JPS59123786A - Tungsten wire - Google Patents

Abstract

PURPOSE:To obtain a tungsten wire undergoing no oxidation even in an atmosphere at high temp. and humidity and having a long usage life by coating the surface of a tungsten wire with a nickel layer of a specified thickness by plating. CONSTITUTION:A nickel layer of >=0.1mum thickness is formed on the surface of a tungsten wire by electroplating or other plating method. Since the Ni layer acts as a protective film for inhibiting the oxidation of the tungsten wire, the surface of the tungsten wire is not oxidized even in an atmosphere at high temp. and humidity, and the wire is not broken, so the tungsten wire can be used for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a tungsten wire that has excellent oxidation resistance and is less likely to break even when used in the atmosphere for a long period of time.

[Technical background of the invention and its problems]

Tungsten is a material with a high melting point, low vapor pressure, high tensile strength, and high rigidity. Taking advantage of all of these properties, tungsten is processed into wire rods and used in a wide variety of applications, including filaments for light bulbs and heaters. .

However, if a tungsten wire is left in the atmosphere for a long time, its surface will become oxidized. In particular, this oxidation effect is accelerated in a high-groove, humid atmosphere or in an atmosphere of various oxidizing gases, and oxides are formed on the surface of the tungsten wire, resulting in a decrease in tensile strength and when tensile stress is applied. (f) A situation occurs in which the wire breaks at a relatively early stage of use.

In other words, tungsten wire has a disadvantage in that it has a short service life when used in the atmosphere, particularly in high temperature and high humidity environments.

[Purpose of the invention]

The object of the present invention is to solve the above-mentioned problems of tungsten wire, and to provide a tungsten wire that does not break even in a high temperature and humid atmosphere and has a long service life.

[Summary of the invention]

The inventors of the present invention have conducted extensive research based on the idea that coating the surface of a tungsten wire with a dense layer of oxidation-resistant metal will prevent oxidation of the surface of the tungsten wire, thereby making effective use of the above-mentioned characteristics. As a result of repeated efforts, they discovered that nickel is an effective metal for achieving this effect, and completed the present invention.

That is, the tungsten wire of the present invention has a thickness of 0.1 μm.
It is characterized by the above nickel layer.

If the thickness of the nickel layer is less than 0.1 .mu.m, the function of the nickel layer as a tungsten wire oxidation protective film will be greatly reduced, resulting in frequent failure of the MS used. In addition, increasing the thickness too much will make it somewhat difficult to form a nickel layer industrially, and furthermore, it cannot be proven in terms of improving the 4-oxidation property, so it is not a waste of money. 2) c In the present invention, usually from 0.2 to
A thickness of about 0.6 μm is preferable not only in terms of oxidation resistance but also in terms of 11I-efficiency.

In order to coat the surface of the tungsten wire with a nickel layer, methods such as electroplating and chemical plating are used. Among these methods, the electroplating method is preferable because it is relatively low cost and can easily form a nickel layer of a desired thickness in close contact with the surface of the tungsten wire.

[Embodiments of the invention]

Nickel layers of various thicknesses were nucleated on the surface of a tungsten wire (with a wire diameter of 0.16 mm) using a conventional electroplating method. Using these tungsten pure gold, 2R bending jig, 9
When bent at 0 degrees and checked for peeling of the plating, it was confirmed that there was no peeling of the plating and the nickel was adhered to the surface of the tungsten. The line was used as a wire, and the situation of the disconnection was investigated. The tensile strength applied to the tungsten wire at this time was ~1.5, and the atmosphere was an air with a temperature of 80 to 90°C and a humidity of 90%.

For each of the 20 tungsten wires, the number of wire breaks after one year of use was counted, and the number was divided by the number of wire breaks in the tungsten wires that did not form a nickel layer to calculate the wire breakage rate.

The results are shown in the figure as a relationship with the thickness of the nickel plating layer.

As is clear from the figure, the tungsten wire of the present invention has a wire breakage rate that is less than that of the tungsten wire covered by the nickel layer when the depth of the nickel layer is 1 μm or more.

〔Effect of the invention〕

The tungsten wire of the present invention is less likely to break even in high temperature and humid atmosphere, and is suitable and useful for use in display glazes for power fuses. Moreover, its manufacturing (
・Since it is so simple, its practical value is 111.

[Brief explanation of drawings]

The figure shows the relationship between the ratio of the nickel layer and the ratio of the tungsten wire.

Claims (1)

[Claims] % protected by a nickel layer with a thickness of 0.1 μm or more
Characterized by tungsten wire.