JP5637429B2 - Titanium hydrogen storage container - Google Patents

Description

  The present invention relates to a titanium hydrogen storage material container that stores a hydrogen storage material such as a hydrogen storage alloy and stores and releases hydrogen from the outside of the container.

Various materials are used for the material of the container that contains the hydrogen storage alloy and absorbs and releases hydrogen. Recently, the use of a lightweight and high-strength titanium material has been studied.
In general, a titanium material has a problem of hydrogen embrittlement in which hydrogen is absorbed in a crystal lattice at a high temperature to form a hydride and embrittle. For this reason, as a method of preventing hydrogen embrittlement of the titanium material, a method of forming a layer that prevents entry of hydrogen such as a nitride layer on the surface of titanium has been devised (see, for example, Patent Documents 1 to 3).
On the other hand, at a relatively low temperature such as room temperature, the problem of hydrogen embrittlement to titanium is unlikely to occur. Therefore, in a container containing a hydrogen storage alloy that absorbs and releases hydrogen at a relatively low temperature such as room temperature It is considered that a container using a titanium material can be put into practical use without forming a nitride layer or the like as it is or by forming the above layer as necessary without causing hydrogen embrittlement.

JP 62-210286A JP-A-3-243759 JP-A-10-282276

However, according to the study by the present inventors, hydrogen embrittlement of the titanium alloy container progressed over time despite filling the titanium alloy container into the titanium alloy container and performing hydrogen absorption / release at room temperature. I found out that
Since this hydrogen embrittlement phenomenon progressed at a relatively low temperature such as room temperature, it is considered that this reaction is different from the reaction between hydrogen gas and titanium alloy at a high temperature, which is the subject of the prior art. That is, hydrogen embrittlement is not caused by contact with simple hydrogen gas, but the hydrogen embrittlement rate is considered to be very large due to the interposition of the hydrogen storage alloy. Further, according to the study by the present inventors, even when a layer for preventing hydrogen intrusion such as a nitride layer is formed on the inner surface of a titanium alloy container and hydrogen is absorbed and released at room temperature, the container is similar to the above. It was found that hydrogen embrittlement occurred.

  The present invention was made against the background of the above circumstances, and in a titanium container containing a hydrogen storage material such as a hydrogen storage alloy, a titanium hydrogen storage capable of preventing hydrogen embrittlement associated with hydrogen absorption / release. An object is to provide a material container.

  As a result of diligent research, the present inventors have found that the above phenomenon is caused by the fact that the hydrogen storage alloy works effectively as a catalyst for dissociating hydrogen molecules into hydrogen atoms, and hydrogen easily enters the titanium material even at room temperature. It is assumed that the titanium material has reached hydrogen embrittlement, and that hydrogen embrittlement cannot be prevented even if a layer that prevents hydrogen intrusion is formed. Further, it is assumed that hydrogen is further solid-phase diffused through the interface between the layer and the container to promote the penetration of hydrogen into the container, and thus the hydrogen embrittlement of the container is caused. It has come to be completed.

That is, among the titanium hydrogen storage material containers of the present invention, the first present invention is a titanium hydrogen storage material container that contains a hydrogen storage material and is heat-exchanged through the outer peripheral surface of the container body. And interposing between the titanium container body and the hydrogen storage material on the inner peripheral side of the titanium container body without being surface-bonded to the titanium container body, and the hydrogen storage material and the titanium. A separator that prevents contact with the container main body, the separator surrounding the inner peripheral side along the inner peripheral surface of the titanium container main body, and overlapping at least both ends in the circumferential direction without fixing each other. The side wall plate of the separator plate has a diameter expanding operation caused by the hydrogen storage material expanded by storing hydrogen, and the inner surface of the titanium container main body on the outer peripheral side. effectively disposed so as to surface contact with the And wherein the Rukoto.

