V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance and method for manufacturing the same

Abstract

The application provides a V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance, and the chemical general formula of the rare earth element doped V-based hydrogen separation alloy is V 100‑x‑y‑z Cr x M y N z ; wherein M includes one or more than one element selected from the group consisting of hydrogen-repelling elements Co, Ni, Fe, Al, W, Mo, Cu, Sn and Mn; N is a rare earth element; 20 < x < 25, y < 5 and does not exceed the maximum solid solubility of M in V, 0 < z < 5, x, y and z are all molar percentages; the V-based hydrogen separation alloy has a dual-phase structure, including a V-based solid solution phase and a dispersedly distributed granular second phase. 77 Ag 23 The V-based hydrogen separation alloy provided by the application has excellent hydrogen embrittlement resistance under the premise of ensuring that the permeation rate of the alloy film is higher than that of commercial Pd

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen separation alloy, in particular to a V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance and a preparation method thereof. BACKGROUND

[0002] Pd-based alloy membrane is the only commercialized hydrogen separation alloy membrane at present, which can purify hydrogen in hydrogen-containing mixed gas to obtain high-purity hydrogen (hydrogen purity is greater than 7N (99.99999%)), meeting the requirements of fuel cells and semiconductors on hydrogen purity. However, the high price of Pd hinders its wide application.

[0003] Nb, V and Ta are rich in natural resources and low in price, and have higher hydrogen permeation rate than Pd and its alloys, and are considered as potential substitutes for Pd-based hydrogen separation alloy membranes. However, compared with Pd 77 Ag 23 The Nb, V and Ta-based alloy membranes have poor hydrogen embrittlement resistance, and will be cracked due to hydrogen embrittlement in the hydrogen permeation process. Therefore, the hydrogen embrittlement cracking problem of the V-based alloy membrane has been the focus of researchers.

[0004] In the prior art, researchers introduce a large amount of second phase to improve the hydrogen embrittlement resistance of the alloy membrane, but the permeation performance is significantly reduced.

[0005] Prior art documents:

[0006] Patent document 1: CN106498254A V-Cu-based hydrogen separation alloy and processing method thereof

[0007] Patent document 2: CN1661124A hydrogen separation-refining multi-phase alloy and its manufacturing method, and hydrogen separation-refining metal membrane and its manufacturing method SUMMARY

[0008] The present application aims at the deficiencies of the prior art, and provides a V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance. The V-based hydrogen separation alloy membrane has excellent hydrogen embrittlement resistance under the premise that the hydrogen permeation rate is higher than that of the commercialized Pd 77 Ag 23 alloy membrane, and is low in cost and can be widely applied.

[0009] According to a first aspect of the object of the present application, a V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance is provided. The chemical general formula of the rare earth element-doped V-based hydrogen separation alloy is V 100-x-y-z Cr x M y N z; wherein M comprises one or more than one element selected from the group consisting of Co, Ni, Fe, Al, W, Mo, Cu, Sn, and Mn; N is a rare earth element; 20 < x < 25, y < 5 and does not exceed the maximum solid solubility of M in V, 0 < z < 5, x, y, and z are all molar percentages.

[0010] In an optional embodiment, N comprises one or more than one element selected from the group consisting of Y, La, Ce, Nd, Gd, and Sm.

[0011] In an optional embodiment, the V-based hydrogen separation alloy with hydrogen embrittlement resistance has a dual-phase structure, which is a V-based solid solution phase and a second phase.

[0012] In an optional embodiment, the second phase is in the form of particles and is dispersed in the grain boundaries and inside the grains of the V-based solid solution.

[0013] According to a second aspect of the object of the present application, a method for preparing the aforementioned V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance is provided, comprising the following steps:

[0014] According to the designed V-based hydrogen separation alloy, the mass of each pure metal raw material corresponding to the requirement is calculated and accurately weighed;

[0015] The weighed pure metals are subjected to arc melting under an argon atmosphere to obtain a V-based hydrogen separation alloy ingot doped with rare earth elements and hydrogen-repelling elements.

