A method for preparing rare earth AB2 type hydrogen storage alloy

Abstract

The present invention provides a rare earth AB 2 A method for preparing a type hydrogen storage alloy, the preparation method comprising: (1) mixing a raw material A and a first rare earth metal, and performing a first smelting and a post-treatment in sequence to obtain a high-purity A ingot; the raw material A comprises sponge Ti and / or sponge Zr; (2) mixing an A source, a B source, and a second rare earth metal, and performing a second smelting to obtain the rare earth AB 2 type hydrogen storage alloy; the A source comprises the high-purity A ingot and optional A raw material of step (1); the B source comprises a Cr source and / or a Mn source. The present invention refines the rare earth metal and the A raw material by the first smelting, which can not only effectively improve the purity of the metal raw material, but also use the high-purity A ingot for the second smelting to prepare the hydrogen storage alloy, so that the platform pressure of the hydrogen storage alloy is more stable, the hysteresis and residual hysteresis are lower, and the hydrogen absorption and desorption performance is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen storage alloys and relates to a preparation method of a rare earth AB2 type hydrogen storage alloy. Background Art

[0002] As the most abundant element on earth, hydrogen has a very high energy density. As a fuel, the calorific value of hydrogen is three times that of gasoline and other fuels. At the same time, the emission of pollutants after combustion is almost zero, making it an ideal energy carrier. Compared with hydrogen production, safe and reliable hydrogen storage technology is still relatively backward, and the storage and transportation costs are relatively high. For this reason, most companies choose to consume the produced H2 on-site. This method is more suitable for some comprehensive hydrogen production and application bases, but in most cases, the production and use locations of hydrogen are inconsistent, so it is particularly important to study efficient and low-energy hydrogen storage and transportation technologies.

[0003] High-pressure hydrogen storage is currently the most widely used hydrogen storage method in China. It compresses hydrogen into high-pressure gas cylinders or tank containers under high pressure. This method has a fast hydrogen storage and release speed and a controllable process. It is currently a relatively mature commercial hydrogen storage technology. However, due to the limited capacity of the gas cylinder, the hydrogen storage quality is too low compared to the weight of the gas cylinder itself, so the efficiency is not high. Since high-pressure hydrogen storage has certain safety hazards, such as hydrogen leakage during transportation or use, it will cause a great safety accident.

[0004] Solid-state hydrogen storage is a promising technology that has received widespread attention in recent years. Solid-state hydrogen storage can be roughly divided into: metal hydride hydrogen storage, chemical hydride, carbon material hydrogen storage, etc. Among them, metal hydride hydrogen storage is the storage and release of hydrogen by metals or alloys under certain conditions. According to the type of alloy, it can be divided 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 with other hydrogen storage alloys, AB2-type hydrogen storage alloys can absorb and release hydrogen at room temperature and pressure, and have a lower cost. It is a type of hydrogen storage material with great application value.

[0005] The A component elements in AB2 type hydrogen storage alloys are generally from Group IVA, such as (Ti, Zr, Hf) and some rare earth elements, and the B component elements are generally various transition or non-transition elements with smaller radius. The hydrogenated AB2 intermetallic compounds belong to the Laves phase, and TiCr2, TiMn2, and ZrMn2-based multi-element alloys are widely studied in the Laves phase. Among them, the TiMn2-based hydrogen storage alloy is a typical representative of titanium-based AB2 type hydrogen storage alloys. The alloys in this system have high hydrogen storage capacity, good hydrogen absorption and desorption kinetics, and low cost. However, due to its poor platform characteristics and large hysteresis, it is urgent to improve the hydrogen storage performance of AB2 type hydrogen storage alloys.

[0006] In addition, during the smelting process of AB2 type hydrogen storage alloy, sponge titanium, sponge zirconium, chromium particles and electrolytic manganese sheets are usually used for smelting. The purity of these raw materials is usually between 99% and 99.7%, and they contain a small amount of impurities, such as Al, Fe, Hf, S, Se, Mg, C, etc. These impurities will be incorporated into the final hydrogen storage alloy sample during alloy smelting, thereby reducing the hydrogen absorption and desorption performance of the hydrogen storage alloy. However, the price of raw materials with higher purity (≥99.9%) is high and cannot meet the cost requirements of industrial production.