  According to the present invention, contact between the titanium container body and the hydrogen storage material is prevented by the separator. Moreover, since the separator and the titanium container main body are not surface-bonded, hydrogen that has entered the separator at the interface between the separator and the titanium container main body does not further enter the titanium container main body by solid phase diffusion. . In addition, when hydrogen atoms that have passed through the separator reach the end face of the separator and come into contact with the atmosphere, they recombine and easily return to hydrogen molecules, avoiding contact of hydrogen with the titanium container body in an atomic state, and hydrogen embrittlement. Is less likely to occur.

This can prevent hydrogen from entering the titanium container body. In particular, when hydrogen is absorbed and released in an atmosphere such as normal temperature without forced heating or forced cooling, it is possible to reliably prevent hydrogen from entering the titanium container body.
The separator plate may be prevented from penetrating the hydrogen gas inside the separator plate and moving to the inner side of the titanium container body. However, in the present invention, the hydrogen gas penetrates and moves to the inner side of the titanium vessel body. It is not essential to avoid doing so. In particular, when hydrogen is absorbed and released at a relatively low temperature (for example, 50 ° C. or less) such as normal temperature, the contact between the hydrogen gas and the titanium container body does not pose a serious problem. However, when handling hydrogen gas at high temperatures, it is desirable to secure a sealed structure with a separator so that the hydrogen gas does not come into contact with the titanium container body so that the hydrogen gas stays in this sealed structure. .

In addition, since it is necessary to prevent the contact between the hydrogen storage material and the titanium container body on the side wall and bottom surface of the container, the separator plate has a bottomed cylindrical shape along the inner surface shape of the titanium container body. Is desirable. Furthermore, by providing a top plate as necessary, the contact between the hydrogen storage material and the titanium container body can be reliably prevented.
The bottomed cylindrical shape includes a side wall plate that surrounds the inner peripheral side along the inner peripheral surface of the titanium container main body, and that is disposed so as to overlap at least both ends in the circumferential direction, and a bottom plate. It is constituted by what it has .
If the side wall plate is expanded in diameter by the hydrogen occlusion material expanded by occlusion of hydrogen and effectively makes surface contact with the inner surface of the titanium container main body on the outer peripheral side, the side wall plate is heated through the outer peripheral surface of the titanium container main body. When exchanging, there is an effect of increasing the heat conduction efficiency. Also in this case, since the side wall plate and the titanium container body are not surface-bonded, hydrogen hardly diffuses through the solid phase through the boundary between the two. However, in the present invention, the shape of the separator is not limited to a specific one, and any shape that prevents the contact between the hydrogen storage material and the titanium container body may be used.

  Furthermore, the material, thickness, etc. of the separator of the present invention are not particularly limited. As the material, a dense material that prevents the permeation of hydrogen atoms is desirable, and pure aluminum or an aluminum alloy that is light in weight and excellent in processing / deformability and excellent in heat conduction can be suitably used. As the thickness of the separator, a range of 0.05 to 1 mm can be shown as suitable. If it is too thin, hydrogen permeates easily, the effect of preventing hydrogen intrusion into the titanium container main body is reduced, and breakage tends to occur with the hydrogen absorption / release cycle. Moreover, since the volume ratio of the separator occupying the internal volume increases as the thickness increases, the hydrogen storage amount decreases.

The hydrogen storage material typically includes a hydrogen storage alloy powder. However, in the present invention, the type of the hydrogen storage material is not limited, and the state of a lump, a powder or the like is not limited. However, it can be said that the effect of the present invention is particularly remarkable in the granular material.
Examples of the hydrogen storage alloy include AB ₅ type (LaNi ₅ etc.), AB ₂ type (TiCr ₂ etc.), BCC type (TiCrV etc.), AB type (TiFe etc.), A ₂ B type (Mg ₂ Ni etc.) and the like. Assuming that the alloy can reversibly absorb and release hydrogen, it is not limited to these.
In order to make the hydrogen storage density as high as possible, the volume filling rate of the storage alloy powder is desirably 40% or more. However, since the filling rate of about 45% is the limit if it is in powder form, it is more desirable to combine it with a resin compounding technique as described in Japanese Patent Nos. 4145339 and 4180105.

