated titanium-aluminum alloy is obtained; the composition of the electrolyte used in the secondary anodic oxidation is as follows: 1-3 g / L G0-POSS, 10-12 g / L composite silicon sol, 15-25 g / L tartaric acid and 50-60 g / L ethylenediaminetetraacetic acid disodium salt. The titanium-aluminum alloy after the surface treatment has excellent corrosion resistance and hydrophobicity.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, specifically to a surface treatment process and application of titanium-aluminum alloy for nano-injection molded parts. Background Technology

[0002] With the increasing demands of modern manufacturing for product performance, appearance, and lightweighting, nano-injection molding technology, as a process that combines metal and plastic through nanotechnology, has been widely applied. Titanium-aluminum alloys, due to their high specific strength, excellent corrosion resistance, and good overall performance, have become one of the commonly used metal materials in nano-injection molded parts. To achieve a good bond between titanium-aluminum alloys and plastics, surface treatment processes become a crucial step.

[0003] Traditional surface treatment methods, such as chemical oxidation and electrochemical oxidation, can improve the surface properties of titanium-aluminum alloys to some extent, but they have limitations in nano-injection molding applications. Nano-injection molding requires the formation of specific nanoscale structures on the metal surface to increase the bonding area and strength with the plastic. Therefore, developing surface treatment processes specifically for titanium-aluminum alloys in nano-injection molding has become an important direction for improving the performance and quality of nano-injection molded parts.

[0004] However, while the oxide film on the surface of traditional titanium-aluminum alloys possesses a certain degree of corrosion resistance, its bonding strength with plastics is relatively low. Existing surface treatment processes struggle to create a sufficient number and depth of nanoscale pores or rough structures on the titanium-aluminum alloy surface, resulting in limited mechanical interlocking between the plastic and the metal, thus affecting the overall strength and reliability of the nano-injection molded parts. Furthermore, the surface treatment effect on titanium-aluminum alloys is often uneven. Some areas may be overtreated, leading to excessive surface roughness or an overly thick oxide film; while other areas may be undertreated, leaving an oxide layer or impurities on the surface. This affects the consistency of the bonding between the plastic and the metal, reducing the quality stability of the nano-injection molded parts.

[0005] Therefore, we propose a surface treatment process and application for titanium-aluminum alloys used in nano-injection molding parts. Summary of the Invention

[0006] The purpose of this invention is to provide a surface treatment process and application for titanium-aluminum alloys used in nano-injection molding, so as to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A surface treatment process for titanium-aluminum alloy used in nano-injection molding includes the following steps: Step 1: After grinding, alkaline washing to remove oil and pickling, the titanium-aluminum alloy is pretreated to obtain the titanium-aluminum alloy. Step 2: Perform a first anodizing on the pretreated titanium-aluminum alloy to remove the oxide film, then perform a second anodizing, and finally perform a sealing treatment to obtain the surface-treated titanium-aluminum alloy.

[0008] Further, the specific steps of the alkaline washing and degreasing are as follows: immerse the titanium-aluminum alloy in a 50-60 g / L NaOH solution, heat to 50-60℃ and react for 45-90 seconds, remove, wash with deionized water, and dry.

[0009] Furthermore, the specific steps of the pickling treatment are as follows: immerse the titanium-aluminum alloy after alkaline washing and degreasing into a 180-200 g / L HNO3 solution, treat it at room temperature for 30-50 seconds, remove it, wash it with deionized water, and dry it.

[0010] Furthermore, the electrolyte used in the primary anodizing process comprises: 120-140 g / L sulfuric acid and 30-40 g / L oxalic acid.

[0011] Furthermore, the process parameters for the primary anodizing are: temperature 18-22℃, current density 1.0-2.5A / dm³. 2 Oxidation time: 15-30 min.

[0012] Further, the specific steps for removing the oxide film are as follows: immersing the titanium-aluminum alloy after one anodizing into a mixed solution composed of 6-7wt% phosphoric acid and 2-3wt% chromic acid at a temperature of 65-75℃ for 50-120s.

[0013] Furthermore, the electrolyte used in the secondary anodizing process comprises: 1-3 g / L GO-POSS, 10-12 g / L composite silica sol, 15-25 g / L tartaric acid, and 50-60 g / L disodium ethylenediaminetetraacetate.

