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

Abstract

The application 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 high-purity metal elements, preparing alloy ingots in an argon atmosphere by adopting electric arc smelting according to set components, and performing rapid quenching treatment on part of the alloy ingots in a strip casting furnace. By adjusting the proportion between Y and Fe elements in the alloy and cooperating with the rapid quenching treatment, the phase composition of the alloy is optimized, the problem that the AB5 type single-phase alloy cannot be obtained is solved, the hydrogen storage alloy has the advantages of simple preparation process and excellent hydrogen storage performance, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen storage alloys, and particularly relates to a preparation method of an AB5 type YFe5 single-phase hydrogen storage alloy. BACKGROUND

[0002] Rare earth (Re) -based metal alloys can store hydrogen gas under normal 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 its large-scale application in the hydrogen storage field. The reversible hydrogen storage function of non-nickel-based rare earth alloys is still very limited.

[0003] ReFe5 alloys have a CaCu5 type crystal structure like Ni-based hydrogen storage alloys, but rare earth elements cannot directly obtain a CaCu5 phase through smelting with Fe. Literature reports that ReFe5 phases with a CaCu5 structure are mostly metastable phases, and it is difficult to form a single-phase structure. According to the Re-Fe binary phase diagram, the stable structures of rare earth iron-based alloys mainly include ReFe2, ReFe3, Re2Fe 17 and Re6Fe 23 structures, but research on these iron-rich rare earth iron-based alloys mainly focuses on magnetic materials, and there is little research on their hydrogen storage performance. At the same time, although some scholars have successfully prepared ReFe5 phases in alloys through 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 complex and difficult to efficiently mass-produce. SUMMARY

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

[0005] To achieve the above purpose, the application adopts the following technical scheme:

[0006] A preparation method of a hydrogen storage alloy with an AB5 type YFe5 single-phase structure, comprising the following steps:

[0007] S1: alloy smelting: selecting metal elements, and performing alloying according to a YFe7 chemical composition, wherein the Y element is 1wt.% in excess, and an alloy ingot is prepared by an electric arc smelting method;

[0008] or, performing alloying according to a YFe 7.2 chemical composition, wherein the Y element is 1wt.% in excess, and an alloy ingot is prepared by an electric arc smelting method;

[0009] S2 rapid quenching: removing the oxide layer on the surface of the alloy ingot, placing it into a small hole in the bottom of the quartz tube for rapid quenching, and then placing the quartz tube into a high-speed spinning belt furnace for rapid quenching in an argon atmosphere to obtain the AB5 type YFe5 single-phase hydrogen storage alloy.

[0010] Preferably, the alloy smelting process in step S1 is repeated 3-4 times to ensure uniformity.

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

[0012] Preferably, the rapid quenching process in step S2 is as follows: the alloy ingot is loaded so that it is located in the middle of the heating coil, argon is filled, the spinning belt furnace copper roller speed is set to 50m / s, then the sample is inductively heated, the alloy is melted when the temperature reaches 1200℃, the temperature is continuously raised to 1300℃, then the belt is spun, and after stopping heating and decelerating the copper roller, the furnace is air cooled to room temperature.

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

[0014] Preferably, the induction furnace is cleaned with argon multiple times before rapid quenching, first vacuumed to 5Pa using a vacuum pump, then opened to 2*10 -3 Pa using a molecular pump, repeated twice to completely remove internal oxygen.

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

[0016] 1. By using appropriate rapid quenching process, the impurity phase such as Y2Fe 17 phase and Y6Fe 23 phase is successfully eliminated, and a single-phase alloy with YFe5 metastable phase structure is successfully prepared by using appropriate spinning speed;

[0017] 2. By using Y and Fe elements for preparation, the appearance of other phases caused by alloying is avoided, and by adjusting the ratio between Y and Fe elements within a certain range, 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, mass production can be realized, and the alloy has wide application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1XRD pattern and refinement pattern of the YFe5 single-phase structure hydrogen storage alloy prepared in Example 1 of the present application.

