Vanadium-based solid solution type hydrogen storage alloy and method for preparing the same

Abstract

This invention belongs to the field of hydrogen storage alloy technology, and discloses a vanadium-based solid solution hydrogen storage alloy and its preparation method. The general formula of the hydrogen storage alloy is Ti. a Cr b V c Al d Si e Ce f In the formula, a, b, c, d, e, and f represent weight percentages, with the following numerical ranges: 11 ≤ a ≤ 13, 12 ≤ b ≤ 19, 56 ≤ c ≤ 62, 0

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage alloy technology, specifically relating to a vanadium-based solid solution hydrogen storage alloy and its preparation method. Background Technology

[0002] Currently, the main technical approach for achieving large-scale production of vanadium-based solid solution alloys at the hundred-kilogram scale is the combination of medium-frequency induction melting and rapid cooling strip casting. However, due to the high melting point of high-vanadium alloy melts exceeding 1700℃, specially designed zirconia crucibles must be used during the preparation process, inevitably introducing impurity elements such as Al and Si. These elements are generally considered harmful impurities and must be removed by adding purifying agents. Furthermore, in actual hundred-kilogram-scale production, fluctuations in melting time control and casting process parameters directly affect the casting success rate of the alloy melt and the uniformity of strip thickness, thus leading to the deterioration of the overall performance of the alloy material. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a vanadium-based solid solution hydrogen storage alloy and its preparation method. By clarifying the content of Al and Si elements in the alloy, optimizing the smelting and casting processes, the success rate of smelting the vanadium-based solid solution alloy is improved and the difficulty of powder preparation is reduced, while ensuring the comprehensive performance of the alloy, in order to meet the needs of the subsequent development of markets such as solid-state hydrogen storage.

[0004] The objective of this invention is achieved through the following technical solution: This invention provides a vanadium-based solid solution hydrogen storage alloy, characterized in that the general formula of the hydrogen storage alloy is Ti. a Cr b V c Al d Si e Ce f In the formula, a, b, c, d, e, and f represent weight percentages, with the following numerical ranges: 11 ≤ a ≤ 13, 12 ≤ b ≤ 19, 56 ≤ c ≤ 62, 0 <d≤2,0<e≤1,9≤f≤13。

[0005] The present invention also provides a method for preparing the hydrogen storage alloy as described above, comprising: The raw materials are placed in a zirconium oxide crucible and smelted in a melting furnace to obtain a molten alloy liquid. The molten alloy liquid is then cast to obtain a vanadium-based solid solution hydrogen storage alloy.

[0006] In some embodiments, the raw materials may also be pretreated.

[0007] In some embodiments, the smelting method is one of medium-frequency induction smelting, high-frequency induction smelting, electric arc smelting, and suspension smelting.

[0008] In some embodiments, the smelting process is as follows: The power of the smelting furnace is increased to the first smelting power in stages and maintained for a third time, and a predetermined time is maintained in each stage; after the raw materials are completely melted, the power of the smelting furnace is increased from the first smelting power to the second smelting power and maintained for a fourth time.

[0009] Furthermore, the phased power increase process includes at least: a first stage, increasing the power to a first intermediate power value and maintaining it for a first duration; and a second stage, increasing the power to a second intermediate power value and maintaining it for a second duration.

[0010] Furthermore, the first intermediate power value is 200~250 kW and the first duration is 10~15 min; the second intermediate power value is 300~350 kW and the second duration is 10~15 min; the first smelting power is 350~400 kW and the third duration is 3~10 min; and / or the second smelting power is 350~400 kW and the fourth duration is 5~10 min.

[0011] In some embodiments, the casting method is as follows: the molten alloy liquid is poured into an intermediate ladle and then flows onto a cooling roller.

[0012] Furthermore, the casting speed is 16~300 kg / min.

