Titanium alloy bipolar plate having high pitting potential and low resistivity, and method for manufacturing the same.

Abstract

This invention provides a titanium alloy bipolar plate having a high pitting potential and low resistivity, and a method for manufacturing the same. [Solution] The present invention discloses a titanium alloy bipolar plate having a high pitting potential and low resistivity, and a method for manufacturing the same. The titanium alloy bipolar plate contains impurity elements (Fe, O, C, N, H) in mass%, with the following components being Mo: 3.0% to 5.0%, Ni: 0.1% to 0.3%, Ru: 0.005% to 0.05%, the remainder being Ti, and a total content of 0.01% or less. The present invention can improve the pitting potential of the titanium alloy bipolar plate in order to ensure that the titanium alloy bipolar plate satisfies the requirements for conductivity, thereby fundamentally solving the problem that titanium alloy bipolar plates have poor corrosion resistance and reduced hydrogen generation efficiency due to a low pitting potential in the operating environment of electrolytic cells for water electrolysis hydrogen production.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis hydrogen production, and specifically to a titanium alloy bipolar plate having a high pore corrosion potential and a low resistivity and a manufacturing method thereof.

Background Art

[0002] As a very promising clean energy in the 21st century, hydrogen energy has characteristics such as rich reserves, zero pollution, high energy density, and wide applications. The utilization of hydrogen energy has been gradually attracting attention from all over the world. Currently, hydrogen production by electrolysis of water has characteristics such as being environmentally friendly, having flexible production, high purity (usually above 99.7%), and generating high-value oxygen as a by-product, and has become the main source of green hydrogen.

[0003] Depending on the material of the electrolytic cell diaphragm, the hydrogen production method by electrolysis of water is basically divided into four types: proton exchange membrane water electrolysis hydrogen production (PEM), alkaline anion exchange membrane water electrolysis hydrogen production (AEM), alkaline water electrolysis hydrogen production (ALK), and high-temperature solid oxide water electrolysis hydrogen production (SOEC). Among them, the PEM water electrolysis hydrogen production device has a compact structure, a high current density, a fast response speed, and a small floor area, so it can operate at a low temperature (20~80°C). The highly dynamic PEM water electrolysis hydrogen production technology is based on the fluctuating energy of renewable energies such as wind energy and solar energy, and is suitable for efficiently converting electrical energy into hydrogen energy for storage, enabling the realization of global energy decarbonization in the future.

[0004] Bipolar plates are a crucial component of PEM water electrolysis hydrogen production equipment. They are connected to each cell in the PEM electrolytic stack, supporting components such as proton exchange membranes and catalysts, and are responsible for transporting substances such as water, oxygen, hydrogen, and electrons, as well as transferring heat, through their own channels. Their manufacturing cost accounts for approximately half of the total cost of the electrolytic stack, and they also play a decisive role in the operational performance and lifespan of the PEM electrolytic stack. Titanium alloys have significant advantages as bipolar plate materials, possessing excellent corrosion resistance, high strength, good thermal conductivity, and low permeability and resistivity. However, titanium alloy bipolar plates are not suitable for the operating environment of electrolytic cells used in PEM water electrolysis hydrogen production, i.e., F - In a sulfuric acid solution environment containing ions, the low pitting potential results in poor corrosion resistance and reduced hydrogen generation efficiency. Therefore, in the high-potential operating environment of the anode of a PEM water electrolysis electrolytic cell, it is necessary to further improve corrosion resistance by increasing the pitting potential of the bipolar plate, thereby increasing the output of the water electrolysis electrolytic cell and improving hydrogen generation efficiency. [Overview of the project] [Problems that the invention aims to solve]

[0005] This invention has been made in view of the above technical problems, and provides a titanium alloy bipolar plate having a high pitting potential and low resistivity, and a method for manufacturing the same, thereby fundamentally solving the problem that titanium alloy bipolar plates have poor corrosion resistance and reduced hydrogen generation efficiency due to a low pitting potential in the operating environment of an electrolytic cell for water electrolysis hydrogen production. [Means for solving the problem]

[0006] To achieve the above objective, a first aspect of the present invention is a titanium alloy bipolar plate having a high pitting potential and low resistivity, wherein the components are, by mass %, It consists of Mo: 3.0%~5.0%, Ni: 0.1%~0.3%, Ru: 0.005%~0.08%, the remainder being Ti, and impurities (Fe, O, C, N, H) with a total content of 0.1% or less.

[0007] In some embodiments of the present invention, the above components are present in mass% It consists of Mo: 3.0%~5.0%, Ni: 0.1%~0.3%, Ru: 0.008%~0.05%, the remainder being Ti, and impurities (Fe, O, C, N, H) with a total content of 0.01% or less.

