Coating-free high corrosion-resistant titanium alloy for bipolar plates and its short-process preparation method

Abstract

This invention belongs to the field of hydrogen energy proton exchange membrane fuel cells, and discloses a coating-free, high-corrosion-resistant titanium alloy for bipolar plates and its short-process preparation method. By appropriately proportioning Ni, Ta, and Ru elements, and utilizing their synergistic effect on the microstructure, the corrosion resistance of the titanium alloy substrate is significantly improved while meeting the conductivity requirements of the bipolar plate, effectively solving the limitation of easily peeling coatings and other surface treatments on the long-term use of bipolar plates. Furthermore, when the Ru content of this invention is 0.17%~0.25%, it not only meets the DOE2025 requirements for bipolar plate conductivity, but also significantly reduces the corrosion current density of constant potential polarization by about 1 to 2 orders of magnitude compared to the DOE2025 requirements. The preparation method of this invention can obtain a highly corrosion-resistant titanium alloy substrate through simple microalloying and homogenization annealing treatments. The process is short and simple to operate, which can effectively extend the service life of fuel cells and contribute to the large-scale commercial application of proton exchange membrane fuel cells.

Description

Technical Field

[0001] This invention belongs to the field of proton exchange membrane fuel cell technology, specifically relating to a coating-free, high corrosion-resistant titanium alloy for bipolar plates and its short-process preparation method. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) use hydrogen and oxygen as fuels to directly convert chemical energy into electrical energy, with water as the only byproduct. Therefore, they are considered one of the most promising energy conversion devices. With the increasing severity of the global energy crisis and environmental pollution, the widespread application of PEMFCs in new energy vehicles, aerospace, and other fields will effectively promote energy transformation and achieve carbon reduction and emission reduction. Bipolar plates, as a key component of PEMFCs, account for approximately 70% of the total weight and 30% of the cost, and their performance directly affects the lifespan of the fuel cell. Currently, stainless steel bipolar plates are widely used commercially, but due to their poor corrosion resistance, the lifespan of fuel cells is unlikely to exceed 5000 hours. Frequent replacements increase costs, thus greatly limiting the application of fuel cells as power output devices in high-end manufacturing industries.

[0003] The industry commonly uses surface treatment to improve the corrosion resistance of bipolar plates, such as physical vapor deposition, to prepare conductive and corrosion-resistant coatings on the surface. However, this method does not improve the corrosion resistance of the bipolar plate substrate material itself and has significant limitations: on the one hand, the coating may partially peel off after long-term operation, exposing the substrate material and accelerating corrosion, thus reducing the operational stability and safety of the fuel cell; on the other hand, surface modification processes significantly increase the manufacturing cost of bipolar plates, which is detrimental to the large-scale commercial application of fuel cells. Therefore, it is necessary to improve the corrosion resistance of the bipolar plate substrate material itself as much as possible while ensuring that conductivity meets the standards.

[0004] Compared to stainless steel, titanium and titanium alloys exhibit superior corrosion resistance and lower specific gravity, making them more suitable as materials for PEMFC bipolar plates. Patent CN112322934A discloses a titanium alloy for PEMFC bipolar plates, which uses pure titanium as raw material and adds elements such as Ni and Ta. After a prolonged homogenization annealing process, the corrosion current density can be optimized to 64~146 μA / cm². 2 Patent CN118422241A discloses a titanium bipolar plate for proton exchange membrane water electrolysis to produce hydrogen. Its composition includes Ni, Mo, and Ru elements. After homogenization, rolling, and annealing, the corrosion current density at room temperature is 1.5~3.0 μA / cm². 2 With the development of hydrogen energy, DOE 2025 requires that the corrosion current density of bipolar plates in PEMFC operating environments be <1 μA / cm². 2 The surface contact resistance after polarization is <10 mΩ·cm 2However, existing titanium and titanium alloys still require coatings or complex processes to meet corrosion resistance requirements in the strong acid, high temperature, and fluoride-rich redox environment of fuel cells. For example, patent CN118572138A proposes a method for improving the conductivity of corrosion-resistant titanium alloy bipolar plate substrates for PEMFCs. This method involves activating a titanium alloy containing elements such as Ni, Nb, and Ta, followed by heating and holding in an ammonia atmosphere to form TiN on the substrate surface. X Only after the layer is applied can the conductivity and corrosion resistance of the bipolar plate meet the DOE2025 requirements.