[0014] Furthermore, the process parameters for the secondary anodizing are: temperature 18-22℃, current density 0.8-1.2A / dm³. 2 Oxidation time: 35-55 min.

[0015] Furthermore, the thickness of the oxide film formed on the surface after the first anodizing is 5-10 μm, and the thickness of the oxide film formed on the surface after the second anodizing is 10-15 μm.

[0016] Furthermore, the preparation method of the G0-POSS is as follows: Step A: Dissolve tris(hydroxymethyl)aminomethane hydrochloride in deionized water, adjust the pH to 8.5 with NaOH solution to obtain Tris buffer; add graphene oxide to Tris buffer, sonicate for 60-90 min, add a mixture of dopamine hydrochloride and deionized water dropwise over 30-50 min, stir magnetically at room temperature for 20-24 h, and obtain polydopamine-modified graphene oxide after centrifugation, washing and drying; Step B: Mix polydopamine-modified graphene oxide, aminated cage-type silsesquioxane and toluene evenly, add Tris buffer, react at 75-85℃ for 5-7h, cool to room temperature, remove the supernatant, centrifuge the lower precipitate until neutral, and dry to obtain G0-POSS.

[0017] Further, in step A, the mass ratio of tris(hydroxymethyl)aminomethane hydrochloride to deionized water is 1:(900-1000), and the concentration of the NaOH solution is 0.1 mol / L.

[0018] Further, in step A, the mass ratio of graphene oxide, Tris buffer, dopamine hydrochloride and deionized water is 1:(800-900):(1-2):(30-40).

[0019] Further, in step B, the mass ratio of polydopamine-modified graphene oxide, aminated cage-like silsesquioxane, toluene, and Tris buffer is 1:(0.3-0.5):(500-600):(150-200).

[0020] In the above technical solution, the self-polymerization advantage of dopamine is used to achieve the reduction and functionalization of graphene oxide (GO) by oxidative polymerization at room temperature and under weak alkaline conditions (pH=8.5), so that the surface of GO has abundant carbonyl groups; then, the aminated cage-type silsesquioxane (POSS-NH2) is reacted with polydopamine-modified graphene oxide by Schiff base reaction to obtain GO-POSS.

[0021] Furthermore, the preparation method of the composite silica sol is as follows: Tetraethyl orthosilicate, anhydrous ethanol, and deionized water were mixed evenly, and hydrochloric acid was added to adjust the pH of the system to 2-3. A mixed solution of phytic acid-silane modified graphene oxide and anhydrous ethanol was added, and the mixture was reacted at 60-70℃ for 4-6 hours. After standing overnight, the composite silica sol was obtained.

[0022] Further, the mass ratio of the tetraethyl orthosilicate, anhydrous ethanol, and deionized water is 1:(3-4):(0.6-0.8).

[0023] Furthermore, the mass ratio of the phytic acid-silane modified graphene oxide, tetraethyl orthosilicate and anhydrous ethanol is 1:(5-7):(15-20).

[0024] Furthermore, the preparation method of the phytic acid-silane modified graphene oxide is as follows: Phytic acid, ethanol, and 3-glycidyloxypropyltrimethoxysilane were mixed evenly and reacted at 60-70℃ for 2-4 h to obtain a phytic acid-silane intermediate. A graphene oxide dispersion was added dropwise to the phytic acid-silane intermediate system, and stirring was continued at 70-80℃ for 22-24 h. After centrifugation, washing, and drying, phytic acid-silane modified graphene oxide was obtained.

[0025] Furthermore, the mass ratio of phytic acid, ethanol and 3-glycidyloxypropyltrimethoxysilane is 1:(3-4):(0.2-0.3).

[0026] Furthermore, the concentration of the graphene oxide dispersion is 1-5 mg / mL, the solvent is deionized water, and the amount of graphene oxide dispersion used is 1-2 times the mass of phytic acid.

