Method for manufacturing rare earth AB2 type hydrogen storage alloy

Abstract

This invention provides a method for producing rare earth AB2 type hydrogen storage alloys. [Solution] The manufacturing method comprises (1) mixing a raw material A containing sponge Ti and / or sponge Zr with a first rare earth metal, performing a first melting and smelting process and post-treatment in sequence to obtain a high-purity A ingot, and (2) mixing an A source containing the high-purity A ingot described in step (1) and an optional A raw material, a B source containing a Cr source and / or Mn source, and a second rare earth metal, performing a second melting and smelting process to obtain the rare earth AB2 type hydrogen storage alloy. The present invention not only effectively improves the purity of the metal raw material by refining the rare earth metal and the A raw material by the first melting and smelting process, but also, by producing a hydrogen storage alloy using a high-purity A ingot in the second melting and smelting process, the hydrogen storage alloy has a more stable plateau pressure, lower hysteresis and residue, and effectively improved hydrogen storage and release characteristics.

Description

[Technical Field]

[0001] This invention belongs to the technical field of hydrogen storage alloys and relates to a method for producing a rare earth AB2 type hydrogen storage alloy. [Background technology]

[0002] Hydrogen, being the most abundant element on Earth, possesses an extremely high energy density. As a fuel, hydrogen gas has three times the heat of combustion of fuels like gasoline, and emits virtually no pollutants after combustion, making it an ideal energy resource carrier. Compared to hydrogen production, safe and reliable hydrogen storage technology is still lagging behind, and storage and transportation costs are high. Therefore, most companies choose to consume the H2 they produce locally. While this approach is suitable for some integrated hydrogen energy production and application sites, in many cases, the production and use locations of hydrogen gas do not coincide, making research into efficient and energy-efficient hydrogen gas storage and transportation technologies particularly important.

[0003] High-pressure hydrogen storage (HSS) is currently the most widely applied HSS method in China. It compresses hydrogen gas into a high-pressure gas cylinder or container. This method offers rapid hydrogen absorption and release, a controllable process, and is a relatively mature HSS technology currently in commercial use. However, its efficiency is limited due to the small capacity of the gas cylinders and the low amount of hydrogen absorbed compared to the cylinder's weight. HSS also presents certain safety concerns; for example, hydrogen gas leakage during transportation or use can cause serious safety accidents.

[0004] Solid hydrogen storage is a promising technology that has attracted widespread attention in recent years. Solid hydrogen storage can be broadly classified into metal hydride hydrogen storage, chemical hydride hydrogen storage, and carbon material hydrogen storage. Here, metal hydride hydrogen storage is the process by which a metal or alloy can absorb and release hydrogen under certain conditions. Depending on the type of alloy, it can be classified into rare earth hydrogen storage alloys, V-based solid solution hydrogen storage alloys, Mg-based hydrogen storage alloys, Ti-based hydrogen storage alloys, etc. Compared to other hydrogen storage alloys, AB2 type hydrogen storage alloys can absorb and release hydrogen at room temperature and atmospheric pressure, and are low-cost, making them highly applicable hydrogen storage materials.

[0005] In AB2-type hydrogen storage alloys, the A component element generally originates from Group 14 elements (e.g., Ti, Zr, Hf) and some rare earth elements, while the B component element generally consists of various transition or non-transition elements with smaller radii. The AB2 intermetallic compounds after hydrogenation belong to the Laves phase, and much research has been done on TiCr2, TiMn2, and ZrMn2-based multi-component alloys in the Laves phase. Here, TiMn2-based hydrogen storage alloys are typical representatives of titanium-based AB2-type hydrogen storage alloys. These alloys have high hydrogen storage capacity, good hydrogen storage and release kinetics, and low cost, but they have poor plateau characteristics and large hysteresis, making improvement of the hydrogen storage performance of AB2-type hydrogen storage alloys an urgent need.

[0006] Furthermore, in the melting and smelting process of AB2 type hydrogen storage alloys, sponge titanium, sponge zirconium, chromium grains, and electrolytic manganese sheets are typically used. The purity of these raw materials is usually between 99% and 99.7%, and they contain small amounts of impurities such as Al, Fe, Hf, S, Se, Mg, and C. These impurities dissolve into the final hydrogen storage alloy sample during the melting and smelting process, reducing the hydrogen storage and release characteristics of the hydrogen storage alloy. On the other hand, highly pure raw materials (≥99.9%) are expensive and cannot meet the cost requirements of industrial production.