[0007] In summary, there is an urgent need to develop a new preparation method for AB2 type hydrogen storage alloy, which can improve the purity of the alloy, improve the hydrogen absorption and desorption properties of the alloy, and at the same time increase the smelting capacity. This is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0008] The object of the present invention is to provide a method for preparing a rare earth AB2 type hydrogen storage alloy, wherein rare earth metals and A raw materials are refined by a first smelting, and then a hydrogen storage alloy prepared by using a high-purity A ingot has a high reversible hydrogen storage capacity, a more stable platform pressure, lower hysteresis and residual hysteresis, and can better meet the use requirements of the linkage between a solid-state hydrogen storage device and a fuel cell; at the same time, the preparation method can significantly improve the smelting capacity and achieve cost reduction and efficiency improvement.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing a rare earth AB2 type hydrogen storage alloy, the preparation method comprising the following steps:

[0011] (1) Mixing raw material A and a first rare earth metal, and sequentially performing first smelting and grinding to obtain a high-purity A ingot;

[0012] The raw material A includes sponge Ti and / or sponge Zr;

[0013] (2) mixing the A source, the B source and the second rare earth metal, and performing a second smelting to obtain the rare earth AB2 type hydrogen storage alloy;

[0014] The A source comprises the high-purity A ingot and optional A raw material in step (1); the B source comprises a Cr source and / or a Mn source.

[0015] The preparation method provided by the present invention refines rare earth metals and raw material A through the first smelting, which can not only effectively improve the purity of the metal raw materials, but also use the high-purity A ingot obtained by the first smelting and post-treatment for the second smelting, so that the platform pressure of the obtained hydrogen storage alloy is more stable, the hysteresis and residual hysteresis are lower, and the hydrogen absorption and desorption performance is effectively improved. At the same time, the volume density of sponge titanium and / or sponge zirconium in the raw material A is relatively small. After the first smelting, the raw material changes from sponge to block, and the volume density of the high-purity A ingot is significantly improved, thereby increasing the charge amount in the crucible during batch preparation, greatly improving the smelting capacity, and achieving cost reduction and efficiency improvement.

[0016] It is worth noting that 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, so that the impurity elements are enriched around the rare earth oxides or form compounds. After the first smelting, the rare earth elements and impurity elements on the surface of the raw material are removed by post-treatment to obtain a high-purity A ingot, thereby achieving the effect of refining and purification. At the same time, the volume density of raw material A after the first smelting is significantly increased, thereby increasing the subsequent smelting capacity, which is suitable for large-scale preparation.

[0017] As a preferred technical solution of the present invention, the purity of the raw material A is ≥99%, for example, it can be 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5% or 99.6%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In the present invention, the density of the sponge Ti is 1.5-1.9 g / cm 3 , for example, it can be 1.5 g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 or 1.9 g / cm 3 The density of the sponge Zr is 4-5g / cm 3 , for example, it can be 4g / cm 3 , 4.1g / cm 3 , 4.2g / cm 3 , 4.3g / cm 3 4.4g / cm 3 , 4.5g / cm 3 , 4.6g / cm 3 , 4.7g / cm 3 , 4.8g / cm 3 , 4.9g / cm 3 or 5g / cm 3 The above values ​​are not limited to the above values, and other values ​​not listed in the above values ​​are also applicable.

[0019] In the present invention, the sponge Ti and sponge Zr are both commercially available products.

[0020] Step (1) The first rare earth metal includes any one of La, Ce, Y, Sm, Er or Gd or a combination of at least two of them, wherein the combination is typically but not limited to: a combination of La and Ce, a combination of Ce and Y or a combination of Sm and Er, etc.

[0021] The atomic ratio of the raw material A to the first rare earth metal in step (1) is 1:(0.005-0.03), for example, it can 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 values, and other values ​​not listed within the numerical range are also applicable.

[0022] It is worth noting that by controlling the atomic ratio range of raw material A and the first rare earth metal, not only can the impurity elements in raw material A be enriched around the rare earth oxide or form compounds, but the impurity elements and rare earth elements can be removed through post-processing, thereby improving the purity of raw material A, but it can also avoid excessive rare earth elements remaining in raw material A, thereby further improving the purity of raw material A.

[0023] As a preferred technical solution of the present invention, in step (1), the first smelting method includes any one of arc melting, induction melting or suspension melting.