[0027] In the above technical solution, phytic acid and epoxy silane are used as raw materials to prepare a phytic acid-silane intermediate through ring-opening polymerization. The prepared phytic acid-silane intermediate is then hydrolyzed with graphene oxide, causing the phytic acid-silane macromolecules to be grafted onto graphene oxide nanosheets, resulting in phytic acid-silane modified graphene oxide. Bio-phytic acid possesses advantages such as strong metal ion chelating ability, non-toxicity, and good biocompatibility. By introducing phytic acid (PA) to modify nanomaterials, the passivation protection effect of the coating on the metal can be improved. Simultaneously, the high aspect ratio and excellent impermeability of graphene oxide nanosheets help enhance the physical shielding effect of the film, thus providing dual corrosion protection for the metal substrate.

[0028] Furthermore, the specific steps of the sealing treatment are as follows: immerse the titanium-aluminum alloy after secondary anodizing in a 30-40 g / L ammonium fluorotitanate solution, seal the holes at 50-55℃ for 30-50 min, remove it, wash it with deionized water, and dry it.

[0029] Compared with the prior art, the beneficial effects of the present invention are: This invention first involves grinding, alkaline washing to remove oil, and acid washing of the titanium-aluminum alloy, followed by anodizing to pre-form the distribution pattern of oxide pores on the substrate surface. The purpose of removing the oxide film is to remove the relatively disordered oxide film formed by the first anodizing, thereby significantly reducing the randomness of the nanopore size. Then, a second anodizing is performed, followed by a sealing treatment to obtain the surface-treated titanium-aluminum alloy. G0-POSS was added to the electrolyte used in the secondary anodizing process. The solution utilizes dopamine, an environmentally friendly bio-based raw material, as a bridge connecting graphene oxide and aminated cage-like silsesquioxane (POSS-NH2). The unique cage-like three-dimensional structure of POSS-NH2 increases the interlayer spacing of graphene oxide, making the path of the corrosive medium tortuous, thereby achieving long-term corrosion resistance. At the same time, the high silicon content in the POSS structure enhances the surface hydrophobicity, reducing the adhesion and contact of the corrosive medium on the alloy surface from the source. It can work synergistically with the ammonium fluorotitanate solution in the sealing process to jointly improve the hydrophobicity. This achieves all-round barrier against corrosive media from the inside out and from the deep layer to the surface, which can effectively enhance the corrosion resistance of the material and extend its service life. The present invention also adds a composite silica sol to the electrolyte. By introducing phytic acid-silane modified graphene oxide into the silica sol, the interfacial bonding ability of GO is significantly improved, which helps to enhance the anti-corrosion performance of the film. The silica sol can gel in the micropores and work with the modified GO to fill and seal the microscopic defects of the oxide film, forming a dense and firmly bonded composite protective layer, thereby improving the integrity and adhesion of the overall film. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that there are no special restrictions on the purchasers of any of the raw materials involved in this invention. Exemplary examples include (in this embodiment) titanium-aluminum alloy: TC2 (Ti-4Al-1.5Mn); graphene oxide: average thickness 1-3nm, diameter 4-7μm, number of layers 2-5, sourced from Zhejiang Zhitai Nano-Micro New Materials Co., Ltd.; and aminated cage-type silsesquioxane: item number Q-0000177, sourced from Xi'an Qiyue Biotechnology Co., Ltd.

