WO2001000891A1 - Hydrogen storage alloy powder and method for producing the same - Google Patents
Hydrogen storage alloy powder and method for producing the same Download PDFInfo
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- WO2001000891A1 WO2001000891A1 PCT/JP2000/004176 JP0004176W WO0100891A1 WO 2001000891 A1 WO2001000891 A1 WO 2001000891A1 JP 0004176 W JP0004176 W JP 0004176W WO 0100891 A1 WO0100891 A1 WO 0100891A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/023—Hydrogen absorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/0005—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes
- C01B3/001—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes characterised by the uptaking medium; Treatment thereof
- C01B3/0031—Intermetallic compounds; Metal alloys; Treatment thereof
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/0005—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes
- C01B3/001—Reversible uptake of hydrogen by an appropriate medium, i.e. based on physical or chemical sorption phenomena or on reversible chemical reactions, e.g. for hydrogen storage purposes ; Reversible gettering of hydrogen; Reversible uptake of hydrogen by electrodes characterised by the uptaking medium; Treatment thereof
- C01B3/0031—Intermetallic compounds; Metal alloys; Treatment thereof
- C01B3/0042—Intermetallic compounds; Metal alloys; Treatment thereof only containing magnesium and nickel; Treatment thereof
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0408—Light metal alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/383—Hydrogen absorbing alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/46—Alloys based on magnesium or aluminium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/041—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by mechanical alloying, e.g. blending, milling
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- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/32—Hydrogen storage
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S420/00—Alloys or metallic compositions
- Y10S420/90—Hydrogen storage
Definitions
- the present invention relates to a hydrogen storage alloy powder and a method for producing the same.
- hydrogen storage alloy powder has been manufactured through various processes such as melting, fabrication, heat treatment, pulverization, and classification, and is used after activation.
- the hydrogen storage alloy powder is generally used in the form of a fine powder having a particle size of 100 / m or less, so that it is easily oxidized in the air. To prevent this oxidation, the hydrogen storage alloy powder must be inert atmosphere. It must be kept inside and handled there, but this leads to deterioration of handling workability.
- the present invention provides a hydrogen storage alloy powder which, by applying a unique mechanical alloying, has excellent PCT characteristics without the conventional activation treatment and can be handled in the air without any trouble. It is an object of the present invention to provide a production method capable of obtaining the above.
- a method for producing a hydrogen storage alloy powder in which a raw material powder is charged into a ball mill and then mechanically alloyed in a hydrogen atmosphere.
- the hydrogen storage alloy powder after production contains a large amount of metal hydride, that is, it has undergone the first hydrogenation step in the conventional activation treatment. become. Therefore, when dehydrogenation heat treatment is performed in a vacuum or hydrogen atmosphere, hydrogen is released from the metal hydride, and The hydrogen storage alloy powder that has not been hydrogenated is also activated by the interparticle movement. As a result, a sufficiently activated hydrogen storage alloy powder can be obtained, and this hydrogen storage alloy powder has excellent PCT characteristics.
- the hydrogen storage alloy powder containing a large amount of metal hydride is more stable than the hydrogen storage alloy powder containing no metal hydride, so even if handled in air, the adverse effect on PCT characteristics due to oxidation etc. is large. Is suppressed.
- the raw material powder is charged into a pot of a ball mill, and then the pot is filled with hydrogen to perform mechanical alloying. At an intermediate stage of the mechanical alloying, hydrogen is recharged to the pot.
- a method for producing a hydrogen storage alloy powder to be filled is provided.
- the hydrogen storage alloy powder can be sufficiently hydrogenated.
- An object of the present invention is to provide a hydrogen storage alloy powder having a high hydrogenation rate and a dehydrogenation rate without an activation treatment and having improved thermodynamic properties.
- V, Mn, Fe, Zr, and Cu are at least one alloying element.
- the average grain size d is d ⁇ A hydrogen storage alloy powder in which a plurality of 20 nm fine particles are dispersed is provided.
- the particle size d refers to the length of the longest part of a microparticle in a microstructure diagram (or a micrograph showing a metal structure). This is the same for Mg crystal grains.
- the fine particles are generated by adding the alloying element AE to the Mg—Ni-based alloy component and performing mechanical alloying, and are stably present. No coarsening is observed.
- microparticles have the effect of promoting the adsorption of hydrogen molecules to the Mg crystal grain surface and the dissociation of the adsorbed hydrogen molecules into hydrogen atoms during the hydrogen storage process.
- an elastic strain field is generated in the interfacial region of the microparticles due to the difference in the atomic plane spacing generated between the Mg and the microparticles in the Mg crystal grains. It becomes a high active area in terms of lugi. Since a plurality of such highly active regions exist in the M crystal grain, inactive Mg activation is activated, and the diffusion of hydrogen atoms into the M crystal grain is promoted. In this way, the hydrogenation rate is increased.
- the diffusion of hydrogen atoms to the surface of the Mg crystal grains is promoted due to the presence of the high-activity region. It promotes the release of hydrogen molecules from the grain surface. In this way, the dehydrogenation rate is increased.
- the metal structure in which fine particles with an average particle size d of d ⁇ 20 nm are dispersed in the Mg crystal grains is a nanocomposite structure, the structural stability of the hydride MgH 2 is suppressed. That is, in this alloy, thermodynamic properties are improved relative to MgH 2, reduction of the hydrogen dissociation temperature is achieved.
- the Ni content is set as described above so that the Mg—Ni alloy can function as a hydrogen storage alloy.
- the content of alloying element A E is preferably AE ⁇ 5.5 wt%.
- An object of the present invention is to provide a production method capable of easily obtaining the hydrogen storage alloy powder having the above configuration.
- An AE powder consisting of at least one alloying element AE selected from Zr and Cu and an Mg powder were mixed with an alloy composition of 2. lwt ⁇ N i ⁇ 47.2 wt, 0.1 wt% ⁇ AE ⁇ 16.
- There is provided a method for producing a hydrogen storage alloy powder in which 3 wt% and the balance of Mg are weighed and then Ni powder, AE powder and Mg powder are charged into a pole mill for mechanical alloying.
- a hydrogen storage alloy powder having the nanocomposite structure can be easily obtained. It is an object of the present invention to provide a hydrogen storage alloy powder having a high hydrogenation rate and dehydrogenation rate without performing activation treatment, and having improved thermodynamic properties and durability. .