[0008] In some embodiments of the present invention, the above components are present in mass% It consists of Mo: 3.5%~5.0%, Ni: 0.1%~0.2%, Ru: 0.01%~0.03%, the remainder being Ti, and impurities (Fe, O, C, N, H) with a total content of 0.01% or less.

[0009] A second aspect of the present invention is a method for producing a titanium alloy bipolar plate having a high pitting potential and low resistivity as described in the first aspect, comprising a raw material blending step, a melting step, a rolling step, and an annealing heat treatment step, of which, The raw materials used in the aforementioned raw material blending process are selected from sponge titanium, titanium foil, electrolytic nickel powder, electrolytic ruthenium powder, and molybdenum particles.

[0010] In some embodiments of the present invention, the melting step uses vacuum arc melting, with a current of 300A to 400A for the vacuum arc melting, 4 to 6 rounds of vacuum arc melting, and a melting time of 1 to 2 minutes per round to obtain a Ti-Mo-Ni-Ru titanium alloy ingot.

[0011] In some embodiments of the present invention, when performing the vacuum arc melting, argon gas is introduced as a protective gas and an ionizing gas, and the vacuum level inside the vacuum arc furnace is set to 5 × 10⁻¹⁰. -3 The Pa level is reduced to below, and a Ti-Mo-Ni-Ru titanium alloy ingot is obtained.

[0012] In some embodiments of the present invention, the rolling process involves homogenizing the Ti-Mo-Ni-Ru titanium alloy ingot obtained by vacuum arc melting, and then rolling it to obtain a Ti-Mo-Ni-Ru titanium alloy slab. The homogenization treatment is performed at a temperature of 700°C to 800°C for 8 to 12 hours.

[0013] In some embodiments of the present invention, the total amount of deformation during rolling is 75% to 85%. In the rolling process described above, rolling is performed in multiple passes, with a deformation of 35-45% in each pass, a rolling temperature of 900°C-920°C in each pass, and a heat retention period of 2-3 minutes between each rolling pass.

[0014] In some embodiments of the present invention, after the homogenization treatment, the Ti-Mo-Ni-Ru titanium alloy ingot is placed in a heating furnace, kept at 910°C for 40 minutes, and then the rolling deformation is performed.

[0015] In some embodiments of the present invention, the annealing heat treatment step involves placing the Ti-Mo-Ni-Ru titanium alloy slab in a heating furnace, controlling the annealing temperature to 700°C to 800°C or lower, maintaining the temperature for 50 to 70 minutes, and then cooling it to room temperature by air cooling. [Effects of the Invention]

[0016] The present invention has the following advantages. The present invention provides a method for manufacturing a titanium alloy bipolar plate having a high pitting potential and low resistivity. This method involves first selecting the components and content of a specific alloy, then optimizing the corresponding process parameters during the melting, rolling, and annealing heat treatment processes, and finally manufacturing the titanium alloy bipolar plate having a high pitting potential and low resistivity. The present invention aims to improve the pitting potential of the manufactured titanium alloy bipolar plate, assuming that the manufactured titanium alloy bipolar plate satisfies the conductivity requirements of a bipolar plate, thereby solving the problem of poor corrosion resistance and reduced hydrogen generation efficiency in the operating environment of an electrolytic cell for water electrolysis hydrogen production, due to the low pitting potential of the titanium alloy bipolar plate. [Brief explanation of the drawing]

[0017] The content, purpose, features, and advantages of the present invention will become clearer from the description of embodiments of the present invention related to the accompanying drawings. In the accompanying drawings, [Figure 1]It is a diagram showing a Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy ingot of Example 1 of the present invention. [Figure 2] It is a diagram showing a rolled and annealed sheet of a Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy of Example 1 of the present invention. [Figure 3] It is a diagram showing Tafel curves of Ti-3.0Mo-0.2Ni-0.01Ru, pure titanium, and TA10 sheets in the state of being rolled and annealed of Example 1 of the present invention in an environment of 0.5M sulfuric acid + 5ppm F- solution. [Figure 4] It is a diagram showing a Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy ingot of Example 2 of the present invention. [Figure 5] It is a diagram showing a rolled and annealed sheet of a Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy of Example 2 of the present invention. [Figure 6] It is a diagram showing a Tafel curve of a Ti-3.5Mo-0.2Ni-0.01Ru sheet in the state of being rolled and annealed of Example 2 of the present invention in an environment of 0.5M sulfuric acid + 5ppm F- solution. [Figure 7] It is a diagram showing a Ti-4Mo-0.2Ni-0.01Ru titanium alloy ingot of Example 3 of the present invention. [Figure 8] It is a diagram showing a rolled and annealed sheet of a Ti-4Mo-0.2Ni-0.01Ru titanium alloy of Example 3 of the present invention. [Figure 9] It is a diagram showing a Tafel curve of a Ti-4Mo-0.2Ni-0.01Ru sheet in the state of being rolled and annealed of Example 3 of the present invention in an environment of 0.5M sulfuric acid + 5ppm F- solution. [Figure 10] It is a diagram showing a Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy ingot of Example 4 of the present invention. [Figure 11] It is a diagram showing a rolled and annealed sheet of a Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy of Example 4 of the present invention. [Figure 12] It is a diagram showing a Tafel curve of a Ti-3.5Mo-0.2Ni-0.04Ru sheet in the state of being rolled and annealed of Example 4 of the present invention in an environment of 0.5M sulfuric acid + 5ppm F- solution. [Figure 13]This figure shows a Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy ingot according to Example 5 of the present invention. [Figure 14] This figure shows a rolled and annealed sheet material of a Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy according to Example 5 of the present invention. [Figure 15] This figure shows the Tafel curve of a Ti-3.5Mo-0.1Ni-0.01Ru sheet material in a rolled and annealed state according to Example 5 of the present invention, under a 0.5M sulfuric acid + 5ppmF- solution environment. [Modes for carrying out the invention]