[0032] Example 1: A surface treatment process for titanium-aluminum alloy used in nano-injection molding, comprising the following processes: Step 1: After polishing, the titanium-aluminum alloy is immersed in a 50g / L NaOH solution for alkaline washing and degreasing. The solution is heated to 50℃ and reacted for 45s. After removal, it is washed with deionized water and dried. The alkaline-washed titanium-aluminum alloy is then immersed in a 180g / L HNO3 solution and treated at room temperature for 30s. After removal, it is washed with deionized water and dried to obtain the pretreated titanium-aluminum alloy. Step Two: Using the pretreated titanium-aluminum alloy as the anode and a graphite carbon rod as the cathode, the pretreated titanium-aluminum alloy is subjected to a primary anodizing process. The electrolyte composition for the primary anodizing is: sulfuric acid 120 g / L and oxalic acid 30 g / L. The process parameters for the primary anodizing are: temperature 18℃ and current density 1.0 A / dm³. 2 The oxidation time is 15 min. The titanium-aluminum alloy after the first anodizing is immersed in a mixed solution of 6 wt% phosphoric acid and 3 wt% chromic acid at 65℃ for 50 s to remove the oxide film. A second anodizing is then performed. The electrolyte for the second anodizing consists of 1 g / L GO-POSS, 10 g / L composite silica sol, 15 g / L tartaric acid, and 50 g / L disodium ethylenediaminetetraacetate. The process parameters for the second anodizing are: temperature 18℃ and current density 0.8 A / dm³. 2 The oxidation time was 35 min. Finally, the titanium-aluminum alloy after secondary anodizing was immersed in 30 g / L ammonium fluorotitanate solution and sealed at 50 °C for 30 min. After being taken out, it was washed with deionized water and dried to obtain the surface-treated titanium-aluminum alloy. The preparation method of G0-POSS is as follows: Step A: Dissolve 1.5g of tris(hydroxymethyl)aminomethane hydrochloride in 1400g of deionized water, adjust the pH to 8.5 with 0.1mol / L NaOH solution to obtain Tris buffer; add 1g of graphene oxide to 800g of Tris buffer, sonicate for 60min, add a mixture of 1g of dopamine hydrochloride and 30g of deionized water dropwise over 30min, stir magnetically at room temperature for 20h, and obtain polydopamine-modified graphene oxide after centrifugation, washing and drying; Step B: Mix 1g of polydopamine-modified graphene oxide, 0.3g of aminated cage-type silsesquioxane and 500g of toluene evenly, add 150g of Tris buffer, react at 75℃ for 5h, cool to room temperature, remove the supernatant, centrifuge the lower precipitate until neutral, and dry to obtain G0-POSS; The preparation method of composite silica sol is as follows: 2g of phytic acid, 6g of ethanol and 0.4g of 3-glycidyloxypropyltrimethoxysilane were mixed evenly and reacted at 60℃ for 2h to obtain a phytic acid-silane intermediate. 2g of 1mg / mL graphene oxide dispersion was added dropwise to the phytic acid-silane intermediate system and stirred at 70℃ for 22h. After centrifugation, washing and drying, phytic acid-silane modified graphene oxide was obtained. Mix 10g of tetraethyl orthosilicate, 30g of anhydrous ethanol and 6g of deionized water evenly, add 1mol / L hydrochloric acid to adjust the pH of the system to 2, add 2g of phytic acid-silane modified graphene oxide and 30g of anhydrous ethanol mixed solution, react at 60℃ for 4h, let stand overnight to obtain composite silica sol.

[0033] Example 2: A surface treatment process for titanium-aluminum alloy used in nano-injection molding, comprising the following processes: Step 1: After polishing, the titanium-aluminum alloy is immersed in a 55g / L NaOH solution for alkaline washing and degreasing. The solution is heated to 55℃ and reacted for 60s. After removal, it is washed with deionized water and dried. The alkaline-washed titanium-aluminum alloy is then immersed in a 190g / L HNO3 solution and treated at room temperature for 40s. After removal, it is washed with deionized water and dried to obtain the pretreated titanium-aluminum alloy. Step Two: Using the pretreated titanium-aluminum alloy as the anode and a graphite carbon rod as the cathode, perform a primary anodizing of the pretreated titanium-aluminum alloy. The electrolyte composition for the primary anodizing is: sulfuric acid 130 g / L and oxalic acid 35 g / L. The process parameters for the primary anodizing are: temperature 20℃ and current density 2.0 A / dm³. 2 The oxidation time is 20 min. The titanium-aluminum alloy after the first anodizing is immersed in a mixed solution of 6.5 wt% phosphoric acid and 2.5 wt% chromic acid at 70℃ for 100 s to remove the oxide film. A second anodizing is then performed. The electrolyte used for the second anodizing consists of 2 g / L GO-POSS, 11 g / L composite silica sol, 20 g / L tartaric acid, and 55 g / L disodium ethylenediaminetetraacetate. The process parameters for the second anodizing are: temperature 20℃, current density 1.0 A / dm³. 2 The oxidation time was 45 min. Finally, the titanium-aluminum alloy after secondary anodizing was immersed in 35 g / L ammonium fluorotitanate solution and sealed at 52℃ for 40 min. After being taken out, it was washed with deionized water and dried to obtain the surface-treated titanium-aluminum alloy. The preparation method of G0-POSS is as follows: Step A: Dissolve 3g of tris(hydroxymethyl)aminomethane hydrochloride in 2800g of deionized water, adjust the pH to 8.5 with 0.1mol / L NaOH solution to obtain Tris buffer; add 2g of graphene oxide to 1700g of Tris buffer, sonicate for 80min, add a mixture of 3g of dopamine hydrochloride and 70g of deionized water dropwise over 40min, stir magnetically at room temperature for 22h, and obtain polydopamine-modified graphene oxide after centrifugation, washing and drying; Step B: Mix 2g of polydopamine-modified graphene oxide, 0.8g of aminated cage-type silsesquioxane and 1100g of toluene evenly, add 360g of Tris buffer, react at 80℃ for 6h, cool to room temperature, remove the supernatant, centrifuge the lower precipitate until neutral, and dry to obtain G0-POSS; The preparation method of composite silica sol is as follows: 1.8 g phytic acid, 6 g ethanol and 0.45 g 3-glycidyloxypropyltrimethoxysilane were mixed evenly and reacted at 65 °C for 3 h to obtain phytic acid-silane intermediate; 2.7 g 3 mg / mL graphene oxide dispersion was added dropwise to the phytic acid-silane intermediate system and stirred at 75 °C for 23 h. After centrifugation, washing and drying, phytic acid-silane modified graphene oxide was obtained. 11g of tetraethyl orthosilicate, 38g of anhydrous ethanol and 8g of deionized water were mixed evenly, and 1mol / L hydrochloric acid was added to adjust the pH of the system to 2.5. A mixed solution of 1.8g of phytic acid-silane modified graphene oxide and 32g of anhydrous ethanol was added, and the mixture was reacted at 65℃ for 5h and allowed to stand overnight to obtain composite silica sol.