[0016] In an optional embodiment, the arc melting process is as follows:

[0017] The weighed pure metal raw materials are poured into a clean copper crucible with a clean inner wall, the arc melting furnace is vacuumed, argon is injected at the same time, and the alloy is melted under an argon atmosphere. Each alloy ingot is melted for at least 8 times, and the alloy ingot needs to be turned over each time.

[0018] In an optional embodiment, the vacuum degree of the arc melting furnace is 3-4 x 10 -4 Pa.

[0019] In an optional embodiment, the method further comprises: using an electric rod coupled plasma spectrometer to analyze the rare earth element-doped V-based hydrogen separation alloy ingot to determine the actual content of each element in the V-based hydrogen separation alloy.

[0020] In the optional embodiment, the preparation method further comprises: taking a 1mm-thick and 16mm-diameter disc sample from the rare earth element-doped V-based hydrogen separation alloy ingot by wire cutting technology, polishing and polishing the front and back surfaces of the disc sample to remove cutting marks, stains and make the surface smooth and bright, and the thickness of the polished and polished disc is between 0.6-0.8mm, and plating 200-300nm of palladium on the front and back surfaces of the disc, and then performing hydrogen permeation and slow cooling test.

[0021] In the optional embodiment, the initial cooling temperature of the hydrogen permeation and slow cooling test is 400℃, the hydrogen pressure difference between the upper and lower ends of the disc is 0.7MPa, and the slow cooling speed is between 2-3℃ / min.

[0022] As can be seen from the technical solutions of the present application above, the V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance of the present application, by designing a special alloy composition, a dual-phase V-based alloy with V-based solid solution phase and second phase is obtained, the second phase in the alloy is in the form of particles and is dispersedly distributed in the grain boundaries and grains of the V-based solid solution, which will not significantly affect the hydrogen permeability of the V-based alloy membrane like continuous distribution of the second phase;

[0023] The hydrogen-repellent elements Cr and M are solid-solved in V, which can reduce the hydrogen concentration in the V-based alloy membrane, reduce the lattice distortion and reduce the internal stress of the alloy membrane; at the same time, the addition of the rare earth element N helps to remove the interstitially solid-solved impurity elements C, N, O, etc., reduce the lattice distortion and further reduce the internal stress of the alloy membrane, M and N thus jointly play a role in improving the hydrogen embrittlement resistance of the alloy membrane, and the removal of impurity elements is also beneficial to the improvement of the ductility of the hydrogen separation alloy;

[0024] Therefore, the V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance of the present application has excellent hydrogen embrittlement resistance under the premise that the hydrogen permeability is higher than that of the commercial Pd 77 Ag 23 alloy membrane. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the scanning electron microscope image of the V 74 Cr 25 Ce1 alloy of Example 1 of the present application.

[0026] Figure 2 is the scanning electron microscope image of the V 76 Cr 21 Cu1Ce2 alloy of Example 2 of the present application.

[0027] Figure 3 is the hydrogen permeability of the V-based hydrogen separation alloy membrane and Pd 77 Ag 23 alloy membrane of Examples 1-2 of the present application.

[0028] Figure 4 is the hydrogen permeation slow cooling curve of the V-based hydrogen separation alloy membrane of the embodiment 1-2 of the present application.

[0029] Figure 5 is the slow cooling graph of the V-based hydrogen separation alloy membrane of the embodiment 1-2 of the present application. DETAILED DESCRIPTION

[0030] In order to understand the technical content of the present application, specific embodiments are described below with reference to the accompanying drawings.

[0031] Aspects of the present application are described in the detailed description, drawings, and claims. The embodiments of the present disclosure are not necessarily intended to encompass all aspects of the present application. It should be understood that various concepts and embodiments introduced above and those described in more detail below can be implemented in any of numerous ways, as the skilled artisan will understand.

[0032] The purpose of the present application is to construct a V-based alloy membrane, which has high hydrogen permeation rate and excellent hydrogen embrittlement resistance without introducing a large number of continuous distribution of second phase affecting the permeation performance, so as to ensure the hydrogen permeation rate of the V-based alloy membrane.