[0018] The present invention will be described below based on examples, but the present invention is not limited to these examples. While certain details are described in detail in the detailed description of the present invention, those skilled in the art will fully understand the parts that are not described in detail. Furthermore, unless explicitly stated otherwise, similar terms such as "includes" and "inclusive" in the specification and claims should be interpreted as "inclusive but not exclusive," rather than exclusive or exhaustive.

[0019] The present invention will describe in detail, in relation to specific embodiments, a titanium alloy bipolar plate having a high pitting potential and low resistivity, and a method for manufacturing the same. In each embodiment, the titanium alloy bipolar plate consists of, by mass%, Mo: 3.0-5.0%, Ni: 0.1-0.3%, Ru: 0.01-0.03%, the remainder being Ti, and impurities, the impurities being Fe, O, C, N, and H, with a total impurity content of 0.01% or less.

[0020] The titanium alloy bipolar plate of the present invention is designed with the above components based on the following principle: Mo improves the pitting potential of pure Ti, while Ni and Ru decrease it. However, Ni and Ru can effectively improve the resistivity of pure Ti. Therefore, in this invention, a large amount of Mo and small amounts of Ni and Ru are added to pure Ti.

[0021] In each example, the method for manufacturing a titanium alloy bipolar plate includes the following steps.

[0022] (1) Raw material blending process: Based on the composition of the bipolar plate, titanium alloy raw materials for dissolution are selected, and the selected raw materials are weighed and blended. The raw materials used in each example are selected from sponge titanium, titanium foil, electrolytic nickel powder, electrolytic ruthenium powder, and molybdenum particles. Here, the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil to prevent them from being blown away by the electric arc during the dissolution process.

[0023] (2) Melting process: The raw materials, which have already been mixed, are melted to obtain a Ti-Mo-Ni-Ru titanium alloy ingot. In each example, the melting is performed using vacuum arc melting, with a vacuum arc melting current of 300-400A, 4-6 rounds of vacuum arc melting, and a melting time of 1-2 minutes per round. After this vacuum arc melting, a Ti-Mo-Ni-Ru titanium alloy ingot is obtained.

[0024] Due to the high affinity between titanium and oxygen, the present invention employs vacuum arc melting to effectively prevent excessive oxygen from dissolving into the titanium alloy, allowing for multiple melting cycles and improving the uniformity of the components.

[0025] (3) Rolling process: The Ti-Mo-Ni-Ru titanium alloy ingot obtained by vacuum arc melting is homogenized and then rolled to obtain a Ti-Mo-Ni-Ru titanium alloy slab. In each example, the homogenization temperature is controlled to 700-800°C and the time to 8-12 hours to ensure a uniform distribution of the β-stable elements Mo, Ni, and Ru, while preventing the grain size from becoming too large.

[0026] The total deformation amount of the rolling deformation is 75-85%. In each embodiment, the rolling deformation is performed by rolling in multiple passes, with a deformation amount of 35-45% in each pass, a rolling temperature of 900-920°C in each pass, and a warming period of 2-3 minutes between each pass. In the present invention, the use of multiple-pass rolling deformation is taken into consideration to ensure sufficient penetration of thermal deformation, and the control of the deformation amount in each pass is aimed at grain refinement.

[0027] (4) Annealing heat treatment: The Ti-Mo-Ni-Ru titanium alloy slab obtained in the rolling process (3) is placed in a heating furnace and kept warm, then air-cooled to obtain the base material for the titanium alloy bipolar plate of the corresponding example. In each example, the annealing temperature is 700-800°C, the warming time is 50-70 min, and then it is cooled to room temperature by air cooling.