[0024] In the present invention, the first smelting is carried out in a vacuum induction melting furnace. Since both Ti and Zr react with the crucible, the quality of Ti and Zr in the smelted ingot will fluctuate slightly, and the atomic ratio of Ti and Zr needs to be accurately controlled before the second smelting. Therefore, sponge Ti and the first rare earth metal, sponge Zr and the first rare earth metal need to be placed in different crucibles for the first smelting. If arc melting or suspension melting is used, Ti and Zr can be smelted together, and the quality of Ti and Zr in the smelted ingot does not change.

[0025] Step (1) The first smelting is carried out in an inert gas.

[0026] In the present invention, the inert gas is argon.

[0027] Step (1) The vacuum degree of the first smelting is ≤5×10 -3 Pa, for example, can be 5×10 -3 Pa, 4×10 -3 Pa, 3×10 -3 Pa, 2×10 -3 Pa or 1×10-3 Pa, etc., but not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0028] The number of times of the first smelting in step (1) is 3-6 times, for example, 3 times, 4 times, 5 times or 6 times, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] The current of the first smelting in step (1) is 80-200 A, 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, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] The time of the first smelting in step (1) is 50-300 s / time, for example, it can be 50 s / time, 80 s / time, 100 s / time, 120 s / time, 150 s / time, 180 s / time, 200 s / time, 220 s / time, 250 s / time, 280 s / time or 300 s / time, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] It is worth noting that by controlling the number of first smelting times, current, time and other parameter ranges, not only can the impurities in the A raw material be fully removed, but also the volume density of the high-purity A ingot can be significantly increased.

[0032] As a preferred technical solution of the present invention, the post-treatment method in step (1) includes grinding or pickling.

[0033] The end point of the post-treatment in step (1) is that the surface of the high-purity A ingot is bright.

[0034] In the present invention, if post-treatment is not performed, the rare earth elements and impurity elements on the surface of the ingot cannot be removed, thereby affecting the purity of the high-purity A ingot.

[0035] In the present invention, the polishing method comprises: using sandpaper or a grinder to polish the surface of the first smelted ingot until the surface is bright.

[0036] In the present invention, the specific solution and amount of pickling are not limited, as long as the oxide scale, impurities and rare earth elements on the surface of the ingot after the first smelting are removed, and those skilled in the art can select according to actual conditions.

[0037] As a preferred technical solution of the present invention, the purity of the high-purity A ingot in step (1) is ≥99.85%, for example, it can be 99.85%, 99.86%, 99.88%, 99.9%, 99.91%, 99.93% or 99.95%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] The high-purity A ingot in step (1) includes a high-purity Ti ingot and / or a high-purity Zr ingot.

[0039] In the present invention, the density of the high-purity Ti ingot is >4.2 g / cm 3 , for example, it can be 4.25g / cm 3 , 4.3g / cm 3 4.35g / cm 3 4.4g / cm 3 4.45g / cm 3 or 4.5g / cm 3 The density of the high-purity Zr ingot is > 6.2 g / cm 3 , for example, it can be 6.25g / cm 3 、6.3g / cm 3 、6.35g / cm 3 、6.4g / cm 3 or 6.45g / cm 3 The above values ​​are not limited to the above values, and other values ​​not listed in the above values ​​are also applicable.

[0040] In the present invention, the purity and bulk density of the obtained high-purity A ingot are significantly increased.

[0041] As a preferred technical solution of the present invention, the source A in step (2) includes a Ti source and a Zr source, and the source A includes the following:

[0042] (a) the A source comprises a high-purity Ti ingot and a high-purity Zr ingot; or (b) the A source comprises a high-purity Ti ingot and sponge Zr; or (c) the A source comprises sponge Ti and a high-purity Zr ingot.

[0043] In the present invention, the A source is preferably a high-purity Ti ingot and a high-purity Zr ingot.

[0044] As a preferred technical solution of the present invention, in step (2), the second rare earth metal includes any one of La, Ce, Y, Sm, Er or Gd, or a combination of at least two thereof.

[0045] The atomic ratio of the A source, the B source and the second rare earth metal in step (2) is (0.8-1.2):(1.8-2.2):(0.008-0.012), for example, it can be 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. Other values ​​not listed within the numerical range are also applicable, preferably 1:2:(0.008-0.012).