[0007] In summary, the development of a new method for manufacturing AB2-type hydrogen storage alloys that can improve alloy purity, enhance the hydrogen storage and release properties of the alloy, and increase melting and smelting production capacity is a problem that those skilled in the art should address as soon as possible. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a method for producing a rare earth AB2 type hydrogen storage alloy. The hydrogen storage alloy produced by refining a rare earth metal and raw material A in a first melting and smelting process, and then using a high-purity A ingot, has a high reversible hydrogen storage capacity, more stable plateau pressure, lower hysteresis and residue, and can better meet the needs for use in conjunction with solid hydrogen storage devices and fuel cells. Furthermore, the production method can significantly improve melting and smelting production capacity, resulting in cost reduction and improved efficiency. [Means for solving the problem]

[0009] To achieve this objective, the present invention employs the following technical solutions.

[0010] The present invention relates to a method for producing rare earth AB2 type hydrogen storage alloys, Step (1) involves mixing raw material A containing sponge Ti and / or sponge Zr with a first rare earth metal, and then sequentially performing a first melting and smelting process and polishing to obtain a high-purity A ingot. (2) Step (2) includes mixing an A source containing the high-purity A ingot described in step (1) and an optional A raw material, a B source containing a Cr source and / or a Mn source, and a second rare earth metal, and performing a second melting and smelting process to obtain the rare earth AB2 type hydrogen storage alloy. This invention provides a method for producing rare earth AB2 type hydrogen storage alloys.

[0011] The manufacturing method according to the present invention can not only effectively improve the purity of the metal raw material by refining rare earth metals and raw material A through primary melting and smelting, but also perform secondary melting and smelting using the high-purity A ingot obtained through primary melting and smelting and post-treatment. The manufactured hydrogen storage alloy has a more stable plateau pressure, lower hysteresis and residue, and effectively improved hydrogen storage and release characteristics. At the same time, the bulk density of sponge titanium and / or sponge zirconium in raw material A is small. After primary melting and smelting, the raw material changes from a sponge shape to a lump shape, and the bulk density of the high-purity A ingot is significantly improved, increasing the charging amount in the crucible during lot production, greatly improving the melting and smelting production capacity, and realizing cost reduction and efficiency improvement.

[0012] In addition, due to the high activity of rare earth elements and the high melting point of rare earth oxides, harmful impurity elements in raw material A can be effectively neutralized. The impurity elements concentrate around the rare earth oxides or form compounds, and after post-treatment after primary melting and smelting, the rare earth elements and impurity elements on the surface of the raw material are removed to obtain a high-purity A ingot, achieving the effect of refining and purification. At the same time, the bulk density of raw material A after primary melting and smelting increases significantly, further improving the subsequent melting and smelting production capacity, and being suitable for large-scale production.

[0013] As a preferred technical solution of the present invention, the purity of the raw material A is ≥99%, for example, it may be 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5% or 99.6%, etc., but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0014] In the present invention, the density of the sponge Ti is 1.5 - 1.9 g / cm 3 For example, it may be 1.5 g / cm 3 1.6 g / cm 3 1.7 g / cm 3 1.8 g / cm 3 or 1.9 g / cm 3 etc., and the density of the sponge Zr is 4 - 5 g / cm 3 For example, it may be 4 g / cm 3 4.1 g / cm3 , 4.2 g / cm 3 , 4.3 g / cm 3 , 4.4 g / cm 3 , 4.5 g / cm 3 , 4.6 g / cm 3 , 4.7 g / cm 3 , 4.8 g / cm 3 , 4.9 g / cm 3 or 5 g / cm 3 etc. may be used, but are not limited to the listed numerical values, and other unlisted numerical values within the numerical range are equally applicable.

[0015] In the present invention, both the sponge Ti and the sponge Zr are commercially available products.

[0016] The first rare earth metal described in step (1) includes any one or at least a combination of two or more of La, Ce, Y, Sm, Er or Gd. Here, typical but non-limiting examples of the combination are combinations of La and Ce, combinations of Ce and Y, or combinations of Sm and Er, etc.

[0017] The atomic ratio of the A raw material to the first rare earth metal described in step (1) is 1:(0.005 - 0.03). For example, it may be 1:0.005, 1:0.006, 1:0.008, 1:0.01, 1:0.012, 1:0.015, 1:0.018, 1:0.02, 1:0.022, 1:0.025, 1:0.028 or 1:0.03, etc., but is not limited to the listed numerical values, and other unlisted numerical values within the numerical range are equally applicable.

[0018] In addition, by controlling the range of the atomic ratio of the A raw material to the first rare earth metal, impurity elements in the A raw material can be concentrated around the rare earth oxide or form compounds, and through post-treatment, the impurity elements and rare earth elements can be removed. This not only ensures improving the purity of the A raw material, but also avoids excessive rare earth elements remaining in the A raw material and can further improve the purity of the A raw material.

[0019] As a preferred technical method of the present invention, the first melting and smelting method described in step (1) includes one of arc melting, induction melting, or flotation melting.

