JPH04311542A - Manufacture of hydrogen storage metal body - Google Patents

Abstract

PURPOSE:To manufacture a hydrogen storage metal body having hydrogen occluded quantity, occluding rate and simple treatment at a low cost by compacting palladium metal fine particles having the specific particle size with a rubber press and sintering in non-oxidizing atmosphere. CONSTITUTION:The palladium fine particles having >=10mum particle size, are compacted into the aimed shape with the rubber press. This powder compact formation is executed e.g. by pressurizing a pressurizing rubber mold 18 in a pressure vessel 10 providing an upper and lower covers 12, 14 with pressurizing fluid supplied through a flow passage 24, gap 26 and flow passage 28 to compact the metal particles 22 incorporated in forming rubber mold 20. A green compact obtd. with this, is sintered in non-oxidizing atmosphere. This sintering is desirably executed e.g. at 900 deg.C for >=3hr in pure argon gas atmosphere. By this method, the optional shaped hydrogen storage metal body having very high occluding rate of the hydrogen containing deuterium at the room temp., much hydrogen occluded quantity and easy treatment, is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a porous metal body capable of storing a large amount of hydrogen (including deuterium) gas at room temperature. More specifically, the present invention relates to a method for manufacturing a hydrogen storage metal body by compacting and sintering fine metal particles such as palladium.

0002

2. Description of the Related Art Metals have the property of absorbing and storing hydrogen, and this has been known for a long time. recent years,
Physical and chemical research has been conducted systematically on hydrogen absorption and release phenomena for various metals and alloys, and as a result, so-called "hydrogen storage alloys" absorb hydrogen gas at room temperature and release it when heated. has been developed. A typical example is an iron-titanium alloy.

[0003] Conventionally, this type of hydrogen storage alloy has generally been manufactured by a metal melting method because it is required that the stoichiometric ratio of the constituent elements be constant and that the composition be uniform as a whole. ing.

0004

[Problem to be solved by the invention] By the way, palladium (
Although it is known that Pd) metal exhibits excellent hydrogen storage properties, it is difficult to handle when it is in the form of fine particles, and is subject to significant restrictions in terms of applications and usage.

On the other hand, in the case of bulk material (melted solidified material),
Since the enthalpy change ΔH of the hydride production reaction of palladium metal is small, the hydrogen absorption rate cannot be significantly improved even if the sample temperature is changed.

However, technically it is possible to increase the hydrogen absorption rate by a wet method such as electrolysis. this is,
This method utilizes the fact that when water is electrolyzed using palladium as a cathode and platinum or the like as an anode, ionized hydrogen ions receive electrons on the surface of the cathode and enter the palladium. Since hydrogen ions are used, the storage rate is extremely high, but since electric power is used to generate hydrogen ions, it is not economical and the device manufacturing and handling are troublesome.

The object of the present invention is to have a large amount of hydrogen gas (deuterium gas) absorbed at room temperature and a very high absorption rate.
It is an object of the present invention to provide a method for manufacturing a hydrogen storage metal body that is easy to handle and can reduce manufacturing costs.

[0008]

[Means for Solving the Problems] Generally, fine metal particles have excellent gas adsorption properties. The present invention has been made focusing on this phenomenon. The present invention is a method for manufacturing a hydrogen storage metal body, in which fine palladium metal particles having a particle size of 10 μm or less are compacted into a desired shape using a rubber press, and the compacted compact is sintered in a non-oxidizing atmosphere. It is desirable that the sintering be performed, for example, in a pure argon (Ar) gas atmosphere at 900° C. for 3 hours or more. In the present invention, the term "hydrogen storage" is used as a broad term that includes deuterium (D2) storage.

[0009] The present invention also includes the case where metallic uranium fine particles or metallic titanium fine particles are used in place of palladium metal.

0010

[Operation] A spongy porous sintered body is obtained by sintering a powder compact of fine metal particles. Since this sintered body is porous, hydrogen (deuterium) gas easily permeates therein, and the rate of hydrogen absorption at room temperature becomes extremely high, resulting in a large amount of hydrogen storage. Since it uses a powder compaction method, it can be manufactured into any shape and is easy to handle.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram showing an example of a rubber press apparatus used in the powder compacting process in the method of the present invention. The right half of the center line shows the state when assembled, and the left half shows the state when pressurized. An upper lid 12 and a lower lid 14 are provided at the upper and lower ends of the cylindrical pressure vessel 10, respectively. An attachment main body 16 is installed inside the pressure vessel 10, and a pressurizing rubber mold 18 and a molding rubber mold 20 are installed inside the attachment main body 16. Then, the inside of the molding rubber mold 20 is filled with metal fine particles 22 to be molded.

