JP3837481B2 - Method for thinning V-Ni alloy - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a method for thinning a V-Ni alloy.
[0002]
[Prior art and its problems]
For example, a hydrogen separation and purification device for producing ultra-high purity hydrogen, which is an important energy source for fuel cell vehicles, has been developed using a Pd alloy as a hydrogen permeable membrane. On the other hand, Pd as an alloy raw material is very expensive and has a difficulty in transmission characteristics at a low temperature of less than 300 ° C.
[0003]
Recently, the inventors of the invention of this application have found that a V-Ni alloy containing 5 to 30 atomic% of Ni has a high hydrogen permeability and is expected to reduce the price. Alloys have a problem that they are poor in workability and difficult to thin. That is, the V-Ni alloy is easily oxidized and the hot melting is difficult because the melting point of the oxide is low. In addition, cracking is likely to occur when the ingot is directly cold-rolled. Therefore, in order to obtain a thickness of 1 mm or less, the ingot must be cut and then thinned by polishing. For this reason, in order to adapt the V-Ni alloy to a hydrogen separation and purification apparatus, it was very inefficient to process it into a membrane shape or a pipe shape, and it was far from practical use.
[0004]
The invention of this application has been made in view of the circumstances as described above, and an object thereof is to realize thinning of the V—Ni alloy, which has been considered difficult to thin as described above.
[0005]
[Means for Solving the Problems]
The inventors of this application have made extensive studies to solve the above-mentioned problems. As a result, by applying sheath rolling to a V-Ni alloy having a high hydrogen permeability, the thinnest film has a thickness of 0.01 mm. It can be thinned, and the thinning is relatively easy, and the thinner it is, the larger hydrogen permeation flow rate can be obtained, and a large amount of hydrogen can be efficiently discharged at low temperature more than 99.99999% or more than the so-called Seven Nine or more. The inventor of this application was completed by obtaining the knowledge that it was possible to purify to high purity.
[0006]
That is, in the invention of this application, a V-Ni alloy containing 5 to 30 atomic% Ni is placed in a sheath tube, enclosed, hot rolled together with the sheath tube, and a V-Ni alloy having a thickness of 0.1 mm to 0.01 mm. A method for thinning a V-Ni alloy is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the invention of this application, as described above, a V—Ni alloy containing 5 to 30 atomic% Ni is placed in a sheath tube, enclosed, and the sheath tube is hot-rolled, that is, sheath-rolled. Sheath rolling is performed, for example, by using a stainless steel tube or the like as a sheath tube, enclosing and placing a V-Ni alloy ingot or the like in the sheath tube, and hot rolling the entire sheath tube. Sheath rolling makes it possible to make V-Ni alloy, which has been considered difficult until now, relatively thin, and the thickness can be reduced to 0.1 mm or less and the thinnest to 0.01 mm.
[0008]
The thinned V-Ni alloy can be used for the diaphragm of the hydrogen separation and purification apparatus.
1 <a><b><c> are cross-sectional views schematically showing a hydrogen separation and purification apparatus.
The V-Ni alloy containing 5 to 30 atomic% of Ni thinned to a thickness of 0.1 mm to 0.01 mm is coated with Pd or an alloy containing Pd on both front and back surfaces to the membrane (1) of the hydrogen separation and purification equipment. It is used. With this diaphragm (1), hydrogen can be purified to an ultra-high purity of 99.99999% or more, so-called Seven Nine or more. The thinner the diaphragm (1), the higher the hydrogen permeation flow rate, and the efficient purification of a large amount of hydrogen at a low temperature becomes possible.
[0009]
More specifically, the diaphragm (1) can be mounted inside the cabinet (2) provided in the hydrogen separation and purification apparatus, but the shape thereof is not particularly limited. For example, in addition to the flat plate shape as shown in FIG. 1 <a>, it may be bent into a bellows shape as shown in FIG. 1 <b>. And these flat plate-shaped and bellows-shaped diaphragms (1) can be arrange | positioned so that a cabinet (2) may be partitioned off.
[0010]
Moreover, the diaphragm (1) can also be made into a pipe shape as shown in FIG. The thinned V-Ni alloy has sufficient bending strength for processing. The cross-sectional shape of the pipe shape may be various shapes such as a star shape, a round shape, an ellipse shape, a quadrangle shape, a triangle shape, a pentagon shape, a hexagon shape, and an octagon shape or more. In the case of a pipe shape, for example, electron beam welding, diffusion bonding, or the like can be applied to the manufactured thin plate. One pipe (1) thus formed in a pipe shape may be arranged in the cabinet (2), or a plurality of diaphragms (1) may be arranged in parallel. When the pipe-shaped diaphragm (1) is provided in the cabinet (2), it can be joined using, for example, a Swagelok joint or electron beam welding.
[0011]
In addition, the code | symbol 3 shown in FIG. 1 <a><b><c> figure is a gas introduction part to a cabinet (2), and the code | symbol 4 is the hydrogen gas derivation | leading-out part after refinement | purification by a diaphragm (1) It is. Reference numeral 5 denotes a residual gas drain.
[0012]
