JP2706359B2 - Manufacturing method of composite fine wire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a composite fine wire, and more particularly to a method for producing a composite fine wire having a relatively thick noble metal surface layer, a catalyst, an insoluble electrode,
The present invention relates to a method for producing a composite fine wire suitable for use in industrial applications such as various sensors.

[Conventional technology]

There are various types and forms of noble metal materials used for industrial applications, and among them, fine noble metal wires are widely used for insoluble electrodes, various sensors and the like, typically as catalysts.

These fine noble metal wires are generally used as solid fine wires through conventional processes such as melting, billet forging, billet forging, wire rolling, and wire drawing.

[Problems to be solved by the invention]

By the way, regarding these precious metal thin wires for industrial use, when examined in detail from the state of use, for example, as can be clearly seen in noble metal fine wires for catalysts, the essential function is mainly performed by the surface layer part, In many cases, the core only plays a role of maintaining the structural strength under use conditions, and even if the core is not necessarily the noble metal material, there are many that can achieve the intended purpose.

This means that even if the precious metal material of the core is collected after use, it becomes a kind of dead stock that does not contribute to the essential function during the period of use, and furthermore, the core When the part is replaced with a material other than the noble metal, it is suggested that dead stock of rare and expensive noble metal material can be eliminated and a great economic effect can be obtained.

In view of the above, the present inventors have manufactured a composite thin wire having a relatively thick noble metal surface layer formed on a core material made of a dissimilar metal material.

However, the conventional composite technology of forming a noble metal surface layer on a thin wire is mainly for forming a thinner and more uniform metal surface layer, as in the composite technology applied to the production of gold-covered wires for jewelry, for example. It has been found that when a composite thin wire having a relatively thick noble metal surface layer is produced, its efficiency is poor and it is difficult to apply it industrially.

Specifically, for obtaining a composite billet as a material for wire drawing, for example, methods such as vapor deposition and thermal spraying, which are often used for forming a noble metal surface layer, are not suitable for forming a thick surface layer. The method of cladding the outer ring of the pipe on the core material is not economical because it requires many steps to produce a thick precious metal pipe itself, and it is not possible to use a plate material that is relatively easy to produce. In the case where a precious metal sheet is wrapped around a core in multiple layers and clad, it is difficult to keep the surface of the sheet, which is a large area, clean, and even if plastic processing or wire drawing at a high processing rate is applied to this, the core and The interface at the interface between the laminated sheets tends to be incomplete, and when a thick noble metal sheet is wound around a core and clad, a clean space between the butted end faces of the noble metal sheet in the circumferential direction is cleaned. State while maintaining It is difficult to combine them, and problems such as easy adhesion of the interface between the core material and the end face of the plate tend to be incomplete. It has become difficult or very uneconomical to obtain good composite billets.

The present inventors have conducted intensive studies by repeating trials in various ways in order to solve these problems. As a result, when a thick noble metal plate is wound around a core material and clad, a circle of the noble metal plate is formed. As long as it can maintain a clean state between the end faces in the circumferential direction, in the course of subsequent plastic working and wire drawing, we have obtained the knowledge that the adhesion between the end faces and the interface between the core materials can be ensured, The present invention has been completed.

That is, the present invention provides a composite fine wire having a relatively thick noble metal surface layer formed on a core material made of a dissimilar metal material,
An object of the present invention is to provide a production method capable of producing efficiently with stable interfacial adhesion.

[Means for solving the problem]

In order to achieve the above object, the present invention has the following configuration.

That is, the method for manufacturing a composite thin wire according to the present invention comprises winding a noble metal plate on a core material to form an inner layer formed by abutting circumferential end faces of the noble metal plate, and winding a noble metal sheet of the same type on the inner layer. After forming a clad composite billet by forming an outer layer covering the abutting part of the inner layer, degassing the inside of this composite billet and closing both ends,
It is characterized in that it is subjected to plastic working to form a composite strand and then drawn.

Further, after the above-mentioned composite billet is sealed in a soft metal capsule and degassed, it is plastically processed into a composite strand,
Thereafter, the wire may be drawn.

[Action]

In the present invention, an inner layer is formed by winding a noble metal plate on a core material and abutting circumferential end faces thereof on each other,
After winding the same kind of noble metal sheet on this inner layer to form an outer layer covering the butted portion of the inner layer, the inside of the clad composite billet was degassed and both ends were closed,
Since it is plastically processed into a composite wire and then drawn,
In the outer layer made of the noble metal sheet, the external influence between the abutting end faces of the inner layer noble metal sheet and between the noble metal sheet of the inner layer and the core material is cut off, and while maintaining a clean state between them, plasticity is reduced. Processing and wire drawing can be performed, and the adhesion at the interface between the components can be ensured. In addition, since this is not affected by the thickness of the inner layer precious metal plate wound on the core material, by appropriately setting the thickness, the thickness of the desired cross-sectional area ratio to the composite fine wire after drawing is obtained. A thick noble metal surface layer can be formed.