[0013] Furthermore, the rotational speed of the cooling roller is 30~120 rpm.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention achieves stable preparation of hydrogen storage alloys in the hundreds of kilograms by precisely defining the effective content range of Al and Si elements in the alloy, controlling the Ti / Cr ratio in the alloy, and combining it with systematic control of casting process parameters. Attached Figure Description

[0015] Figure 1 The XRD patterns are of the hydrogen storage alloys obtained in Examples 1, 6-8 and Comparative Example 1. Figure 2 This is a comparison chart of melting time and Al / Si content in Example 1. Detailed Implementation

[0016] This invention provides a vanadium-based solid solution hydrogen storage alloy, characterized in that the general formula of the hydrogen storage alloy is Ti. a Cr b V c Al d Si e Ce f, where a, b, c, d, e, and f represent weight percentages, and their numerical ranges are: 11 ≤ a ≤ 13, 12 ≤ b ≤ 19, 56 ≤ c ≤ 62, 0 < d ≤ 2, 0 < e ≤ 1, 9 ≤ f ≤ 13.

[0017] It should be noted that the Ti content range of this alloy is 11 ≤ a ≤ 13, and the Cr content range is 12 ≤ c ≤ 19. If the Ti / Cr value > 1, it will affect the alloy's hydrogen absorption and desorption plateau to decrease and desorption to be difficult. If the Ti / Cr value < 0.58, the alloy's hydrogen absorption and desorption plateau will increase and the hydrogen storage capacity will decrease. The V content range is 56 ≤ c ≤ 62. If the V content is lower than 56, the alloy's hydrogen absorption and desorption performance will decrease, and at the same time, it will affect the alloy's cycle stability. If the V content is higher than 62, the alloy will be difficult to activate and the effective hydrogen desorption amount will be low, and at the same time, the preparation difficulty will increase and it will be difficult to achieve mass production; the Al content range is 0 < d ≤ 2, and the plateau pressure will increase with the increase of the Al content, and the hydrogen storage capacity will not decrease significantly; if the Al content is higher than 2, the alloy's hydrogen absorption and desorption plateau will increase significantly and the hydrogen storage capacity will decrease. The Si content range is 0 < c ≤ 1. The doping of the Si content changes the alloy's BCC phase structure and increases the Laves phase content. When Si > 1, it affects the increase of the alloy's hydrogen desorption plateau and the slope factor becomes larger and steeper. When the Si content is lower than 1, it is beneficial to the activation of the material. The Ce content range is 9 ≤ c ≤ 13. If the Ce content is higher than 13, it will affect the charging amount during the alloy preparation process and affect the decrease of the alloy's hydrogen absorption and desorption plateau and the slope factor becoming larger and steeper. If the Ce content is lower than 9, the alloy is easily oxidized during production, the hydrogen absorption and desorption rate decreases, and the activation difficulty increases.

[0018] The present invention also provides a preparation method for the hydrogen storage alloy as described above, including: Pretreatment and preparation of raw materials: Use a polishing machine and a dryer to pretreat the raw materials to remove oxides, impurities, moisture, etc. on the surface of the raw materials. The raw materials are vanadium-chromium alloy, chromium, titanium, and cerium. Weigh and prepare the raw materials according to the mass ratio of the BCC-type alloy components to be prepared.

[0019] Preparation of the baking furnace: Place the raw materials in a 500 kg vacuum medium-frequency induction furnace equipped with a zirconia crucible, and connect the power supplies of the mechanical pump and the Roots pump. Turn on the mechanical pump and the Roots pump to evacuate.

[0020] Baking the furnace: Connect the power supplies of the 500 kg vacuum medium-frequency induction melting furnace and the cooling equipment, slowly increase the power to 250 kW and maintain it for 5 minutes. After removing the moisture and volatile impurities in the furnace, stop baking; Preparation for melting: Continue to evacuate for no less than 30 minutes and the pressure in the furnace drops below 30 Pa. Introduce a protective gas for at least 2 times of furnace washing and the pressure in the furnace drops below 30 Pa each time. After the furnace washing is completed, introduce a protective gas.

