AB5 type rare earth iron-based single-phase hydrogen storage alloy and preparation method thereof

Abstract

The invention discloses an AB5 type rare earth iron-based single-phase hydrogen storage alloy and a preparation method thereof, and the preparation method comprises the following steps: selecting a high-purity metal simple substance, burdening according to set components, and preparing an alloy ingot in an argon atmosphere by adopting electric arc melting; and taking a part of cast ingot alloy, and carrying out rapid quenching treatment in a melt-spinning furnace. The problem that an AB5 type single phase cannot be obtained is solved by adjusting the proportion of the Y element and the Fe element in the alloy, matching with rapid quenching treatment and optimizing the phase composition of the alloy, and the alloy has the advantages of being simple in preparation process and excellent in hydrogen storage performance and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen storage alloys, and in particular relates to a method for mechanically preparing an AB5 type YFe5 single-phase hydrogen storage alloy. Background Art

[0002] Rare earth (Re)-based metal alloys can store hydrogen at room temperature and pressure and are an ideal hydrogen storage material. Rare earth nickel-based hydrogen storage alloys are currently widely used rare earth hydrogen storage materials, but the high cost of nickel restricts their large-scale application in the field of hydrogen energy storage. Research on the reversible hydrogen storage function of non-nickel-based rare earth alloys is still very limited.

[0003] ReFe5 alloys have the same CaCu5 crystal structure as Ni-based hydrogen storage alloys. However, rare earth elements cannot directly obtain CaCu5 phases by smelting with Fe. Literature reports that ReFe5 phases with CaCu5 structure are mostly metastable phases, and their single-phase structure is difficult to form. From the Re-Fe binary phase diagram, it can be seen that the stable structures of rare earth iron-based alloy phases mainly include ReFe2, ReFe3, Re2Fe 17 and Re6Fe 23 Phase structure, however, the research on these iron-rich rare earth iron-based alloys is mainly concentrated in the field of magnetic materials, and there is little research on their hydrogen storage properties, and their reversible hydrogen storage properties have not been explored. At the same time, although some scholars have successfully prepared ReFe5 phase in the alloy by alloying and adjusting the heat treatment process, this is usually accompanied by the presence of a second phase, which seriously affects the stability of the alloy structure; at the same time, the preparation process is complicated and difficult to prepare in batches efficiently. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an AB5 type rare earth iron-based single-phase hydrogen storage alloy and a preparation method thereof by regulating the element composition ratio and adjusting the operating parameters of the rapid quenching process.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for preparing a hydrogen storage alloy having an AB5 type YFe5 single-phase structure comprises the following steps:

[0007] S1: preparing alloy by mixing metal elements according to the chemical composition of YFe7, wherein the Y element is excessive by 1wt.%, and preparing alloy ingots by arc melting;

[0008] Or, according to YFe 7.2 The chemical composition is prepared, wherein the Y element is excessively 1wt.%, and an alloy ingot is prepared by arc melting method;

[0009] S2 rapid quenching: remove the oxide layer on the surface of the alloy ingot, place it in a quartz tube with small holes at the bottom for rapid quenching, then put the quartz tube into a high-speed belt-spinning furnace, and perform rapid quenching in an argon atmosphere to obtain the AB5 type YFe5 single-phase hydrogen storage alloy described in the present invention.

[0010] Preferably, the alloy is turned over and smelted repeatedly 3-4 times during the smelting process in step S1 to ensure uniformity.

[0011] Preferably, the quartz tube with the small hole in step S2 meets the size characteristics: the diameter of the bottom hole is 0.5 mm.

[0012] Preferably, the specific process of rapid quenching in step S2 is as follows: load the alloy ingot so that it is exactly located in the middle of the heating coil, fill with argon gas, set the rotation speed of the copper roller of the belt-spinning furnace to 50m / s, then induction heat the sample, and the alloy melts after reaching 1200°C. Continue to increase the temperature to 1300°C, then carry out belt spinning, stop heating and slow down the copper roller after completion, and air cool to room temperature with the furnace.