- the present invention provides a hydrogen storage alloy powder in which fine particles are dispersed.
- the grain size of the Mg crystal grain refers to the length of the longest part of the Mg crystal grain in a microscopic structure diagram (or a microscopic photograph showing the metal structure), and the average value is the average grain size of the Mg crystal grain. It is.
- the particle diameter d of the microparticle refers to the length of the longest part.
- a metal structure in which a plurality of microparticles with an average particle size d of d ⁇ 2 Onm are dispersed in and within the Mg crystal grains with an average particle size D of D ⁇ 500 nm is a nanocomposite structure.
- Mg powder, the specified amount of AE powder consisting of the alloying element AE is added, followed by mechanical alloying in a hydrogen atmosphere and subsequent dehydrogenation heat treatment in a vacuum or hydrogen atmosphere.
- the fine particles exist stably and do not become coarse during the hydrogen absorption and desorption processes before and after 300 ° C, so that the coarsening of the Mg crystal grains is suppressed. In other words, the nanocomposite structure persists for a long time.
- the microparticles have the effect of promoting the adsorption of hydrogen molecules to the surface of Mg crystal grains and the dissociation of the adsorbed hydrogen molecules into hydrogen atoms during the hydrogen storage process. Also, due to the difference in atomic spacing between Mg and the microparticles in the Mg crystal grains, an elastic strain field is generated in the interface region of the microparticles, which becomes a highly active region with high energy. . The presence of a plurality of such highly active regions in the Mg crystal grains activates the inactive Mg phase and promotes the diffusion of hydrogen atoms into the Mg crystal grains. In this way, the hydrogenation rate is increased.
- the hydrogen storage capacity can be increased to approximately 6 wt% or more.
- the diffusion of hydrogen atoms to the surface of Mg crystal grains is promoted due to the presence of the high-activity region. It promotes the release of hydrogen molecules from the surface. In this way, the dehydrogenation rate is increased.
- the structural stability of the hydride MgH 2 is suppressed.
- the thermodynamic properties for MgH 2 are improved, and the hydrogen dissociation temperature is reduced.
- the present invention makes it possible to obtain a hydrogen storage alloy powder having characteristics such as a high hydrogenation rate and a high hydrogen storage capacity, and a high dehydrogenation rate without activation treatment.
- An object of the present invention is to provide the above-described production method capable of improving thermodynamic properties and durability of an occlusion alloy powder.
- an AE powder composed of at least one alloying element AE selected from Ti, V, Mn, 6 and 1 ⁇ 1, and an Mg powder, AE powder and Mg powder were put into a ball mill, mechanically alloyed in a hydrogen atmosphere, and then vacuumed.
- the average particle size D of a plurality of Mg grains constituting the matrix is D ⁇ 500 nm, and the average
- a method for producing a hydrogen storage alloy powder in which a plurality of fine particles having an average particle diameter d of d ⁇ 20 nm are dispersed is provided.
- the grain size of the Mg crystal grain refers to the length of the longest part of the Mg crystal grain in the microstructure diagram (or a micrograph showing the metal structure). It is. Similarly, the particle diameter d of the fine particles refers to the length of the longest part.
- Mg crystals with an average grain size D of D ⁇ 500 nm and The hydrogen storage alloy powder having a metal structure in which a plurality of fine particles having an average particle size d of d ⁇ 20 nm are dispersed at the grain boundaries, that is, a nanocomposite structure, can be easily obtained.
- Fig. 1 is the X-ray diffraction diagram of Example (1)
- Fig. 2 is the collation diagram of Fig. 1
- Fig. 3 is the graph showing the relationship between elapsed time, temperature, and pressure in the hydrogen storage measurement of Example (1).
- Fig. 4 shows the microstructure of Example (1)
- Fig. 5 shows the PCT curves of Examples (1) and (02)
- Fig. 6 shows the graph of the TG-DTA results for Example (2)
- Fig. 7 shows the results.
- FIG. 10 Graph showing the results of TG-DTA for Example (04)
- Figure 8 is a graph showing the results of TMA for Example (2)
- Figure 9 is a graph showing the results of TMA for Example (04)
- Figure 10 is an example ( Figures showing the PCT curves of 2) and (03)
- Figure 11 is a graph showing the hydrogen storage characteristics for Example (2)
- Figure 12 is a graph showing the hydrogen release characteristics for Examples (2), (03) and (04).
- Fig. 13 shows the PCT curves for Examples (2) and (04)
- Fig. 14 shows the microscopic structure of Example (3)
- Fig. 15 shows the hydrogenation rate test for Examples (3) and (05). Time and hydrogen in Fig.
- FIG. 16 shows the relationship between the elapsed time and the hydrogenation amount in the dehydrogenation rate test for Examples (3) and (05).
- Fig. 16 shows the PCT for Example (3).
- Fig. 18 shows the main part of the microstructure of Example (06).
- Fig. 19 shows the relationship between the elapsed time and the hydrogenation amount in the dehydrogenation rate test for Examples (3) and (06).
- Fig. 20 is an enlarged view of the main part of Fig. 19
- Fig. 21 is a microscopic microstructure of the hydrogen storage alloy powder by mechanical alloying
- Fig. 22 is an enlarged view of the arrows shown in Figs. 21 and 22, and
- Fig. 23 is an example (4). ),
- FIG. 24 is a graph showing the relationship between the elapsed time and the hydrogenation amount in the hydrogenation rate test for Examples (4), (07) and (08), and Fig. 25 is Example (4), (24).
- Figure 26 shows the hydrogenation for examples (5) and (6).
- Fig. 27 is a graph showing the relationship between the elapsed time and the hydrogenation amount in the temperature test.
- Fig. 27 is a graph showing the relationship between the elapsed time and the hydrogenation amount in the dehydrogenation rate test for Examples (4) to (6).
- Fig. 29 shows the PC T curve for example (5).
- Fig. 29 shows the PC T curve for example (6).
- Fig. 30 shows a T-curve.
- Fig. 30 is a graph showing the relationship between the elapsed time and the amount of hydrogenation in the hydrogenation rate test for examples (7) and (0 10).