[0034] Example 3: A surface treatment process for titanium-aluminum alloy used in nano-injection molding, comprising the following processes: Step 1: After polishing, the titanium-aluminum alloy is immersed in a 60g / L NaOH solution for alkaline washing and degreasing. The solution is heated to 60℃ and reacted for 90s. After removal, it is washed with deionized water and dried. The alkaline-washed titanium-aluminum alloy is then immersed in a 200g / L HNO3 solution and treated at room temperature for 50s. After removal, it is washed with deionized water and dried to obtain the pretreated titanium-aluminum alloy. Step Two: Using the pretreated titanium-aluminum alloy as the anode and a graphite carbon rod as the cathode, perform a primary anodizing of the pretreated titanium-aluminum alloy. The electrolyte composition for the primary anodizing is: sulfuric acid 140 g / L and oxalic acid 40 g / L. The process parameters for the primary anodizing are: temperature 22℃ and current density 2.5 A / dm³. 2The oxidation time is 30 min. The titanium-aluminum alloy after the first anodizing is immersed in a mixed solution of 7 wt% phosphoric acid and 2 wt% chromic acid at 75℃ for 120 s to remove the oxide film. A second anodizing is then performed. The electrolyte used for the second anodizing consists of 3 g / L GO-POSS, 12 g / L composite silica sol, 25 g / L tartaric acid, and 60 g / L disodium ethylenediaminetetraacetate. The process parameters for the second anodizing are: temperature 22℃ and current density 1.2 A / dm³. 2 The oxidation time was 55 min. Finally, the titanium-aluminum alloy after secondary anodizing was immersed in 40 g / L ammonium fluorotitanate solution and sealed at 55℃ for 50 min. After being taken out, it was washed with deionized water and dried. The process parameters for sealing were as follows: to obtain the surface-treated titanium-aluminum alloy. The preparation method of G0-POSS is as follows: Step A: Dissolve 4g of tris(hydroxymethyl)aminomethane hydrochloride in 4000g of deionized water, adjust the pH to 8.5 with 0.1mol / L NaOH solution to obtain Tris buffer; add 3g of graphene oxide to 2700g of Tris buffer, sonicate for 90min, add a mixture of 6g of dopamine hydrochloride and 240g of deionized water dropwise over 50min, stir magnetically at room temperature for 24h, and obtain polydopamine-modified graphene oxide after centrifugation, washing and drying; Step B: Mix 3g of polydopamine-modified graphene oxide, 1.5g of aminated cage-type silsesquioxane and 1800g of toluene evenly, add 600g of Tris buffer, react at 85℃ for 7h, cool to room temperature, remove the supernatant, centrifuge the lower precipitate until neutral, and dry to obtain G0-POSS; The preparation method of composite silica sol is as follows: 2g of phytic acid, 8g of ethanol and 0.6g of 3-glycidyloxypropyltrimethoxysilane were mixed evenly and reacted at 70℃ for 4h to obtain phytic acid-silane intermediate; 4g of 5mg / mL graphene oxide dispersion was added dropwise to the phytic acid-silane intermediate system and stirred at 80℃ for 24h. After centrifugation, washing and drying, phytic acid-silane modified graphene oxide was obtained. 14g of tetraethyl orthosilicate, 56g of anhydrous ethanol and 11.2g of deionized water were mixed evenly, and 1mol / L hydrochloric acid was added to adjust the pH of the system to 3. A mixed solution of 2g of phytic acid-silane modified graphene oxide and 40g of anhydrous ethanol was added, and the mixture was reacted at 70℃ for 6h and allowed to stand overnight to obtain composite silica sol.