  Further, the shape and material of the titanium container main body are not limited to specific ones in the present invention, and any material can be used as long as it is airtight and can accommodate the hydrogen storage material. For example, a cylindrical shape, a spherical shape, a box shape and the like can be mentioned, but the shape is not questioned. Moreover, as titanium material, α + β alloy such as Ti-3Al-2.5V, Ti-6Al-4V, Ti-6Al-6V-2Sn, α alloy such as Ti-5Al-2.5Sn, Ti-6Al Examples include near α alloys such as -1Mo-1V, β alloys such as Ti-13V-11Cr-3Al, Ti-8Mo-8V-2Fe-3Al, or corrosion resistant alloys such as pure titanium and Ti-0.5Pb. As mentioned.

  As described above, in the present invention, the separator that prevents contact between the hydrogen storage material and the titanium container main body is interposed between the hydrogen storage material and the container main body, and the titanium container main body and the separator are surface-bonded. Therefore, the hydrogen atoms generated by the catalytic effect of the hydrogen storage material enter the separator and diffuse in the solid phase, and further reach the surface of the container body and prevent it from entering the interior, resulting in a titanium container body. Suppresses hydrogen embrittlement.

It is a disassembled perspective view of the titanium hydrogen storage material container of one Embodiment of this invention. Similarly, it is an exploded perspective view at the time of lid closing. Similarly, it is a disassembled perspective view of the titanium hydrogen storage material container in other embodiment. Similarly, it is the figure which showed the time-dependent change of the circumferential distortion of the container in an Example. Similarly, it is the figure which showed the time-dependent change of the circumferential distortion of the container in a comparative example.

Below, one Embodiment of this invention is described based on FIG.
The titanium container body 1 made of pure titanium or titanium alloy has a bottomed cylindrical shape, and is open at one end in the axial direction.
The side wall plate separator 2 prepared to be stored in the titanium container body 1 is made of pure aluminum or an aluminum alloy and has a plate thickness in the range of 0.05 to 1 mm. The separator plate 2 has substantially the same width as the axial length of the titanium container body 1, and when the separator plate 2 is rolled up and stored on the cylinder inner surface of the titanium container body 1, both end portions in the circumferential direction are Overlapping length (overlap). The amount of overlap can be set as appropriate, and it is desirable that the overlap is not performed.
Moreover, the separator 3 for the bottom plate disposed on one end side of the separator 2 is made of the same material as the separator 2 and has a thickness within a range of 0.05 to 1 mm. Further, the separator 3 has a low-height peripheral wall 30 erected so as to substantially overlap the inner peripheral surface when the separator 2 is rolled and stored in the titanium container body 1. By inserting the separator 3 into the separator 2 through the peripheral wall 30, the hydrogen storage alloy can be accommodated. The separator plate 2 may be housed in the titanium container body 1 by cutting or bending a single plate according to the shape of the titanium container body 1.

As shown in FIG. 1, the separator 3 and the separator 2 are combined and stored in a titanium container body 1. The cylindrical separator 2 is in close contact with the inner peripheral surface of the titanium container body 1. Alternatively, the outer peripheral surface of the separator plate 2 may be brought into close contact with the inner peripheral surface of the titanium container main body 1 after being stored in the titanium container main body 1 by a spring action to expand the diameter of the separator 2.
A cylindrical separator 2 housed in a titanium container body 1 is filled with hydrogen storage alloy powder 5. A separator 3 is located on the bottom side of the separator 2, and the separators 2 and 3 reliably prevent contact between the hydrogen storage alloy powder 5 and the titanium container body 1. At this time, the hydrogen storage alloy powder 5 is preferably filled in the voids in the titanium container body 1 at a filling rate (volume%) of 40% or more.

