JPH0715160B2 - Molybdenum foil used for glass sealing part of lamp and surface smoothing method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a molybdenum (Mo) foil used for a glass sealing part of a lamp and a surface smoothing method thereof.

[Technical background of the invention and its problems]

For lamps, especially in halogen lamps, Mo foil is used to connect the external lead wire and the internal lead wire at the hard glass or quartz glass sealing portion, but when the surface condition of the Mo foil is rough, It is difficult to completely seal the Mo foil, and due to the difference in the coefficient of thermal expansion between Mo and glass, the stress applied to the glass becomes more complicated as the surface becomes rough, and after sealing, due to leakage during the lamp manufacturing process. Oxidation of filaments and other serious adverse effects on lamp characteristics.

Therefore, a Mo foil having a smooth surface with a surface roughness of 5 μm or less is strongly demanded.

[Object of the Invention]

The present invention solves the above problems and has a surface roughness of 5 μm.
It is an object of the present invention to provide a Mo foil having the following smooth surface and a surface smoothing method for obtaining such Mo foil. The surface roughness referred to in the present invention means the maximum height (Rma defined by JIS-B0601.
x) is meant.

[Outline of Invention]

In order to achieve the above-mentioned object, the present inventor has applied various electrolytic polishing methods known as a surface smoothing method to Mo foils and conducted various studies, and the types and temperatures of electrolytic polishing liquids in the electrolytic polishing method, and electrolysis. As a result of studying the current density and its electrolytic power supply, it is possible to make the surface of the Mo foil extremely smooth in the case of the mode described later, and when each is incorporated into the product, it is concluded that the characteristics are extremely good. Reached

That is, it is used for the glass sealing part of the lamp of the present invention.
The Mo foil has a surface roughness of 5 μm or less, and the surface smoothing method of the Mo foil used in the glass sealing portion of the lamp is the same as the Mo foil at a sulfuric acid concentration of 30 to 80% and a temperature of 40%. ℃
It is characterized in that it is immersed in the following electrolytic solution and subjected to electrolytic polishing treatment at a current density of 30 to 50 A / dm ² to make the surface roughness 5 μm or less.

First, a sulfuric acid solution is used as the electrolytic solution. The concentration of the liquid should be high, and if the concentration of sulfuric acid is too low, the smoothing effect will be small. However, if the density is too high, it will be difficult to obtain the current density described later, and in order to keep the current density within a predetermined range, it is necessary to increase the size of incidental equipment, which results in a high capital investment amount and is not economical. In the present invention, 30 to 80% is suitable, and preferably 40 to 60%.

It is more effective that the temperature of the electrolytic solution is lower, and 40 ° C or lower is used. On the other hand, from the viewpoint of production technology, the temperature is preferably 10 ° C or higher, so that the range of 10 to 40 ° C is preferable. Furthermore, it is necessary to minimize the temperature fluctuation during electrolytic polishing, and it is particularly desirable to keep it within ± 10 ° C.

Further, when the current density applied to the Mo foil during the electrolytic polishing treatment is too small or too large, surface etching occurs and conversely the surface unevenness becomes large. In the present invention, 30 to 50
Managed by A / dm ² . Preferably, it is about 35-45 A / dm ² .

The surface roughness of the Mo foil obtained by the method of the present invention is affected by the surface state of the Mo foil before electrolytic polishing treatment and its size and shape, and therefore electrolytic polishing time, that is, electrolytic It is necessary that the polishing amount be appropriately adjusted depending on the desired smoothness and the form of the Mo foil before the treatment.

Example of Invention

Example 1 A sintered body of Mo obtained by the powder metallurgy method was rolled and rolled,
A foil having a width of 2.1 mm and a thickness of 29.5 μm was manufactured. This foil is immersed in an electrolytic solution with a sulfuric acid concentration of 50% and a solution temperature of 30 to 35 ° C, and electrolytically polished at a constant rate of direct current electrolysis current density of 38 A / dm ² and 15 m / min,
A Mo foil having a width of 2.0 mm and a thickness of 28 μm was obtained. This foil is 20mm long
As a result of cutting into pieces and measuring with a surface roughness meter, the maximum surface roughness was 0.9 μm. M obtained by the above electrolytic polishing method
o Incorporating foil into a halogen lamp, we investigated the relationship between the lamp failure rate due to slow leak during lighting and 4000 lamps, but no occurrence of eyelashes. In addition, in the conventional results of the Mo foil (surface roughness: 7 μm) obtained by the conventional electrolytic polishing method, the leak generated during the lamp manufacturing process was 0.1 to 0.2% due to the Mo foil.

〔The invention's effect〕

As is clear from the above description, the Mo foil used for the glass-sealed portion of the lamp obtained by the method of the present invention has an extremely smooth surface, and thus is extremely useful as a Mo foil used for the glass-sealed portion of the lamp. It is useful.

Claims (2)

[Claims] 1. A molybdenum foil used for a glass-sealed portion of a lamp, which has a surface roughness of 5 μm or less. 2. A molybdenum foil with a sulfuric acid concentration of 30 to 80% and a temperature of 40.
It is used in the glass sealing part of a lamp, which is characterized in that its surface roughness is 5 μm or less by immersing it in an electrolytic solution at a temperature of ℃ or below and performing electrolytic polishing treatment at a current density of 30 to 50 A / dm ^2. Surface smoothing method for molybdenum foil.