[0033] Based on this, in the exemplary embodiments of the present application, a V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance is provided, and the chemical general formula of the rare earth element doped V-based hydrogen separation alloy is V 100-x-y-z Cr x M y N z ; wherein M includes one or more than one element of the hydrogen-repelling elements Co, Ni, Fe, Al, W, Mo, Cu, Sn, and Mn; N is a rare earth element; 20 < x ≤ 25, y ≤ 5 and does not exceed the maximum solid solubility of M in V, 0 < z ≤ 5, x, y, z are all mole percentages.

[0034] In the optional embodiment, N includes one or more than one element of Y, La, Ce, Nd, Gd, and Sm.

[0035] In the optional embodiment, the hydrogen embrittlement resistant V-based hydrogen separation alloy has a dual-phase structure, and the dual-phase structure is a V-based solid solution phase and a second phase.

[0036] In the optional embodiment, the second phase is in the form of particles and is dispersedly distributed in the grain boundaries and intracrystalline of the V-based solid solution.

[0037] According to the second aspect of the purpose of the present application, a preparation method of the aforementioned V-based hydrogen separation alloy with excellent hydrogen embrittlement resistance is provided, which comprises the following steps:

[0038] According to the designed V-based hydrogen separation alloy, the mass corresponding to each pure metal raw material required is calculated, and accurate weighing is performed;

[0039] The weighed each pure metal is subjected to arc melting under an argon atmosphere to obtain a rare earth and hydrogen-repelling element co-doped V-based hydrogen separation alloy ingot.

[0040] In an optional embodiment, the process of arc melting is as follows:

[0041] The weighed each pure metal raw material is poured into a clean copper crucible with a clean inner wall, the arc melting furnace is vacuumed, argon is flushed in, and the alloy is melted under an argon atmosphere. Each alloy ingot is melted for at least 8 times, and the alloy ingot needs to be turned over each time.

[0042] In an optional embodiment, the vacuum degree of the arc melting furnace is 3-4×10 -4 Pa.

[0043] In an optional embodiment, the preparation method further comprises: using an electric pole coupled plasma spectrometer to perform element analysis on the rare earth element doped V-based hydrogen separation alloy ingot to determine the actual content of each element in the V-based hydrogen separation alloy.

[0044] In an optional embodiment, the preparation method further comprises: using a wire cutting technology to cut a 1mm thick and 16mm diameter disc sample from the rare earth element doped V-based hydrogen separation alloy ingot, polishing and polishing the front and back surfaces of the disc sample to remove cutting marks and stains, making the surface smooth and bright, and the thickness of the polished and polished disc is between 0.6-0.8mm, plating 200-300nm of palladium on the front and back surfaces of the disc, and then performing hydrogen permeation and slow cooling test.

[0045] In an optional embodiment, the initial cooling temperature of the hydrogen permeation and slow cooling test is 400℃, the hydrogen pressure difference between the upper and lower ends of the disc is 0.7MPa, and the slow cooling speed is between 2-3℃ / min.

[0046] In a typical example embodiment, the aforementioned V-based hydrogen separation alloy with hydrogen embrittlement resistance is prepared by the following steps:

[0047] Step 1, raw material composition calculation: calculate the mass of pure metals required for V 100-x-y-z Cr x M y N z hydrogen separation alloy.

[0048] Weighing: using an electronic balance with an accuracy of one ten-thousandth to weigh the mass of each pure metal in the raw material of the V 100-x-y-z Cr x M y N z alloy.

[0049] Step 2, arc melting: polish the inner wall of the copper crucible in the vacuum arc melting furnace with sandpaper, clean the crucible and the inner wall of the arc melting furnace with ethanol, then pour the metal raw material into the copper crucible; then, first vacuumize the arc melting furnace with a mechanical pump, then perform 2 times of argon cleaning and mechanical pump vacuumization; after the last mechanical pump vacuumization, continue to vacuumize with a molecular pump, when the vacuum degree reaches 3-4*10 -4 Pa, stop vacuumizing, then flush argon into the arc melting furnace, then perform arc melting on the alloy raw material in the argon atmosphere, control the melting current between 200-400A, in order to improve the uniformity of the alloy ingot composition, at least melt 8 times for each alloy ingot, and turn over the alloy ingot during each melting.