[0046] As a preferred technical solution of the present invention, it is characterized in that the second smelting method in step (2) includes any one of arc melting, induction melting or suspension melting.

[0047] The vacuum degree of the second smelting is ≤-0.06MPa.

[0048] The power of the second smelting is 55-65kW, for example, it can be 55kW, 56kW, 57kW, 58kW, 59kW, 60kW, 61kW, 62kW, 63kW, 64kW or 65kW, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] The second smelting time is 5-10 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] Before the second smelting, the process also includes: preheating for 10-15 minutes at a power of 25-35 kW.

[0051] The preheating power is 25-35kW, for example, it can be 25kW, 26kW, 27kW, 28kW, 29kW, 30kW, 31kW, 32kW, 33kW, 34kW or 35kW, etc., and the preheating time is 10-15min, for example, it can be 10min, 11min, 12min, 13min, 14min or 15min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] The second smelting also includes: casting and furnace cooling in sequence.

[0053] The casting power is 25-35kW, for example, it can be 25kW, 26kW, 27kW, 28kW, 29kW, 30kW, 31kW, 32kW, 33kW, 34kW or 35kW, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] As a preferred technical solution of the present invention, the hysteresis factor of the rare earth AB2 type hydrogen storage alloy is less than 0.73, for example, it can be 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 unlisted values ​​within the numerical range are also applicable.

[0055] It is worth noting that, compared with the direct smelting method of raw material A, the rare earth AB2 type hydrogen storage alloy prepared by the preparation method provided by the present invention has an effective hydrogen release amount increased from 1.72wt% to 1.86wt%, and the hysteresis factor is reduced from 0.802 to 0.667. Under the premise of the same volume of raw materials, the smelting capacity is increased by more than 17%, and the smelting capacity is increased by more than 28% under optimal conditions.

[0056] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0057] (1) Mix raw material A and the first rare earth metal in an atomic ratio of 1:(0.005-0.03), and then place in an inert gas with a vacuum degree of ≤5×10 -3 The first smelting is carried out at 1000 rpm and a current of 80-200A, followed by post-treatment until the surface of the high-purity A ingot is bright, thereby obtaining a high-purity A ingot with a purity of ≥99.85%;

[0058] The A raw material includes sponge Ti and / or sponge Zr; the purity of the A raw material is ≥99%; the first rare earth metal includes any one of La, Ce, Y, Sm, Er or Gd or a combination of at least two;

[0059] The first smelting is performed 3-6 times and the time is 50-300s / time;

[0060] The high-purity A ingot includes a high-purity Ti ingot and / or a high-purity Zr ingot;

[0061] (2) Mixing source A, source B and a second rare earth metal according to an atomic ratio of (0.8-1.2):(1.8-2.2):(0.008-0.012), and then preheating at a power of 25-35 kW for 10-15 min, followed by a second smelting at a vacuum degree of ≤-0.06 MPa and a power of 55-65 kW for 5-10 min, and then casting at a power of 25-35 kW, and finally cooling with the furnace to obtain a rare earth AB2 type hydrogen storage alloy with a hysteresis factor of <0.73;

[0062] The B source includes a Cr source and / or a Mn source; the second rare earth metal includes any one or a combination of at least two of La, Ce, Y, Sm, Er or Gd;

[0063] The A source is a Ti source and a Zr source, and the A source includes the following situations:

[0064] (a) the A source comprises a high-purity Ti ingot and a high-purity Zr ingot; or

[0065] (b) the A source comprises high purity Ti ingot and sponge Zr; or

[0066] (c) The A source includes sponge Ti and high-purity Zr ingot.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) The preparation method provided by the present invention, after mixing the A raw material with the rare earth metal, performs refining through the first smelting and combines with the control of corresponding process parameters, which can not only effectively improve the purity of the metal raw material, but also use the high-purity A ingot for the second smelting to prepare the hydrogen storage alloy, so that the platform pressure of the hydrogen storage alloy is more stable, the hysteresis and residual hysteresis are lower, and the hydrogen absorption and desorption performance is effectively improved, which can better meet the use requirements of the solid-state hydrogen storage device and the fuel cell linkage, and has a high application value;