  The titanium container body 1 is filled with the hydrogen storage alloy powder 5 and then covered with a thin plate-like inner lid 6 provided with a hydrogen conduction port 60 so as to close the opening, and further covers the inner lid 6 and is made of titanium. A cup-shaped outer lid 7 that seals the container body 1 is joined to the titanium container body 1. The inner lid 6 is preferably made of a material that hardly causes hydrogen embrittlement. The outer lid 7 can be made of a titanium material, and the outer lid 7 is provided with a hydrogen pipe 70 communicating with the hydrogen conduction port 60. Hydrogen can be transferred between the outside and the titanium container body 1 through the hydrogen pipe 70. The titanium hydrogen storage material container of this invention is comprised by the said structure.

In the titanium hydrogen storage material container, for example, high-pressure hydrogen gas is introduced into the titanium container body 1 through the hydrogen pipe 70, and the hydrogen storage alloy powder 5 stores hydrogen. By this occlusion, the hydrogen-occlusion alloy powder 5 expands and acts to expand the diameter of the separator 2, and the surface contact between the separator 2 and the titanium container body 1 becomes closer.
Thereafter, hydrogen can be released from the hydrogen-absorbing alloy powder 5 by contact with ambient temperature atmosphere or seawater through the outer peripheral surface of the titanium container body 1.
At the time of the absorption and release of hydrogen, hydrogen enters the separators 2 and 3, but there is no solid-phase diffusion from the separators 2 and 3 to the titanium container body 1, and the hydrogen does not enter the titanium container body 1. Invasion is suppressed, and hydrogen embrittlement can be prevented.

Further, the separator 2 may be formed into a bottomed cylindrical separator 10 as shown in FIG. 3 by integral molding in addition to cutting, rounding, bending and the like of the plate material as described above. As shown in FIG. 3A, the separator 10 has a cylindrical side wall part 11 and a bottom part 12 integrated with the side wall part 11. The separator 10 is integrally formed by processing such as deep drawing.
When the separator 10 is stored in the titanium container body 1, the outer diameter is set so that the titanium container body 1 and the outer peripheral surface of the side wall portion 11 are substantially in contact with each other. As shown in FIG. 3 (b), after the separator 10 is stored in the titanium container body 1, the hydrogen storage alloy powder is stored as described above, and the titanium container body is used by using an inner lid, an outer lid, and the like. 1 is sealed and hydrogen is absorbed and released.
Also in the titanium hydrogen storage material container using the separator 10, hydrogen embrittlement of the titanium container main body is prevented and the container can be used as a lightweight container as in the above embodiment.

  In addition, the said embodiment is only an example of this invention and will not specifically limit the form, if it does not deviate from the meaning of this invention.

Examples of the present invention will be described below.
A bottomed cylindrical container (outer diameter 34 mm, wall thickness 2 mm, length 80 mm) made of Ti-6Al-4V was prepared as a titanium container body. Next, using a thin aluminum plate having a thickness of 0.2 mm, a side wall plate, a bottom plate, and a lid plate having a shape suitable for the inside of the cylindrical container were produced as separators in the same manner as shown in FIGS. The side wall plate was produced by cutting a thin plate into a suitable size, bending it into a cylindrical shape, and overlapping both ends in the circumferential direction. The bottom plate and the cover plate were made into a cup shape by deep drawing, and a hydrogen conduction hole was provided in the cover plate.
Next, the produced side wall plate and bottom plate were inserted into the cylindrical container, and AB type ₅ hydrogen storage alloy powder was filled at a filling rate of 55% by volume in terms of the internal volume ratio. Thereafter, a lid plate was put on, and an outer lid made of titanium having a hydrogen introduction tube was put on and sealed.
Further, in order to measure the strain of the titanium container body, strain gauges are provided on the outer peripheral surface of the container body at four locations at angles of 0 °, 90 °, 180 °, and 270 ° with respect to the central axis of the cylindrical container. Pasted.

