JPH03249156A - Method for treating the surface of metallic wire rod - Google Patents

Abstract

PURPOSE:To uniformize the heat dissipation capacity of a metallic wire rod and to prevent the generation of its defect in short service life by oxidizing a wire rod of a refractory metal having a prescribed diameter under heating, thereafter subjecting it to finish wire drawing and furthermore executing surface electrolytic grinding. CONSTITUTION:A wire rod of a refractory metal having a wire diameter in the range of 1.03 to 1.5 times the finishing wire diameter and >=1000 deg.C m.p. is oxidized under heating in the air or in an oxidizing atmosphere at >=700 deg.C to roast and scatter stains. Next, the wire rod is subjected to finish wire drawing. Furthermore, >=5% of the wire diameter is subjected to surface electrolytic polishing to remove an oxidized film formed in the initial beating and oxidizing stage. In this way, the surface of a wire rod having die marks can be modified.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a high melting point metal wire (W or M
The present invention relates to a surface treatment method for metal wires (O, etc.), and in particular to a method for surface treatment of metal wires that can achieve uniform heat dissipation by modifying the surface of the wire and prevent short life defects by removing dirt.

[Prior Art] Heaters or filaments used in electron tubes such as color cathode ray tubes are generally required to be used at high temperatures and for long periods of time, so high melting point metal wires, especially wires made of tungsten or its alloys, are used. Ru. Tungsten is a material with high hardness, so carbide dies or diamond dies are used as wire drawing dies, and graphite lubricant is applied and heated wire drawing is performed, but the wire rods obtained in this way always have die marks. Scars called ``scars'' are formed in the axial direction. Because impurities such as graphite remain in these scratches,
Heaters used at high temperatures are prone to embrittlement fractures due to carbide or alloying of tungsten with other foreign substances. Therefore, in order to obtain high reliability, it is necessary to clean the surface of the tungsten wire, which is the heater core wire. is essential.

As a means to deal with this, improvements in various conditions such as wire drawing, cleaning, and post-drawing electrolysis have been considered (for example, Japanese Patent Publication No. 45-1728, Japanese Patent Publication No. 46-421F).
02, etc.).

[Problem M to be solved by the invention] However, in the prior art, it is difficult to remove dirt deeply embedded in the recessed part of the dice mark by immersion cleaning with a cleaning solution or electrolysis, and the dirt is electrically insulating. It was impossible to completely remove the dice marks because they had a large effect on the uniformity of electrolysis.

The purpose of the present invention is to solve the above-mentioned problems of the prior art, to improve the surface of wire rods with dice marks to make the heat dissipation uniform, and to prevent short life defects by removing dirt. It is an object of the present invention to provide a method for surface treatment of metal wires that can improve the surface treatment of metal wires.

[Means for Solving the Problems] The above object is to provide a method for smoothing the surface of a wire when drawing a high melting point metal wire with a melting point of 1000'c or higher using a wire drawing die. 1.03 to 1.5 of wire diameter
A wire rod having a wire diameter within the range of twice the wire diameter is heated and oxidized for 0.02 seconds or more at a temperature of 700°C or higher in air or an oxidizing atmosphere, (b) then finished wire drawing, and (c) the wire diameter is further increased. This can be achieved by performing surface electropolishing of 5% or more.

[Function] First, in the heating oxidation step (a), a cleaning effect of roasting and scattering of dirt and oxidation of metal is obtained.

However, since it is not possible to accurately set the wire diameter in the above step, in the next step (b), finishing wire drawing is performed using a wire drawing die. However, the wire drawing in this case needs to be limited to a wire diameter that takes into account the amount of electrolysis in the next step. Further, in this case, there is no strong adhesion of impurities during wire drawing.

In the wire drawing process (b) above, the oxide film formed in the process (a) is not removed, so the oxide film is finally removed in the electrolytic process (c), and at the same time the final wire is diameter.

[Example] Hereinafter, the method for surface treatment of a metal wire according to the present invention will be specifically explained with reference to Examples.

First, using the thermal oxidation treatment apparatus shown in FIG. 1, a tungsten wire having a wire diameter in the range of 1.03 to 1.5 times the final finished wire diameter was subjected to surface thermal oxidation treatment.

In the figure, 1 is a tungsten wire, 2 is a wire spool, 3 is a heating burner, and 4 is a take-up spool.

Using this processing equipment, the processing speed is 60 m/win.
The heating area above 00℃ is 200mm, that is, 700℃
The surface of the tungsten wire was subjected to oxidation treatment by heating at a temperature of 'C or higher for 0.2 seconds.

Next, the wire was finished and drawn to a wire diameter that took into account the amount of electrolysis in advance, and then surface electrolytic treatment was performed using the electrolysis apparatus shown in FIG. In the figure, 5 is an electrolytic cell, 6 is a washing tank, and 7 is a drying oven.

The surface of the tungsten wire thus obtained had a much better surface condition than the surface of a tungsten wire treated only with conventional electrolytic treatment. In addition, a heater was made using the tungsten wire obtained in this way, mounted on a cathode ray tube, and subjected to an on/off life test at a heater core temperature of 1400°C (1150"c in normal operation). In the case of a sample using a tungsten wire treated only, the heater broke after about 1000 hours, but in the case of a sample using a tungsten wire treated with the treatment method of the present invention, a service life of more than 3000 hours was obtained, which is a significant improvement. The results showed that a longer lifespan could be obtained.

Above, we have explained the example of tungsten wire.
Similar results can be obtained not only with tungsten wires but also with tungsten alloy wires such as tungsten-rhenium wires and other high melting point metal wires (for example, molybdenum wires).

[Effects of the Invention] As described above, by using the method of the present invention as a surface treatment method for metal wires, the problems of the prior art can be solved, and the surface treatment of wires having dice marks can be improved. It has been possible to provide a surface treatment method for metal wires that can achieve uniform heat dissipation through modification and prevent short life defects through the removal of dirt.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a heating oxidation treatment apparatus for wire rods used in implementing the method of the present invention, and FIG. 2 is a diagram showing the configuration of a surface electrolytic treatment apparatus for wire rods used in implementing the method of the present invention. be. l... Tungsten wire, 3... Heating burner 5... Electrolytic bath, 7... Drying oven. 2... Strand wire spool, 4... Take-up spool, 6... Washing tank, 1st cause 2nd figure 1 ---- Single metal gland 2------ Single metal gland suar 3--- -One Calorie Heat Burner 4---One Condolence 1! I sales lithoul 5 ------- Electrolyte 6 - - 1 - Water 5 Priority production 7 ------- Refinery furnace

Claims (1)

[Claims] 1. In a method for smoothing the surface of a wire when drawing a high melting point metal wire with a melting point of 1000°C or higher using a wire drawing die,
A wire rod having a wire diameter in the range of 1.03 to 1.5 times the finished wire drawing diameter is heated and oxidized in the air or in an oxidizing atmosphere at a temperature of 700°C or more for 0.02 seconds or more, and then finished wire drawing. 1. A method for surface treatment of a metal wire, which further comprises performing surface electrolytic polishing of 5% or more of the wire diameter.