[0069] (2) The preparation method provided by the present invention has a relatively small volume density of sponge titanium and / or sponge zirconium in raw material A. Through the first smelting and combined with the control of corresponding process parameters, raw material A is changed from sponge to block, and the volume density of high-purity A ingot is also significantly improved, thereby increasing the loading amount in the crucible during batch preparation, being suitable for large-scale preparation, greatly improving the smelting capacity, and achieving cost reduction and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 The PCT curves (298K) of hydrogen absorption and desorption of the hydrogen storage alloys prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0071] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0072] In the following examples and comparative examples, the purity of the sponge Ti is 99.68%, the purity of the sponge Zr is 99.39%, and the sponge Ti, sponge Zr, Cr particles, and electrolytic Mn sheets are all commercially available products.

[0073] Example 1

[0074] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy, the preparation method comprising the following steps:

[0075] (1) Sponge Ti and La metal were mixed in an atomic ratio of 1:0.01 and placed in the first crucible. Sponge Zr and La metal were mixed in an atomic ratio of 1:0.01 and placed in the second crucible. Then, the mixture was placed in an argon atmosphere with a vacuum degree of 5×10 -3 The first smelting was carried out at 150A and 150A, and after cooling, the ingots were polished with a hand grinder until the surface of the ingots was bright, thereby obtaining high-purity Ti ingots and high-purity Zr ingots respectively;

[0076] The first smelting is performed 5 times and the time is 120s / time;

[0077] (2) The high-purity Ti ingot obtained in step (1), the high-purity Zr ingot obtained, Cr particles, electrolytic Mn sheets and La metal are mixed in an atomic ratio of 0.7:0.3:1:1:0.01, and then preheated at a power of 30 kW for 12 min, followed by a second smelting at a vacuum degree of -0.06 MPa and a power of 60 kW for 8 min, and then cast at a power of 30 kW, and finally cooled to room temperature with the furnace to obtain the rare earth AB2 type hydrogen storage alloy.

[0078] Example 2

[0079] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Zr is not subjected to the first smelting in step (1), that is, the high-purity Zr ingot in step (2) is replaced by sponge Zr, other conditions are the same as those in Example 1.

[0080] Example 3

[0081] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Ti is not subjected to the first smelting in step (1), that is, the high-purity Ti ingot in step (2) is replaced by sponge Ti, other conditions are the same as those in Example 1.

[0082] Example 4

[0083] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that La metal is replaced by Ce metal in step (1) and step (2), other conditions are the same as those in embodiment 1.

[0084] Example 5

[0085] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Zr is not subjected to the first smelting in step (1), that is, the high-purity Zr ingot in step (2) is replaced by sponge Zr, other conditions are the same as those in Example 4.

[0086] Example 6

[0087] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Ti is not subjected to the first smelting in step (1), that is, the high-purity Ti ingot in step (2) is replaced by sponge Ti, other conditions are the same as those in Example 4.

[0088] Example 7

[0089] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the atomic ratio of sponge Ti and La metal in step (1) is 1:0.03, and the atomic ratio of sponge Zr and La metal is 1:0.03, other conditions are the same as those in Example 1.

[0090] Example 8

[0091] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Zr is not subjected to the first smelting in step (1), that is, the high-purity Zr ingot in step (2) is replaced by sponge Zr, other conditions are the same as those in Example 7.

[0092] Example 9

[0093] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Ti is not subjected to the first smelting in step (1), that is, the high-purity Ti ingot in step (2) is replaced by sponge Ti, other conditions are the same as those in Example 7.

[0094] Example 10

[0095] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that La metal in step (1) and step (2) is replaced by Ce metal, and the atomic ratio of sponge Ti and Ce metal in step (1) is 1:0.03, and the atomic ratio of sponge Zr and Ce metal is 1:0.03, other conditions are the same as those in Example 1.

[0096] Embodiment 11

[0097] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Zr is not subjected to the first smelting in step (1), that is, the high-purity Zr ingot in step (2) is replaced by sponge Zr, other conditions are the same as those in Example 10.

[0098] Example 12

[0099] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the sponge Ti is not subjected to the first smelting in step (1), that is, the high-purity Ti ingot in step (2) is replaced by sponge Ti, other conditions are the same as those in Example 11.