  In the hydrogen storage material container, hydrogen was repeatedly absorbed and released, and the deformation amount of the container body at that time was measured with the strain gauge. Specific conditions for absorbing and releasing hydrogen are as follows. First, after evacuating the container at 80 ° C., activation was performed by introducing 0.99 MPa of hydrogen at 20 ° C. or lower. After activation, a cycle test of 0.99 MPa hydrogen absorption and atmospheric pressure hydrogen release was performed in a 20 ° C. water bath.

FIG. 4 shows the change over time of the container body strain in this example. Table 1 shows the maximum circumferential strain of the container body, the burst pressure, and the hydrogen concentration inside the titanium container body.
The strain level was a maximum of 170 × 10 ⁻⁶ or less at the stage after 35 days, and was within the range of elastic deformation. When the test was interrupted 35 days later and a water pressure burst test was conducted on the container body, the burst pressure was 125 MPa, which was approximately equal to the calculated value of 124 MPa. From the results of the cross-sectional structure observation, it was confirmed that the same structure as before the test was retained. The hydrogen concentration in the titanium container body was 20 ppm before the test, and 34 ppm after the test, which was within the expected range. From the above, it was found that hydrogen embrittlement hardly occurred.

(Comparative example)
Prepare the same Ti-6Al-4V cylindrical container (outer diameter 34 mm, wall thickness 2 mm, length 80 mm) as the titanium container body, and insert the aluminum thin plate as a separator in the inside. Instead, AB type ₅ hydrogen storage alloy powder was directly packed at a filling rate of 55% by volume by internal volume ratio. The other conditions were the same as those in the example, a hydrogen absorption / release cycle test was performed, and the strain change was measured.

FIG. 5 shows changes with time in the container body strain in this comparative example. Table 1 shows the maximum circumferential strain of the container body, the burst pressure, and the hydrogen concentration inside the titanium container body.
The strain gradually increased with time and reached a maximum of 9590 × 10 ⁻⁶ after 40 days from the test. When the test was interrupted after 40 days and a water pressure burst test was conducted on the container body, it was brittlely fractured at 53 MPa even though the calculated burst pressure was 124 MPa. When the cross-sectional structure of the titanium container body was observed, a hydride layer was observed on the inner surface. The hydrogen concentration in the titanium container body was 20 ppm before the test, and reached 4000 ppm after the test. From the above, it was clear that hydrogen embrittlement occurred.

  As described above, it was confirmed that hydrogen embrittlement can be effectively suppressed by interposing an aluminum thin plate between the hydrogen storage alloy and the titanium container body without surface bonding.

DESCRIPTION OF SYMBOLS 1 Titanium container body 2 Separation plate 3 Separation plate 5 Hydrogen storage alloy powder 10 Separation plate 11 Side wall portion 12 Bottom portion

Claims (5)

In a titanium hydrogen storage material container that contains a hydrogen storage material and is heat-exchanged through the outer peripheral surface of the container main body, the titanium container main body and the titanium container main body on the inner peripheral side of the titanium container main body A separator that intervenes between the titanium container body and the hydrogen storage material and prevents contact between the hydrogen storage material and the titanium container body without being combined; A side wall plate that surrounds the inner peripheral side along the inner peripheral surface of the container main body and that is disposed so as to overlap at least both ends in the circumferential direction without being fixed to each other; and a bottom plate; The titanium hydrogen is characterized in that a diameter expansion operation is caused by the hydrogen occlusion material expanded by occlusion of hydrogen, and is arranged so as to effectively come into surface contact with the inner surface of the titanium container main body on the outer peripheral side. Occlusion material container.   2. The titanium hydrogen storage material container according to claim 1, wherein the separator has a bottomed cylindrical shape along an inner surface shape of the titanium container main body. The titanium separator according to claim 1 or 2 , wherein the separator is made of pure aluminum or an aluminum alloy. The titanium separator according to any one of claims 1 to 3 , wherein the separator has a thickness of 0.05 to 1 mm. The hydrogen storage material, titanium hydrogen absorption material container according to any one of claims 1 to 4, characterized in that a hydrogen absorbing alloy powder contained in the titanium container body at the filling rate of 40% or more .

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