[0020] In the present invention, the first melting and smelting is carried out in a vacuum induction melting furnace, and since both Ti and Zr react with the crucible, the mass of Ti and Zr in the melted and smelted ingot fluctuates slightly. However, since it is necessary to precisely control the atomic ratio of Ti and Zr before the second melting and smelting, it is necessary to carry out the first melting and smelting by placing sponge Ti and the first rare earth metal, and sponge Zr and the first rare earth metal, in different crucibles. When arc melting or levitation melting is employed, Ti and Zr can be melted and smelted together, and the mass of Ti and Zr in the ingot after melting and smelting does not change.

[0021] The first melting and smelting described in step (1) is carried out in an inert gas environment.

[0022] In this invention, the inert gas is argon gas.

[0023] Vacuum degree of the first melting and smelting described in step (1) ≤ 5 × 10 -3 Pa is, for example, 5 × 10 -3 Pa, 4×10 -3 Pa, 3 x 10 -3 Pa, 2 × 10 -3 Pa or 1 × 10 -3 While Pa, etc., may also be used, the system is not limited to the listed numbers; other unlisted numbers within the numerical range are also treated similarly.

[0024] The number of times the first melting and smelting described in step (1) is 3 to 6 times, for example, 3, 4, 5, or 6 times, but it is not limited to the listed numbers, and other numbers within the numerical range that are not listed also apply.

[0025] The current for the first melting and smelting described in step (1) is 80 to 200 A, and may be, for example, 80 A, 90 A, 100 A, 110 A, 120 A, 130 A, 140 A, 150 A, 160 A, 170 A, 180 A, 190 A, or 200 A, but is not limited to the listed values, and other values ​​within the numerical range that are not listed also apply.

[0026] The time for the first melting and smelting described in step (1) is 50 to 300 s / cycle, and may be, for example, 50 s / cycle, 80 s / cycle, 100 s / cycle, 120 s / cycle, 150 s / cycle, 180 s / cycle, 200 s / cycle, 220 s / cycle, 250 s / cycle, 280 s / cycle, or 300 s / cycle, but is not limited to the listed numbers, and other numbers within the numerical range that are not listed will also apply.

[0027] Furthermore, by controlling the range of parameters such as the number of times, current, and time of the first melting and smelting process, it is possible not only to sufficiently remove impurities from the raw material A, but also to significantly increase the volume density of the high-purity A ingot.

[0028] As a preferred technical example of the present invention, the post-treatment described in step (1) includes polishing or pickling.

[0029] The endpoint of the post-processing described in step (1) is that the surface of the high-purity A ingot is glossy.

[0030] In the present invention, if post-processing is not performed, rare earth elements and impurity elements on the surface of the ingot cannot be removed, and furthermore, the purity of the high-purity A ingot is affected.

[0031] In the present invention, the polishing method includes polishing the surface of the first melted and smelted ingot using sandpaper or a sander until the surface is glossy.

[0032] In this invention, the specific pickling solution and its amount are not limited, and it is sufficient to remove scale, impurities, and rare earth elements from the surface of the ingot after the first melting and smelting process. Those skilled in the art can select the appropriate solution depending on the actual situation.

[0033] A preferred technical example of the present invention is that the purity of the high-purity ingot A described in step (1) is ≥ 99.85%, and may be, for example, 99.85%, 99.86%, 99.88%, 99.9%, 99.91%, 99.93%, or 99.95%, but is not limited to the listed values, and other values ​​within the numerical range that are not listed are also applicable.

[0034] The high-purity A ingot described in step (1) includes a high-purity Ti ingot and / or a high-purity Zr ingot.

[0035] In the present invention, the density of the high-purity Ti ingot is >4.2 g / cm³ 3 For example, 4.25 g / cm³ 3 4.3 g / cm³ 3 4.35 g / cm³ 3 4.4 g / cm³ 3 4.45 g / cm³ 3 Or 4.5 g / cm³ 3 It may be the case that the density of the high-purity Zr ingot is >6.2 g / cm³. 3 For example, 6.25 g / cm³ 3 6.3 g / cm³ 3 6.35 g / cm³ 3 6.4 g / cm³ 3 Or 6.45 g / cm³ 3 Other values ​​may also be used, but the system is not limited to the listed numbers; other unlisted numbers within the numerical range also apply similarly.

[0036] In this invention, the purity and volume density of the obtained high-purity A ingot are significantly increased.

[0037] As a preferred technical example of the present invention, the A source described in step (2) includes a Ti source and a Zr source, and the A source includes the following cases: (a) Source A comprises a high-purity Ti ingot and a high-purity Zr ingot, or (b) Source A comprises a high-purity Ti ingot and sponge Zr, or (c) Source A comprises sponge Ti and a high-purity Zr ingot.