[0020] Figure 2 P-C-T hydrogen storage performance diagram of the YFe5 single-phase structure hydrogen storage alloy prepared in Example 1 of the present application at different temperatures.

[0021] Figure 3 XRD comparison diagram of the YFe5 single-phase structure hydrogen storage alloy prepared in Example 1 of the present application before and after cycling.

[0022] Figure 4 XRD pattern and refinement pattern of the YFe5 single-phase structure hydrogen storage alloy prepared in Example 2 of the present application.

[0023] Figure 5 P-C-T hydrogen storage performance diagram of the YFe5 single-phase structure hydrogen storage alloy prepared in Example 2 of the present application at different temperatures. DETAILED DESCRIPTION

[0024] The present application will be further described below in combination with the drawings and examples.

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

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

[0027] 1. Example 1

[0028] A preparation method of a hydrogen storage alloy with an AB5 type YFe5 single-phase structure, comprising:

[0029] (1) smelting the original alloy: selecting high-purity Y and Fe metal elements, and dosing according to the YFe7 chemical composition, wherein the Y element is 1wt.% in excess to compensate for the element volatilization in the smelting process, then arc smelting is used to prepare the as-cast alloy, argon is used to clean the arc furnace cavity for 3 times to ensure that the oxygen is removed, and the argon is supplemented to-0.05MPa after the last cleaning process, then the arc smelting is carried out, and the ingot needs to be turned over 3-4 times during the smelting process to ensure the uniformity of the alloy smelting;

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

[0031] (3) Rapid quenching process: First, close all the air vents of the induction furnace, clean it with argon for 2 passes to remove oxygen from the induction furnace cavity, and then supplement the argon pressure to -0.05 MPa after the second cleaning. At the same time, the quartz tube blowing pressure is supplemented to 0.05 MPa, then the copper roller speed is set to 50 m / s, the induction coil control power is turned on after the speed reaches, and the ingot is inductively heated to 1200℃. The alloy ingot melts and rolls, and the temperature is continuously raised to 1300℃ to ensure that it does not cool and solidify during the descent. Then press the spinning button to complete the rapid quenching, and then turn off the coil power and copper roller switch. Wait for the rapid quenching alloy to cool to room temperature with the furnace.

[0032] (4) Grind and crush the rapidly quenched sample prepared above, take 300 mesh sieved alloy powder for XRD test, test angle is 10°-90°, use Maud software to refine the XRD, alloy XRD spectrum and refined fitting graph as shown in Figure 1 , the results show that the alloy is composed of YFe5 single phase, and the phase abundance is 100wt.%. Take 200-400 mesh sieved alloy powder for gaseous P-C-T hydrogen storage performance test, test temperature is 50℃, 100℃, 150℃, 200℃, 250℃ and 300℃ respectively, test pressure is 13 MPa, test equipment is Zhejiang ZDMH-4 hydrogen storage material performance tester, and the alloy is completely activated for performance test. The P-C-T test curve is shown in Figure 2 , the maximum hydrogen storage capacity of the alloy at 50℃ is 0.37wt.%, the maximum hydrogen storage capacity at 100℃ is 0.92wt.%, the maximum hydrogen storage capacity at 150℃ is 1.14wt.%, the maximum hydrogen storage capacity at 200℃ is 1.29wt.%, the maximum hydrogen storage capacity at 250℃ is 1.38wt.%, and the maximum hydrogen storage capacity at 300℃ is 1.49wt.%. The maximum reversible capacity is 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 , it can be seen that the alloy maintains a stable crystal structure during the 10-week hydrogen absorption and desorption cycle.