[0028] In this invention, the purpose of the annealing heat treatment is to remove residual stress in the hot-rolled slab and eliminate the thermal deformation texture. Here, the annealing temperature and annealing time are set in principle to prevent the growth of recrystallized grains, while taking into account the completion of recrystallization.

[0029] The following embodiments represent only some preferred embodiments and do not limit the scope and technical means of the invention described above.

[0030] Example 1 (1) Raw material blending process: According to the nominal composition of the alloy, Ti-3.0Mo-0.2Ni-0.01Ru (mass%), titanium particles (purity ≥ 99.99 wt%), high-purity titanium foil (thickness 0.03 mm, purity 99.99 wt%), electrolytic nickel powder (purity 99.99 wt%), electrolytic ruthenium powder (purity 99.99 wt%), and molybdenum particles (purity 99.99 wt%) are weighed and blended as raw materials, with a total weight of 25 g.

[0031] (2) Melting process: After pre-cleaning the inner wall of the copper crucible of the non-consumable vacuum arc furnace, the mixed molten raw materials are charged in, and the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil. The furnace interior is 5 × 10-3 After evacuating to Pa, high-purity argon gas is introduced as a protective and ionization gas to achieve a vacuum of approximately 0.05 MPa. Electromagnetic stirring is performed while controlling the current during melting to not exceed 400 A, with a melting time of 1 minute per cycle. The ingot is then inverted and melted again, and this melting process is repeated five times to ensure uniformity of the ingot's composition. Subsequently, suction casting is performed using a copper mold to obtain a Ti-3.0Mo-0.2Ni-0.01Ru ingot as shown in Figure 1.

[0032] (3) Rolling process: A Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy ingot is placed in a heating furnace for homogenization, heated at 800°C for 12 hours, and then cooled to room temperature by air cooling. Before rolling, the ingot is placed in the heating furnace and heated at 910°C for 40 minutes, after which it is rolled and deformed in a two-roll hot rolling mill. A multi-pass rolling deformation process is employed, with a total reduction rate of 80% and a pass reduction rate of 40%. Between each rolling pass, the hot-rolled slab is returned to the heating furnace for reheating and heated at 910°C for 2 minutes to ensure the rolling temperature. After rolling is complete, it is air-cooled to obtain a hot-rolled sheet of Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy.

[0033] (4) Annealing heat treatment process: A hot-rolled sheet of Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy is placed in a heating furnace and subjected to annealing heat treatment at 750°C for 60 minutes. The annealed sheet material is then cooled to room temperature by air cooling to obtain a Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy sheet material as shown in Figure 2.

[0034] (5) Performance testing: Based on the "GB / T 40299-2021" standard, a Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy sheet was cut into corrosion-resistant test specimens, polished, and immediately afterward tested using an electrochemical measuring device. When the polished surface was tested at room temperature under 0.5M sulfuric acid + 5ppmF- solution conditions, a Tafel curve as shown in Figure 3 was obtained, with a pitting potential of 2.3V, which is higher than the pitting potential of pure titanium (2V) and the pitting potential of TA10, a representative titanium alloy brand (1.8V).

[0035] The bulk resistivity of the Ti-3.0Mo-0.2Ni-0.01Ru titanium alloy is 0.63 μΩ·m, which is close to the resistivity of pure titanium (0.6-0.7 μΩ·m) and lower than the resistivity of TC4 alloy (1.6-1.8 μΩ·m). It exhibits excellent conductivity and can meet the conductivity requirements of bipolar plates.

[0036] Example 2 (1) Raw material blending process: According to the nominal alloy composition Ti-3.5Mo-0.2Ni-0.01Ru (mass%), titanium particles (purity ≥ 99.99 wt%), high-purity titanium foil (thickness 0.03 mm, purity 99.99 wt%), electrolytic nickel powder (purity 99.99 wt%), electrolytic ruthenium powder (purity 99.99 wt%), and molybdenum particles (purity 99.99 wt%) are weighed and blended as raw materials, with a total weight of 25 g.

[0037] (2) Melting process: The pre-mixed molten raw materials are placed in a water-cooled copper crucible of a non-consumable vacuum arc furnace. Here, the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil. The inner wall of the copper crucible needs to be pre-cleaned. The inside of the vacuum arc furnace is 5 × 10 -3 After evacuating to below Pa, high-purity argon gas is introduced as a protective and ionization gas to achieve a vacuum of approximately 0.05 MPa. Electromagnetic stirring is performed while controlling the current during melting to not exceed 400 A, with a melting time of approximately 1 minute per cycle. The ingot is then inverted and melted again, and this melting process is repeated five times to ensure uniformity of the ingot's composition. Subsequently, suction casting is performed using a copper mold to obtain a Ti-3.5Mo-0.2Ni-0.01Ru ingot as shown in Figure 4.