- Fig. 31 is an example (7), (0). 10 is a graph showing the relationship between the elapsed time and the amount of hydrogenation in a dehydrogenation rate test for 10).
- the raw material powder is put into a ball mill and then mechanically alloyed in a hydrogen atmosphere.
- the hydrogenation rate A is defined as B wt% of the hydrogen storage alloy powder after mechanical alloying, and hydrogen storage when all the hydridable metal elements of the hydrogen storage alloy powder are hydrogenated.
- A (B / C) XI 0 0 ().
- the rotation speed of the pole mill is controlled to generate an acceleration within the pot of 5 to 20 times the gravitational acceleration.
- the raw material powders can be sufficiently pulverized and pressed to form an alloy, and the metal structure of the alloy can be refined to a nanometer size.
- Hydrogen that creates the atmosphere also contributes to this miniaturization.
- the acceleration is less than 5 times the gravitational acceleration, hydrogenation does not proceed sufficiently.
- the acceleration exceeds 20 times, the alloy powders are united and cannot maintain a good powder state. Does not progress.
- the hydrogen storage alloy powder after mechanical alloying was dehydrogenated with the temperature t set at 80 ° C ⁇ t ⁇ 450 ° C and the time h set at 0.5 h ⁇ h ⁇ 10 h. Heat treatment is applied.
- the atmosphere at this time is preferably a vacuum or a hydrogen atmosphere.
- This dehydrogenation heat treatment contributes to the activation of the hydrogen storage alloy powder as described above. However, if the conditions for the atmosphere, temperature, and time are not satisfied, advanced activation of the hydrogen storage alloy powder cannot be expected. Further, in order to quickly activate the hydrogen storage alloy powder by the dehydrogenation heat treatment, it is preferable that the hydrogenation rate A of the hydrogen storage alloy powder after mechanical coloring is A ⁇ 50%.
- the activation of the hydrogen-absorbing alloy powder by the dehydrogenation treatment also involves the average particle size D of a plurality of metal crystal grains constituting the matrix. Is 100 nm ⁇ D ⁇ 500 nm, preferably 100 nm ⁇ D ⁇ 3 O Onm. In other words, it is desirable that nanostructures appear in the powder. It is necessary that this nanostructure is revealed by mechanical alloying and exists after dehydrogenation.
- the grain size of a metal crystal grain refers to the length of the longest part of a metal crystal grain in a microstructure diagram (or a micrograph showing the metal structure).
- the particle diameter d of the hydrogen storage alloy powder Is 0. l; m ⁇ d. It is desirable that ⁇ 200. Particle size d.
- d Q ⁇ 0.1 m
- the alloy powder reacts very easily with oxygen and moisture, making it difficult to handle in air.
- This kind of hydrogen storage alloy powder corresponds to Mg alloy powder, which consists of 0.1 wt% ⁇ AE ⁇ 2 Owt% and the balance Mg, whose AE is Ti, V, It has at least one alloying element selected from Mn, Fe, Ni, Cu and A1.
- the content of the alloying element AE is less than AE, 0.1 lwt%, the amount of fine particles present in the M crystal grains and at the grain boundaries is insufficient, and excellent hydrogen absorption / desorption characteristics cannot be obtained.
- AE> 20 wt% the V f (volume fraction) of the matrix decreases, so that a high hydrogen storage amount of 6 wt% or more cannot be obtained.
- Mg powder particle size is less than each 200 m (75 mesh)
- N i powders and F e powder M g 93 is the composition of the hydrogen storage alloy.
- 2 N i 4 6 Fe, 2 (the unit of the numerical value is wt%) was weighed to obtain a total of 2.5 g of the mixed powder.
- This mixed powder is mixed with a planetary ball mill (Furitsch, P-5) Placed in pots of capacity 80 ml (manufactured by JISS US 316) ball (manufactured JISS US 316) of 10 mm diameter with 18, was evacuated to a pop Bok is 10- 3 Torr.
- IMP a was pressurized with hydrogen in the bot, and mechanical erosion was performed under the conditions of a pot rotation speed of 78 Orpm, a disk rotation speed of 360 r, and a processing time of 9 hours. During this mechanical alloying, an acceleration nine times the gravitational acceleration was generated in the pot. After the mechanical alloying, 2.3 g of hydrogen storage alloy powder was collected in air. The particle size of this powder was 30 // m or less. This is example (1).
- FIG. 1 is a collation diagram of Fig. 1. From Fig. 2, the presence of Mg, Ni and Fe in Example (1) was confirmed, and the formation of metal hydride MgH, was confirmed. Was.
- Example (1) The hydrogen storage capacity of example (1) was measured using a PCT device (see JI SH7201). As shown in Fig. 3, the hydrogen storage capacity B of example (1) was B5.34wt%. It turned out that there was power. In this example (1), the hydrogen storage capacity C when all Mg is hydrogenated is C7.08wt%, so the hydrogenation rate A in example (1) is A75%.
- Non-hydrogenated particles when exposed to the atmosphere, generate heat due to oxidation.
- hydrogen storage alloy powder with a hydrogenation rate A of A ⁇ 50% adverse effects on PCT characteristics due to the heat generation are avoided. .
- Example (1) in (c) Example (1), in a vacuum (10- 3 the To rr), it was subjected to dehydrogenation heat treatment under conditions of 350 ° C, 2 hours.
- ⁇ In this example (01) is the particle size d. Is d. Despite being ⁇ 45 m, it was not hydrogenated, so when it came into contact with the air for concentration, it adsorbed oxygen in the air and caused an exothermic reaction, and some particles ignited. Such an example (01) cannot be used as a hydrogen storage alloy powder.
- an example (02) of a hydrogen storage alloy powder as a comparative example was obtained.
- This example (02) does not include the hydride MgH 2 .
- Example (02) was subjected to the following activation treatment.
- this treatment after evacuation, heating is performed at 350 ° C for 5 hours, followed by 1 MPa of hydrogen pressurization for 10 hours, and this heating and hydrogen pressurization is repeated as one cycle, and the cycle is repeated 10 times. It was conducted. The heating from the second cycle is for dehydrogenation.
- Example (1) has excellent PCT characteristics, and has a high hydrogen storage capacity of 7 wt% when hydrogen is applied up to IMPa.