[0005] Therefore, developing a titanium alloy substrate with excellent corrosion resistance in the working environment of fuel cells is of great significance for improving the service life of proton exchange membrane fuel cells, reducing costs, and promoting the large-scale commercial application of fuel cells, while meeting the performance requirements of DOE2025 for bipolar plate substrates and avoiding the problems caused by surface treatment. Summary of the Invention

[0006] In view of this, the present invention provides a coating-free high corrosion-resistant titanium alloy for bipolar plates and a short-process preparation method thereof, which mainly aims to solve the problems that existing titanium and titanium alloy bipolar plate substrates have low corrosion resistance in the strong acid, high temperature and fluoride-rich working environment of fuel cells, and that the preparation process is complicated and cannot meet the DOE2025 performance requirements.

[0007] To achieve the above objectives, on the one hand, the present invention provides a coating-free, high corrosion-resistant titanium alloy for bipolar plates, the chemical composition of which, by mass percentage, comprises: Ni: 0.45%~0.55%, Ta: 0.25%~0.35%, Ru: 0.15%~0.40%, O < 0.10%, Fe < 0.02%, N < 0.01%, C < 0.01%, H < 0.005%, with the balance being Ti and unavoidable impurity elements.

[0008] In some embodiments, the mass fraction of Ru element is 0.17% to 0.25%.

[0009] In some embodiments, the mass fractions of Ni, Ta, and Ru are 0.50%, 0.30%, and 0.20%, respectively, and the mass fraction deviation of each element is ≤0.005%.

[0010] In some embodiments, the high corrosion-resistant titanium alloy is subjected to pH=3, 70°C, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H2SO4 solution, and the Tafel self-corrosion potential was > -0.40 V vs. Hg / Hg2SO4.

[0011] In some embodiments, the high corrosion-resistant titanium alloy is subjected to pH=3, 70°C, and 2ppmF. -Electrochemical tests were performed in a 0.5 mol / L H₂SO₄ solution, and the corrosion current density under constant potential polarization was <1 μA / cm. 2 The surface contact resistance after 50 hours of constant potential polarization is <10 mΩ / cm. 2 .

[0012] In some embodiments, the high corrosion-resistant titanium alloy is subjected to pH=3, 70°C, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H₂SO₄ solution. The Tafel self-corrosion potential was > -0.30 V vs. Hg / Hg₂SO₄, and the corrosion current density under potentiostatic polarization was < 0.20 μA / cm². 2 .

[0013] On the other hand, the present invention provides a short-process preparation method for the high corrosion-resistant titanium alloy of the above embodiments, comprising the following steps:

[0014] S1. Melting and casting: The raw materials of Ni, Ta and Ru are provided in elemental form or in intermediate alloys of elemental form and Ti. After being weighed according to the chemical composition ratio, they are melted in a vacuum non-consumable arc furnace under the protective atmosphere of argon or helium and cast into button ingots.

[0015] S2. Homogenization treatment: Anneal the button ingots and hold them at 980℃~1020℃ for 1h~2h to obtain a homogeneous titanium alloy.

[0016] S3. Cutting and polishing: The homogeneous titanium alloy is cut into the required size, and its surface is ground with sandpaper of increasing grit. Then, it is polished with a semi-automatic or automatic polishing machine until the surface is bright, thus obtaining a highly corrosion-resistant titanium alloy.

[0017] In some embodiments, the raw materials include sponge titanium with a purity greater than 99.7%, Ti-40Ta master alloy, nickel-titanium wire, and Ru powder with a purity greater than 99.5%.

[0018] In some embodiments, the number of melting operations is configured to be no less than 5 times.

[0019] In some embodiments, the annealing temperature is 1000°C and the holding time is 1 hour.

[0020] Based on the above technical solution, the beneficial effects of the coating-free high corrosion-resistant titanium alloy for bipolar plates and its short-process preparation method provided by the present invention are as follows:

[0021] 1. The high corrosion-resistant titanium alloy of this invention exhibits a significantly reduced corrosion current density under simulated fuel cell cathode testing environments characterized by strong acid, high temperature, and high fluoride ion content, thereby greatly improving the durability and service life of fuel cell bipolar plates. Compared with existing technologies, the titanium alloy of this invention, in electrochemical tests at 70°C, 2 ppm F-, and pH=3, has a Tafel self-corrosion potential > -0.40 V vs. Hg / Hg2SO4, and not only exhibits a constant potential polarization corrosion current density < 1 μA / cm². 2 It meets the DOE 2025 standard, and its conductivity, specifically, the surface contact resistance after 50 hours of constant potential polarization, is <10 mΩ / cm. 2 This also meets the requirements for the use of bipolar plates.