[0033] 2. Example 2

[0034] A preparation method of a hydrogen storage alloy with AB5 type YFe5 single phase structure, comprising:

[0035] (1) smelting a raw alloy: selecting high-purity Y and Fe metal elements, and preparing a raw alloy according to YFe 7.2 Chemical composition, wherein the Y element is 1 wt.% in excess to compensate for element volatilization during smelting, and then an arc smelting is used to prepare a cast alloy, argon is used to clean the arc furnace cavity for 3 times to ensure that oxygen is removed, and argon is supplemented to -0.05 MPa after the last cleaning process, and then arc smelting is performed, and the cast ingot needs to be turned over 3-4 times during smelting to ensure the uniformity of alloy smelting;

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

[0037] (3) rapid quenching process: first, close all the air vents of the induction furnace, clean it with argon for 2 times to remove oxygen in the induction furnace cavity, and supplement argon pressure to -0.05 MPa after the second cleaning, and at the same time, supplement the quartz tube blowing pressure to 0.05 MPa, then set the copper roller speed to 50 m / s, open the induction coil control power after the speed reaches, and heat the cast ingot to 1200℃, the alloy ingot melts and rolls, continue to increase the temperature to 1300℃ to ensure that it will not cool and solidify during the descending process, then press the spinning button to complete the rapid quenching, and then turn off the coil power and copper roller switch, and wait for the rapid quenching alloy to air cool to room temperature with the furnace.

[0038] (4) grind and crush the rapid quenching sample prepared above, take 300 mesh sieved alloy powder for XRD test, the test angle is 10°-90°, and the Maud software is used for refining treatment of XRD, and the XRD spectrum and refined fitting diagram of the alloy are as shown in Figure 4 The results show that the alloy is composed of YFe5 single phase, and the phase abundance is 100 wt.%. Take 200-400 mesh sieved alloy powder for gaseous P-C-T hydrogen storage performance test, the test temperature is 50℃, 100℃, 150℃ and 200℃ respectively, the test pressure is 13 MPa, the test equipment is Zhejiang ZDMH-4 hydrogen storage material performance tester, and the P-C-T test curve is as shown inFigure 5 As shown, the maximum hydrogen storage capacity of the alloy is 0.32 wt.% at 50°C, 0.78 wt.% at 100°C, 1.02 wt.% at 150°C, and 1.19 wt.% at 200°C; and the maximum reversible capacity is 0.15 wt.%, 0.41 wt.%, 0.78 wt.% and 1.02 wt.% respectively.

Claims

1. An AB5-type rare earth iron-based single-phase hydrogen storage alloy, characterized in that, It has stable AB5 type single-phase structure; the hydrogen storage alloy expression is YFe7 or YFe 7.2 .

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

3. The method of producing an AB5 type YFe5 single-phase hydrogen storage alloy according to claim 1 or 2, characterized by, The method comprises the following steps: S1: Alloying and melting: selecting metal elements, alloying according to the chemical composition of YFe7, wherein the Y element is 1 wt.% in excess, and preparing an alloy ingot by using an electric arc melting method; or, according to YFe 7.2 The alloy ingot is prepared by arc melting method with the chemical composition of Y element excess 1 wt.%. S2: Rapid quenching treatment: taking the melted alloy ingot, placing it into a quartz tube with a small hole at the bottom, and then placing it into a suitable position of an induction coil of a spinning belt furnace, and then performing rapid quenching treatment by spinning belt under an argon atmosphere.

4. The method of claim 3, wherein, The diameter of the small hole at the bottom of the quartz tube is 0.5 mm; and the relationship between the mass of the alloy ingot sample and the quartz tube is that 4-5 g of the ingot sample is placed in the quartz tube with an inner diameter of 11 mm.

5. The method of claim 3, wherein, The specific process of the rapid quenching treatment in S2 is as follows: the argon pressure in the induction furnace cavity is supplemented to -0.05 MPa, the quartz tube pressure is supplemented to 0.05 MPa, the copper roller speed is set to 50 m / s, the ingot is heated to 1200 DEG C by the induction coil after the speed reaches, and then rapid quenching is performed by spinning belt, and after completion, the coil power supply and the copper roller are turned off, and the furnace is air-cooled to room temperature.

6. The method of claim 3, wherein, The induction furnace cavity was washed with argon several times before heat treatment, the steps were as follows: first, vacuum to 5 Pa by using vacuum pump, then open the molecular pump to vacuum to 2*10 -3 Pa, repeat twice to completely exhaust the internal oxygen.

7. The AB5 type single-phase hydrogen storage alloy prepared by the preparation method according to any one of claims 2-6.

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