[0038] (3) Rolling process: A Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy ingot is placed in a heating furnace for homogenization, heated at 800°C for 12 hours, and then cooled to room temperature by air cooling. Before rolling, the ingot is placed in a heating furnace and heated at 910°C for 40 minutes, after which it is subjected to rolling deformation in a two-roll hot rolling mill. A multi-pass rolling deformation process is employed, with a total reduction rate of 80% and a pass reduction rate of 40%. Between each rolling pass, the hot-rolled slab is returned to the heating furnace for reheating and heated at 910°C for 2 minutes to ensure the rolling temperature. After rolling is complete, it is air-cooled to obtain a Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy hot-rolled sheet.

[0039] (4) Annealing heat treatment process: A Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy hot-rolled sheet is placed in a heating furnace and subjected to annealing heat treatment at 750°C for 60 minutes. The annealed sheet is then cooled to room temperature by air cooling to obtain a Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy sheet as shown in Figure 5.

[0040] (5) Performance testing: A Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy sheet was cut into corrosion-resistant test pieces, polished, and immediately afterward tested using an electrochemical measuring device. When the polished surface was tested at room temperature under 0.5M sulfuric acid + 5ppmF- solution conditions, a Tafel curve as shown in Figure 6 was obtained, with a pitting potential of 2.4V, which is higher than the pitting potential of pure titanium and TA10, a representative titanium alloy. The bulk resistivity of the Ti-3.5Mo-0.2Ni-0.01Ru titanium alloy is 0.65 μΩ·m, which is close to the resistivity of pure titanium (0.6-0.7 μΩ·m) and lower than that of the Ti-6Al-4V alloy (1.6-1.8 μΩ·m). It exhibits excellent conductivity and can meet the conductivity requirements of bipolar plates.

[0041] Example 3 (1) Raw material blending process: According to the nominal composition of the alloy, Ti-4Mo-0.2Ni-0.01Ru (mass%), titanium particles (purity ≥ 99.99 wt%), high-purity titanium foil (thickness 0.03 mm, purity 99.99 wt%), electrolytic nickel powder (purity 99.99 wt%), electrolytic ruthenium powder (purity 99.99 wt%), and molybdenum particles (purity 99.99 wt%) are weighed and blended as raw materials, with a total weight of 25 g.

[0042] (2) Melting process: The pre-mixed molten raw materials are placed in a water-cooled copper crucible of a non-consumable vacuum arc furnace. Here, the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil, and the inner wall of the copper crucible needs to be pre-cleaned. The inside of the vacuum arc furnace is 5 × 10 -3 After evacuating to below Pa, high-purity argon gas is introduced as a protective and ionization gas to achieve a vacuum of approximately 0.05 MPa. Electromagnetic stirring is performed while controlling the current during melting to not exceed 400 A, with a melting time of approximately 1 minute per cycle. The ingot is then inverted and melted again, and this melting process is repeated five times to ensure uniformity of the ingot's composition. Subsequently, suction casting is performed using a copper mold to obtain a Ti-4Mo-0.2Ni-0.01Ru ingot as shown in Figure 7.

[0043] (3) Rolling process: A Ti-4Mo-0.2Ni-0.01Ru titanium alloy ingot is placed in a heating furnace for homogenization, maintained at 800°C for 12 hours, and then cooled to room temperature by air cooling. Before rolling, the ingot is placed in a heating furnace and kept at 910°C for 40 minutes, after which it is subjected to rolling deformation in a two-roll hot rolling mill. A multi-pass rolling deformation process is employed, with a total reduction rate of 80% and a pass reduction rate of 40%. Between each rolling pass, the hot-rolled slab is returned to the heating furnace for reheating and kept at 910°C for 2 minutes to ensure the rolling temperature is maintained. After the rolling is complete, it is air-cooled to obtain a Ti-4Mo-0.2Ni-0.01Ru titanium alloy hot-rolled sheet.

[0044] (4) Annealing heat treatment process: A Ti-4Mo-0.2Ni-0.01Ru titanium alloy hot-rolled sheet is placed in a heating furnace and subjected to annealing heat treatment at 750°C for 60 minutes. The annealed sheet is then cooled to room temperature by air cooling to obtain the Ti-4Mo-0.2Ni-0.01Ru titanium alloy sheet shown in Figure 8.

[0045] (5) Performance testing: A Ti-4Mo-0.2Ni-0.01Ru titanium alloy sheet was cut into corrosion-resistant test specimens, polished, and immediately afterward tested using an electrochemical measuring device. When the polished surface was tested at room temperature under conditions of 0.5M sulfuric acid + 5ppmF- solution, a Tafel curve as shown in Figure 9 was obtained, with a pitting potential of 2.4V, exceeding that of pure titanium and TA10, a representative titanium alloy.

