Corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plate and industrialized manufacturing method thereof

Abstract

The application discloses a kind of corrosion-resistant high plasticity titanium alloy foil for wide bipolar plate and its industrialized preparation method, in view of the high requirements of fuel cell bipolar plate to conductivity and corrosion resistance, using Ni, Nb, Cu micro-alloying design, improve the corrosion resistance and plasticity of material;Adopting three vacuum self-consumption smelting method, guarantee titanium alloy ingot composition uniformity, through hot rolling, cold rolling, degreasing pickling, annealing and other processes, obtain 0.08~0.15mm thickness specification titanium alloy foil.The titanium alloy foil has excellent seawater corrosion resistance and plasticity, can meet the forming requirement of processing thickness ≥0.08mm, and can adapt to the service environment of hydrogen fuel cell bipolar plate, can replace the stainless steel substrate used in the present stage bipolar plate, achieve the effect of weight reduction, improve the corrosion resistance of substrate, thereby greatly prolong the service life of battery, will effectively solve the bottleneck problems of current domestic proton exchange membrane battery substrate, such as poor comprehensive performance, high manufacturing cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen fuel cells, and particularly relates to a corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plates and an industrial production method thereof. BACKGROUND

[0002] The bipolar plate is a key component of a proton exchange membrane fuel cell (PEMFC), and the quality of the bipolar plate accounts for about 70% of the entire cell stack, and the cost accounts for about 40% of the entire cell stack. The bipolar plate titanium alloy substrate has excellent corrosion resistance, higher specific strength, and light weight. The bipolar plate can be roughly divided into three types: carbon materials, metal materials, and composite materials of metal and carbon. Among them, aluminum, nickel, titanium, and stainless steel can be used to manufacture bipolar plates. The metal bipolar plate is easy to process, can be mass-produced, has low cost, is thin, and has high volume specific power and specific energy of the battery. The pure titanium bipolar plate has excellent corrosion resistance, but has high resistance and poor conductivity, which cannot meet the requirements of the conductivity of the bipolar plate. In the prior art, such as the patent "Preparation method of fine-grain TA15 titanium alloy foil" with publication number CN113578959A, cladding rolling is adopted, the manufacturing process is complicated, the manufacturing cost is high, the prepared titanium alloy foil has fine grains, and the foil prepared by the method has high strength and low plasticity, which is not conducive to the later forming of the bipolar plate. SUMMARY

[0003] To overcome the defects of the prior art, the application aims at the high requirements of the fuel cell bipolar plate on conductivity and corrosion resistance, improves the corrosion resistance and plasticity of the titanium alloy by micro-alloying the titanium alloy, ensures the uniformity of the titanium alloy ingot by adopting a three-time vacuum self-consumption smelting method, and finally obtains a titanium alloy foil with a thickness of 0.08mm to 0.15mm through processes such as hot rolling, cold rolling, degreasing and pickling, and annealing; and further realizes the mass production of the new type of wide titanium alloy bipolar plate, greatly improves the service life of the titanium alloy bipolar plate, and reduces the production cost.

[0004] To achieve the above-mentioned application purposes, the application provides a corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plates. The composition design of the titanium alloy foil is as follows: a small amount of Ni, Nb, and Cu alloy elements are added to improve the conductivity and corrosion resistance of the titanium substrate, and the element addition amount is (mass percentage): 0.01%≤[Ni]≤0.08%, 1%≤[Nb]≤2%, 0.05%≤[Cu]≤1.5%, the balance is titanium element and unavoidable impurities. In view of the high requirements of the fuel cell bipolar plate on conductivity and corrosion resistance, the Ni, Nb, and Cu micro-alloying design improves the corrosion resistance and plasticity of the material.

[0005] An industrial production method of the above-mentioned corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plates, the industrial production method comprises the following process scheme:

[0006] ① Vacuum consumable furnace smelting: using 0A grade sponge titanium, high purity copper (purity ≥ 99.9%), high purity nickel powder (purity ≥ 99.9%), high purity niobium powder (purity ≥ 99.9%) as raw materials, according to the mass percentage of the composition design of the titanium alloy foil, three times of vacuum consumable furnace smelting is carried out, the vacuum degree in the vacuum consumable furnace during smelting is ≤ 3.0 Pa, the stable arc current is 5-12 A, the smelting voltage is 20-40 V, the smelting current is 10-30 kA, and Φ 300-600 mm ingots are obtained. The ingots are peeled and flattened to remove surface oxides and impurities, and then hot worked after surface polishing.

[0007] The vacuum consumable furnace smelting method is adopted, which has good non-metallic impurity removal capability and can ensure the purity and composition uniformity of the titanium alloy ingot.

