JPS5811501B2 - tungsten material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in tungsten materials used primarily as filament materials for tubes, and its purpose is to provide tungsten materials that recrystallize at relatively low temperatures.

Generally, the tungsten material used for these tube filaments is pure tungsten with Al added as a doping agent.
2O3, K2O15i02 alone or in combination 0.01w
t%~1. It can be obtained by adding Owt%.

The purpose of adding these dopants is to improve the droop resistance (non-sag property) of the wire at high temperatures.

Tungsten wire is usually made by press-molding metal powder.
This is sintered by electrical heating, and the resulting sintered body is rolled and rolled.
Obtained by drawing a line.

The wire thus obtained is wound into a coil and then subjected to a so-called forming process in which it is heated in hydrogen or vacuum to form a filament.

The heat treatment for these moldings is usually 1500℃~1600℃.
The process is carried out at a high temperature close to the recrystallization temperature of .degree.

From this point of view, a wire with a recrystallization temperature as low as possible is preferable, and forming is possible at a relatively low temperature for a wire with a low recrystallization temperature.

However, wires that undergo recrystallization at low temperatures generally have drawbacks such as deterioration in non-sag properties.

For example, pure tungsten wire containing no dopants has a 0.
Recrystallization temperature at 39mmφ is 1500-1600℃
and the recrystallization temperature of normal doped tungsten wire 210
Although the sag value is significantly lower than that at 0 to 2200°C, such a wire has an abnormally large sag value and cannot be used as a filament material.

The present invention was completed as a result of various studies on dopants to be added to tungsten powder in order to improve the above-mentioned drawbacks.

The feature of the present invention is that A, which is a common dopant,
l2O3, K2O15jO2 alone or in combination 0.01
wt%~1. Added Owt% and further added 0.003w of Ti.
By containing t% to 0.03wt%, recrystallization occurs at a relatively low temperature and the structure after recrystallization is also good. It is to provide.

Next, the content of the present invention will be further explained according to embodiments.

An aqueous solution of potassium silicate and potassium nitrate is added to the blue oxide obtained by reducing ammonium paratungstate crystals obtained through a normal scouring process in hydrogen in an electric furnace with a temperature gradient of 400°C to 550°C. Al2O3, K2
0.03%, 0.2%, 0 as O1SiO2, respectively
．． It was doped to 4%.

The doped blue oxide is further heated in hydrogen at 600°C to 850°C.
Tungsten metal powder was obtained by reduction in an electric furnace with a temperature gradient of °C.

This powder was further washed with hydrofluoric acid to dissolve and remove excess dopant and other impurities.

Metallic Ti powder (35
0 mesh) from 0.003wt% to 0.05wt
The relationship between the amount of Ti added and the wire properties was examined using samples mixed at various ratios up to %.

The Ti-doped powder was further press-molded and electrically sintered using a conventional method.

The sintered body was subjected to conventional rolling and wire drawing processes to obtain a wire of a predetermined size.

The relationship between the Ti doping amount, sag value, and recrystallization temperature at Q, 39 mmφ is shown in FIGS. 1 and 2.

The method of measuring the sag value is to bend the wire into a hairpin shape, set the distance between both ends to 12 mm, and apply a weight to the wire.
After forming with a current of 80% of the fusing current, the weight is removed and heating is carried out with a current of 80% of the fusing current.

The amount of deformation at this time is defined as the sag value by the difference between A and B in FIG.

As is clear from FIG. 1, the recrystallization temperature of the wire decreases in proportion to the Ti doping amount.

When doped with TiO and 05 wt%, a decrease of about 500° C. was observed compared to the wire without Ti addition.

Also, from Figure 2, regarding the sag value, the Ti doping amount is 0.03.
At more than 0.03 wt%, the deterioration becomes significant, but at less than 0.03 wt%, the deterioration of the sag value is not so great that it can be used as a filament material.

These effects of the present invention are considered to be due to the alloying of W and Ti or the deoxidizing effect of Ti.

As is clear from Figures 1 and 2 above, the amount of Ti added is 0.0.
If it is less than 0.03 wt%, the recrystallization temperature will hardly decrease, and if it is more than 0.03 wt%, the sag will be significantly degraded and cannot be used in actual use.

Therefore, the amount of Ti added in the present invention is from 0.003 wt% to
It was defined as 0.03 wt%.

As is clear from the above facts, the amount of Ti added is 0.003w.
Within the range of t% to 0.03wt%, the object of the present invention, which is to lower the recrystallization temperature while preventing deterioration of sag, was sufficiently achieved.

Further, the tungsten material of the present invention has better workability in the rolling percussion wire drawing process than ordinary doped tungsten materials, and has the effect of improving manufacturing yield.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the amount of Ti added and the recrystallization temperature at a diameter of 0.39 mm. FIG. 2 shows the relationship between the amount of Ti added and the sag value at a diameter of 0.39 mm. FIG. 3 is a diagram explaining the method of measuring the sag value, and shows the shape of the wire before heating with electricity, and FIG. 4 shows the shape of the wire after heating with electricity.

Claims (1)

[Claims] 1 General dopants Al2O3, K2O1SiO
2, alone or in combination, from 0.01 wt% to 1. Owt%
A tungsten material whose recrystallization temperature is lowered by adding 0.003 wt% to 0.03 wt% of Ti.