- Example (02) although the activation treatment was performed for a long time as described above, the PCT characteristics were significantly inferior to Example (1). This is because although the pressurized hydrogen pressure is set to 4 MPa in the general activation process, the pressurized hydrogen pressure is set to 1 MPa in the activation process, so that sufficient activation is achieved. It is thought that this was due to the lack of conversion.
- Example (1) can be used at a pressurized hydrogen pressure of 1 MPa or less by filling the tank and performing dehydrogenation heat treatment.
- a pressurized hydrogen pressure of 1 MPa or less by filling the tank and performing dehydrogenation heat treatment.
- the pressurized hydrogen pressure is less than IMPa, there is an advantage that the degree of freedom in designing the filling tank is increased.
- the plateau region is very flat, it is possible to store and release approximately 7 wt% of hydrogen in a hydrogen pressure range of 0.1 to 1 MPa.
- Example (02) requires a pressurized hydrogen pressure of 4 to 6 MPa,
- the tank is of a high pressure type, and the tank shape and wall thickness of the components are greatly restricted, and the weight increase accompanying this is very large. If the activation was performed in advance in another high-pressure vessel, it would not be possible to fill the tank in the atmosphere because Example (02) is in the activated state. Also, considering the hydrogen pressurized atmosphere in the tank, it is necessary to weld the lid to the tank body. Therefore, it is conceivable to perform all powder filling and welding operations in an inert atmosphere, but this is not practical. In addition, if the quantity of example (0 2) reaches the level of several 10 kg, the above work would be extremely difficult.
- Example I the combination of mechanical alloying under a hydrogen atmosphere and heat treatment for dehydrogenation facilitates activation of hard-to-activate powders with high Mg concentration, for example, Mg alloy powder. It is possible to obtain hydrogen storage alloy powder that has been successfully converted and that can be handled in the atmosphere.
- the raw material powder is put into a pot of a ball mill, and then the pot is filled with hydrogen to perform mechanical alloying. At a middle stage of the mechanical alloying, hydrogen is re-added to the pot. The filling is performed.
- hydrogen storage alloy powders with a hydrogenation rate A of A ⁇ 50% are stable in the atmosphere, and can be handled in the atmosphere. In this case, when the non-hydrogenated particles are exposed to the atmosphere, they generate heat due to oxidation. However, in the hydrogen storage alloy powder having the hydrogenation rate A as described above, the adverse effect on the PCT characteristics due to the heat generation is avoided. You.
- the temperature t was set to 80 ⁇ t ⁇ 450 ° C and the time h was set to 0.5 hours ⁇ h ⁇ 10 hours in a hydrogen atmosphere.
- a fixed dehydrogenation heat treatment is applied. This dehydrogenation heat treatment contributes to the activation of the hydrogen storage alloy powder as described above. However, if the temperature and time conditions are not satisfied, a high degree of activation of the hydrogen storage alloy powder cannot be expected.
- the metal hydride in the hydrogen-absorbing alloy powder obtained by the above method is described in Examples Since it exists in an unstable state (a state close to a solid solution phase) as compared with the hydride in the example (1) of Example I, it can be applied in a hydrogen atmosphere at a certain pressure or less even if a vacuum state does not appear. Releases hydrogen easily by heat.
- the hydrogen atmosphere pressure is determined by the heating temperature conditions. Of course, dehydrogenation heat treatment in vacuum is also possible.
- the hydrogenation rate A of the hydrogen storage alloy powder after mechanical coloring is A ⁇ 50%.
- the activation of the hydrogen-absorbing alloy powder by the dehydrogenation heat treatment also involves the average particle size D of a plurality of metal crystal grains constituting the matrix, and for sufficient activation, the average particle size D is required. 100 nm ⁇ D ⁇ 500 nm, preferably 100 nm ⁇ D ⁇ 300 nm. In other words, it is desirable that nanostructures appear in the powder. It is necessary that this nanostructure is revealed by mechanical alloying and exists after dehydrogenation.
- the definition of the metal grain size is the same as that of Example I.
- the volume change rate F of the hydrogen storage alloy powder due to hydrogen release (hydrogen storage) is preferably F ⁇ 17.5%.
- the hydrogen absorbed in the hydrogen-absorbing alloy powder after the mechanical alloying includes one that forms a stable metal hydride in the crystal grain and one that exists in a solid solution state in the grain boundary region.
- the volume change rate F of this hydrogen-absorbing alloy powder is smaller than the volume change rate F of only hydrogen that forms a stable metal hydride, and F ⁇ 17.5%.
- the particle size d of the hydrogen storage alloy powder after the dehydrogenation heat treatment Is 0.1 m ⁇ d. ⁇ 200 m is desirable.
- Particle size d. Is d.
- the alloy powder reacts very easily with oxygen and moisture, making it difficult to handle in air.
- d. At 200 am, the specific surface area of the powder becomes smaller, and the hydrogen absorption / desorption rate decreases.
- This type of hydrogen storage alloy powder corresponds to Mg alloy powder, which consists of 0.26 wt% ⁇ AE ⁇ 12 wt% and the balance Mg, whose AE is Ti, V, ⁇ , Fe, Ni, Cu, and A1 and at least one alloying element.
- M g powder particle size is less than each 200 m (75 mesh)
- N i powders and F e powder M g 95 is the composition of the hydrogen storage alloy. 4 N i 3. 5 F e M (unit numbers wt%) was weighed so as to obtain a mixed powder of a total of 3 g.
- This mixed powder was put in a planetary ball mill (Furitsch Ltd., P- 5) capacity 80ml pot (manufactured by JISSUS 316) to a diameter of 10 negation balls (manufactured by JISS US 316) with 18, the pot is 10- 2 Torr Vacuum was applied until After evacuation, the pot was filled with hydrogen and IMP a was pressurized with hydrogen, and mechanical alloying was performed under the conditions of a pot rotation speed of 780 m, a disk rotation speed of 360 m, and a processing time of 10 hours. went. Since hydrogen was absorbed by the powder during the mechanical alloying and decreased, seven hours after the start of the mechanical alloying, the pot was refilled with hydrogen and IMP a was pressurized with hydrogen. .
- Example 2 For comparison, the manufacturing conditions other than the requirement that the hydrogen atmosphere in the mechanical alloying was changed to an argon atmosphere and that the hydrogen storage alloy powder was collected in the glove box were compared with those in Example (2).