[0008] ② Plate forging processing: the ingot obtained in step ① is forged for three times, the heating temperature of the first forging is 1050-1150℃, and the holding time is 180-360 min; the heating temperature of the second forging is 950-1050℃, and the holding time is 120-360 min; the heating temperature of the third forging is 850-950℃, and the holding time is 120-360 min, and the plate with a thickness of 200-250 mm is forged, and after milling processing, the plate is rolled.

[0009] ③ Hot rolling and cold rolling processing: the plate obtained in step ② is hot rolled for multiple times to obtain hot rolled plate with a thickness of 3-4 mm, and after annealing treatment and surface polishing treatment at 500-650℃, the hot rolled plate is cold rolled to obtain cold rolled strip with a thickness of 1-1.5 mm, and the annealing temperature is 500-650℃.

[0010] ④ Foil rolling: the cold rolled strip obtained in step ③ is rolled into foil by 20-roll narrow titanium strip rolling mill for multiple rolling processes, and when the thickness of the strip is 0.3-0.4 mm, the strip is annealed online at 500-650℃, and finally the titanium alloy foil with a width of 450-550 mm and a thickness of 0.08-0.15 mm is obtained.

[0011] The 20-roll narrow titanium strip rolling mill ensures the accuracy of the width and thickness of the foil and industrial production.

[0012] ⑤ Product annealing: the titanium alloy foil obtained in step ④ is annealed by using a vacuum annealing furnace with a vacuum degree ≤ 10 -3 Pa, an annealing temperature of 650-750℃, and an annealing time of 7-10 h.

[0013] The titanium alloy foil is annealed by using a vacuum annealing furnace with high vacuum degree, so that the surface of the foil is prevented from being polluted by oxides, and the cleanliness of the surface is ensured, and long-time annealing is adopted, which is beneficial to improving the formability of the foil.

[0014] In the technical scheme, further, the impurity element content of the 0A grade titanium sponge is [C] %≤0.01 %, [N] %≤0.01 %, [O] %≤0.04 %, [H] %≤0.001 %, and [Fe] %≤0.02 %; the impurity element content of the high-purity nickel powder is [Fe] %≤0.05 %, [N] %≤0.01 %, and [O] %≤0.04 %; the impurity element content of the high-purity niobium powder is [Fe] %≤0.05 %, [N] %≤0.01 %, and [O] %≤0.04 %; and the impurity element content of the high-purity copper is [Fe] %≤0.05 %, [N] %≤0.01 %, and [O] %≤0.04 %.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The titanium alloy foil for bipolar plates prepared by the process scheme of the present application has excellent seawater corrosion resistance and plasticity, can meet the forming requirements of titanium alloy foils with a thickness of ≥0.08 mm, can adapt to the service environment of hydrogen fuel cell bipolar plates, is an ideal bipolar plate material, can replace the stainless steel substrate used in the current bipolar plates, achieves the effect of weight reduction, improves the corrosion resistance of the substrate, and greatly prolongs the service life of the battery, thereby effectively solving the bottleneck problems of poor comprehensive performance of domestic proton exchange membrane battery substrates and high manufacturing cost. DETAILED DESCRIPTION

[0017] The present application is further described below in combination with specific embodiments, but the present application is not limited in any way by the embodiments. To avoid redundancy, in the following embodiments, the raw materials are all commercially available products if not otherwise specified, and the methods used are all conventional methods if not otherwise specified.

[0018] The obtained titanium alloy foils are subjected to tensile property, tensile strength, elongation, and corrosion current tests, and the thickness deviation of the foils is measured; the corrosion current test method is in accordance with the national standard GB / T20042.6-2011 “Proton Exchange Membrane Fuel Cell Part 6: Bipolar Plate Property Test Method”; the thickness and mechanical property test methods are in accordance with the standards YB / T 4432-2014 and GB / T228.1-2010, respectively.

[0019] Example 1

[0020] The titanium alloy foil material for wide bipolar plate has the following component design: trace amounts of Ni, Nb and Cu are added to improve the conductivity and corrosion resistance of the titanium base material, and the element addition amount is [Ni]%=0.03%, [Nb]%=1.5%, [Cu]%=0.08%, the balance is titanium element and inevitable impurities.

[0021] The industrial production method of the titanium alloy foil material for wide bipolar plate has the following process scheme:

[0022] ① Vacuum consumable furnace smelting: 0A grade titanium sponge, high-purity Cu (purity ≥ 99.9%), high-purity nickel powder (purity ≥ 99.9%) and high-purity niobium powder (purity ≥ 99.9%) are used as raw materials, and the mass percentage of the component design of the titanium alloy foil material is used for batching, three times of vacuum consumable furnace smelting is carried out, the vacuum degree in the vacuum consumable furnace during smelting is ≤3.0 Pa, the arc current of three times of vacuum smelting is 6A, 9A and 11A respectively, the smelting voltage of three times of vacuum smelting is 28V, 32V and 35V respectively, and the smelting current of three times of vacuum smelting is 16kA, 21kA and 25kA respectively to obtain Φ550mm specification ingot, which is peeled and flat-headed to remove surface oxides and impurities, and then is subjected to hot working after surface polishing.