[0013] Preferably, during the entire rapid quenching process, the argon atmosphere pressure of the induction furnace is always maintained at about -0.05 MPa, and the blowing pressure of the quartz tube is maintained at about 0.05 MPa, with a pressure difference of 0.1 MPa.

[0014] Preferably, the induction furnace is cleaned several times with argon before rapid quenching. First, the vacuum is pumped to 5 Pa, and then the molecular pump is turned on to vacuum to 2*10 -3 Pa, repeat twice to completely exhaust the internal oxygen.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] 1. Successfully eliminate impurities such as Y2Fe through appropriate rapid quenching process 17 Phase and Y6Fe 23 phase, and successfully prepared a single-phase alloy with a YFe5 metastable phase structure by using a suitable belt spinning speed.

[0017] 2. The preparation is carried out through Y and Fe elements, which avoids the appearance of other phases caused by alloying preparation, and by adjusting the ratio between Y and Fe elements within a certain range, the YFe5 single-phase structure can be stably obtained;

[0018] 3. The elements and phase structure of the alloy are simple and controllable, the preparation process is simple and efficient, and large-scale production can be achieved, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1XRD spectrum and refined spectrum of the YFe5 single-phase hydrogen storage alloy prepared in Example 1 of the present invention.

[0020] Figure 2 The PCT hydrogen storage performance diagram of the YFe5 single-phase hydrogen storage alloy prepared in Example 1 of the present invention at different temperatures.

[0021] Figure 3 This is a comparison diagram of the XRD patterns of the YFe5 single-phase hydrogen storage alloy prepared in Example 1 of the present invention before and after cycling.

[0022] Figure 4 XRD spectrum and refined spectrum of the YFe5 single-phase hydrogen storage alloy prepared in Example 2 of the present invention.

[0023] Figure 5 The PCT hydrogen storage performance diagram of the YFe5 single-phase hydrogen storage alloy prepared in Example 2 of the present invention at different temperatures. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] The ReFe5 phase in the rare earth iron-based hydrogen storage alloy is generally considered to be a metastable phase structure that cannot be directly obtained by smelting. However, the existence of the ReFe2 phase and the ReFe3 superlattice phase proves the value of studying them. At the same time, a large number of research reports have proved that the rare earth nickel-based LaNi5 phase has good hydrogen storage performance and application prospects. Therefore, ReFe5 with the same phase structure and higher cost advantage is worth studying and exploring. At the same time, there is currently no report on the YFe5 single-phase alloy, and the preparation means and method reported in the present invention are very meaningful.

[0026] The specific preparation steps of the AB5 type YFe5 single-phase structure hydrogen storage alloy of the present invention are:

[0027] 1. Embodiment 1

[0028] A method for preparing a hydrogen storage alloy having an AB5 type YFe5 single-phase structure, comprising:

[0029] (1) Melting the original alloy: Select high-purity Y and Fe metal elements and prepare the ingredients according to the chemical composition of YFe7, wherein the Y element is in excess of 1wt.% to compensate for the volatilization of elements during the melting process, and then use arc melting to prepare the cast alloy. Use argon to clean the arc furnace cavity three times to ensure that oxygen is removed, and replenish argon to -0.05MPa after the last cleaning process, and then carry out arc melting. During the melting process, the ingot needs to be turned over 3 to 4 times to ensure the uniformity of alloy melting;

[0030] (2) Sample pretreatment: First, remove the oxide impurity layer on the surface of the alloy prepared by arc melting, then crush it, take 4-5g of the ingot sample and place it in a quartz tube with an inner diameter of 11mm for belt spinning. There is a small hole with a diameter of 0.5mm at the bottom of the quartz tube. Put the quartz tube with the sample into the induction coil in the induction furnace, adjust the position of the quartz tube so that its lowest point is 2-3mm above the copper roller during belt spinning, and is located in the middle of the coil during induction heating to ensure uniform heating;