[0021] Melting: When the heating power is 200~250 kW and 300~350 kW, maintain it for 10~15 minutes. When the heating power is 350~400 kW, maintain it for 3~10 minutes and observe the melting of the raw materials in the melting furnace. After the raw materials are completely melted, increase the power to 350~400 kW and maintain the power for 5~10 minutes.

[0022] Casting: The casting speed is controlled at 16~300 kg / min, the copper roller speed is controlled at 30~120 rpm / min, the alloy melt is poured from the melting furnace into two-stage tundishes, and then flows downstream to a rapid cooling strip spinning device with cold water flowing in for rapid cooling to produce alloy strip spinning sheets.

[0023] It should be noted that the Al and Si in the hydrogen storage alloy are derived from the vanadium-chromium alloy and the zirconium oxide crucible, and do not need to be added actively.

[0024] If the alloy strip is too thin, its structural stability is poor and its hydrogen storage capacity decreases; if it is too thick, compositional segregation and structural defects occur, and internal stress is high. The suitable thickness range is 1-4 mm.

[0025] The present invention will be further described in detail with reference to specific embodiments. The following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.

[0026] Example 1: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0027] The alloy is designed with a Ti composition. 11 Cr 19 V 56 Al 0.9 Si 0.6 Ce 12.5 ; The specific preparation method is as follows: Raw material pretreatment and preparation: The raw materials are pretreated using a polishing machine and a dryer to remove oxides, impurities, and moisture from their surfaces. The raw materials are vanadium-chromium alloy (V+Cr≥94wt%, Al+Si≤1.4wt%, Panzhihua Iron and Steel Group), chromium (≥99.0wt%), titanium (≥99.6wt%), and cerium (≥99.0wt%). The materials are weighed and prepared according to the required mass ratio of the BCC-type alloy composition.

[0028] Furnace preparation: Place the raw materials into a 500 kg vacuum medium-frequency induction furnace containing a zirconia crucible, and connect the power supply to the mechanical pump and the Roots pump. Turn on the mechanical pump and the Roots pump to evacuate the furnace.

[0029] Oven drying: Connect the power supply to the 500 kg vacuum medium frequency induction melting furnace and cooling equipment, slowly increase the power to 250kW and maintain it for 5 minutes, remove the moisture and volatile impurities contained in the furnace, and then stop drying; Melting preparation: Continue vacuuming for at least 30 minutes until the furnace pressure drops below 30 Pa. Introduce protective gas to perform at least two furnace washes, with the furnace pressure dropping below 30 Pa each time. After the furnace washes are completed, introduce protective gas.

[0030] Melting: Maintain the heating power at 250 kW and 300 kW for 10 minutes, and at 350 kW for 3 minutes, then observe the melting of the raw materials in the furnace. After the raw materials are completely melted, increase the power to 400 kW and maintain the power for 5 minutes.

[0031] Casting: The casting speed is controlled at 200 kg / min, the copper roller speed is controlled at 60 rpm / min, the alloy melt is poured from the melting furnace into two-stage tundishes, and then flows downstream to a rapid cooling strip spinning device with cold water to be rapidly cooled to produce alloy strips.

[0032] The thickness of the alloy strip is 2.7 mm.

[0033] Example 2: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0034] The alloy is designed with a Ti composition. 12 Cr 15 V 58 Al 1.5 Si1Ce 12.5 Everything else is the same as in Example 1.

[0035] The thickness of the alloy strip is 2.9 mm.

[0036] Example 3: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0037] The alloy is designed with a Ti composition. 13 Cr 13 V 62 Al 1.9 Si 0.8 Ce 9.3 Everything else is the same as in Example 1.

[0038] The thickness of the alloy strip is 2.7 mm.

[0039] Example 4: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0040] The alloy is designed with a Ti composition. 11 Cr 16 V 58 Al 1.9 Si 0.8 Ce 9.3 Everything else is the same as in Example 1.

[0041] The thickness of the alloy strip is 2.8 mm.