[0100] Embodiment 13

[0101] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy, the preparation method comprising the following steps:

[0102] (1) Sponge Ti and La metal were mixed in an atomic ratio of 1:0.02 and placed in the first crucible. Sponge Zr and La metal were mixed in an atomic ratio of 1:0.02 and placed in the second crucible. Then, the mixture was placed in an argon atmosphere with a vacuum degree of 1×10 -3 The first smelting was carried out at 100A and 100A, and after cooling, the ingots were polished with a hand grinder until the surface of the ingots was bright, thereby obtaining high-purity Ti ingots and high-purity Zr ingots respectively;

[0103] The first smelting is performed 5 times and the time is 300s / time;

[0104] (2) The high-purity Ti ingot obtained in step (1), the high-purity Zr ingot obtained, Cr particles, electrolytic Mn sheets and La metal are mixed in an atomic ratio of 0.7:0.3:1:1:0.01, and then preheated at a power of 25 kW for 15 min, followed by a second smelting at a vacuum degree of -0.06 MPa and a power of 55 kW for 10 min, and then cast at a power of 35 kW, and finally cooled to room temperature with the furnace to obtain the rare earth AB2 type hydrogen storage alloy.

[0105] Embodiment 14

[0106] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy, the preparation method comprising the following steps:

[0107] (1) Sponge Ti and La metal were mixed in an atomic ratio of 1:0.01 and placed in the first crucible. Sponge Zr and La metal were mixed in an atomic ratio of 1:0.01 and placed in the second crucible. Then, the mixture was placed in an argon atmosphere with a vacuum degree of 2×10 -3 The first smelting was carried out at 200A and 200A, and after cooling, the ingots were polished with a hand grinder until the surface of the ingots was bright, thereby obtaining high-purity Ti ingots and high-purity Zr ingots respectively;

[0108] The first smelting is performed 4 times, and the time is 60s / time;

[0109] (2) The high-purity Ti ingot obtained in step (1), the high-purity Zr ingot obtained, Cr particles, electrolytic Mn sheets and La metal are mixed in an atomic ratio of 0.7:0.3:1:1:0.01, and then preheated at a power of 35 kW for 10 min, followed by a second smelting at a vacuum degree of -0.06 MPa and a power of 65 kW for 6 min, and then cast at a power of 25 kW, and finally cooled to room temperature with the furnace to obtain the rare earth AB2 type hydrogen storage alloy.

[0110] Embodiment 15

[0111] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the atomic ratio of sponge Zr and La metal in step (1) is 1:0.003, other conditions are the same as those in Example 3.

[0112] Example 16

[0113] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the atomic ratio of sponge Zr and La metal in step (1) is 1:0.1, other conditions are the same as those in Example 3.

[0114] Embodiment 17

[0115] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the current of the first smelting in step (1) is 40A, other conditions are the same as those in Example 3.

[0116] Embodiment 18

[0117] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the current of the first smelting in step (1) is 300A, other conditions are the same as those in Example 3.

[0118] Embodiment 19

[0119] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the time for the first smelting in step (1) is 20 s / time, other conditions are the same as those in Example 3.

[0120] Embodiment 20

[0121] This embodiment provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that the time of the first smelting in step (1) is 400 s / time, other conditions are the same as those in Example 3.

[0122] Comparative Example 1

[0123] This comparative example provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that step (1) is not performed, that is, the high-purity Ti ingot and the high-purity Zr ingot in step (2) are replaced by sponge Ti and sponge Zr respectively, other conditions are the same as those in Example 1.

[0124] Comparative Example 2

[0125] This comparative example provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that step (1) is not performed, that is, the high-purity Ti ingot and the high-purity Zr ingot in step (2) are replaced by sponge Ti and sponge Zr respectively, other conditions are the same as those in Example 4.

[0126] Comparative Example 3

[0127] This comparative example provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except for replacing the La metal in step (1) with Al metal, other conditions are the same as those in Example 3.

[0128] Comparative Example 4

[0129] This comparative example provides a method for preparing a rare earth AB2 type hydrogen storage alloy. Except that La metal is not added in step (1), but a first smelting is performed, other conditions are the same as those in Example 3.