[0023] ② Slab forging processing: the ingot obtained in step ① is subjected to three times of forging, the heating temperature of the first forging is 1150℃, the holding time is 330min; the heating temperature of the second forging is 1050℃, the holding time is 330min; the heating temperature of the third forging is 950℃, the holding time is 330min, the slab with a thickness of 200mm is forged, and after milling processing, the slab is subjected to plate rolling.

[0024] ③ Hot rolling and cold rolling processing: the slab obtained in step ② is subjected to multiple times of hot rolling processing to obtain 3.5mm thickness specification hot rolled plate, after annealing treatment and surface polishing treatment of the hot rolled plate at 600℃, the cold rolling processing is carried out, and the 1.5mm thickness specification cold rolled strip is rolled, and the on-line stress relief annealing treatment is carried out at 600℃.

[0025] ④ Foil rolling: the cold rolled strip obtained in step ③ is subjected to multiple rolling processes of foil rolling by using a 20-roll narrow titanium strip rolling mill, when the thickness of the strip is 0.3mm, the on-line stress relief annealing is carried out at an annealing temperature of 650℃, and finally the titanium alloy foil material with a width of 500mm and a thickness of 0.1mm is obtained.

[0026] ⑤ Product annealing: the foil material in step ④ is subjected to annealing treatment, a vacuum annealing furnace is used, the furnace vacuum degree is ≤10 -3 Pa, the annealing temperature is 700℃, and the annealing time is 8h.

[0027] The performance test results of the titanium alloy foil obtained in Example 1 are shown in Table 1.

[0028] Example 2

[0029] A corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plates, the titanium alloy foil having a component design of trace addition of Ni, Nb, and Cu alloying elements to improve the electrical conductivity and corrosion resistance of the titanium base material, the element addition amounts being [Ni] % = 0.05%, [Nb] % = 1.0%, [Cu] % = 1.2%, the balance being titanium elements and unavoidable impurities.

[0030] An industrial production method of the above-mentioned corrosion-resistant high-plasticity titanium alloy foil for wide bipolar plates, the industrial production method comprising the following process scheme:

[0031] ① Vacuum consumable furnace melting: using 0A grade titanium sponge, high-purity Cu (purity ≥ 99.9%), high-purity nickel powder (purity ≥ 99.9%), and high-purity niobium powder (purity ≥ 99.9%) as raw materials, and according to the mass percentage of the component design of the titanium alloy foil, the raw materials are proportioned and subjected to three times of vacuum consumable furnace melting, the vacuum degree in the vacuum consumable furnace during the melting process is ≤ 3.0 Pa, the arc current for the three times of vacuum melting is 6 A, 9 A, and 11 A respectively, the melting voltage for the three times of vacuum melting is 28 V, 32 V, and 35 V respectively, and the melting current for the three times of vacuum melting is 16 kA, 21 kA, and 25 kA respectively to obtain a Φ500 mm size ingot, which is subjected to skinning and flat head processing to remove surface oxides and impurities, and then is subjected to hot working after surface polishing.

[0032] ② Slab forging processing: the ingot obtained in step ① is subjected to three times of forging. The heating temperature for the first time of forging is 1100℃, and the holding time is 300 min; the heating temperature for the second time of forging is 1000℃, and the holding time is 300 min; the heating temperature for the third time of forging is 900℃, and the holding time is 300 min. The forging is a slab with a thickness of 250 mm, which is subjected to milling processing and then is subjected to plate rolling.

[0033] ③ Hot rolling and cold rolling processing: the slab obtained in step ② is subjected to multiple times of hot rolling processing to obtain a 3.5 mm thickness size hot rolled plate, which is subjected to annealing treatment at 600℃ and surface polishing treatment, and then is subjected to cold rolling processing to be rolled into a 1.5 mm thickness size cold rolled strip, which is subjected to online stress relief annealing treatment at an annealing temperature of 600℃.

[0034] ④ Foil rolling: the cold rolled strip obtained in step ③ is subjected to multiple rolling processes of foil rolling by using a 20-roll narrow titanium strip rolling mill, and when the thickness of the strip is 0.3 mm, online stress relief annealing is performed at an annealing temperature of 650℃, and finally a titanium alloy foil with a width of 500 mm and a thickness of 0.1 mm is obtained.

[0035] ⑤ Finished product annealing: The foil obtained in step ④ is annealed using a vacuum annealing furnace with a vacuum degree ≤10. -3 Pa, annealing temperature 700℃, annealing time 8h.

[0036] The performance test results of the titanium alloy foil obtained in Example 2 are shown in Table 1.