[0012] Palladium metal fine particles with a particle size of about 10 μm (
(purity of 99.9% or more) was filled into the molding rubber mold 20 of the above-mentioned rubber press device, and compacted at a pressure of about 1 t/cm 2 by supplying pressurized fluid from outside the device. The pressurized fluid is fed through a channel 24 formed in the lower lid 14, a gap 26 between the pressure vessel 10 and the attachment body 16, a channel 28 formed in the attachment body 16, etc. Press 18. And molding rubber mold 20
The metal fine particles 22 are pressure-molded by the following steps. There is no need to mix a binder or the like into the metal fine particles 22 filled in the present invention. If the particle size is 10 μm or less, it can be molded into the desired shape using such a rubber press. Using a rubber press is
This is because molding can be performed directly using only fine metal particles, pressure can be applied from all directions, and a molded article of any shape can be obtained.

Next, the compacted compact of palladium metal fine particles thus obtained is sintered. Figure 2 shows an example of a heating furnace used in the sintering process. The heating furnace 40 is a furnace having a configuration in which a heating coil 44 is arranged around the outer periphery of a furnace core tube 42 and the atmosphere can be controlled. The powder compact 30 is inserted into the furnace core tube 40 and sintered under predetermined conditions. In the case of a powder compact of palladium metal fine particles, the sintering conditions were as follows. ■Sintering temperature: 900℃ ■Sintering time: 3 hours or more ■Sintering atmosphere: pure argon gas ■Gas flow conditions: 50ml/min The packing density of the obtained sintered body is approximately 56.5% (specific gravity 6 .8).

By the way, in low-temperature nuclear fusion research, palladium and titanium are used in the dry method (a method in which deuterium gas is occluded in metal). Palladium is a hydrogen storage metal, but its storage rate is considerably lower than that of titanium. The metal sintered body produced by the method of the present invention is porous, and by using it, a large amount of deuterium gas can be easily stored, and the storage rate is also high. The characteristics will be explained below.

FIG. 3 is a deuterium gas occlusion characteristic diagram of the palladium metal fine particle sintered body obtained according to the present invention. The horizontal axis shows the measurement time (one scale corresponds to 10 minutes), and the vertical axis shows the deuterium gas D2 pressure. The measurements were carried out at room temperature by installing a deuterium gas pipe with a valve and a pressure gauge inside the pressure vessel, and placing the sintered compact sample inside. At first, deuterium gas is introduced to point a (580 Torr), and if it is left as it is, after about 15 minutes it reaches point b (115 Torr).
The pressure decreases to rr). This means that deuterium gas was occluded in the sintered body sample. Similarly, deuterium gas was fed to point c and left to stand until point d, and then deuterium gas was fed to point e and left to stand until point f. From this,
It can be seen that a large amount of deuterium gas is rapidly absorbed into the sintered sample.

In order to demonstrate the effectiveness of the present invention, Table 1 shows the comparison results of the deuterium storage performance between a palladium metal fine particle sintered body and a bulk material. This comparison data shows that deuterium gas pressure is always applied from the outside at 500 Torr or more, and the equilibrium pressure is 5.
The Pd atomic ratio and absorbed gas amount were determined when the sample was left to stand until the temperature reached 00 Torr, and the Pd atomic ratio was calculated based on the weight increase.

[0017]

[Table 1]

Although the above examples are all results for palladium, sintered bodies obtained in a similar manner using fine particles of titanium or uranium also exhibit excellent hydrogen storage properties. The particle size of the metal fine particles is 10 μm or less.
This is because if it exceeds this, it becomes difficult to mold with a rubber press. The sintering atmosphere may be an inert gas atmosphere or a reducing atmosphere using hydrogen gas.

[0019]

[Effects of the Invention] As described above, since the present invention molds fine metal particles using a rubber press, it is possible to manufacture a hydrogen storage metal body of any shape suitable for the intended use, and it is easy to use. Since the resulting hydrogen storage metal body is porous, the hydrogen (deuterium) storage rate at room temperature is much higher than that of ordinary bulk materials, and the amount of storage is also increased. Furthermore, the hydrogen storage properties do not change even when cut with a wet cutter (high-speed cutter or electrical discharge machine), so when thin pieces are needed, they can be easily processed into the desired shape and are extremely easy to handle. Furthermore, since a rubber press is used, the manufacturing cost is lower than when using a HIP (hot isostatic press) device, which is advantageous.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a rubber press used in the molding process of the method of the present invention.

FIG. 2 is an explanatory diagram of a heating furnace used in the sintering process of the method of the present invention.

FIG. 3 is a deuterium gas absorption characteristic diagram for a sintered body sample.

[Explanation of symbols]

10 Pressure vessel 12 Top lid 14 Lower lid 16 Attachment body 18 Pressure rubber mold 20 Molding rubber mold 22 Metal fine particles 30　Powder compact 40 Heating furnace 42 Furnace core tube 44 Heating coil

Claims (3)

[Claims] 1. A hydrogen storage metal body characterized by compacting palladium metal fine particles with a particle size of 10 μm or less into a desired shape using a rubber press, and sintering the compacted body in a non-oxidizing atmosphere. manufacturing method. [Claim 2] 90% in a pure argon gas atmosphere
The method according to claim 1, wherein the sintering is carried out at 0°C for 3 hours or more. 3. The method according to claim 1, wherein metallic titanium particles or metallic uranium particles are used in place of the palladium metal particles.