- the hydrogen storage alloy powder was obtained with the same settings.
- this hydrogen storage alloy powder was subjected to two types of activation treatment. A kind of processing After the evacuation, heating was performed at 350 ° C for 5 hours, and then IMP a was pressurized with hydrogen for 10 hours, and the heating and hydrogen pressurization were repeated as one cycle, and the cycle was repeated 10 times.
- the hydrogenated alloy powder in the hydrogenated state after the treatment is taken as example (03).
- Another type of treatment is that after evacuation, heating is performed at 370 ° C for 5 hours, followed by 5 MPa of hydrogen pressurization for 10 hours, and this heating and hydrogen pressurization is repeated as one cycle and repeated 10 cycles.
- the hydrogen-absorbing alloy powder in the hydrogenated state that has been subjected to this method and has undergone this treatment is taken as an example (04). In both processes, the heating from the second cycle is for dehydrogenation.
- Example (2) When the qualitative analysis of Example (2) was performed by X-ray diffraction, the presence of Mg, Ni and Fe was confirmed as in Example (1) of Example I, and it was a metal hydride. generation of Mg H 2 was observed.
- hydrogen release starts at about 250 ° C at a heating rate of 20 ° CZmin.
- the hydrogen release start temperature in example (2) is 250 ° C.
- the hydrogen storage amount B was found to be 5.49 wt%, calculated from the weight loss amount.
- hydrogen release starts at about 390 ° C at a heating rate of 20 ° C / min.
- the hydrogen release start temperature in example (04) is 390 ° C.
- the hydrogen storage amount was found to be approximately 6.70 wt%, calculated from the weight loss. Such a large amount of hydrogen storage is due to the high-temperature, long-time, high-pressure activation treatment.
- Example (2) The most notable difference between Example (2) and Example (04) lies in the hydrogen release temperature, and the hydrogen release temperature in Example (2) is 140 ° C lower than that in Example (04). From this, the Mg hydride in Example (2) is more unstable than that in Example (04). It turns out there is.
- Example (2) To apply dehydrogenation heat treatment to (2), heat it to 350 ° C to release hydrogen, and maintain the heated state at 350 ° C until the hydrogen atmosphere pressure reaches 0.1 IMPa. did. The treatment time was about 0.5 hours, during which 99% of the stored hydrogen was released.
- Particle size d of example (2). Is d. ⁇ 30 m, and the average grain size D of multiple Mg crystal grains constituting the matrix was found to be D 300 nm. In addition, many fine particles with an average particle size of less than 20 nm existed inside the Mg crystal grains.
- Example (2) has excellent PCT characteristics and has a high hydrogen storage capacity of 7.15 wt% when hydrogen is pressurized to 1 MPa.
- Example (03) although the activation treatment was performed for a long time as described above, the PCT characteristics were significantly inferior to Example (2). This is considered to be because sufficient activation was not performed because the pressurized hydrogen pressure in the activation treatment was set to 1 MPa as described in Example I. From the results in Fig. 10, Example (2) can be used at a pressurized hydrogen pressure of 1 MPa or less by filling the tank and performing dehydrogenation heat treatment without evacuation. As described above, when the pressurized hydrogen pressure is lower than IMPa, there is an advantage that the degree of freedom in designing the filling tank is increased. Since the plateau region is also very flat, it can store and release more than 7 wt% of hydrogen in the hydrogen pressure range of 0.1 to IMPa. On the other hand, Examples (03) and (04) have the same problems as described in Example I for Example (02).
- Figure 11 shows the temperature dependence of the hydrogen storage rate for Example (2). This data was obtained by maintaining the storage temperature at a specified temperature between 50 ° C and 300 ° C and applying a hydrogen pressure of 1.0 MPa from a vacuum state. From Fig. 11, it can be seen that Example (2) absorbs hydrogen even at 50 ° C, but has an excellent hydrogen storage rate at 150 ° C and above.
- Figure 12 shows the hydrogen release rates for Example (2), Example (03), Example (04), and pure Mg powder that had not been subjected to ball milling (however, this powder was activated and hydrogenated). Show. This data was obtained at a discharge temperature of 300 ° C and an initial hydrogen pressure of 0.03 MPa. From Fig. 12, it can be seen that Example (2) has better hydrogen release characteristics than the others.
- Figure 13 shows the PCT characteristic measurement results for Example (2) and Example (04). This data was obtained by performing a hydrogen release test at 305 ° C according to the same measurement method as above (JI SH7201). From Fig. 13, it can be seen that example (2) indicated by a black square has better hydrogen storage capacity and equilibrium dissociation pressure than example (04) indicated by a black circle. Also, in Fig. 13, the white triangle points indicate the PCT characteristics for example (2) after one cycle of insertion and extraction and 1000 cycles. Example (2) has almost the same PCT characteristics as the initial state even after 1000 cycles, indicating excellent durability.
- a highly practical hydrogen storage alloy powder (effective hydrogen storage capacity: 6.6 wt% or more) is obtained for storing hydrogen supplied to fuel cells and hydrogen vehicles. be able to.
- this hydrogen storage alloy powder does not require the activation treatment (high-pressure hydrogen pressurization and vacuuming) in the tank, which was required conventionally. After the mechanical alloying, the tank is filled, it is mounted on the vehicle as it is, and it can be used normally only by releasing hydrogen once under a hydrogen pressure of 0.1 to 1.0 MPa in the vehicle.
- the pot was pressurized with hydrogen from IMP a, and mechanical alloying was performed under the conditions of a pot rotation speed of 780 ⁇ , a disk rotation speed of 360 rpm, and a processing time of 8 hours.
- 2.3 g of hydrogen storage alloy powder was collected in the glove box. The particle size of this powder was 40 m or less. This is example (3).
- Example (3) the metallographic structure was observed using a transmission electron microscope and the attached EDX (energy dispersive X-ray diffraction). As shown in the microstructure diagram in Fig. 14, fine particles with an average particle size d of d ⁇ 20 nm are dispersed in multiple Mg grains (and grain boundaries), as shown in the microstructure diagram of Fig. 14. It has been found.
- Example (05) the average grain size D of the multiple Mg grains constituting the matrix was D ⁇ 3 / im, and no fine particles were found in the Mg grains. For F, the deviation of Fe was observed.