[0037] Table 1. Performance test results of titanium alloy foil obtained in the examples and comparative examples.

[0038] Comparative Example - Pure Titanium TA1 Example 1 Example 2 Room Temperature Tensile Strength (MPa) 230 350 420 Elongation (%) 34 38 35 Foil Thickness (mm) 0.1 0.1 0.1 Foil Thickness Deviation (mm) 0.002 0.002 0.002 Corrosion current (A / cm 2 ) 4.13 x 10 -6 ]] 4.3 x 10 -7 ]] 3.4 x 10 -7 ]]>

[0039] As shown in Table 1, the titanium alloy foil prepared in Example 1 has a room temperature tensile strength of 350 MPa, an elongation of 38%, a foil thickness deviation of no more than ±0.005 mm, and a corrosion current of no more than 4.5 × 10⁻⁶. -7 A / cm 2 The titanium alloy foil prepared in Example 2 has a room temperature tensile strength of 420 MPa, an elongation of 35%, a foil thickness deviation of no more than ±0.005 mm, and a corrosion current of no more than 3.5 × 10⁻⁶ mm. -7 A / cm 2 The comparative example, pure titanium TA1, exhibited lower plasticity than Examples 1-2, higher corrosion current, and poorer corrosion resistance.

[0040] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A corrosion-resistant, high-ductility titanium alloy foil for wide-width bipolar plates, characterized in that, The titanium alloy foil is designed with the following composition: Ni, Nb, and Cu alloying elements are added in trace amounts, with the following mass percentages: 0.01% ≤ [Ni]% ≤ 0.08%, 1% ≤ [Nb]% ≤ 2%, 0.05% ≤ [Cu]% ≤ 1.5%, and the balance being titanium and unavoidable impurities. The industrial manufacturing method for the corrosion-resistant, high-ductility titanium alloy foil used in the wide-width bipolar plate includes the following process: ① Vacuum self-consuming furnace smelting: 0A grade sponge titanium, high-purity copper, high-purity nickel powder, and high-purity niobium powder are used as raw materials. The raw materials are prepared according to the mass percentage of the titanium alloy foil composition design. The process involves three vacuum self-consuming furnace smeltings. During the smelting process, the vacuum degree in the vacuum self-consuming furnace is ≤3.0Pa, the arc stabilizing current is 5~12A, the smelting voltage is 20~40V, and the smelting current is 10~30kA. Ingots with a specification of Φ300~600mm are obtained. The ingots are peeled and flattened to remove surface oxides and impurities. After the surface is polished, they are subjected to heat treatment. ② Slab forging: The ingot obtained in step ① is forged in three stages. The first stage forging is heated at 1050℃~1150℃ and held for 180~360min; the second stage forging is heated at 950℃~1050℃ and held for 120~360min; the third stage forging is heated at 850℃~950℃ and held for 120~360min, forging into a slab with a thickness of 200~250mm. After milling, the slab is rolled. ③ Hot rolling and cold rolling: The slab obtained in step ② is subjected to multiple hot rolling processes to obtain hot-rolled plates with a thickness of 3-4 mm. After annealing and surface polishing at 500℃-650℃, the hot-rolled plates are cold-rolled to obtain cold-rolled strips with a thickness of 1-1.5 mm. The strips are then subjected to online stress-relief annealing at an annealing temperature of 500℃-650℃. ④ Foil rolling: The cold-rolled strip obtained in step ③ is rolled into foil through multiple passes using a 20-roll narrow titanium strip mill. When the strip thickness is 0.3 to 0.4 mm, online stress-relief annealing is performed at a temperature of 500℃ to 650℃. Finally, titanium alloy foil with a width of 450 mm to 550 mm and a thickness of 0.08 mm to 0.15 mm is obtained. ⑤ Finished product annealing: The titanium alloy foil obtained in step ④ is annealed using a vacuum annealing furnace with a vacuum degree ≤10. -3 Pa, annealing temperature 650℃~750℃, annealing time 7~10h.

2. The corrosion-resistant, high-ductility titanium alloy foil for wide-width bipolar plates according to claim 1, characterized in that, In step ①, the purity of the high-purity nickel powder, high-purity niobium powder, and high-purity copper is ≥99.9%; the impurity element content of the 0A grade sponge titanium is [C]%≤0.01%, [N]%≤0.01%, [O]%≤0.04%, [H]%≤0.001%, and [Fe]%≤0.02%; the impurity element content of the high-purity nickel powder is [Fe]%≤0.05%, [N]%≤0.01%, and [O]%≤0.04%; the impurity element content of the high-purity niobium powder is [Fe]%≤0.05%, [N]%≤0.01%, and [O]%≤0.04%; and the impurity element content of the high-purity copper is [Fe]%≤0.05%, [N]%≤0.01%, and [O]%≤0.04%.