When a V-Ni alloy sheet is used for the diaphragm (1), both front and back sides are coated with Pd or an alloy containing Pd, which prevents surface oxidation that degrades the hydrogen permeation performance of the V-Ni alloy. At the same time, it is for promoting the dissociation reaction into atomic hydrogen, that is, the separation reaction, which is necessary when hydrogen gas, which is a diatomic molecule, dissolves in the V-Ni alloy. There is no particular limitation on the method of coating Pd or an alloy containing Pd on the front and back surfaces of the V-Ni alloy, and vacuum deposition, electroplating, electroless plating, and the like are conceivable. Among these, the electroless plating method is preferable because it can uniformly coat even a complicated shape. In addition, there is no restriction | limiting in particular also about the thickness of the alloy containing Pd or Pd to coat | cover, It can set suitably in consideration of the whole thickness of a diaphragm (1). The coating of Pd or an alloy containing Pd is performed after the production of the diaphragm (1).
[0013]
The above V-Ni alloy sheet can contain up to 5 atomic percent of Mn and other elements as inevitable impurity elements, or as the third element, the fourth element, etc., as long as the hydrogen permeability is not adversely affected. .
[0014]
【Example】
V-15 atomic% Ni alloy was melted by arc melting method in argon. After removing the oxide film formed on the surface, a V-15 atomic% Ni alloy was placed in the stainless steel tube, and the stainless steel tube was sealed by electron beam welding in a vacuum. Next, the sealed stainless steel tube was hot-rolled to a thickness of 5 mm at 1150 ° C., and sheath rolling was performed. Thereafter, solution quenching heat treatment was performed at 1200 ° C. The solution quenching heat treatment is a process of rapidly cooling a high temperature state in which Ni atoms are uniformly dissolved in V and lowering it to a low temperature, and realizes hydrogen permeability of V-Ni alloy and workability to various shapes. Then, it was divided into four parts, and each was cold-rolled to a thickness of 0.1 mm, 0.3 mm, 0.4 mm, and 1.1 mm using ordinary rolls at room temperature. The surface of the thin sheet is finished neatly by cold rolling. No cracks or cracks were found in any of the thin plates after rolling. It has been confirmed that thinning of V-Ni alloys, which has been considered difficult to be thin, is possible.
[0015]
A disk-shaped sample with a diameter of about 12 mm was cut out from each thin plate produced, and the surface was finished to a mirror surface by chemical polishing with mechanical polishing and etching using emery paper or alumina abrasive grains, and then the sample was vacuum-deposited. The front and back sides were coated with Pd to a thickness of about 0.1 μm.
[0016]
The sample thus prepared was mounted in a hydrogen permeation test apparatus and a hydrogen permeation test was performed. During the test, the sample temperature was set to 523 K, a hydrogen pressure of 500 torr was applied to the inlet side, and the outlet side was evacuated. And hydrogen permeability was compared with Pd-25Ag alloy which is at a practical level. The results are shown in the graph of FIG. In the graph of FIG. 2, the vertical axis represents the hydrogen flux, and the hydrogen flux means the volume of hydrogen flowing per unit area and per unit time.
[0017]
As can be seen from the graph in FIG. 2, the hydrogen permeation flow rate increases in inverse proportion to the thickness of the sample, and the V-15Ni alloy sheet coated with Pd on both sides is more hydrogen permeable than the Pd-25Ag alloy. The flow rate increases.
[0018]
Further, when a bending test was performed on a V-15Ni alloy thin plate having a thickness of about 0.1 mm and both surfaces coated with Pd, it showed sufficient bending workability and no cracks or other defects were observed in the curved portion. In addition, the weldability was also examined using an electron beam, but the weld was sound and no cracks or other defects were observed. It is confirmed that the diaphragm (1) having various shapes illustrated in FIGS. 1 <a><b><c> can be realized.
[0019]
Of course, the invention of this application is not limited by the above embodiments and examples. It goes without saying that various aspects are possible with regard to details such as the configuration and structure of the hydrogen separation and purification apparatus excluding the diaphragm, the shape of the diaphragm, the preparation conditions, and the thickness of Pd or the alloy containing Pd coated on both the front and back surfaces. Nor.
[0020]
【The invention's effect】
As described above in detail, the invention of this application realizes thinning of the V-Ni alloy, which has been considered difficult to thin. Hydrogen separation and purification equipment equipped with V-Ni alloy thin plates as partition walls of various shapes will be provided, and it will be possible to produce ultra high purity hydrogen of 99.99999% or more, which is an important energy source for fuel cell vehicles, etc. at low cost Be expected.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a hydrogen separation and purification apparatus, respectively.
FIG. 2 is a graph showing the relationship between the reciprocal of the thickness at 523K and the hydrogen flux of a sample mounted in the hydrogen permeation test apparatus.
[Explanation of symbols]
1 Diaphragm 2 Cabinet 3 Gas inlet 4 Hydrogen gas outlet 5 Drain

Claims (1)

A V-Ni alloy containing 5 to 30 atomic% Ni is placed in a sheath and enclosed, and the sheath and tube are hot-rolled to obtain a thin sheet of V-Ni alloy with a thickness of 0.1 mm to 0.01 mm. To thin the V-Ni alloy.

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