Further, after the above-mentioned composite billet is sealed in a soft metal capsule and degassed, it is plastically processed into a composite strand,
When the wire is drawn after that, in addition to the metal capsule serving as a protective metal layer, the influence of the outside can be more reliably blocked and the adhesiveness of the interface between the components can be stabilized, and in addition, The soft protective metal layer may be used as a kind of lubricating layer, so that plastic working and wire drawing can be performed more easily.

Incidentally, the plastic working in the method of the present invention is a plastic working such as cold and hot rolling, hot extrusion or the like, mainly using the reduced surface area of the composite billet.

The core material is a metal material other than a noble metal, and a metal material having relatively excellent workability is selected from metal materials that can complement the structural strength required by the composite thin wire under the conditions of use. You.

〔Example〕

 Hereinafter, examples of the present invention will be described.

First, a niobium rod finished with an outer diameter of 53.7 mm and a length of 100 mm, a platinum plate with a thickness of 4.2 mm and a width of 100 mm, a thickness of 1.0 mm and a width of 1 mm
While preparing a 00 mm platinum plate, outer diameter 68.5 mm, wall thickness 1.5 m
A copper cylinder having a length of 130 mm and a length of 130 mm and a copper disk having a thickness of 20 mm and a diameter of 64.5 mm were prepared.

Then, a 4.2 mm-thick platinum plate was pre-bent-formed into a cylindrical shape with an outer diameter of 62.6 mm, and both ends in the circumferential direction were machined into contact surfaces that overlap each other obliquely and abut each other. After pre-bending a 1.0 mm thick platinum plate into a cylindrical shape with an outer diameter of 65.1 mm, processing both ends in the circumferential direction into abutting surfaces that abut each other, degreasing and washing all of these materials Then, the surface is cleaned, and thereafter, these are combined according to the following procedure, and as shown in FIG. 1a which is a longitudinal sectional view and FIG. 1b which is an AA sectional view of FIG. ,
It was molded into an integral composite billet (1).

First, as shown in FIG. 1, the niobium rod is used as a core material (2), and a platinum plate (thickness: 4.2 mm) preformed in a cylindrical shape is fitted over the core material (2). An inner layer (3) is formed. Subsequently, a platinum plate (1.0 mm thick) preformed in a cylindrical shape is fitted over the inner layer (3), and the two ends in the circumferential direction are abutted while being tightened. The outer layers (4) were formed by welding between the surfaces, and these were formed into an integral composite billet (1). At this time, in order to prevent the influence of the welding of the outer layer (4) from affecting the contact surface (3a) of the inner layer (3), the outer layer (4)
Of the inner layer (3) is located on the opposite side, which is sufficiently shifted in the circumferential direction from the position of the contact surface (3a) of the inner layer (3). In addition, this means that the outer layer (4) of the same material covers the contact surface (3a) of the inner layer (3), so that during the subsequent plastic working, the contact surface (3a) of the inner layer (3) is formed. It is required to prevent foreign materials from entering the inside.

The outer layer (4) is used as long as the core material (2) and the inner and outer layers (3) and (4) can be integrated and the contact surface (3a) of the inner layer (3) can be covered. Platinum plate (1.0m thick
In m), at the time of the preforming, the contact surfaces at both ends in the circumferential direction may be welded, formed into a cylinder, and externally fitted on the inner layer (3) to be integrated.

Next, as shown in FIG. 2 which is a longitudinal sectional view of the composite billet (1), the composite billet (1) is combined with a tubular portion (5a) made of the above-described copper cylinder. It is sealed in a copper protective case (5) composed of the above-mentioned copper disk lids (5b) and (5c). At this time, in this embodiment, these are arranged in a vacuum chamber. And the tube (5a) and the lids (5b) (5c) under vacuum
The composite billet (1) was degassed and sealed in the protective case (5) by EB welding.

Next, in a state where the composite billet (1) is sealed in the protective case (5), hot extrusion is performed by a conventional method.
It was formed into a composite strand having an outer diameter of 20 mm.

Here, a sample was taken from the obtained composite strand, and the core material, the inner layer, the outer layer, and the interface between the protective layer and the interface between the circumferential end faces of the inner layer were examined. All the interfaces between the constituent materials exhibited a texture characteristic in which sound intermetallic bonding was achieved. In addition, since the contact surface (3a) of the inner layer (3) is covered with the outer layer (4) of the same material, copper, which is the material of the protective case (5), does not intrude into the gap, and a sound metal It exhibited an inter-bonded state.

Next, the obtained composite strand was treated with an outer diameter of 1.
After preliminarily drawn to 0 mm, the predrawn wire was subjected to a soft annealing treatment. Then, this pre-drawn wire is divided into two lots, one of which is finish-drawn as it is, and the other of which is subjected to pickling treatment to remove copper in the outermost layer which has formed the protective layer cover. After removing, finish wire drawing, each outer diameter
A 76 μ composite wire was used. Further, the composite fine wires of the other lots that were finished and drawn without being pickled and decoppered were subjected to pickling treatment after the drawing and decoppered.