[0038] In the present invention, the A source is preferably a high-purity Ti ingot and a high-purity Zr ingot.

[0039] As a preferred technical example of the present invention, the second rare earth metal described in step (2) includes one or at least two of La, Ce, Y, Sm, Er, or Gd.

[0040] The atomic ratio of source A, source B, and second rare earth metal described in step (2) is (0.8~1.2):(1.8~2.2):(0.008~0.012), and may be, for example, 1:2:0.008, 1:2:0.009, 1:2:0.01, 1:2:0.011, or 1:2:0.012, but is not limited to the listed values, and other unlisted values ​​within the numerical range may be applied similarly, with 1:2:(0.008~0.012) being preferred.

[0041] As a preferred technical method of the present invention, the second melting and smelting method described in step (2) is characterized by including one of arc melting, induction melting, or flotation melting.

[0042] The vacuum level in the second melting and smelting process is ≤ -0.06 MPa.

[0043] The power for the second melting and smelting process is 55-65kW, and may be, for example, 55kW, 56kW, 57kW, 58kW, 59kW, 60kW, 61kW, 62kW, 63kW, 64kW, or 65kW, but is not limited to the listed values, and other values ​​within the range that are not listed will also apply.

[0044] The duration of the second melting and smelting process is 5 to 10 minutes, and may be, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes, but is not limited to the listed values, and other values ​​within the range that are not listed will also apply.

[0045] The process further includes preheating for 10-15 minutes with an electric power of 25-35 kW before the second melting and smelting process.

[0046] The power for preheating is 25 to 35 kW, and may be, for example, 25 kW, 26 kW, 27 kW, 28 kW, 29 kW, 30 kW, 31 kW, 32 kW, 33 kW, 34 kW, or 35 kW, and the preheating time is 10 to 15 min, and may be, for example, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min, but is not limited to the listed values, and other values ​​within the numerical range that are not listed will also apply.

[0047] The process further includes casting and furnace cooling, which are carried out sequentially after the second melting and smelting process.

[0048] The power for the casting is 25-35 kW, and may be, for example, 25 kW, 26 kW, 27 kW, 28 kW, 29 kW, 30 kW, 31 kW, 32 kW, 33 kW, 34 kW, or 35 kW, but is not limited to the listed values, and other values ​​within the range that are not listed also apply.

[0049] A preferred technical example of the present invention is a hysteresis factor of the rare-earth AB2 type hydrogen storage alloy < 0.73, which may be, for example, 0.72, 0.71, 0.7, 0.69, 0.68, 0.67, or 0.66, but is not limited to the listed values, and other values ​​within the numerical range that are not listed are also applicable.

[0050] Furthermore, the rare earth AB2 type hydrogen storage alloy produced by the manufacturing method according to the present invention exhibits an increased effective hydrogen release rate from 1.72 wt% to 1.86 wt% compared to the direct dissolution method of raw material A, a reduction in the hysteresis factor from 0.802 to 0.667, and, assuming the same volume of raw materials, an improvement of 17% or more in dissolution and smelting production capacity, and an improvement of 28% or more under favorable conditions.

[0051] As a preferred technical example of the present invention, the manufacturing method includes the following steps:

[0052] (1) Mix raw material A and the first rare earth metal in an atomic ratio of 1:(0.005~0.03), then inert gas, vacuum degree ≤ 5 × 10 -3 First melting and smelting is performed at Pa and a current of 80-200A, and then post-treatment is performed until the surface of the high-purity A ingot is glossy, thereby obtaining a high-purity A ingot with a purity of ≥99.85%. The raw material A comprises sponge Ti and / or sponge Zr, and the purity of the raw material A is ≥ 99%. The first rare earth metal comprises one or at least two of the following: La, Ce, Y, Sm, Er, or Gd. The number of times the first melting and smelting process is 3 to 6, and the time per process is 50 to 300 seconds. The high-purity A ingot includes a high-purity Ti ingot and / or a high-purity Zr ingot.

[0053] (2) Mixing source A, source B, and a second rare earth metal in an atomic ratio of (0.8~1.2):(1.8~2.2):(0.008~0.012), preheating at 25~35kW for 10~15min, then performing a second melting and smelting process at a vacuum of ≤-0.06MPa and 55~65kW for 5~10min, followed by casting at 25~35kW, and finally furnace cooling to obtain a rare earth AB2 type hydrogen storage alloy with a hysteresis factor <0.73. The B source includes a Cr source and / or a Mn source. The second rare earth metal includes one or at least two of the following: La, Ce, Y, Sm, Er, or Gd. The A source is a Ti source and a Zr source, and the A source includes the following cases: (a) Source A includes a high-purity Ti ingot and a high-purity Zr ingot, or (b) Source A comprises a high-purity Ti ingot and sponge Zr, or (c) The A source includes sponge Ti and high-purity Zr ingots. [Effects of the Invention]

[0054] Compared to the prior art, the present invention offers the following beneficial effects.