[0046] The bulk resistivity of the Ti-4Mo-0.2Ni-0.01Ru titanium alloy is 0.6 μΩ·m, which is close to the resistivity of pure titanium (0.6-0.7 μΩ·m) and lower than that of the Ti-6Al-4V alloy (1.6-1.8 μΩ·m). It exhibits excellent conductivity and can meet the conductivity requirements of bipolar plates.

[0047] Example 4 (1) Raw material blending process: According to the nominal composition of the alloy, Ti-3.5Mo-0.2Ni-0.04Ru (mass%), titanium particles (purity ≥ 99.99 wt%), high-purity titanium foil (thickness 0.03 mm, purity 99.99 wt%), electrolytic nickel powder (purity 99.99 wt%), electrolytic ruthenium powder (purity 99.99 wt%), and molybdenum particles (purity 99.99 wt%) are weighed and blended as raw materials, with a total weight of 25 g.

[0048] (2) Melting process: The pre-mixed molten raw materials are placed in a water-cooled copper crucible of a non-consumable vacuum arc furnace. Here, the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil, and the inner wall of the copper crucible needs to be pre-cleaned. The inside of the vacuum arc furnace is 5 × 10 -3After evacuating to below Pa, high-purity argon gas is introduced as a protective and ionization gas to achieve a vacuum of approximately 0.05 MPa. Electromagnetic stirring is performed while controlling the current during melting to not exceed 400 A, with each melting cycle lasting approximately 1 minute. The ingot is then inverted and melted again, and this melting process is repeated five times to ensure uniformity of the ingot's composition. Subsequently, suction casting is performed using a copper mold to obtain a Ti-3.5Mo-0.2Ni-0.04Ru ingot as shown in Figure 10.

[0049] (3) Rolling process: A Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy ingot is placed in a heating furnace for homogenization, heated at 800°C for 12 hours, and then cooled to room temperature by air cooling. Before rolling, the ingot is placed in a heating furnace and heated at 910°C for 40 minutes, after which it is subjected to rolling deformation in a two-roll hot rolling mill. A multi-pass rolling deformation process is employed, with a total reduction rate of 80% and a pass reduction rate of 40%. Between each rolling pass, the hot-rolled slab is returned to the heating furnace for reheating and heated at 910°C for 2 minutes to ensure the rolling temperature. After rolling is complete, it is air-cooled to obtain a Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy hot-rolled sheet.

[0050] (4) Annealing heat treatment process: A Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy hot-rolled sheet is placed in a heating furnace and subjected to annealing heat treatment at 750°C for 60 minutes. The annealed sheet material is then cooled to room temperature by air cooling to obtain a Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy sheet material as shown in Figure 11.

[0051] (5) Performance testing: A Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy sheet was cut into corrosion-resistant test specimens, polished, and immediately afterward tested using an electrochemical measuring device. When the polished surface was tested at room temperature under conditions of 0.5M sulfuric acid + 5ppmF- solution, a Tafel curve as shown in Figure 12 was obtained, with a pitting potential of 2.4V, which is higher than the pitting potential of pure titanium and TA10, a representative titanium alloy.

[0052] The bulk resistivity of the Ti-3.5Mo-0.2Ni-0.04Ru titanium alloy is 0.55 μΩ·m, which is close to the resistivity of pure titanium (0.6-0.7 μΩ·m) and lower than that of the Ti-6Al-4V alloy (1.6-1.8 μΩ·m). This gives it excellent conductivity and allows it to meet the conductivity requirements of bipolar plates.

[0053] Example 5 (1) Raw material blending process: According to the nominal composition of the alloy, Ti-3.5Mo-0.1Ni-0.01Ru (mass%), titanium particles (purity ≥ 99.99 wt%), high-purity titanium foil (thickness 0.03 mm, purity 99.99 wt%), electrolytic nickel powder (purity 99.99 wt%), electrolytic ruthenium powder (purity 99.99 wt%), and molybdenum particles (purity 99.99 wt%) are weighed and blended as raw materials, with a total weight of 25 g.

[0054] (2) Melting process: The pre-mixed molten raw materials are placed in a water-cooled copper crucible of a non-consumable vacuum arc furnace. Here, the electrolytic nickel powder and electrolytic ruthenium powder are wrapped in titanium foil, and the inner wall of the copper crucible needs to be pre-cleaned. The inside of the vacuum arc furnace is 5 × 10 -3 After evacuating to below Pa, high-purity argon gas was introduced as a protective and ionization gas to achieve a vacuum of approximately 0.05 MPa. Electromagnetic stirring was performed while controlling the current during melting to not exceed 400 A, with each melting cycle lasting approximately 1 minute. The ingot was then inverted and melted again, and this melting process was repeated five times to ensure uniformity of the ingot's composition. Subsequently, suction casting was performed using a copper mold to obtain a Ti-3.5Mo-0.1Ni-0.01Ru ingot as shown in Figure 13.