[0035] Comparative Example 1: Comparative Example 1 is based on Example 2. In Comparative Example 1, the electrolyte used for secondary anodizing did not introduce GO-POSS. The remaining process steps and reaction parameters were the same as in Example 2.

[0036] Comparative Example 2: Comparative Example 2 is based on Example 2. In Comparative Example 2, the composite silica sol in the electrolyte used for secondary anodizing is replaced with the same mass of silica sol. The remaining process steps and reaction parameters are the same as in Example 2. The preparation method of silica sol is as follows: Mix 11g of tetraethyl orthosilicate, 38g of anhydrous ethanol and 8g of deionized water evenly, add 1mol / L hydrochloric acid to adjust the pH of the system to 2.5, react at 65℃ for 5h, let stand overnight to obtain silica sol.

[0037] Comparative Example 3: Comparative Example 3 is based on Example 2. No sealing treatment was performed on Comparative Example 3. The remaining process steps and reaction parameters are the same as those in Example 2.

[0038] Experiment: Surface-treated titanium-aluminum alloys obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare samples. Their properties were tested and the results were recorded. The water contact angle of the sample surface was tested using a contact angle meter with a water droplet volume of 5LL. Three different locations were randomly selected on the sample surface, and the average value of the test results was taken. The sample was placed in a salt spray chamber at a temperature of 35℃ for 60 days, and the salt spray resistance of the aluminum alloy was tested using a 5wt% sodium chloride aqueous solution. The coating adhesion test was conducted according to the standard GB / T 9286-2021 "Cross-cut test of paint and varnish film". Paint was sprayed on the sample surface, and after curing, 6 or 11 parallel scratches with equal spacing (1mm or 2mm) were made on the sample coating. Then, scratches with the same spacing and number of scratches were made perpendicular to the former scratches, and the rating was performed.

[0039] The test results are shown in Table 1.

[0040] Table 1. Test results of relevant properties of titanium-aluminum alloy after surface treatment Based on the data in the table above, the following conclusions can be clearly drawn: Compared with Examples 1-3, the water contact angle, corrosion resistance and adhesion of the products obtained in Comparative Examples 1 and 2 all decreased, indicating that the present invention significantly improved the hydrophobicity and corrosion resistance of the material by introducing GO-POSS. At the same time, the composite silica sol prepared by the present invention, compared with silica sol, has enhanced interfacial bonding and barrier effect due to the introduction of phytic acid-silane modified graphene oxide, thus having a better anti-corrosion effect and bonding force, and synergistically improving the overall performance of the material.

[0041] Compared with Examples 1-3, the water contact angle, corrosion resistance and adhesion of the product obtained in Comparative Example 3 all decreased. It can be seen that the present invention further improves the hydrophobicity and corrosion barrier ability of the material by introducing ammonium fluorotitanate solution and POSS hydrophobic layer to play a synergistic role.

[0042] 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.