[0055] (1) The manufacturing method according to the present invention involves mixing raw material A with a rare earth metal, then refining it by a first melting and smelting process, and by combining this with the control of corresponding process parameters, it is possible to effectively improve the purity of the metal raw material. Furthermore, by subsequently performing a second melting and smelting process using the high-purity A ingot to produce a hydrogen storage alloy, the hydrogen storage alloy exhibits more stable plateau pressure, lower hysteresis and residue, and effectively improved hydrogen storage and release characteristics, better meeting the needs for use in conjunction with solid hydrogen storage devices and fuel cells, thus possessing high applicability value.

[0056] (2) In the manufacturing method according to the present invention, because the volume density of sponge titanium and / or sponge zirconium in raw material A is low, by combining the control of the corresponding process parameters in the first melting and smelting process, raw material A changes from a sponge-like state to a lump-like state, and the volume density of the high-purity A ingot also improves significantly. This increases the amount that can be charged into the crucible during lot production, making it suitable for large-scale production, greatly improving melting and smelting production capacity, and achieving cost reduction and improved efficiency. [Brief explanation of the drawing]

[0057] [Figure 1] This is a PCT graph (298K) of hydrogen storage and release for the hydrogen storage alloys produced in Example 1 and Comparative Example 1. [Modes for carrying out the invention]

[0058] The technical aspects of the present invention will be further explained below with reference to specific embodiments. Those skilled in the art will understand that the above embodiments are merely for the purpose of understanding the present invention and should not be considered as specifically limiting the present invention.

[0059] In the following examples and comparative examples, the purity of the sponge Ti is 99.68% in all cases, and the purity of the sponge Zr is 99.39% in all cases. The sponge Ti, sponge Zr, Cr granules, and electrolytic Mn sheet are all commercially available products.

[0060] [Example 1] This embodiment provides a method for producing a rare-earth AB2 type hydrogen storage alloy, the production method comprising the following steps.

[0061] (1) Mix sponge Ti and La metal in an atomic ratio of 1:0.01 and place in the first crucible. Mix sponge Zr and La metal in an atomic ratio of 1:0.01 and place in the second crucible. Then, argon gas, vacuum of 5 × 10⁻⁶ -3 The first melting and smelting process was carried out at Pa and a current of 150A. After cooling, the surface of the ingots was polished with a hand mill until it was glossy, and high-purity Ti ingots and high-purity Zr ingots were obtained, respectively. The first melting and smelting process was repeated five times, with a duration of 120 seconds per cycle.

[0062] (2) After mixing the high-purity Ti ingot obtained in step (1), the obtained high-purity Zr ingot, Cr grains, electrolytic Mn sheet, and La metal in an atomic ratio of 0.7:0.3:1:1:0.01, the mixture was preheated at 30kW for 12 minutes, followed by a second melting and smelting process at a vacuum of -0.06MPa and 60kW for 8 minutes, then casting was carried out at 30kW, and finally the mixture was cooled to room temperature to obtain the rare earth AB2 type hydrogen storage alloy.

[0063] [Example 2] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy. In step (1), the first melting and smelting process was not performed on sponge Zr, i.e., the high-purity Zr ingot in step (2) was replaced with sponge Zr. All other conditions were the same as in Example 1.

[0064] [Example 3] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 1, except that the first melting and smelting of sponge Ti was not performed in step (1), that is, the high-purity Ti ingot in step (2) was replaced with sponge Ti.

[0065] [Example 4] This example provides a method for producing a rare-earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 1, except that the La metal in step (1) and step (2) was replaced with Ce metal.

[0066] [Example 5] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 4, except that the first melting and smelting of sponge Zr was not performed in step (1), that is, the high-purity Zr ingot in step (2) was replaced with sponge Zr.

[0067] [Example 6] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 4, except that the first melting and smelting of sponge Ti was not performed in step (1), that is, the high-purity Ti ingot in step (2) was replaced with sponge Ti.

[0068] [Example 7] This embodiment provides a method for producing a rare-earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 1, except that the atomic ratio of sponge Ti to La metal in step (1) was 1:0.03 and the atomic ratio of sponge Zr to La metal was 1:0.03.

[0069] [Example 8] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 7, except that the first melting and smelting of sponge Zr was not performed in step (1), that is, the high-purity Zr ingot in step (2) was replaced with sponge Zr.

[0070] [Example 9] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 7, except that the first melting and smelting of sponge Ti was not performed in step (1), that is, the high-purity Ti ingot in step (2) was replaced with sponge Ti.