[0055] (3) Rolling process: A Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy ingot is homogenized in a heating furnace, kept at 800°C for 12 hours, and then cooled to room temperature by air cooling. Before rolling, the ingot is placed in a heating furnace and kept at 910°C for 40 minutes, and then subjected to rolling deformation in a two-roll hot rolling mill. A multi-pass rolling deformation process is employed, with a total reduction rate of 80% and a pass reduction rate of 40%. Between each rolling pass, the hot-rolled slab is returned to the heating furnace for reheating and kept at 910°C for 2 minutes to ensure the rolling temperature. After rolling is complete, it is air-cooled to obtain a Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy hot-rolled sheet.

[0056] (4) Annealing heat treatment process: A Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy hot-rolled sheet is placed in a heating furnace and subjected to annealing heat treatment at 750°C for 60 minutes. The annealed sheet material is then cooled to room temperature by air cooling to obtain a Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy sheet material as shown in Figure 14.

[0057] (5) Performance testing: A Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy sheet was cut into corrosion-resistant test pieces, polished, and immediately afterward tested using an electrochemical measuring device. When the polished surface was tested at room temperature under 0.5M sulfuric acid + 5ppmF- solution conditions, a Tafel curve as shown in Figure 15 was obtained, with a pitting potential of 2.4V, which is higher than the pitting potential of pure titanium and TA10, a representative titanium alloy.

[0058] The bulk resistivity of the Ti-3.5Mo-0.1Ni-0.01Ru titanium alloy is 0.63 μΩ·m, which is close to the resistivity of pure titanium (0.6-0.7 μΩ·m) and lower than that of the Ti-6Al-4V alloy (1.6-1.8 μΩ·m). This demonstrates excellent conductivity and can meet the conductivity requirements of bipolar plates.

[0059] The above embodiments merely illustrate the embodiments of the present invention in detail and do not limit the scope of the present invention. Those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the technical concept of the present invention, and all of these are included within the scope of protection of the present invention. Accordingly, the scope of protection of the patent for the present invention shall be defined by the appended claims.

[0060] (Note) (Note 1) A titanium alloy bipolar plate having a high pitting potential and low resistivity, characterized in that, by mass%, its components consist of Mo: 3.0%~5.0%, Ni: 0.1%~0.3%, Ru: 0.005%~0.05%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.1% or less.

[0061] (Note 2) A titanium alloy bipolar plate as described in Appendix 1, characterized in that, by mass%, its components consist of Mo: 3.0% to 5.0%, Ni: 0.1% to 0.3%, Ru: 0.008% to 0.03%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.01% or less.

[0062] (Note 3) A titanium alloy bipolar plate as described in Appendix 2, characterized in that, by mass%, its components consist of Mo: 3.5% to 5.0%, Ni: 0.1% to 0.2%, Ru: 0.01% to 0.03%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.01% or less.

[0063] (Note 4) A method for manufacturing a titanium alloy bipolar plate having a high pitting potential and low resistivity as described in any of Appendix 1 to 3, comprising a raw material blending step, a melting step, a rolling step, and an annealing heat treatment step, A method for producing a titanium alloy bipolar plate having a high pitting potential and low resistivity, characterized in that the raw materials used in the raw material blending step are selected from sponge titanium, titanium foil, electrolytic nickel powder, electrolytic ruthenium powder, and molybdenum particles.

[0064] (Note 5) The method for manufacturing a titanium alloy bipolar plate as described in Appendix 4, characterized in that the melting step uses vacuum arc melting, the current for the vacuum arc melting is 300A to 400A, the number of vacuum arc melting cycles is 4 to 6, and the melting time per cycle is 1 min to 2 min.

[0065] (Note 6) When performing the aforementioned vacuum arc melting, argon gas is introduced as a protective gas and ionization gas, and the vacuum level inside the vacuum arc furnace is set to 5 × 10⁻¹⁰. -3 A method for producing a titanium alloy bipolar plate according to Appendix 4 or 5, characterized by maintaining the temperature below Pa and obtaining a Ti-Mo-Ni-Ru titanium alloy ingot.

[0066] (Note 7) In the rolling process, the Ti-Mo-Ni-Ru titanium alloy ingot obtained by the vacuum arc melting [5.1] is homogenized and then rolled to obtain a Ti-Mo-Ni-Ru titanium alloy slab. A method for manufacturing a titanium alloy bipolar plate as described in Appendix 6, characterized in that the temperature of the homogenization treatment is 700°C to 800°C and the duration is 8 to 12 hours.