Claims

1. A surface treatment process for titanium-aluminum alloys used in nano-injection molding, characterized in that: Includes the following steps: Step 1: After grinding, alkaline washing to remove oil and pickling, the titanium-aluminum alloy is pretreated to obtain the titanium-aluminum alloy. Step 2: Perform a first anodizing on the pretreated titanium-aluminum alloy to remove the oxide film, then perform a second anodizing, and finally perform a sealing treatment to obtain the surface-treated titanium-aluminum alloy. The electrolyte used for the secondary anodizing consists of: 1-3 g / L GO-POSS, 10-12 g / L composite silica sol, 15-25 g / L tartaric acid, and 50-60 g / L disodium ethylenediaminetetraacetate.

2. The surface treatment process for titanium-aluminum alloy for nano-injection molding according to claim 1, characterized in that: The specific steps for alkaline washing and degreasing are as follows: immerse the titanium-aluminum alloy in a 50-60 g / L NaOH solution, heat to 50-60℃ and react for 45-90 seconds, remove, wash with deionized water, and dry.

3. The surface treatment process for titanium-aluminum alloy for nano-injection molding according to claim 1, characterized in that: The specific steps of the pickling treatment are as follows: immerse the titanium-aluminum alloy after alkaline washing and degreasing into a 180-200 g / L HNO3 solution, treat it at room temperature for 30-50 seconds, remove it, wash it with deionized water, and dry it.

4. The surface treatment process for titanium-aluminum alloy for nano-injection molded parts according to claim 1, characterized in that: The electrolyte used in the primary anodizing process consists of: 120-140 g / L sulfuric acid and 30-40 g / L oxalic acid.

5. The surface treatment process for titanium-aluminum alloy for nano-injection molded parts according to claim 4, characterized in that: The specific steps for removing the oxide film are as follows: immerse the titanium-aluminum alloy after one anodizing into a mixed solution consisting of 6-7wt% phosphoric acid and 2-3wt% chromic acid at a temperature of 65-75℃ for 50-120 seconds.

6. The surface treatment process for titanium-aluminum alloy for nano-injection molding according to claim 1, characterized in that: The preparation method of the G0-POSS is as follows: Step A: Dissolve tris(hydroxymethyl)aminomethane hydrochloride in deionized water, adjust the pH to 8.5 with NaOH solution to obtain Tris buffer; add graphene oxide to Tris buffer, sonicate for 60-90 min, add a mixture of dopamine hydrochloride and deionized water dropwise over 30-50 min, stir magnetically at room temperature for 20-24 h, and obtain polydopamine-modified graphene oxide after centrifugation, washing and drying; Step B: Mix polydopamine-modified graphene oxide, aminated cage-type silsesquioxane and toluene evenly, add Tris buffer, react at 75-85℃ for 5-7h, cool to room temperature, remove the supernatant, centrifuge the lower precipitate until neutral, and dry to obtain G0-POSS.

7. The surface treatment process for titanium-aluminum alloy for nano-injection molding according to claim 1, characterized in that: The preparation method of the composite silica sol is as follows: Tetraethyl orthosilicate, anhydrous ethanol, and deionized water were mixed evenly, and hydrochloric acid was added to adjust the pH of the system to 2-3. A mixed solution of phytic acid-silane modified graphene oxide and anhydrous ethanol was added, and the mixture was reacted at 60-70℃ for 4-6 hours. After standing overnight, the composite silica sol was obtained.

8. The surface treatment process for titanium-aluminum alloy for nano-injection molding according to claim 7, characterized in that: The preparation method of the phytic acid-silane modified graphene oxide is as follows: Phytic acid, ethanol, and 3-glycidyloxypropyltrimethoxysilane were mixed evenly and reacted at 60-70℃ for 2-4 h to obtain a phytic acid-silane intermediate. A graphene oxide dispersion was added dropwise to the phytic acid-silane intermediate system, and stirring was continued at 70-80℃ for 22-24 h. After centrifugation, washing, and drying, phytic acid-silane modified graphene oxide was obtained.

9. The surface treatment process for titanium-aluminum alloy for nano-injection molding parts according to claim 1, characterized in that: The specific steps of the sealing treatment are as follows: immerse the titanium-aluminum alloy after secondary anodizing in a 30-40 g / L ammonium fluorotitanate solution, seal the holes at 50-55℃ for 30-50 min, remove it, wash it with deionized water, and dry it.

10. An application of a titanium-aluminum alloy for nano-injection molding, characterized in that: A titanium-aluminum alloy for nano-injection molding parts according to any one of claims 1-9 is used in nano-injection molding process.

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