[0071] [Example 10] This embodiment provides a method for producing a rare-earth AB2 type hydrogen storage alloy, in which the La metal in step (1) and step (2) is replaced with Ce metal, and the atomic ratio of sponge Ti to Ce metal in step (1) is 1:0.03, and the atomic ratio of sponge Zr to Ce metal is 1:0.03, all other conditions are the same as in Example 1.

[0072] [Example 11] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 10, except that the first melting and smelting of sponge Zr was not performed in step (1), that is, the high-purity Zr ingot in step (2) was replaced with sponge Zr.

[0073] [Example 12] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 11, except that the first melting and smelting of sponge Ti was not performed in step (1), that is, the high-purity Ti ingot in step (2) was replaced with sponge Ti.

[0074] [Example 13] This embodiment provides a method for producing a rare-earth AB2 type hydrogen storage alloy, the production method comprising the following steps.

[0075] (1) Mix sponge Ti and La metal in an atomic ratio of 1:0.02 and place in the first crucible. Mix sponge Zr and La metal in an atomic ratio of 1:0.02 and place in the second crucible. Then, argon gas, vacuum of 1 × 10⁻⁶ -3 The first melting and smelting process was carried out at Pa and a current of 100A. After cooling, the surface of the ingot was polished with a hand mill until it was glossy, and high-purity Ti ingots and high-purity Zr ingots were obtained, respectively. The first melting and smelting process was repeated five times, with a duration of 300 seconds per cycle.

[0076] (2) After mixing the high-purity Ti ingot obtained in step (1), the obtained high-purity Zr ingot, Cr grains, electrolytic Mn sheet, and La metal in an atomic ratio of 0.7:0.3:1:1:0.01, the mixture was preheated at 25kW for 15 minutes, followed by a second melting and smelting process at a vacuum of -0.06MPa and 55kW for 10 minutes, then casting was carried out at 35kW, and finally the mixture was cooled to room temperature to obtain the rare earth AB2 type hydrogen storage alloy.

[0077] [Example 14] This embodiment provides a method for producing a rare-earth AB2 type hydrogen storage alloy, the production method comprising the following steps.

[0078] (1) Mix sponge Ti and La metal in an atomic ratio of 1:0.01 and place in the first crucible. Mix sponge Zr and La metal in an atomic ratio of 1:0.01 and place in the second crucible. Then, argon gas, vacuum of 2 × 10⁻⁶ -3 The first melting and smelting process was carried out at Pa and a current of 200A. After cooling, the surface of the ingots was polished with a hand mill until it was glossy, and high-purity Ti ingots and high-purity Zr ingots were obtained, respectively. The first melting and smelting process was repeated four times, with a duration of 60 seconds per cycle.

[0079] (2) The high-purity Ti ingot obtained in step (1) in an atomic ratio of 0.7:0.3:1:1:0.01, the obtained high-purity Zr ingot, Cr grains, electrolytic Mn sheet, and La metal were mixed, preheated at 35 kW for 10 minutes, then a second melting and smelting was carried out at a vacuum of -0.06 MPa and a power of 65 kW for 6 minutes, then casting was carried out at a power of 25 kW, and finally the mixture was furnace-cooled to room temperature to obtain the rare earth AB2 type hydrogen storage alloy.

[0080] [Example 15] This example provides a method for producing a rare-earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the atomic ratio of sponge Zr to La metal in step (1) was 1:0.003.

[0081] [Example 16] This example provides a method for producing a rare-earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the atomic ratio of sponge Zr to La metal in step (1) was 1:0.1.

[0082] [Example 17] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the current for the first melting and smelting in step (1) was 40A.

[0083] [Example 18] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the current for the first melting and smelting in step (1) was 300 A.

[0084] [Example 19] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the time for the first melting and smelting in step (1) was 20 s / cycle. [Example 20] This embodiment provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the time for the first melting and smelting in step (1) was 400 s / cycle.

[0085] [Comparative Example 1] This comparative example provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 1, except that the operation in step (1) was omitted, i.e., the high-purity Ti ingot and high-purity Zr ingot in step (2) were replaced with sponge Ti and sponge Zr, respectively.

[0086] [Comparative Example 2] This comparative example provides a method for producing a rare earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 4, except that the operation in step (1) was omitted, i.e., the high-purity Ti ingot and high-purity Zr ingot in step (2) were replaced with sponge Ti and sponge Zr, respectively.

[0087] [Comparative Example 3] This comparative example provides a method for producing a rare-earth AB2 type hydrogen storage alloy, and all other conditions were the same as in Example 3, except that the La metal in step (1) was replaced with Al metal.

[0088] [Comparative Example 4] This comparative example provides a method for producing a rare earth AB2 type hydrogen storage alloy. Although La metal was not added in step (1), all other conditions were the same as in Example 3, except that the first melting and smelting process was performed.