[0042] Example 5: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0043] The alloy is designed with a Ti composition. 11 Cr 19 V 56 Al 1.3 Si 0.2 Ce 12.5 Everything else is the same as in Example 1.

[0044] The thickness of the alloy strip is 3.5 mm.

[0045] Example 6: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0046] The copper roller speed was controlled at 30 rpm / min during casting, and the rest was the same as in Example 1.

[0047] The thickness of the alloy strip is 4 mm.

[0048] Example 7: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0049] The copper roller speed was controlled at 90 rpm / min during casting, and the rest was the same as in Example 1.

[0050] The thickness of the alloy strip is 1.4 mm.

[0051] Example 8: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0052] The copper roller speed was controlled at 120 rpm / min during casting, and the rest was the same as in Example 1.

[0053] The thickness of the alloy strip is 0.6 mm.

[0054] Example 9: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0055] The casting speed was 16 kg / min, and the rest was the same as in Example 1.

[0056] The thickness of the alloy strip is 2.3 mm.

[0057] Example 10: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0058] The casting speed was 50 kg / min, and the rest was the same as in Example 1.

[0059] The thickness of the alloy strip is 2.5mm.

[0060] Example 11: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0061] The casting speed was 100 kg / min, and the rest was the same as in Example 1.

[0062] The thickness of the alloy strip is 2.6 mm.

[0063] Example 12: This embodiment provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0064] The casting speed was 300 kg / min, and the rest was the same as in Example 1.

[0065] The thickness of the alloy strip is 3.3 mm.

[0066] Comparative Example 1: This comparative example provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0067] The alloy is designed with a Ti composition. 13 Cr 13 V 61 Al 2.3 Si 1.4 Ce 9.3 Everything else is the same as in Example 1.

[0068] The thickness of the alloy strip is 2.9 mm.

[0069] Comparative Example 2: This comparative example provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0070] The alloy is designed with a Ti composition. 13 Cr 13 V 61 Al 1.7 Si 1.2 Ce10.1 Everything else is the same as in Example 1.

[0071] The thickness of the alloy strip is 2.6 mm.

[0072] Comparative Example 3: This comparative example provides a vanadium-based solid solution hydrogen storage alloy and its preparation method.

[0073] The copper roller speed was controlled at 150 rpm / min during casting, and the rest was the same as in Example 1.

[0074] Due to excessive rotation speed and high temperature of the spinning belt, the belt pieces were re-stacked and clumped together in the recycling container.

[0075] The hydrogen storage alloys obtained in Examples 1, 6-8, and Comparative Example 1 were tested by XRD (using a Bruker D8 ADVANCE X-ray diffractometer, Germany). Figure 1 This confirms that the hydrogen storage alloy obtained by the alloy composition and preparation method provided by the present invention is a BCC type hydrogen storage alloy.

[0076] The melting time and Al / Si content in Example 1 were statistically analyzed, and the specific results are as follows: Figure 2 As shown, with the extension of melting time, Al and Si appear in the alloy, and the Al / Si content increases. This can be attributed to the corrosion of the crucible caused by the high temperature of the alloy melt, leading to the introduction of Al / Si from the crucible. Within the scope of this patent, the overall melting time must be controlled within 37 minutes to avoid seriously affecting the performance of the alloy strip.

[0077] The performance of the hydrogen storage alloys in the examples and comparative examples was tested using the following methods: First, the alloy is placed in a water bath or constant temperature furnace at the corresponding activation temperature and vacuum activated for 2 hours. After activation, hydrogen is absorbed to saturation in a 10℃ water bath, and then hydrogen release PCT test is performed in a 60℃ water bath to determine the effective hydrogen absorption amount.