[0050] Step 3, wire cutting and sample polishing: use the wire cutting technology to cut a 1mm-thick and 16mm-diameter disc sample from the V-based alloy ingot prepared by arc melting, polish and polish the surface of the disc sample, remove the cutting marks and stains, and make the surface smooth and bright.

[0051] Step 4, surface Pd plating: use magnetron sputtering to plate a 200-300nm-thick Pd layer on the front and back surfaces of the polished disc sample, for hydrogen permeability and hydrogen embrittlement resistance performance testing.

[0052] The V-based hydrogen separation alloy membrane of the present application has a hydrogen flux of 0 when the temperature cools to a certain value during the hydrogen permeation slow cooling process, and the alloy membrane will not be broken due to hydrogen embrittlement, and has excellent hydrogen embrittlement resistance.

[0053] The present application will be further described by examples.

[0054] Unless otherwise specified, the materials in the examples are prepared according to the existing method, or directly purchased from the market as commercial raw materials.

[0055] Example 1

[0056] Calculate the mass of pure V, Cr and Ce in the V 74 Cr 25 Ce1 alloy, and the mass is 28.944g, 9.98g and 1.076g respectively.

[0057] Use a millionth electronic balance to weigh V 74 Cr 25 Ce1 alloy.

[0058] The inner wall of the copper crucible in the vacuum arc melting furnace is polished with sandpaper, and the crucible and the inner wall of the arc melting furnace are cleaned with ethanol, and then the metal raw material is poured into the copper crucible; then the arc melting furnace is first vacuumed by a mechanical pump, and then vacuumed by a mechanical pump twice; after the last mechanical pump vacuuming, continue to vacuum with a molecular pump, when the vacuum degree reaches 4×10 -4 Pa, stop vacuuming, then flush argon into the arc melting furnace, then arc melt the alloy raw material in the argon atmosphere, and the melting current is 400A; in order to improve the uniformity of the alloy ingot composition, each alloy ingot is melted 8 times, and the alloy ingot is turned over each time.

[0059] The V 74 Cr 25 Ce1 alloy ingot is taken off from the alloy ingot, and a round sample with a thickness of 1mm and a diameter of 16mm is taken off.

[0060] The front and back surfaces of the round sample are polished in sequence using 240, 600 and 1200 grit sandpaper to remove oil stains and cutting marks, and then the front and back surfaces of the sample polished by sandpaper are polished in sequence using 2.5μm, 1μm and 50nm silicon oxide suspension until the surface is clean and smooth, and finally the thickness of the round sample is about 0.75. Then, the polished and polished V 74 Cr 25 Ce1 alloy is analyzed by scanning electron microscope and the front and back surfaces are plated with about 200nm thick palladium layer.

[0061] Example 2

[0062] The mass of the V 76 Cr 21 Cu1Ce2 alloy is calculated, and the mass of pure V, Cr, Cu and Ce is 29.179g, 8.23g, 0.479g and 2.112g respectively.

[0063] The mass of the V 76 Cr 21 Cu1Ce2 alloy is calculated.

[0064] The inner wall of the copper crucible in the vacuum arc melting furnace is polished with sandpaper, and the crucible and the inner wall of the arc melting furnace are cleaned with ethanol, and then the metal raw material is poured into the copper crucible; then the arc melting furnace is first vacuumed by a mechanical pump, and then vacuumed by a mechanical pump twice; after the last mechanical pump vacuuming, continue to vacuum with a molecular pump, when the vacuum degree reaches 4×10 -4At 8 Pa, the vacuuming is stopped, and then argon is injected into the arc melting furnace, and then the alloy raw material is arc melted in an argon atmosphere, and the melting current is 400 A; in order to improve the uniformity of the alloy ingot composition, each alloy ingot is melted 8 times, and the alloy ingot is turned over each time.