[0031] (3) Rapid quenching process: First, close all the vents of the induction furnace and clean it twice with argon to remove the oxygen in the induction furnace cavity. After the second cleaning, add the argon pressure to -0.05MPa and the quartz tube blowing pressure to 0.05MPa. Then set the copper roller speed to 50m / s. After the speed is reached, turn on the induction coil control power supply to induction heat the ingot to 1200℃. The alloy ingot melts and tumbles. Continue to raise the temperature to 1300℃ to ensure that it will not cool and solidify during the descent process. Then press the belt throwing button to complete the rapid quenching. Then turn off the coil power supply and the copper roller switch, and wait for the rapidly quenched alloy to air cool to room temperature with the furnace.

[0032] (4) The rapid quenching sample prepared above was ground and crushed, and the alloy powder sieved with 300 mesh was subjected to XRD test. The test angle was 10°-90°, and the XRD was refined using Maud software. The XRD spectrum and refined fitting diagram of the alloy are shown in Fig. Figure 1 As shown, the results show that the alloy is composed of YFe5 single phase with a phase abundance of 100wt.%. The alloy powder sieved with 200-400 mesh was taken for gaseous PCT hydrogen storage performance test. The test temperatures were 50℃, 100℃, 150℃, 200℃, 250℃ and 300℃, respectively. The test cutoff pressure was 13MPa. The test equipment was Zhejiang University ZDMH-4 hydrogen storage material performance tester. The performance test was carried out after the alloy was fully activated. The PCT test curve is shown in Figure 2 As shown, the maximum hydrogen storage capacity of the alloy at 50°C is 0.37wt.%, the maximum hydrogen storage capacity at 100°C is 0.92wt.%, the maximum hydrogen storage capacity at 150°C is 1.14wt.%, the maximum hydrogen storage capacity at 200°C is 1.29wt.%, the maximum hydrogen storage capacity at 250°C is 1.38wt.% and the maximum hydrogen storage capacity at 300°C is 1.49wt.%; the maximum reversible capacities are 0.11wt.%, 0.52wt.%, 0.83wt.%, 1.07wt.%, 1.17wt.% and 1.32wt.%, respectively. The XRD patterns of the alloy before and after cycling are shown in Figure 3 As shown, it can be seen that the alloy maintained a stable crystal structure during 10 cycles of hydrogen absorption and desorption.

[0033] 2. Embodiment 2

[0034] A method for preparing a hydrogen storage alloy having an AB5 type YFe5 single-phase structure, comprising:

[0035] (1) Melting the original alloy: Select high-purity Y and Fe metal elements, and 7.2 The chemical composition is prepared, wherein the Y element is excessive by 1wt.% to compensate for the volatilization of the element during the smelting process, and then the cast alloy is prepared by arc melting. The arc furnace cavity is cleaned 3 times with argon to ensure the removal of oxygen, and the argon is replenished to -0.05MPa after the last cleaning process, and then arc melting is carried out. During the melting process, the ingot needs to be turned over 3 to 4 times to ensure the uniformity of the alloy melting;

[0036] (2) Sample pretreatment: First, remove the oxide impurity layer on the surface of the alloy prepared by arc melting, then crush it, take 4-5g of the ingot sample and place it in a quartz tube with an inner diameter of 11mm for belt spinning. There is a small hole with a diameter of 0.5mm at the bottom of the quartz tube. Put the quartz tube with the sample into the induction coil in the induction furnace, adjust the position of the quartz tube so that its lowest point is 2-3mm above the copper roller during belt spinning, and is located in the middle of the coil during induction heating to ensure uniform heating;

[0037] (3) Rapid quenching process: First, close all the vents of the induction furnace and clean it twice with argon to remove the oxygen in the induction furnace cavity. After the second cleaning, add the argon pressure to -0.05MPa and the quartz tube blowing pressure to 0.05MPa. Then set the copper roller speed to 50m / s. After the speed is reached, turn on the induction coil control power supply to induction heat the ingot to 1200℃. The alloy ingot melts and tumbles. Continue to raise the temperature to 1300℃ to ensure that it will not cool and solidify during the descent process. Then press the belt throwing button to complete the rapid quenching. Then turn off the coil power supply and the copper roller switch, and wait for the rapidly quenched alloy to air cool to room temperature with the furnace.