[0089] Using an inductively coupled plasma spectrometer, purity detection was performed on the high-purity Ti ingots and high-purity Zr ingots obtained in step (1) of the above examples and comparative examples. Furthermore, hydrogen storage performance tests and production capacity calculations were performed on the rare-earth AB2 type hydrogen storage alloys produced in the above examples and comparative examples. The hydrogen storage performance test method was performed in reference to GB / T 33291-2016.

[0090] Figure 1 shows the hydrogen storage and release PCT graph (298K) of the hydrogen storage alloys produced in Example 1 and Comparative Example 1 of the present invention. From the figure, it can be seen that the hydrogen storage alloy produced in Example 1 had a more stable plateau pressure and lower hysteresis and residue.

[0091] The measurement results for the above examples and comparative examples are shown in Table 1. [Table 1]

[0092] From Table 1, the following was found:

[0093] (1) The manufacturing method according to Examples 1 to 14 of the present invention involves mixing raw material A with rare earth metals, then refining by a first melting and smelting process, and by linking this to the control of corresponding process parameters, it is possible to effectively improve the purity of the metal raw material. Furthermore, by subsequently performing a second melting and smelting process using the high-purity A ingot to produce a hydrogen storage alloy, the hydrogen storage alloy exhibits more stable plateau pressure, lower hysteresis and residue, a hysteresis factor of 0.725 or less, effectively improving hydrogen storage and release characteristics. In addition, the volume density of the high-purity A ingot is significantly improved, thereby increasing the amount of material that can be loaded into the crucible during lot production, making it suitable for large-scale production, significantly improving melting and smelting production capacity, achieving cost reduction and improved efficiency. Compared to the direct melting method of raw material A, the melting and smelting production capacity is improved by more than 17%, assuming the same volume of raw material.

[0094] (2) By comparing Example 3 with Examples 15-16 together, it was found that if the amount of first rare earth metal added is too small, impurities in the sponge Zr cannot be sufficiently removed, the purity of the hydrogen storage alloy decreases, and hysteresis becomes large. If the amount of first rare earth metal added is too large, the performance does not differ significantly from Example 3, but the cost of raw materials and post-processing increases because there is too much ineffective addition of the first rare earth metal.

[0095] (3) By comparing Example 3 with Examples 17-18 together, it was found that if the current for the first melting and smelting is too low, not only will impurities in the sponge Zr not be sufficiently removed, but the volume density of the ingot will not be effectively increased, and if the current for the first melting and smelting is too high, the heating temperature will be too high, leading to increased energy consumption and / or device damage.

[0096] (4) By comparing Example 3 with Examples 19-20 together, it was found that if the first melting and smelting time is too short, not only are impurities in the sponge Zr not sufficiently removed, but the volume density of the ingot cannot be effectively increased, and if the first melting and smelting time is too long, energy consumption increases because the power is used for a long time.

[0097] (5) By comparing Examples 1 and 4 with Comparative Examples 1 and 2, it was found that when sponge Ti and sponge Zr are used as raw materials and melted directly, the hydrogen storage alloy produced has a reduced effective hydrogen release rate, poor plateau characteristics, large hysteresis, and low volume density of sponge Ti and sponge Zr, which is unfavorable for improving melting and smelting production capacity.

[0098] (6) By comparing Example 3 and Comparative Example 3 together, it was found that when sponge Zr is refined using the oxygen scavenger Al metal instead of rare earth metals, the aluminum metal contributes to grain refinement and reduces hysteresis in the hydrogen storage alloy, but impurities in the sponge Zr cannot be sufficiently removed, so the purity of the Zr source is lower than the purity of the sponge Zr, and furthermore the purity of the hydrogen storage alloy decreases, resulting in a decrease in the maximum hydrogen storage capacity and effective hydrogen release capacity. By comparing Example 3 and Comparative Example 4 together, it was found that when the first melting and smelting is performed on sponge Zr alone without adding the first rare earth metal, most of the impurities in the raw material are not removed, so the improvement in the hydrogen storage and release characteristics of the material is limited.

[0099] Although the detailed structural features of the present invention have been described by the above embodiments, the applicant declares that the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented in accordance with the above detailed structural features. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions and additions of auxiliary components to the members used in the present invention, and selection of specific forms are all included within the scope of protection and disclosure of the present invention.

Claims

1. Rare earth AB ２ A method for manufacturing a hydrogen storage alloy of the type, (1) A raw material A selected from sponge Ti and / or sponge Zr in an atomic ratio of 1:(0.005 to 0.03) is mixed with a first rare earth metal, a first melting and smelting is performed, and then post-treatment including polishing or pickling is performed to remove rare earth elements and impurity elements from the surface of the ingot to obtain a high-purity A ingot. (2) Mix the A source selected from the high-purity A ingot and any A raw material described in step (1), the B source selected from the Cr source and / or Mn source, and the second rare earth metal, and perform a second melting and smelting process, and the rare earth AB ２ The steps include (2) obtaining a hydrogen storage alloy of type A manufacturing method characterized by the following features.