A sample was taken from the obtained two lots of composite fine wires, and their cross-sectional properties were examined.
A 30% platinum layer with a cross-sectional area ratio that satisfies the expected value is evenly formed on the core material, and the interface between the core material and the platinum layer and between the inner and outer platinum layers is caused by peeling, lifting, etc. It exhibited a healthy intermetallic bonding state that was not observed at all.

As described above, in the present embodiment, even when platinum, which is a noble metal material relatively inferior in workability, is used, a composite fine wire having an intended thick platinum surface layer on a core material made of a dissimilar metal material is always used. It could be obtained efficiently by hot extrusion and wire drawing of the method.

By the way, the composite fine wire obtained in the present example was woven into a mesh of a predetermined mesh, and this mesh was used as a catalyst network of a nitric acid plant. It could be used without losing its catalysis. Also, in this case, the amount of rare and expensive platinum used is reduced by about
This has been significantly reduced to 30%.

In the present embodiment, the composite billet (1) is sealed in a copper protective case (5). For example, as shown in FIG. Dummy material (6) conventionally provided at both ends of the
(7) is EB-welded to the end of the outer layer (4) under vacuum, and the inside of the composite billet (1) is degassed and the both ends are closed and integrated to omit the protective case (5). You can also.

Further, in this embodiment, the cylindrical portion (5a) and the lids (5b) and (5c) of the protective case (5) are EB-welded under vacuum to thereby form the inside of the protective case (5) into which the composite billet (1) is inserted. This is, for example, as shown in FIG. 4 which is a longitudinal sectional view thereof, using a conventional capsule (8) provided with a deaeration tube (8a). Can also. In this case, TIG welding under the atmosphere can be applied to assemble the capsule (8).

The material for the protective case (5) and the capsule (8) has a ductility sufficient to be able to cut off external influences in the process of plastic working and wire drawing and to serve as a kind of lubricating layer. If so, a metal material other than copper may be used in consideration of the reaction characteristics with the target noble metal material.

In the present embodiment, niobium was used as the core material, but this is merely an example, and the core material is a metal material other than a noble metal. What is necessary is to select a metal material that is relatively excellent in workability in consideration of the reaction characteristics with the target noble metal material from among the complementary metal materials.

Further, in the present embodiment, the composite billet was subjected to hot extrusion to form a composite strand. However, as long as the composite billet is configured to conform to the gist of the present invention, for example, instead of hot extrusion, the composite billet may be replaced with hot extrusion. The composite wires may be formed by hot rolling, or the composite wires may be subjected to cold or hot rolling and then drawn. When wire drawing is performed after cold rolling is applied to the composite billet, diffusion bonding between the core material and the noble metal surface layer may be achieved by strain relief annealing after wire drawing.

Furthermore, when a protective case or capsule is used, the composite billet can be subjected to hot isostatic pressing before being subjected to hot extrusion or rolling to form a composite strand.

〔The invention's effect〕

As described above, according to the method for producing a composite fine wire of the present invention, a composite fine wire having a relatively thick noble metal surface layer formed on a core material made of a dissimilar metal material has stable interfacial adhesion. It can be manufactured efficiently. Furthermore, the composite fine wire according to the method of the present invention is rare and expensive when used for industrial applications such as a catalyst mainly performed by the surface precious metal material, as compared with the conventional solid precious metal fine wire. It is possible to obtain a great economic effect that the use amount of a precious metal material can be greatly reduced.

[Brief description of the drawings]

1a is a longitudinal sectional view showing a composite billet according to an embodiment of the method of the present invention, FIG. 1b is a transverse sectional view taken along the line AA of FIG. 1a, and FIG. FIG. 3 is a longitudinal sectional view showing a composite billet encapsulated in the present invention, FIG. 3 is a longitudinal sectional view showing a composite billet according to another embodiment of the method of the present invention, and FIG. 4 is encapsulated in another embodiment of the method of the present invention. It is a longitudinal cross-sectional view which shows the composite billet. (1) Composite billet (2) Core material (3) Inner layer (4) Outer layer (5) Protective case

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-99217 (JP, A) JP-A-1-306014 (JP, A) JP-A-49-115970 (JP, A)

Claims (2)

(57) [Claims] 1. An outer layer which is formed by winding a noble metal plate on a core material and abutting the circumferential end faces thereof to each other, and winding a noble metal thin plate of the same kind on the inner layer to cover the butted portion of the inner layer. After forming a clad composite billet, degassing the inside of this composite billet and closing both ends, plastic working is performed to obtain a composite wire, and then drawing is performed. Manufacturing method of fine wire. 2. A composite billet according to claim 1, which is enclosed in a soft metal capsule, degassed, plastically processed into a composite strand, and then drawn. Manufacturing method of composite fine wire.