JPH0787940B2 - Manufacturing method of extra fine platinum clad wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to the production of extra fine platinum / molybdenum or extra fine platinum / tungsten clad wire (hereinafter simply referred to as extra fine platinum clad wire) used for various electrodes, filaments, heaters and the like. Regarding the method.

(Prior Art) In an ultrafine platinum clad wire, a high-purity platinum layer on the surface prevents primary and secondary electron emission, and molybdenum or tungsten in the core wire receives high-temperature strength. Various electrodes including grit wire,
It is used in filaments for Pirani cages, heaters for vapor deposition, and sealing wires for quartz.

The ultrafine platinum clad wire for such a purpose has conventionally been manufactured by a hot wire drawing method after a platinum pipe is covered with a molybdenum or tungsten rod to be in close contact therewith.

(Problems to be solved by the invention) However, in the above manufacturing method, the adhesion between the platinum pipe and the molybdenum or tungsten rod is poor, and the outer peripheral surface of the molybdenum or tungsten rod is oxidized during hot drawing. , The platinum pipe swells, peels off, or breaks, making it impossible to process. In addition, it is difficult and troublesome to control the strict temperature condition of hot wire drawing. Further, it was impossible to perform strong processing, and the number of processings was large, so it was difficult to process extra fine wires.

Further, the extra fine platinum clad wire with a bulged platinum jacket obtained by the above-mentioned manufacturing method had a high temperature during use, and the blister of the platinum jacket had an effect during a thermal cycle, resulting in a short life.

(Object of the Invention) The present invention has been made to solve the above problems,
An object of the present invention is to provide a manufacturing method capable of producing an ultrafine platinum / molybdenum clad wire in which the outer peripheral surface of the core material of molybdenum or tungsten is not oxidized and the platinum outer cover does not swell, peel off, or break. It is what

(Means for Solving Problems) A method for manufacturing an ultrafine platinum clad wire according to the present invention for solving the above problems is to manufacture a clad wire using platinum as a jacket and molybdenum or tungsten as a core material. In addition, after the air between the jacket and the core material is sucked and removed by a vacuum pump, the swaging process is repeated while hot, and then the wire drawing process is performed to a desired wire diameter.

(Operation) As described above, in the method for manufacturing an ultrafine platinum molybdenum clad wire according to the present invention, since the air between the jacket and the core material is sucked and removed by a vacuum pump, the swaging process is repeated during the heat. The surface of the tungsten core material does not oxidize, and the platinum jacket is pressed against the molybdenum or tungsten core material, and the boundary portions of the pressure contact bite into each other closely to be in close contact with each other. Therefore, the platinum coat does not swell, peel off, or break during subsequent heat treatment or wire drawing.

(Example) An example of a method for producing an ultrafine platinum clad wire of the present invention will be described with reference to the drawings. First, as shown in Fig. 1, an inner diameter of 4.85 mm,
Platinum pipe 1 with an outer diameter of 5.45 mm and a length of 900 mm has a diameter of 5.45 mm and a thickness of 0.
After the 4 mm disc 2 was welded and sealed, a molybdenum rod 3 having a diameter of 4.75 mm was inserted. Next, as shown in FIG. 3, a vacuuming hose 4 made of silicon rubber is fitted to the opening side of the other end of the platinum pipe 1 and the inner length 4 of the platinum pipe 1 having a length of 450 mm.
Exposed 00mm. Next, a vacuum pump (not shown) connected to the evacuation hose 4 was driven to suck and remove air in the gap between the platinum pipe 1 and the molybdenum 3. Then platinum pipe 1
Apply a carbon lubricant to the outer periphery of the product and repeat hot swaging at 800 ℃ to obtain a diameter of 2m as shown in Fig. 4.
After forming a platinum clad wire 5 having a length of m and a length of 2 m, heat-treating the platinum clad wire at 800 ° C. for 30 minutes in a hydrogen atmosphere, and then performing hot wire drawing 8 to 9 times to obtain a platinum clad wire having a diameter of 1 mm and a length of 8 m. Done Next, this platinum clad wire was subjected to the same heat treatment and cold drawing 25 to 26 times repeatedly to finally obtain an ultrafine platinum clad wire 5'having a diameter of 0.07 mm and a platinum thickness of 10 μm (0.01 mm). .

The cross section of the ultrafine platinum clad wire 5'obtained in this way is as shown in FIG. 5, a platinum jacket 1'and a molybdenum core 3 '.
The boundary portions of the above were intimately bite into each other and adhered to each other, and there was no swelling, peeling or breakage of the platinum outer cover 1 '.
This is because the air between the platinum pipe 1 and the molybdenum rod 3 is sucked and removed by the vacuum pump during the hot swaging process, so that the outer peripheral surface of the molybdenum rod 3 is not oxidized and the platinum pipe 1 is pressure-bonded to the molybdenum rod 3. It's nothing else.

The ultrafine platinum clad wire was boiled in a mixed acid (nitric acid 50: hydrochloric acid 50) for 1 hour and then the liquid was analyzed, but molybdenum was not detected therein. Even when heated in air at 1000 ° C. for 30 minutes, the boundary between the platinum jacket 1 ′ and the molybdenum core material 3 ′ was not oxidized, and the platinum jacket 1 ′ did not swell or peel off.

Also, when tungsten was used as the core material, the same results as in the case of molybdenum were obtained.

(Effects of the Invention) As can be seen from the above description, the method for manufacturing an ultrafine platinum clad wire according to the present invention is performed after the air between the platinum sheath and the molybdenum or tungsten core material is sucked and removed by a vacuum pump. Since the swaging process is repeated while hot, and then the wire drawing process is performed to the required wire diameter, the outer peripheral surface of molybdenum or tungsten does not oxidize, and the boundary between platinum and molybdenum or tungsten bites into each other closely and adheres closely. However, there is an effect that it is possible to obtain a platinum clad wire of good quality without swelling, peeling, or breakage of the platinum outer cover.

[Brief description of drawings]

1 to 4 are views showing the steps of the method for producing an ultrafine platinum clad wire according to the present invention, and FIG. 5 is an enlarged sectional view of the ultrafine platinum clad wire obtained by the production method according to the present invention.

Claims (1)

[Claims] 1. When manufacturing an ultrafine clad wire having platinum as a jacket and molybdenum or tungsten as a core material, air between the jacket and the core material is sucked and removed by a vacuum pump and then hot. The method for producing an ultrafine platinum clad wire is characterized in that the swaging process is repeated and then the wire is drawn to a desired wire diameter.