[0078] The activation temperature, casting parameters, and hydrogen storage performance test results are shown in Table 1. A comparison of the performance of the hydrogen storage alloys obtained in Examples 1-3 revealed that, within the composition range of this application, higher Al content resulted in higher equilibrium hydrogen pressure and higher effective hydrogen release, reaching 2.3 wt%. A comparison of the performance of the hydrogen storage alloys obtained in Examples 1 and 5 revealed that increasing the Si content helped lower the activation temperature. A comparison of the performance of the hydrogen storage alloys obtained in Examples 1-4 revealed that increasing the Ti / Cr ratio could increase the effective hydrogen release. A comparison of the performance of the hydrogen storage alloys obtained in Example 3 with those in Comparative Examples 1 and 2 revealed that when both Al and Si contents exceeded the applicable range of this application, the effective hydrogen release decreased significantly. However, when only the Si content exceeded the applicable range of this application, although the effect on the effective hydrogen release also decreased, it was not significant.

[0079] Comparing the performance of the hydrogen storage alloys obtained in Examples 1, 6-8 and Comparative Example 3, it was found that the faster the copper roller speed, the thinner the alloy strip. When the alloy strip is too thin, it may be easily oxidized, the activation temperature will rise, the effective hydrogen release will decrease, and the speed will be too fast, which will cause the alloy strip to melt and clump together, making it difficult to break. When the alloy strip is too thick, there may be segregation of internal structural components and internal stress, which will also reduce the effective hydrogen release and increase the difficulty of subsequent powdering.

[0080] Comparing the performance of the hydrogen storage alloys obtained in Examples 1 and 9-12, it was found that due to the high temperature and rapid cooling of the alloy melt, when the casting speed of the alloy melt is too slow, it will gradually solidify during the casting process, resulting in serious material accumulation in the tundish; when the casting speed is too fast, the impact force of the alloy melt is too great, causing the alloy melt to splash everywhere in the furnace.

[0081] Table 1

[0082] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A vanadium-based solid solution hydrogen storage alloy, characterized in that, The general formula of the hydrogen storage alloy is Ti. a Cr b V c Al d Si e Ce f In the formula, a, b, c, d, e, and f represent weight percentages, with the following numerical ranges: 11 ≤ a ≤ 13, 12 ≤ b ≤ 19, 56 ≤ c ≤ 62, 0 <d≤2,0<e≤1,9≤f≤13。 2. A method for preparing the hydrogen storage alloy as described in claim 1, characterized in that, include: The raw materials are placed in a zirconium oxide crucible and smelted in a melting furnace to obtain a molten alloy liquid. The molten alloy liquid is then cast to obtain a vanadium-based solid solution hydrogen storage alloy.

3. The preparation method according to claim 2, characterized in that, It also includes pretreatment of the raw materials.

4. The preparation method according to claim 2, characterized in that, The smelting method is one of medium-frequency induction smelting, high-frequency induction smelting, electric arc smelting, and suspension smelting.

5. The preparation method according to claim 2, characterized in that, The smelting process is as follows: The power of the smelting furnace is increased to the first smelting power in stages and maintained for a third time, and a predetermined time is maintained in each stage; after the raw materials are completely melted, the power of the smelting furnace is increased from the first smelting power to the second smelting power and maintained for a fourth time.

6. The preparation method according to claim 5, characterized in that, The phased power increase process includes at least the following: a first stage, increasing the power to a first intermediate power value and maintaining it for a first duration; and a second stage, increasing the power to a second intermediate power value and maintaining it for a second duration.

7. The preparation method according to claim 6, characterized in that, The first intermediate power value is 200~250 kW, and the first duration is 10~15 min; the second intermediate power value is 300~350 kW, and the second duration is 10~15 min; the first smelting power is 350~400 kW, and the third duration is 3~10 min; and / or The second smelting power is 350~400 kW, and the fourth smelting time is 5~10 min.

8. The preparation method according to claim 2, characterized in that, The casting method is as follows: the molten alloy liquid is poured into an intermediate ladle and then flows onto a cooling roller.

9. The preparation method according to claim 8, characterized in that, The casting speed is 16~300 kg / min.

10. The preparation method according to claim 9, characterized in that, The rotational speed of the cooling roller is 30~120 rpm.

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