[0130] The purity of the high-purity Ti ingot and the high-purity Zr ingot obtained in step (1) of the above embodiment and the comparative example was detected by an inductively coupled plasma spectrometer, and the hydrogen storage performance and capacity calculation of the rare earth AB2 type hydrogen storage alloy obtained in the above embodiment and the comparative example were performed. The test method of the hydrogen storage performance was carried out in accordance with GB / T 33291-2016.

[0131] Figure 1 The PCT curves (298K) of hydrogen absorption and desorption of the hydrogen storage alloys prepared in Example 1 of the present invention and Comparative Example 1 show that the hydrogen storage alloy prepared in Example 1 has a more stable platform pressure, and lower hysteresis and residual hysteresis.

[0132] The test results of the above embodiments and comparative examples are shown in Table 1.

[0133] Table 1

[0134]

[0135] From Table 1, we can see that:

[0136] (1) The preparation method provided in Examples 1-14 of the present invention, after mixing the raw material A with the rare earth metal, performs refining through the first smelting and combines with the control of corresponding process parameters, which can not only effectively improve the purity of the metal raw material, but also use the high-purity A ingot for the second smelting to prepare the hydrogen storage alloy, so that the platform pressure of the hydrogen storage alloy is more stable, the hysteresis and residual hysteresis are lower, the hysteresis factor is lower than 0.725, the hydrogen absorption and desorption performance is effectively improved, and the volume density of the high-purity A ingot is also significantly improved, thereby increasing the loading amount in the crucible during batch preparation, which is suitable for large-scale preparation, greatly improving the smelting capacity, and achieving cost reduction and efficiency improvement. Compared with the direct smelting method of raw material A, under the premise of the same volume of raw materials, the smelting capacity is increased by more than 17%;

[0137] (2) It can be seen from the comparison between Example 3 and Examples 15-16 that when the amount of the first rare earth metal added is too little, the impurities in the sponge Zr cannot be fully removed, which further leads to a decrease in the purity of the hydrogen storage alloy and a large hysteresis; when the amount of the first rare earth metal added is too much, although the performance is not much different from that of Example 3, the ineffective addition of the first rare earth metal leads to an increase in the cost of raw materials and post-processing;

[0138] (3) By comparing Example 3 with Examples 17-18, it can be seen that when the current of the first smelting is too low, not only can the impurities in the sponge Zr not be fully removed, but also the volume density of the ingot cannot be effectively increased; when the current of the first smelting is too high, the heating temperature is too high, resulting in increased energy consumption and / or equipment damage;

[0139] (4) By comparing Example 3 with Examples 19-20, it can be seen that when the first smelting time is too short, not only can the impurities in the sponge Zr not be fully removed, but also the volume density of the ingot cannot be effectively increased; when the first smelting time is too long, the energy consumption increases due to the long power consumption time;

[0140] (5) By comparing Examples 1 and 4 with Comparative Examples 1 and 2, it can be seen that when sponge Ti and sponge Zr are used as raw materials for direct smelting, the effective hydrogen release amount of the obtained hydrogen storage alloy decreases, the platform characteristics are poor, the hysteresis is large, and the volume density of sponge Ti and sponge Zr is small, which is not conducive to improving the smelting capacity;

[0141] (6) By comparing Example 3 with Comparative Example 3, it can be seen that when the deoxidizer Al metal is used to replace the rare earth metal to refine the sponge Zr, although the aluminum metal helps to refine the grains and reduce the hysteresis of the hydrogen storage alloy, it cannot fully remove the impurities in the sponge Zr, resulting in the purity of the Zr source being lower than the purity of the sponge Zr, further resulting in a decrease in the purity of the hydrogen storage alloy, and a decrease in the maximum hydrogen absorption amount and the effective hydrogen release amount. By comparing Example 3 with Comparative Example 4, it can be seen that when the first rare earth metal is not added and only the sponge Zr is subjected to the first smelting, most of the impurities in the raw material are not removed, resulting in limited improvement in the hydrogen absorption and desorption performance of the material.

[0142] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a rare earth AB2 type hydrogen storage alloy, characterized in that: The preparation method comprises the following steps: (1) Mixing raw material A and a first rare earth metal in an atomic ratio of 1:(0.005-0.03), performing a first smelting, and then performing a post-treatment to remove rare earth elements and impurity elements on the surface of the ingot to obtain a high-purity A ingot; The raw material A is selected from sponge Ti and / or sponge Zr; The post-treatment method includes grinding or pickling; (2) mixing the A source, the B source and the second rare earth metal, and performing a second smelting to obtain the rare earth AB2 type hydrogen storage alloy; The A source is selected from the high-purity A ingot and optional A raw material in step (1); the B source is selected from a Cr source and / or a Mn source.

2. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) Mix raw material A and the first rare earth metal in an atomic ratio of 1:(0.005-0.03), and then place in an inert gas with a vacuum degree of ≤5×10 -3 The first smelting is carried out at 1000 Pa and a current of 80-200A, followed by post-treatment to remove rare earth elements and impurity elements on the surface of the ingot until the surface of the high-purity A ingot is bright, 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%; the first rare earth metal includes any one or a combination of at least two of La, Ce, Y, Sm, Er or Gd; The first smelting is performed 3-6 times and the time is 50-300s / time; (2) Mixing source A, source B and a second rare earth metal according to an atomic ratio of (0.8-1.2):(1.8-2.2):(0.008-0.012), and then preheating at a power of 25-35 kW for 10-15 min, followed by a second smelting at a vacuum degree of ≤-0.06 MPa and a power of 55-65 kW for 5-10 min, and then casting at a power of 25-35 kW, and finally cooling with the furnace to obtain a rare earth AB2 type hydrogen storage alloy with a hysteresis factor of <0.73; The A source is selected from the high-purity A ingot and optional A raw material in step (1); the B source is selected from a Cr source and / or a Mn source; and the second rare earth metal includes any one or a combination of at least two of La, Ce, Y, Sm, Er or Gd.

3. A method for preparing a rare earth AB2 type hydrogen storage alloy, characterized in that: The preparation method comprises the following steps: (1) mixing sponge Ti and a first rare earth metal in an atomic ratio of 1:(0.005-0.03) and placing them in a first crucible, and mixing sponge Zr and a first rare earth metal in an atomic ratio of 1:(0.005-0.03) and placing them in a second crucible, performing a first smelting, and then performing a post-treatment to remove rare earth elements and impurity elements on the surface of the ingot, to obtain a high-purity Ti ingot and a high-purity Zr ingot, respectively; The post-treatment method includes grinding or pickling; (2) mixing the A source, the B source and the second rare earth metal, and performing a second smelting to obtain the rare earth AB2 type hydrogen storage alloy; The A source is selected from the high-purity Ti ingot and the high-purity Zr ingot in step (1); the B source is selected from a Cr source and / or a Mn source.

4. The preparation method according to claim 1 or 3, characterized in that: The purity of the raw material A is ≥99%; Step (1) The first rare earth metal includes any one of La, Ce, Y, Sm, Er or Gd, or a combination of at least two of them.

5. The preparation method according to claim 1 or 3, characterized in that: Step (1) The first smelting method includes any one of arc melting, induction melting or suspension melting; Step (1) The first smelting is carried out in an inert gas; Step (1) The vacuum degree of the first smelting is ≤5×10 -3 Pa; Step (1) The first smelting is performed 3 to 6 times; Step (1) The current of the first smelting is 80-200A; Step (1) The first smelting time is 50-300s / time.

6. The preparation method according to claim 1 or 3, characterized in that: The end point of the post-treatment in step (1) is that the surface of the high-purity A ingot is bright.

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

8. The preparation method according to claim 1 or 3, characterized in that: Step (2) the second rare earth metal includes any one of La, Ce, Y, Sm, Er or Gd or a combination of at least two thereof; In step (2), the atomic ratio of the A source, the B source and the second rare earth metal is (0.8-1.2):(1.8-2.2):(0.008-0.012).

9. The preparation method according to claim 1 or 3, characterized in that: Step (2) the second smelting method includes any one of arc melting, induction melting or suspension melting; The vacuum degree of the second smelting is ≤-0.06MPa; The power of the second smelting is 55-65kW; The second smelting time is 5-10min; Prior to the second smelting, the process also includes: preheating for 10-15 minutes at a power of 25-35 kW; The second smelting further includes: casting and furnace cooling in sequence; The casting power is 25-35 kW.

10. The preparation method according to claim 1 or 3, characterized in that: The hysteresis factor of the rare earth AB2 type hydrogen storage alloy is less than 0.73.

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