[0065] The V 76 Cr 21 The round sample with a thickness of 1 mm and a diameter of 16 mm is taken from the Cu1Ce2 alloy ingot.

[0066] The front and back surfaces of the round sample are polished with 240, 600 and 1200 grit sandpaper in sequence to remove oil stains and cutting marks, and then the front and back surfaces of the sample polished by sandpaper are polished with 2.5 μm, 1 μm and 50 nm silicon oxide suspensions in sequence until the surface is clean and smooth, and finally the thickness of the round sample is about 0.7. Then, the polished and polished V 76 Cr 21 The Cu1Ce2 alloy is subjected to scanning electron microscope analysis and the back surface is plated with a palladium layer with a thickness of about 200 nm.

[0067] The following tests use samples prepared by the method of Example 1 and Example 2.

[0068] Scanning electron microscopy analysis

[0069] Figure 1 It is shown that the V 74 Cr 25 The Ce1 alloy is a dual-phase structure, and the white granular second phase is dispersedly distributed in the grain boundaries and grains of the V-based solid solution.

[0070] Figure 2 It is shown that the V 76 Cr 21 The Cu1Ce2 alloy is a dual-phase structure, and the white granular second phase is dispersedly distributed in the grain boundaries and grains of the V-based solid solution.

[0071] Hydrogen permeation rate and hydrogen embrittlement resistance

[0072] The hydrogen permeation experiment and the hydrogen embrittlement experiment both use a hydrogen permeation device produced by Nanjing Gaogan Company.

[0073] Hydrogen permeation experiment: Put the Pd-coated alloy membrane into the mold, seal with oxygen-free copper gasket, and slowly tighten the mold. Use high-purity nitrogen to clean the pipeline, then increase the gas pressure and check the pipeline airtightness. If the airtightness is good, open the mechanical pump for vacuumizing, and at the same time, open the heating device to heat to 400℃ at a rate of 10℃ / min. After the temperature is stable, close the mechanical pump, fill 50kPa pressure hydrogen into the membrane upper end of the pipeline and keep for 2.5h for activation treatment. After activation, set 100kPa, 150kPa, 200kPa, 250kPa, 300kPa, 350kPa, 400kPa, 450kPa, 500kPa, 550kPa, 600kPa, 650kPa, 700kPa hydrogen pressure on the upper end of the pipeline in turn, and record the hydrogen flow rate through the mass flow meter when the pressure and flow rate are stable, and calculate the hydrogen flux J. Then, according to Φ = J·d / △P 0.5 , the permeation rate Φ is obtained by linear fitting of the graph with △P 0.5 as the horizontal coordinate and Jd as the vertical coordinate, wherein △P 0.5 = Pu 0.5 -Pd 0.5 , P u , P d are the hydrogen pressures at the upper and lower ends of the membrane respectively, and d is the membrane thickness.

[0074] Hydrogen embrittlement resistance experiment: The process is similar to the above, after the activation treatment of the membrane, the hydrogen pressure difference is set to 700kPa, and the cooling is started at a rate of 2.5℃ / min at 400℃. The relationship between temperature and hydrogen flow rate is analyzed, and the slow cooling curve is drawn. When the flow rate suddenly increases, it means that the membrane cracks. When the flow rate cools to a certain temperature of 0, it means that the membrane does not crack, and the hydrogen embrittlement resistance is excellent.

[0075] Figure 3 V 74 Cr 25 Ce1and V 76 Cr 21 Cu1Ce2alloy membrane hydrogen permeation rate is 2.6×10 -8 , 3.2×10 - 8 mol·m -1 ·s -1 ·Pa -0.5 , which is higher than the hydrogen permeation rate of commercial Pd 77 Ag 23 alloy membrane under the same conditions (2.52×10 - 8 mol·m -1 ·s -1 ·Pa -0.5 ), which meets the prerequisite condition of hydrogen permeation rate.