- Example (3) hydrogenation rate test and dehydration at 300 ° C according to the vacuum origin method specified by the pressure-composition isotherm (PCT curve) measurement method (PCT curve) by the volumetric method (JI SH7201) An oxidation rate test was performed.
- PCT curve pressure-composition isotherm
- PCT curve measurement method
- JI SH7201 volumetric method
- Figure 15 shows the results of the hydrogenation rate test at a measurement temperature of 300 ° C.
- high-pressure hydrogen pressure of 3.2 MPa was applied from a vacuum state.
- Example (3) and Example (0 5) is the same composition (Mg 93. 3 N i 2 . 3 Fe 4. 4) in which the spite, and caused a large difference between the two relates to the hydrogenation rate,
- Example (3) has an excellent hydrogenation property, in which more than 5 wt% of hydrogen is absorbed for 60 seconds after hydrogen introduction.
- Example (3) finally has a high hydrogen storage capacity of 6.5 wt% or more.
- Figure 16 shows the results of the dehydrogenation rate test at a measurement temperature of 300 ° C.
- the initial hydrogen pressure was 0.03 MPa because of the pressure at 300 ° C in Example (3) and Example (05) and the restrictions on the specifications of the equipment.
- the slope of the hydrogen release curve after the start of release was extremely steeper than that in Example (05), and thus Example (3) had excellent dehydrogenation. It can be seen that it has a conversion speed.
- the hydrogen release in Example (3) is constant at about 5.3 wt% because the hydrogen pressure in the sample container increases with the release of hydrogen, and the equilibrium dissociation pressure is reached when 5.3 wt% is released. Is reached.
- Figure 17 shows the hydrogen release curve (PCT curve) as a result of PCT measurement for Example (3).
- the improvement of the thermodynamic properties for MgH The separation temperature was found to be about 15 ° C lower than that of the conventional pure Mg.
- Mg powder and Ni powder each having a purity of 99.9%, were weighed so as to have an Mg 2 Ni composition, and then the weighed material was melted by high frequency and then fabricated to obtain an ingot.
- This ingot was coarsely ground, and then mechanically alloying was performed using the coarsely ground powder under the same conditions as described in [A_1] above, and then the hydrogen storage alloy powder was collected in a glove box. .
- the hydrogen-absorbing alloy powder thus obtained is taken as an example (06).
- Example (06) the metallographic structure was observed using a transmission electron microscope.
- Figure 18 shows the main part of the microstructure of Example (06).
- the matrix was composed of Mg 2 Ni crystal grains, and the average crystal grain size D 2 was D 2 ⁇ 50 nm. However, no fine particles exist in the Mg 2 Ni crystal grains.
- Example (06) was subjected to heat treatment for dehydrogenation in a vacuum for the reason described in [A_4] above, and then the dehydrogenation rate test was performed at 300 ° C according to the vacuum origin method described above. Was done.
- Fig. 19 shows the results of the dehydrogenation rate test
- Fig. 20 is an enlarged view of Fig. 19 from time 0 to 600 seconds.
- the data for Example (3) is also shown for comparison (see also Figure 16).
- the initial set hydrogen pressure was 0.03 MPa due to the pressure at 300 ° C in Example (3) and Example (06) and restrictions on the equipment specifications.
- Mg 2 N i alloys Mg-based hydrogen storage alloy in Suruga have the fastest dehydrogenation rate, as is clear from FIG. 19, 20, example (3) is much compared to such an example (06) It can be seen that it has an excellent dehydrogenation rate.
- the dehydrogenation heat treatment may be performed in a hydrogen atmosphere, and the temperature t is set to 80 ° C ⁇ t ⁇ 45 and the time h is set to 0.5 hours ⁇ h ⁇ 10 hours.
- Example m it has excellent practicability such as a high hydrogenation rate and a high hydrogen storage capacity without activation treatment, and a high dehydrogenation rate.
- application It is possible to provide a hydrogen storage alloy powder having a wide range and a production method capable of easily obtaining the hydrogen storage alloy powder.
- the hydrogen storage alloy powder consists of 0.1 wt% ⁇ AE ⁇ 2 Owt% and the balance Mg.
- AE corresponds to at least one alloying element selected from Ti, V, Mn and Fe or at least one alloying element selected from Ti, V, Mn, Fe and Ni.
- the average grain size D of a plurality of Mg grains constituting the matrix is D ⁇ 500 nm, and a plurality of Mg grains having an average grain size d ⁇ 20 nm are included in the Mg grains. It has a nanocomposite structure in which fine particles are dispersed. These fine particles may also be present at the grain boundaries of Mg.
- Such hydrogen-absorbing alloy powders are selected from Ti, V, Mn, Fe and at least one type of alloying element AE, or AE powder or Ti, V, Mn, Fe and Ni.
- AE powder consisting of at least one alloying element AE and Mg powder are weighed so that the alloy composition consists of 0.1 wt% ⁇ AE ⁇ 2 Owt% and the balance of Mg. Is placed in a ball mill, mechanically alloyed in a hydrogen atmosphere, and then subjected to a dehydrogenation heat treatment in a vacuum or hydrogen atmosphere.
- the average particle size D of a plurality of Mg crystal grains constituting the matrix is D ⁇ 300 nm.
- the average particle size D1 of a plurality of AE crystal grains is defined as D1 ⁇ 800 nm.
- the rotation speed of the Po ⁇ ) remill is controlled to generate acceleration in the pot of 5 to 20 times the gravitational acceleration.
- the AE powder and the Mg powder can be sufficiently pulverized and pressed to form an alloy, and the metal structure of the hydrogen-absorbing alloy powder can be refined to the nm size. Hydrogen that creates the atmosphere also contributes to this miniaturization.
- the dehydrogenation heat treatment is performed to return the Mg hydride generated in the mechanical alloying to Mg alone and to obtain the nanocomposite structure. This treatment is performed in a vacuum or hydrogen atmosphere at a temperature t of 80 ° C ⁇ t ⁇ 450 ° C, preferably at 330 ° C ⁇ t ⁇ 380 ° C, and a time h of 0.5 hours ⁇ h. ⁇ 10 hours, preferably 2 hours ⁇ h ⁇ 5 hours.
