JPS63313451A - Manufacture of end blocking material for high pressure discharge lamp - Google Patents

Abstract

PURPOSE:To make such airtightness that is stable for hours securable by using the cermet made up of alumina powder, containing the specified quantity of a magnesium constituent as a base, for a ceramic light emitting tube end blocking material. CONSTITUTION:At the time of sintering a mixed body between metal (one type selected from Mo, Cr, Fe and Ni or more) and aluminum oxide (alumina) and thereby manufacturing a cermet sintering body, such material powder that contained a magnesium constituent as much as 500ppm-1500ppm in a base material is used. For example, aluminum powder, containing the magnesium constituent as much as 100ppm, and tungsten are mixed together, and after being pressed and desorbed, it is attached to an electrode and a lead rod, then it is baked in a vacuum. with this constitution, a very dense cermet sintering body is produced in the state that a thermal expansion characteristic and conductivity are satisfied, thus high airtight reliability is maintainable over hours.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of manufacturing an end closure material for a high-pressure discharge lamp having a translucent alumina arc tube.

(Prior Art) Cermet, which is a mixed sintered body of metal and oxide, is being developed as an end sealing material for high-pressure metal vapor discharge lamps with translucent alumina arc tubes. Taking a mixed sintered body of tungsten (W) and alumina (A et al. 03) as an example, the equity is 60-3.
As exemplified in Japanese Patent No. 5422, in order to obtain conductivity with a small amount of W, relatively large At,03 particles are mixed with much smaller W particles.

A4. W is connected in a network around O and therefore conductive.

The two basic characteristics required of the plugging material are: (1) It must have thermal expansion characteristics equivalent to those of an Affi, O, arc tube, and (2) It must be airtight. For the request of ■, Al, 0
In the case of cermets based on 3, no major problems arise due to optimization of the composition. Regarding the airtightness of the cermet, since the cermet itself is a sintered body, the degree of densification (relative density) is the criterion for evaluation. It will be done. The sintering properties of cermet vary depending on the ratio of u*os/W,
As the amount of W increases, the degree of densification tends to decrease somewhat. This is Ag□0. It is thought that this is because W and W essentially do not cause a phase reaction, and W exists as a foreign substance in the sintering of Affi, O,. Similarly, thermal expansion characteristics and conductivity (electrical resistance) are also directly related to the ratio of A to W. For example, the smaller the amount of W, the closer the thermal expansion characteristics are to those of an arc tube (alumina). On the other hand, the larger the amount of W, the better the conductivity.

As described above, the three items of densification, thermal expansion characteristics, and electrical conductivity change sensitively depending on the composition, so a considerably high level of technology is required to obtain a cermet sintered body that simultaneously satisfies these three items. When the sintered cermet is used as an end sealing material for a high-pressure metal vapor discharge lamp with a translucent alumina arc tube, it has a structure in which electrodes and lead rods are embedded at both ends, as shown in Figure 1. Figure 2. It will be incorporated like this. When the lamp is actually lit, the arc tube reaches a high temperature of over 1000 degrees Celsius, and the cermet also reaches a very high temperature, so the closure member is required to have long-term airtight reliability under harsh environments. .

Here, the biggest problem is a decrease in airtightness during long-time lighting. Possible causes include: (1) minute amounts of gas permeate through the sintered body itself due to insufficient densification; and (2) cracks occur due to thermal strain due to low strength as a result. In order to deal with such problems in advance,
Conventionally, solder glass or the like has been used to cover the end sealing material to compensate for the decrease in airtight reliability. However, in such a state, it cannot withstand long-term use and cannot be said to be an essential solution. Obtaining a body was a major bottleneck in the development of the lamp system.

(Problems to be Solved by the Invention) In view of the above points, the present invention aims to provide a dense cermet sintered body that satisfies thermal expansion characteristics and conductivity.

[Structure of the invention] (Means for solving the problem) Mixture of metal (one or more selected from W, No, Cr, Fe, and Ni) and aluminum oxide (alumina; A et O3) In producing a cermet sintered body by sintering the body, a raw material powder containing alumina as a starting material and a magnesium component (Mg) of 500 ppi* to 1500 ppm is used.

(Function) The cermet end closure material of the present invention satisfies desired thermal expansion characteristics and conductivity, and since it is a dense cermet sintered body, it maintains high airtight reliability over a long period of time.

(Example) Examples of the present invention will be described below.

Example-1 Magnesium (Mg) component is each 0.500.10
00゜1500, 2000.6 types of aluminum powder containing 80vt% and tungsten (11) containing 2500ppm
After mixing 20vt%, pressing, and detaching, the electrode,
A lead rod was attached and baked at 1700° C. for 2 hours in a vacuum. FIG. 3 shows the relationship between the relative density ratio (%) calculated from the density measurement sample fired at the same time and the amount of magnesium component in the starting alumina powder.

Using this cermet, the distance between the electrodes is 15cm, as shown in Figure 2.
Arao3. A mixture of sio, s CeO, was melted at 1500 °C, and NaQ was used as an inclusion.
5B.

5clls gmgsHg 15mg, Ar20To
rr was added to make it a 1501 metal halide lamp.

A prototype of 502 lamps was produced for each, and a lighting experiment was conducted. As a result, a lamp using a cermet starting from M (components 500°1000, 1500 ppm aluminium)
None of the lamps had a slow leak when lit for hours, but the lamps with Mg content of 0°2000pp and 2500pp■ were 7p150p and 9p150p, respectively.

Slow leakage was observed at a rate of 10p/SOp.

〔Effect of the invention〕

As described above, when a cermet made from alumina powder containing a predetermined amount of magnesium component is used as the ceramic arc tube end sealing material, stable airtightness can be obtained for a long time.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views, and FIG. 3 is a characteristic curve diagram. Figure 1 Figure 2 o sm y#e tstra
2ρθy 2 series 6 Remina (AIO)
J! Sim Q? Bune Ichiuri, (M9 Tsuga Tabi i (pp
m) Figure 8

Claims (1)

[Claims] (1) A member (cermet) made by sintering a mixture of metal (one or more selected from W, Mo, Cr, Fe, and Ni) and aluminum oxide (alumina; Al_2O_3) is used as a ceramic arc tube. In a high-pressure discharge lamp used as an end-blocking material, magnesium (Mg) is added to alumina as a starting material in producing the end-blocking material (cermet).
A method for producing an end-closing material for a high-pressure discharge lamp, characterized in that raw material powder containing 500 ppm to 1500 ppm of components is used.