[0038] (4) The rapid quenching sample prepared above was ground and crushed, and the alloy powder sieved with 300 mesh was subjected to XRD test. The test angle was 10°-90°, and the XRD was refined using Maud software. The XRD spectrum and refined fitting diagram of the alloy are shown in Fig. Figure 4 As shown, the results show that the alloy is composed of YFe5 single phase with a phase abundance of 100wt.%. The alloy powder sieved with 200-400 mesh was taken for gaseous PCT hydrogen storage performance test. The test temperatures were 50℃, 100℃, 150℃ and 200℃ respectively. The test cutoff pressure was 13MPa. The test equipment was Zhejiang University ZDMH-4 hydrogen storage material performance tester. The performance test was carried out after the alloy was fully activated. The PCT test curve is shown in Figure 5 As shown, the maximum hydrogen storage capacity of the alloy at 50°C is 0.32wt.%, the maximum hydrogen storage capacity at 100°C is 0.78wt.%, the maximum hydrogen storage capacity at 150°C is 1.02wt.%, and the maximum hydrogen storage capacity at 200°C is 1.19wt.%; the maximum reversible capacities are 0.15wt.%, 0.41wt.%, 0.78wt.% and 1.02wt.% respectively.

Claims

1. An AB5 type rare earth iron-based single-phase hydrogen storage alloy, characterized in that: It has a stable AB5 type single-phase structure.

2. The hydrogen storage alloy according to claim 1, characterized in that The AB5 phase content is 100 wt.%.

3. The hydrogen storage alloy according to claim 1, characterized in that The hydrogen storage alloy is expressed as YFe 7。 4. The hydrogen storage alloy according to claim 1, characterized in that The hydrogen storage alloy is expressed as YFe 7.2。 5. The method for preparing the AB5 type YFe5 single-phase hydrogen storage alloy according to any one of claims 1 to 4, characterized in that: The steps include: S1: preparing alloy by mixing metal elements according to the chemical composition of YFe7, wherein the Y element is in excess of 1wt.%, and preparing alloy ingots by arc melting; Or, according to YFe 7.2 The chemical composition is prepared, wherein the Y element is excessively 1wt.%, and an alloy ingot is prepared by arc melting method; S2 Rapid Quenching Treatment: Take the smelted alloy ingot, put it into a quartz tube with a small hole at the bottom, and then put it into the appropriate position of the induction coil in the belt-spinning furnace for rapid quenching treatment under argon atmosphere.

6. The method according to claim 5, characterized in that The diameter of the small hole at the bottom of the quartz tube is 0.5 mm; the relationship between the mass of the alloy ingot sample and the quartz tube is: 4 to 5 g of the ingot sample is placed in a quartz tube with an inner diameter of 11 mm.

7. The method according to claim 5, characterized in that The specific process of the rapid quenching treatment in S2 is as follows: replenish the argon pressure in the induction furnace cavity to -0.05MPa, replenish the quartz tube pressure to 0.05MPa, set the copper roller speed to 50m / s, and after the speed is reached, heat the ingot to 1200°C through the induction coil, and then perform belt-swinging rapid quenching. After completion, turn off the coil power supply and the copper roller, and air cool to room temperature with the furnace.

8. The method according to claim 5, characterized in that Before heat treatment, the induction furnace cavity was washed with argon several times. The steps were as follows: first, the vacuum was pumped to 5 Pa, and then the molecular pump was turned on to vacuum to 2*10 -3 Pa, repeat twice to completely exhaust the internal oxygen.

9. An AB5 type single-phase hydrogen storage alloy is prepared according to the preparation method described in any one of claims 5 to 8.

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