- V 1 (The unit of the numerical value is wt, which is the same for the following chemical formula.)
- the total weight of the mixed powder was 2.5 g.
- This mixed powder was put in a planetary ball mill (Furitsch Ltd., P -5) capacity 80 ml pots (manufactured by JIS SUS 316) to a diameter of 10mm pole (manufactured by JIS SUS 316) together with 18, the pot is 10- 3 Torr The evacuation was performed until.
- a plurality of V crystal grains are substantially uniformly dispersed in a matrix, which is an aggregate of a plurality of Mg crystal grains.
- the hydrogen storage alloy powder was subjected to a dehydrogenation heat treatment in a vacuum at 350 ° C for 3 hours.
- the microstructure of the hydrogen storage alloy powder was observed by the same method as described above.
- This hydrogen storage alloy powder is referred to as Example (4).
- Mg powder and V powder each having a purity of 99.9%, were mixed with hydrogen-absorbing alloy Mg ⁇ V. Then, the weighed material was melted by high frequency, and then poured to obtain an ingot. Observation of the metal structure of this ingot showed that V hardly dissolved in Mg, and thus a separate Mg phase and V phase were observed. Next, the ingot was pulverized and classified in a glove box, and a hydrogen storage alloy powder having a particle size of less than 50 zm was collected. After that, the powder was activated. This is taken as example (07).
- the activation treatment is performed by maintaining the inside of the vessel containing the powder at 350 ° C and 10-4 Torr, then applying 4 MPa of hydrogen to the vessel, and repeating this for 10 cycles, one cycle of which. It was conducted. Also, the same ⁇ , the Kona ⁇ and classification and activation treatment performed in the same manner as described above sequentially, M 45. 3 N i 54 . 7 such a composition, hydrogen-absorbing alloy powder particle size is smaller than 50 m I got This is example (08).
- FIG 24 shows the results of the hydrogenation rate test at a measurement temperature of 300 ° C.
- a high-pressure hydrogen pressurization of 3.2 MPa was performed from a vacuum state.
- Example (4) and Example (07) had the same composition (Mg 90 V 10 ), there was a large difference between the two with regard to the hydrogenation rate. It has excellent hydrogenation properties, storing more than 6 wt% of hydrogen in 100 seconds after introduction.
- Example (4) finally has a high hydrogen storage capacity of 6.7 wt%.
- the Mg alloy in Example (08) is It belongs to the alloy system with the fastest reaction rate among conventional Mg alloys, but the hydrogenation characteristics of Example (4) are superior to those of Example (08).
- Figure 25 shows the results of the dehydrogenation rate test at a measurement temperature of 300 ° C.
- the initial set hydrogen pressure was 0.03 MPa because of the pressure at 300 ° C in Example (4) and Examples (07) and (08) and the restrictions on the equipment specifications.
- the slope of the hydrogen release curve after the start of release was extremely steeper than that in Example (08), and thus Example (4) showed excellent dehydration. It can be seen that it has a rate of digestion.
- Example (07) almost no hydrogen was released under the initially set hydrogen pressure, which was the same even after 3600 seconds.
- the hydrogen release in Example (4) is constant at about 5 wt% because the hydrogen pressure in the sample container increases with the release of hydrogen and the equilibrium dissociation occurs when about 5 wt% is released. This is because pressure has been reached.
- Example (09) Using 3 g of 99.9% pure Mg powder, mechanical alloying was performed under the same conditions as in [Example 1] and (A), and the same activation treatment as in Example (05) was performed. Then, a hydrogen storage material powder was obtained. This is example (09). In this example (09), the fine particles in example (4) do not exist. Next, a hydrogenation rate test was performed on Example (09) in the same manner as described above. Example (09) absorbed more than 3. Owt% of hydrogen in 100 seconds after hydrogen introduction, and finally It was found to have a high hydrogen storage capacity of 7.4 wt%.
- Example (4) the hydrogen storage capacity after 1000 cycles was almost the same as before the test, but in Example (09), the hydrogen storage capacity after 1000 cycles was before the test. About 60%.
- Example (4) rises to about 430 ° C due to the hydrogen pressure of 3 MPa in the cycle test, the fine particles in Example (4) do not become coarse due to this temperature rise.
- the coarsening of the Mg crystal grains constituting the matrix is also suppressed, and the above-described nanocomposite structure is maintained even when the temperature rises and falls.
- Mg alone or Mg alloys are heated to 200 ° C or more, the crystal grains become coarse.
- the case of the above temperature rise process (09) is no exception, and sintering and solidification occur simultaneously. As a result, the hydrogen storage characteristics deteriorate over time.
- Example for (5) and (6) in the same manner as above, hydrogen was applied at 300 ° C in accordance with the vacuum origin method specified in the pressure-composition isotherm (PCT curve) measurement method (PCT curve) by the volumetric method (JI SH7201). A hydrogenation rate test and a dehydrogenation rate test were respectively performed.
- Figure 26 shows the results of the hydrogenation rate test at a measurement temperature of 300 ° C. In this test, a high-pressure hydrogen pressurization of 3.2 MPa was performed from a vacuum state.
- Example (6) has almost the same hydrogenation characteristics as example (4), and has excellent hydrogenation characteristics, storing more than 6 wt% of hydrogen in 100 seconds after hydrogen introduction.
- Example (6) finally has a high hydrogen storage capacity of 6.7 wt%.
- Example (5) has better hydrogenation characteristics than Example (6), and eventually has a hydrogen storage capacity of 7.1 wt%.
- Figure 27 shows the results of the dehydrogenation rate test at a measurement temperature of 300 ° C.
- the initial set hydrogen pressure was 0.03 MPa due to the plateau pressure at 300 ° C in Examples (5) and (6) and restrictions on the equipment specifications.
- the slope of the hydrogen release curve after the start of release is steeper than that in Example (4); therefore, Examples (5) and (6) Has a better dehydrogenation rate than Example (4).
- the reason why the hydrogen release in Examples (5) and (6) is constant at about 5 wt% is that the hydrogen pressure in the sample container increases with the release of hydrogen, as described above, and the hydrogen release is about 5 wt%. This is because an equilibrium dissociation pressure was reached at the point of release.