[0022] 2. Compared with existing pure titanium and titanium alloy grades, the titanium alloy of this invention has a unique composition ratio. By adding trace amounts of Ni, Ta, and Ru, and utilizing the synergistic effect of these three elements on the microstructure, the corrosion resistance of the substrate is significantly improved while maintaining the conductivity of the bipolar plate. This effectively solves the limitation imposed by easily peeling coatings and other surface treatments on the long-term use of bipolar plates. Furthermore, when the Ru content in this invention is 0.17%~0.25%, the Tafel self-corrosion potential is increased by approximately 25%, and the corrosion current density of constant potential polarization is significantly reduced by approximately 1 to 2 orders of magnitude compared to the DOE2025 requirement, greatly improving the corrosion resistance of the bipolar plate.

[0023] 3. Compared with the prior art, the microalloying high corrosion-resistant titanium alloy preparation process of the present invention is simple, time-saving and easy to operate. It does not require complex deformation procedures, coating processes, long-term heat preservation and special atmosphere heat treatment. Only a short time of homogenization annealing is needed to make the bipolar plate substrate have excellent conductivity and corrosion resistance at the same time, extend the service life of fuel cells, improve production efficiency and reduce process costs, and help promote the large-scale commercial application of proton exchange membrane fuel cells. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention, wherein:

[0025] Figure 1 Tafel curve of the titanium alloy substrate prepared for Comparative Example 1;

[0026] Figure 2 Tafel curves of the titanium alloy substrate prepared in Comparative Example 2;

[0027] Figure 3 Tafel curve of the titanium alloy substrate prepared for Comparative Example 3;

[0028] Figure 4 Tafel curve of the titanium alloy substrate prepared in Example 1;

[0029] Figure 5 Tafel curve of the titanium alloy substrate prepared in Example 2;

[0030] Figure 6 Tafel curves of the titanium alloy substrate prepared in Comparative Example 4;

[0031] Figure 7 The potentiostatic polarization curve of the titanium alloy substrate prepared in Example 1;

[0032] Figure 8 The surface contact resistance curve of the titanium alloy substrate prepared in Example 1 after constant potential polarization. Detailed Implementation

[0033] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. The accompanying drawings are for illustrative purposes only and are schematic diagrams; they should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, it is understandable that some well-known processes or steps and their descriptions may be omitted in the technical solutions, which is intended to better explain the embodiments of the present invention.

[0034] The present invention provides a coating-free, high corrosion-resistant titanium alloy for bipolar plates, the chemical composition of which, by mass percentage, comprises: Ni: 0.45%~0.55%, Ta: 0.25%~0.35%, Ru: 0.15%~0.40%, O < 0.10%, Fe < 0.02%, N < 0.01%, C < 0.01%, H < 0.005%, with the balance being Ti and unavoidable impurity elements.

[0035] The added Ni element is electropositive, accumulating on the alloy surface to form a high reduction current, promoting passivation of the titanium alloy bipolar substrate. However, too little Ni will not provide protection; too much Ni will precipitate a large amount of intermetallic compound Ti₂Ni, reducing the alloy's conductivity. The added Ta element is easy to passivate, rapidly forming Ta₂O₅ with excellent corrosion resistance on the titanium alloy surface, reducing the anodic activity of the titanium alloy surface and improving the substrate's passivation ability. However, the solid solubility of Ta in Ti at room temperature is limited; excessive Ta addition will precipitate a second phase, easily causing micro-current corrosion, while too little Ta will not improve corrosion resistance. Therefore, the mass fraction of Ni in the high corrosion-resistant titanium alloy of this invention is limited to the range of 0.45%~0.55%, and the mass fraction of Ta is limited to the range of 0.25%~0.35%.