2. After mixing raw material A and a first rare earth metal in an atomic ratio of 1:(0.005-0.03), an inert gas and a vacuum of ≤5 × 10⁻⁶ are used. －３ The process involves first melting and smelting at Pa and an electric current of 80 to 200 A, then post-processing the surface of the high-purity A ingot until it is glossy to remove rare earth elements and impurity elements from the surface of the ingot, thereby obtaining a high-purity A ingot with a purity of ≥ 99.85%, The raw material A is selected from sponge Ti and / or sponge Zr, the purity of the raw material A is ≥ 99%, and the first rare earth metal includes one or at least two of La, Ce, Y, Sm, Er, or Gd. Step (1) is a step in which the number of first melting and smelting steps is 3 to 6 times and the time is 50 to 300 s / step, After mixing source A, source B, and a second rare earth metal in an atomic ratio of (0.8-1.2):(1.8-2.2):(0.008-0.012), preheating is performed for 10-15 mins at a power of 25-35 kW, followed by a second melting and smelting process for 5-10 mins at a vacuum of ≤-0.06 MPa and a power of 55-65 kW, then casting is performed at a power of 25-35 kW, and finally furnace cooling is performed to obtain rare earth AB with a hysteresis factor <0.

73. ２ A step to obtain a hydrogen storage alloy of type, Step (2) includes: the A source being selected from the high-purity A ingot and any A raw material described in step (1), the B source being selected from the Cr source and / or Mn source, and the second rare earth metal being one or at least two of La, Ce, Y, Sm, Er, or Gd; The manufacturing method according to claim 1, characterized in that it

3. Rare earth AB ２ A method for manufacturing a hydrogen storage alloy of the type, The process involves mixing sponge Ti and a first rare earth metal in an atomic ratio of 1:(0.005-0.03) and placing the mixture in a first crucible, mixing sponge Zr and a first rare earth metal in an atomic ratio of 1:(0.005-0.03) and placing the mixture in a second crucible, performing a first melting and smelting process, and then performing post-processing to remove rare earth elements and impurity elements from the surface of the ingots to obtain high-purity Ti ingots and high-purity Zr ingots, respectively. The post-treatment method includes step (1) polishing or pickling, Source A, source B, and a second rare earth metal are mixed, and a second melting and smelting process is carried out, resulting in the aforementioned rare earth AB ２ A step to obtain a hydrogen storage alloy of type, Step (2) includes selecting the A source from the high-purity Ti ingot and high-purity Zr ingot described in step (1), and selecting the B source from the Cr source and / or Mn source. A manufacturing method characterized by the following features.

4. The purity of the aforementioned raw material A is ≥ 99%, The first rare earth metal described in step (1) includes one or at least two of the following: La, Ce, Y, Sm, Er, or Gd. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

5. The first melting and smelting method described in step (1) includes one of the following: arc melting, induction melting, or flotation melting. The first melting and smelting described in step (1) is carried out in an inert gas environment. Vacuum degree of the first melting and smelting described in step (1) ≤ 5 × 10 －３ Pa is, The number of times the first melting and smelting described in step (1) is 3 to 6 times, The current for the first melting and smelting described in step (1) is 80 to 200 A. The time for the first melting and smelting described in step (1) is 50 to 300 seconds per cycle. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

6. The endpoint of the post-processing described in step (1) is that the surface of the high-purity A ingot is glossy. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

7. The purity of the high-purity ingot A described in step (1) is ≥ 99.85%. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

8. The second rare earth metal described in step (2) includes one or at least two of the following: La, Ce, Y, Sm, Er, or Gd. The atomic ratios of source A, source B, and the second rare earth metal described in step (2) are (0.8–1.2):(1.8–2.2):(0.008–0.012). The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

9. The second melting and smelting method described in step (2) includes one of the following: arc melting, induction melting, or flotation melting. The vacuum level of the second melting and smelting process is ≤ -0.06 MPa. The power consumption for the second melting and smelting process is 55-65 kW. The duration of the second melting and smelting process is 5 to 10 minutes. The process further includes preheating for 10 to 15 minutes with an electric power of 25 to 35 kW before the second melting and smelting process, The process further includes casting and furnace cooling, which are carried out sequentially after the second melting and smelting process. The power used for the aforementioned casting is 25-35 kW. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

10. The aforementioned rare earth element AB ２ The hysteresis factor of the hydrogen storage alloy is <0.

73. The manufacturing method according to claim 1 or 3, characterized in that it is a method of production according to claim 1 or 3.

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