- Figures 28 and 29 show the hydrogen release curves (PCT curves) for Examples (5) and (6), respectively. Under the measurement conditions, the convergence time was 5 minutes, and the plateau judgment was 0.3 Log (P). / (wt) respectively.
- the V and Mn contents in the above-mentioned Mg VM n-based hydrogen storage alloy are set to 2 wt% ⁇ V ⁇ 8 wt% and 0.5 wt ⁇ Mn ⁇ 4 wt%, respectively.
- V and Mn do not satisfy the above ranges, V and Mn are alloyed preferentially, and fine particles are undesirably coarsened.
- the Ti content is set to 4wt% ⁇ Ti ⁇ 15wt%. In this case, the initial activity decreases when the Ti content is Ti ⁇ 4 wt%, while the hydrogen storage amount decreases when Ti> 15 wt%.
- the metallographic structure was observed using a transmission electron microscope and the attached EDX.
- the microscopic structure showed that the average grain size D of the multiple Mg grains constituting the matrix was D ⁇ 500. It was found that a plurality of fine particles with an average particle size d of d ⁇ 20 nm were dispersed in the Mg crystal grains.
- the average grain size D of the plurality of Mg grains constituting the matrix was D ⁇ 3 m, and no fine particles were found in these Mg grains. Had segregation of Fe.
- Example (7) and Example (010) the hydrogenation rate was set to 300 at 300 in accordance with the vacuum origin method specified in the pressure-composition isotherm (PCT curve) measurement method (JI SH7201) by the volumetric method. A test and a dehydrogenation rate test were each performed. Figure 30 shows the results of the hydrogenation rate test at a measurement temperature of 300 ° C. In this test, a high-pressure hydrogen pressurization of 3.2 MPa was performed from a vacuum state.
- Example (7) and Example (0 10) have the same composition (Mg 9 , 2 Ni, 6 Fe, 2 ), there is a large difference between them in terms of hydrogenation rate. In Example (7), 5 wt% was obtained for 60 seconds after hydrogen introduction. It has the excellent hydrogenation properties of absorbing hydrogen. Example (7) finally has a high hydrogen storage capacity of 7. Owt%.
- Figure 31 shows the results of the dehydrogenation rate test at a measurement temperature of 300 ° C.
- the initial set hydrogen pressure was 0.03 MPa due to restrictions on the plastic pressure at 300 ° C and the specifications of the equipment in Examples (7) and (010).
- the slope of the hydrogen release curve after the start of release was extremely steeper than that in Example (010), and thus Example (7) showed excellent dehydrogenation. It can be seen that it has a conversion speed.
- the hydrogen release in Example (7) is constant at about 5.3 wt% because the hydrogen pressure in the sample container increases with the release of hydrogen and the equilibrium dissociation occurs when about 5.3 wt% is released. This is because pressure has been reached.
- Example IV it has excellent hydrogenation rate and high hydrogen storage capacity without activation treatment, and furthermore has excellent dehydrogenation rate and excellent durability. It is possible to provide a hydrogen-absorbing alloy powder having properties and a wide range of industrial applications, and a production method capable of easily obtaining the hydrogen-absorbing alloy powder.
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Description
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US10/018,740 US6689193B1 (en) | 1999-06-24 | 2000-06-26 | Hydrogen storage alloy powder and method for producing the same |
DE60029333T DE60029333T8 (de) | 1999-06-24 | 2000-06-26 | Herstellungsverfahren für wasserstoffspeicherndes metallpulver |
CA002377952A CA2377952C (en) | 1999-06-24 | 2000-06-26 | Hydrogen absorbing alloy powder, and process for producing the same |
EP00940834A EP1215294B1 (en) | 1999-06-24 | 2000-06-26 | Method for producing hydrogen storage alloy powder |
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WO2002066695A1 (en) * | 2001-02-20 | 2002-08-29 | Mitsui Mining & Smelting Co., Ltd. | Hydrogen occlusion alloy |
JP2009202092A (ja) * | 2008-02-27 | 2009-09-10 | Honda Motor Co Ltd | 水素吸蔵材及びその製造方法 |
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GB0408393D0 (en) * | 2004-04-15 | 2004-05-19 | Johnson Matthey Plc | Particulate alloy comprising magnesium and nickel |
CA2588807C (en) * | 2004-12-07 | 2015-10-06 | The University Of Queensland | Magnesium alloys for hydrogen storage |
CN1299819C (zh) * | 2005-04-18 | 2007-02-14 | 中国科学院长春应用化学研究所 | 一种具有贮氢功能的正二十面体钛基准晶材料及其制备方法 |
WO2006114728A1 (en) * | 2005-04-25 | 2006-11-02 | Koninklijke Philips Electronics N.V. | Hydrogen storage material and method for preparation of such a material |
US8784579B2 (en) * | 2008-04-22 | 2014-07-22 | Joka Buha | Magnesium grain refining using vanadium |
CN101307405B (zh) * | 2008-07-04 | 2010-04-14 | 北京科技大学 | 一种镁钒复合储氢合金 |
WO2011103627A1 (en) | 2010-02-24 | 2011-09-01 | Hydrexia Pty Ltd | Hydrogen release system |
CN101962724B (zh) * | 2010-10-26 | 2011-12-21 | 中国科学院青海盐湖研究所 | 一种Mg-RE-Ni合金储氢材料的制备方法 |
JP2018527459A (ja) | 2015-07-23 | 2018-09-20 | ハイドレキシア ピーティーワイ リミテッド | 水素貯蔵のためのMgベース合金 |
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WO2002066695A1 (en) * | 2001-02-20 | 2002-08-29 | Mitsui Mining & Smelting Co., Ltd. | Hydrogen occlusion alloy |
JP2009202092A (ja) * | 2008-02-27 | 2009-09-10 | Honda Motor Co Ltd | 水素吸蔵材及びその製造方法 |
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EP1215294B1 (en) | 2006-07-12 |
US6689193B1 (en) | 2004-02-10 |
EP1215294A1 (en) | 2002-06-19 |
DE60029333T8 (de) | 2007-03-15 |
EP1215294A4 (en) | 2003-05-28 |
CA2377952C (en) | 2007-08-14 |
DE60029333T2 (de) | 2006-11-16 |
CA2377952A1 (en) | 2001-01-04 |
DE60029333D1 (de) | 2006-08-24 |
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