[0036] The added Ru element is also a readily passivating element, and its addition helps to inhibit the corrosion process and improve the corrosion resistance of titanium alloys. However, excessive Ru content not only increases costs but also reduces the dissolution rate of the passivation film on titanium alloys, affecting their corrosion resistance. This invention has found that the addition of Ni, Ta, and Ru elements has a synergistic effect on improving the corrosion resistance of the microstructure. Specifically, the combined effect of Ni and Ru on improving the corrosion resistance of titanium alloys is consistent with the effect of adding more Ru alone. Therefore, considering the combined effect of the elements on improving corrosion resistance and economic costs, the mass fraction of Ru in the high corrosion-resistant titanium alloy of this invention is limited to the range of 0.15%~0.40%, which is suitable for use at pH=3, 70℃, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H2SO4 solution, and the Tafel self-corrosion potential was > -0.40 V vs. Hg / Hg2SO4.

[0037] More preferably, the mass fraction of Ru in the high corrosion-resistant titanium alloy of the present invention is 0.17%~0.25%, and under the same electrochemical testing conditions as described above, its potentiostatic polarization corrosion current density is <1μA / cm. 2 The surface contact resistance after 50 hours of constant potential polarization is <10 mΩ / cm. 2 All of them meet the DOE2025 standard.

[0038] More preferably, the mass fractions of Ni, Ta, and Ru in the high corrosion-resistant titanium alloy of the present invention are 0.50%, 0.30%, and 0.20%, respectively, and the mass fraction deviation of each element is ≤0.005%. Under the same electrochemical testing conditions as described above, its Tafel self-corrosion potential is >0.30 Vvs.Hg / Hg2SO4, and the corrosion current density under constant potential polarization is <0.20 μA / cm. 2Compared to the DOE2025 requirements, this is reduced by about 1 to 2 orders of magnitude, significantly improving the corrosion resistance of bipolar plates.

[0039] The following detailed description of specific embodiments of the present invention, in conjunction with examples, comparative examples, and accompanying drawings, further verifies the beneficial effects of the present invention.

[0040] Comparative Example 1 (Ni: 0.50%, Ta: 0.30%, Ru: 0%)

[0041] In this comparative example, the titanium alloy substrate uses Ti, Ni, Ta, and Ru as raw materials. The mass fractions of each element are: Ni = 0.50%, Ta = 0.30%, Ru = 0%, O = 0.08%, Fe = 0.015%, N = 0.008%, C = 0.008%, H = 0.004%, with the balance being Ti and unavoidable impurities. The preparation process of this titanium alloy substrate includes the following steps:

[0042] S1. Smelting and Casting:

[0043] The raw materials for Ni, Ta, and Ru were provided in elemental form or as intermediate alloys of elemental form and titanium, and were precisely weighed according to the composition ratio. Titanium alloy button ingots were prepared using a vacuum non-consumable arc furnace. Based on the mass percentage of each element in the aforementioned titanium alloy base material, sponge titanium with a purity greater than 99.7%, Ti-40Ta intermediate alloy, and nickel-titanium wire were selected and melted using a vacuum non-consumable arc furnace melting method. Argon was used as a protective gas during the melting process. To improve compositional uniformity, the mixture was remelted five times. After melting, the ingots were cast to produce the button ingots.

[0044] S2. Homogenization treatment:

[0045] To further improve the compositional uniformity of the titanium alloy ingot and eliminate stress, the button ingot obtained from S1 was homogenized and annealed at 1000℃ for 1 hour to obtain a homogeneous titanium alloy.

[0046] S3. Cutting and Polishing:

[0047] The homogeneous titanium alloy after S2 annealing was wire-cut into circular samples with a diameter of 20 mm and a thickness of 2 mm. The surface of the sample was then ground with 400 grit, 800 grit, 1200 grit, 1500 grit and 2000 grit sandpaper in sequence, and then polished with a semi-automatic or automatic polishing machine until the sample surface was bright, thus obtaining the titanium alloy substrate to be tested electrochemically.

[0048] Comparative Example 2 (Ni: 0.50%, Ta: 0.30%, Ru: 0.05%)

[0049] Compared with Comparative Example 1, in the titanium alloy substrate of Comparative Example 2, the mass fraction of Ru element is 0.05%, the smelting raw material is Ru powder with a purity greater than 99.5%, and other parameters and processes remain unchanged.

[0050] Comparative Example 3 (Ni: 0.50%, Ta: 0.30%, Ru: 0.10%)

[0051] Compared with Comparative Example 1, in the titanium alloy substrate of Comparative Example 3, the mass fraction of Ru element is 0.10%, the smelting raw material is Ru powder with a purity greater than 99.5%, and other parameters and processes remain unchanged.