[0076] Figure 4 Medium V 74 Cr 25 Ce1 and V 76 Cr 21 The slow cooling curve of the hydrogen embrittlement resistance of the Cu1Ce2 alloy film, the hydrogen flow F of the two alloys is 0 when slowly cooling to a certain temperature, and Figure 5 The surface of the three alloy films after slow cooling is complete without cracks, indicating that the alloy film is not broken and has excellent hydrogen embrittlement resistance.

[0077] As can be seen from the above, the V-based hydrogen separation alloy with hydrogen embrittlement resistance is successfully prepared, and the alloy film prepared by using the V-based hydrogen separation alloy with hydrogen embrittlement resistance has excellent hydrogen embrittlement resistance under the premise of ensuring higher permeability than commercial Pd-based alloy film.

[0078] Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Those skilled in the art can make various modifications and improvements without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the definition of the claims.

Claims

1. A V-based hydrogen separation alloy with excellent resistance to hydrogen embrittlement, characterized in that, The general chemical formula of rare earth element-doped V-based hydrogen separation alloys is V. 100-x-y-z Cr x M y N z Wherein, M includes one or more of the hydrogen-repellent elements Co, Ni, Fe, Al, W, Mo, Cu, Sn, and Mn; N is a rare earth element; 20 < x ≤ 25, y ≤ 5 and not exceeding the maximum solid solubility of M in V, 0 < z ≤ 5, and x, y, and z are all mole percentages.

2. The V-based hydrogen separation alloy with excellent resistance to hydrogen embrittlement according to claim 1, characterized in that, N includes one or more elements selected from Y, La, Ce, Nd, Gd, and Sm.

3. The V-based hydrogen separation alloy with excellent resistance to hydrogen embrittlement according to claim 1, characterized in that, The hydrogen-resistant V-based hydrogen separation alloy has a dual-phase structure, which consists of a V-based solid solution phase and a second phase.

4. The V-based hydrogen separation alloy with excellent resistance to hydrogen embrittlement according to claim 3, characterized in that, The second phase is granular and dispersed in the grain boundaries and within the grains of the V-based solid solution.

5. A method for preparing a V-based hydrogen separation alloy with excellent resistance to hydrogen embrittlement as described in any one of claims 1-4, characterized in that, Includes the following steps: Based on the designed V-based hydrogen separation alloy, calculate the required mass of each pure metal raw material and weigh them accurately. The weighed pure metals were subjected to arc melting in an argon atmosphere to obtain a V-based hydrogen separation alloy ingot co-doped with rare earth and hydrogen-repellent elements.

6. The preparation method according to claim 5, characterized in that, The electric arc melting process is as follows: The weighed pure metal raw materials are poured into a clean copper crucible. The electric arc melting furnace is evacuated and argon gas is introduced at the same time. The alloy is melted in an argon atmosphere. Each alloy ingot is melted at least 8 times, and the alloy ingot needs to be turned over each time it is melted.

7. The preparation method according to claim 6, characterized in that, The vacuum degree of the electric arc melting furnace is (3~4)×10 - 4 Pa.

8. The preparation method according to claim 5, characterized in that, The preparation method also includes: using pole-coupled plasma spectrometry to perform elemental analysis on rare earth element-doped V-based hydrogen separation alloy ingots to determine the actual content of each element in the V-based hydrogen separation alloy.

9. The preparation method according to claim 5, characterized in that, The preparation method also includes: taking a 1 mm thick and 16 mm diameter circular sample from a rare earth element doped V-based hydrogen separation alloy ingot using wire cutting technology, grinding and polishing both sides of the circular sample to remove cutting marks and stains, making the surface smooth and bright. After grinding and polishing, the thickness of the circular sample is between 0.6 and 0.8 mm. 200 to 300 nm palladium is plated on both sides of the circular sample, and then a hydrogen permeation slow cooling test is performed.

10. The preparation method according to claim 9, characterized in that, The initial cooling temperature for the hydrogen permeation slow cooling test was 400 ℃, the hydrogen pressure difference between the upper and lower ends of the disc was 0.7 MPa, and the slow cooling rate was between 2-3 ℃ / min.

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