[0067] (Note 8) The amount of deformation due to the rolling deformation was 75% to 85% in total. The method for manufacturing a titanium alloy bipolar plate as described in Appendix 7, characterized in that the rolling deformation is performed by rolling through multiple passes, with a deformation amount of 35-45% in each pass, a rolling temperature of 900°C-920°C in each pass, and a heat retention period of 2-3 minutes between each rolling pass.

[0068] (Note 9) A method for manufacturing a titanium alloy bipolar plate as described in Appendix 8, characterized in that, after the homogenization treatment, the Ti-Mo-Ni-Ru titanium alloy ingot is placed in a heating furnace, kept at 910°C for 40 minutes, and then the rolling deformation is performed.

[0069] (Note 10) A method for manufacturing a titanium alloy bipolar plate according to any of the appendices 7 to 9, wherein in the annealing heat treatment step, the Ti-Mo-Ni-Ru titanium alloy slab is placed in a heating furnace, the annealing temperature is controlled to 700°C to 800°C or lower, the holding time is maintained for 50 min to 70 min, and then the plate is cooled to room temperature by air cooling.

Claims

1. A titanium alloy bipolar plate having a high pitting potential and low resistivity, characterized in that, by mass percent, its components consist of Mo: 3.0% to 5.0%, Ni: 0.1% to 0.3%, Ru: 0.005% to 0.05%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.1% or less.

2. The titanium alloy bipolar plate according to claim 1, characterized in that, by mass percent, its components consist of Mo: 3.0% to 5.0%, Ni: 0.1% to 0.3%, Ru: 0.008% to 0.03%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.01% or less.

3. The titanium alloy bipolar plate according to claim 2, characterized in that, by mass percent, its components consist of Mo: 3.5% to 5.0%, Ni: 0.1% to 0.2%, Ru: 0.01% to 0.03%, the remainder being Ti, and impurities Fe, O, C, N, and H with a total content of 0.01% or less.

4. A method for producing a titanium alloy bipolar plate having a high pitting potential and low resistivity according to any one of claims 1 to 3, comprising a raw material blending step, a melting step, a rolling step and an annealing heat treatment step, A method for producing a titanium alloy bipolar plate having a high pitting potential and low resistivity, characterized in that the raw materials used in the raw material blending step are selected from sponge titanium, titanium foil, electrolytic nickel powder, electrolytic ruthenium powder, and molybdenum particles.

5. The method for manufacturing a titanium alloy bipolar plate according to claim 4, characterized in that the melting step uses vacuum arc melting, the current for the vacuum arc melting is 300A to 400A, the number of vacuum arc melting cycles is 4 to 6, and the melting time per cycle is 1 min to 2 min.

6. When performing the aforementioned vacuum arc melting, argon gas is introduced as a protective gas and ionization gas, and the vacuum level inside the vacuum arc furnace is set to 5 × 10⁻¹⁰. －３ A method for producing a titanium alloy bipolar plate according to claim 4 or 5, characterized by maintaining the temperature below Pa to obtain a Ti-Mo-Ni-Ru titanium alloy ingot.

7. In the rolling process, the Ti-Mo-Ni-Ru titanium alloy ingot obtained by the vacuum arc melting is homogenized and then rolled and deformed to obtain a Ti-Mo-Ni-Ru titanium alloy slab. The method for manufacturing a titanium alloy bipolar plate according to claim 6, characterized in that the temperature of the homogenization treatment is 700°C to 800°C and the time is 8 hours to 12 hours.

8. The amount of deformation due to the rolling deformation was 75% to 85% in total. The method for manufacturing a titanium alloy bipolar plate according to claim 7, characterized in that the rolling deformation is performed by rolling through multiple passes, the amount of deformation in each pass is 35 to 45%, the rolling temperature in each pass is 900°C to 920°C, and the temperature is maintained for 2 min to 3 min between each rolling pass.

9. The method for manufacturing a titanium alloy bipolar plate according to claim 8, characterized in that, after the homogenization treatment, the Ti-Mo-Ni-Ru titanium alloy ingot is placed in a heating furnace, heated at 910°C for 40 mins, and then the rolling deformation is performed.

10. A method for manufacturing a titanium alloy bipolar plate according to any one of claims 7 to 9, wherein in the annealing heat treatment step, the Ti-Mo-Ni-Ru titanium alloy slab is placed in a heating furnace, the annealing temperature is controlled to 700°C to 800°C or lower, the holding time is maintained for 50 min to 70 min, and then cooled to room temperature by air cooling.

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