[0052] Example 1 (Ni: 0.50%, Ta: 0.30%, Ru: 0.20%)

[0053] Compared with Comparative Example 1, in the titanium alloy substrate of this Example 1, the mass fraction of Ru element is 0.20%, the smelting raw material is Ru powder with a purity greater than 99.5%, and other parameters and processes remain unchanged.

[0054] Example 2 (Ni: 0.50%, Ta: 0.30%, Ru: 0.40%)

[0055] Compared with Comparative Example 1, in the titanium alloy substrate of this Example 2, the mass fraction of Ru element is 0.40%, the smelting raw material is Ru powder with a purity greater than 99.5%, and other parameters and processes remain unchanged.

[0056] Comparative Example 4 (Ni: 0.50%, Ta: 0.30%, Ru: 0.80%)

[0057] Compared with Comparative Example 1, in the titanium alloy substrate of Comparative Example 4, the mass fraction of Ru element is 0.80%, the smelting raw material is Ru powder with a purity greater than 99.5%, and other parameters and processes remain unchanged.

[0058] Based on the microalloying composition of the above comparative examples and embodiments, the simplified names of each titanium alloy substrate are: Ti-0.5Ni-0.3Ta-XRu, where X represents 0%, 0.05%, 0.10%, 0.20%, 0.40%, and 0.80%. The polished samples from the above comparative examples and embodiments were immediately subjected to electrochemical treatment at 70°C and 2 ppmF using an electrochemical workstation. - Electrochemical tests were performed in a corrosive solution containing 0.5 mol / L H₂SO₄ and pH=3. The relevant Tafel curves are shown below. Figures 1 to 6 As shown.

[0059] As shown in Table 1, compared with Comparative Example 1, the Tafel self-corrosion potential of the titanium alloy substrates in the other comparative examples and embodiments was improved in the simulated fuel cell working environment, which is attributed to the addition of element Ru. Among them, the titanium alloy substrate with 0.20% Ru added in Example 1 showed the best corrosion resistance, and the corrosion current density under constant potential polarization at a working voltage of 0.6 V vs. Hg / Hg2SO4 was <1 μA / cm. 2 The surface contact resistance after 50 hours of constant potential polarization is <10 mΩ / cm. 2 Not only do they all meet the DOE2025 standard, but their corrosion current density is also significantly reduced by about 1 to 2 orders of magnitude compared to the DOE2025 standard, resulting in a significant improvement in corrosion resistance.

[0060] The microstructure of the Ti-0.5Ni-0.3Ta-XRu alloy consists of alternating strip-shaped α and β phases, with corrosion initially occurring at the α phase interface. Experimental analysis revealed that the passivation film on the Ru-containing alloy surface contains more stable, corrosion-resistant components (such as TiO2, Ta2O5, and RuO2). The addition of Ru refines the lath structure in the titanium alloy, increases the number of phase interfaces, and provides more nucleation sites for passivation film formation. On one hand, a thicker passivation film can be formed rapidly on the alloy surface; on the other hand, the formed passivation film is more stable and dense. Furthermore, the addition of Ru makes the distribution of Ni in the α and β phases more uniform, reducing the potential difference between the two phases and mitigating interphase corrosion to some extent. Therefore, except for Comparative Example 1, the corrosion resistance of the Ru-containing alloys is improved. However, while the phase interfaces provide nucleation sites for passivation film formation, they also adsorb corrosive ions, accelerating the dissolution rate of the alloy passivation film. The passivation film on the alloy surface is a dynamic process in which formation and dissolution occur simultaneously. Therefore, compared with the alloy of Example 1, the corrosion resistance of the alloy of Example 2 decreased slightly, while the corrosion resistance of Comparative Example 4 decreased more significantly. This is because the further refinement of the strip-like structure generates more phase interfaces, resulting in the adsorption of more F. - Corrosive ions increase the dissolution rate of the alloy passivation film, thus accelerating the corrosion process.

[0061] In summary, the titanium alloys prepared by adding the alloying elements and their contents as described in this invention, compared with pure titanium and typical existing titanium alloys, exhibit superior performance in terms of F content. - The corrosion resistance of the titanium alloys in the fuel cell testing environment of ionic sulfuric acid solution (70°C) was significantly improved to varying degrees. Among them, the Ti-0.5Ni-0.3Ta-0.2Ru titanium alloy system exhibited significantly higher corrosion resistance than typical existing titanium alloys, meeting the DOE2025 standard, and also possessed excellent electrical conductivity, thus meeting the DOE2025 requirements. Therefore, in terms of both corrosion resistance and electrical conductivity, the titanium alloys provided by this invention are more suitable as bipolar plate materials for proton exchange membrane fuel cells.

[0062] Table 1. Self-corrosion potential and corrosion current density of Tafel in each comparative example and embodiment.

[0063] Serial Number Titanium alloy composition (wt.%) <![CDATA[Self - corrosion potential (V vs. Hg / Hg2SO4) <!-- 5 -->]]> Comparative Example 1 Ti-0.5Ni-0.3Ta -0.87 Comparative Example 2 Ti-0.5Ni-0.3Ta-0.05Ru -0.79 Comparative Example 3 Ti-0.5Ni-0.3Ta-0.1Ru -0.73 Example 1 Ti-0.5Ni-0.3Ta-0.2Ru -0.24 Example 2 Ti-0.5Ni-0.3Ta-0.4Ru -0.37 Comparative Example 4 Ti-0.5Ni-0.3Ta-0.8Ru -0.56

[0064] Table 2 Corrosion current density and interfacial contact resistance after 50 hours of constant potential polarization in Example 1

[0065] Serial Number Titanium alloy composition (wt.%) <![CDATA[Corrosion current density (μA / cm 2 )]]> <![CDATA[Interface contact resistance (mΩ / cm 2 )]]> Example 1 Ti-0.5Ni-0.3Ta-0.2Ru 0.014 9.548

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A coating-free, high corrosion-resistant titanium alloy for bipolar plates, characterized in that: The chemical composition of the high corrosion-resistant titanium alloy, by mass percentage, includes: Ni: 0.45%~0.55%, Ta: 0.25%~0.35%, Ru: 0.17%~0.25%, O < 0.10%, Fe < 0.02%, N < 0.01%, C < 0.01%, H < 0.005%, with the balance being Ti and unavoidable impurity elements; The short-process preparation method of the high corrosion-resistant titanium alloy includes the following steps: S1. Melting and casting: The raw materials of Ni, Ta and Ru are provided in elemental form or in an intermediate alloy of elemental form and Ti. After being weighed according to the chemical composition ratio, they are melted in a vacuum non-consumable arc furnace under an argon or helium protective atmosphere and cast into button ingots. S2. Homogenization treatment: The button ingot is annealed and held at 980℃~1020℃ for 1h~2h to obtain a homogeneous titanium alloy. S3. Cutting and polishing: The homogeneous titanium alloy is cut into the required size, and its surface is ground by sanding with sandpaper of increasing grit. Then, it is polished with a semi-automatic or automatic polishing machine until the surface is bright, thus obtaining a high corrosion-resistant titanium alloy.

2. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The mass fractions of Ni, Ta, and Ru are 0.50%, 0.30%, and 0.20%, respectively, and the mass fraction deviation of each element is ≤0.005%.

3. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The high corrosion-resistant titanium alloy is tested at pH=3, 70℃, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H2SO4 solution, and the Tafel self-corrosion potential was > -0.40 V vs. Hg / Hg2SO4.

4. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The high corrosion-resistant titanium alloy is tested at pH=3, 70℃, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H₂SO₄ solution, and the corrosion current density under constant potential polarization was <1 μA / cm. 2 The surface contact resistance after 50 hours of constant potential polarization is <10 mΩ / cm. 2 .

5. The high corrosion-resistant titanium alloy according to claim 2, characterized in that, The high corrosion-resistant titanium alloy is tested at pH=3, 70℃, and 2ppmF. - Electrochemical tests were performed in a 0.5 mol / L H₂SO₄ solution. The Tafel self-corrosion potential was > -0.30 V vs. Hg / Hg₂SO₄, and the corrosion current density under potentiostatic polarization was < 0.20 μA / cm². 2 .

6. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The raw materials include sponge titanium with a purity greater than 99.7%, Ti-40Ta master alloy, nickel-titanium wire, and Ru powder with a purity greater than 99.5%.

7. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The number of melting operations is configured to be no less than 5 times.

8. The high corrosion-resistant titanium alloy according to claim 1, characterized in that, The annealing temperature is 1000℃ and the holding time is 1 hour.

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