JPS5910940B2 - Heat-resistant sealing glass composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant sealed glass silk composition suitable for hermetically sealing, for example, metal and porcelain, or porcelain and porcelain.

Generally, the method of sealing porcelain and porcelain or metal and porcelain with glass is widely used because the sealing can be completed with only a single heat treatment step, and the process is simple.

Various glasses are used as the sealing material in such a sealing method, but when particularly high heat resistance is required, glass whose main components are Al203 and CaO is used because it is easy to vitrify. , MgO, Sro, BaO, ¥2 as subcomponents to control the coefficient of thermal expansion, etc.
Glasses to which 03, Zr02, T102, etc. are added singly or in combination have been used in the past.

On the other hand, the structure of the sealed part of a sealed body using such glass often requires a complicated shape and a narrow sealing gap.
Conventional sealing materials having glass compositions have viscosity at high temperatures and surface tension characteristics that cause bubbles to form in the glass of the sealed portion, impairing sealing performance and lowering the yield of sealed bodies.

If air bubbles form in the seal, the airtightness will deteriorate, which not only causes leakage in pressurized or depressurized containers, but also ensures a long service life because the seal pass is substantially reduced. Therefore, a highly reliable sealed body cannot be provided.

The present invention was made in an attempt to improve the defects of the sealed body due to the generation of bubbles in the sealed part due to the use of the conventional sealing glass as described in the previous article.
- By studying the characteristics of Al203-based glass, we found a composition range for heat-resistant sealing glass that generates fewer bubbles during sealing, and completed this invention.

That is, this invention includes the four components MgO-BaO-CaO-Al203 as essential components, and the proportion of each component is MgO8.
~12% by weight, BaO2~6% by weight, (CaO+Al2
03) It relates to a heat-resistant sealing glass composition characterized by having a weight of 82 to 90%.

The case where the present invention is applied to the arc tube of the high-pressure Na-IJ lamp will be described in detail below with reference to Examples and drawings.

The quality of the heat-resistant sealing material of the present invention was determined by sealing the arc tube of a high-pressure sodium lamp as shown in FIG. 1 and observing the presence or absence of air bubbles in the sealed portion.

The arc tube of the high-pressure sodium lamp shown in Fig. 1 is fitted with a translucent alumina porcelain pipe 1 and a porcelain cap 2 made of the same material with a small gap, and a hole provided in the center of the porcelain cap. The metal pipe 4 inserted with a small gap is sealed with heat-resistant sealing glass 5 in vacuum at 1350~15
Manufactured by sealing at 50°C.

Although not directly related to the present invention, 3 is a discharge electrode connected to the metal pipe 4.

The presence or absence of air bubbles in the sealed portion of the arc tube manufactured as described above was determined by the process described below.
A wide composition range of the four-component glass of B20-Ca0-Al203 was evaluated.

The heat-resistant sealing glass according to the present invention has a predetermined weight of raw material compounds such as magnesium oxide, barium oxide, calcium oxide, and aluminum oxide, for example, 100% of magnesium oxide.
g, 40 g of barium oxide, 369 g of calcium oxide, and 491 g of aluminum oxide are weighed, each raw material is thoroughly mixed, placed in, for example, a platinum crucible or an alumina crucible, and heated and melted at 1400° C. to 1600° C. for 3 to 5 hours.

This sufficiently vitrified melt is rapidly cooled, coarsely pulverized, glass calefed, and, if necessary, coarsely pulverized into a fine powder to form powdered glass or pelletized for use.

Table 1 shows the results of determining the state of bubble generation when glass of various compositions manufactured by the above method was applied to seal the arc tube of a high-pressure sodium lamp. No bubbles were observed in the glass compositions in the above range, and the rate of bubble generation was significant in the other composition ranges.

According to the inventors' study, the effective composition range is 1 to 6 in Table 1.
MgO is 8 to 12 weight percent, BaO is 2-
It was found that the weight ratio was 6 and (CaO+AA203) was 82-90 weight ratio.

The blending ratio of CaO and Al203 is preferably in the range of 70 to 95 parts by weight based on 100 parts by weight of Al203.

If the blending ratio of CaO and Al203 is out of the range listed above, it becomes difficult to vitrify.

The fact that the glass composition range of the present invention is extremely effective in preventing bubble generation in the sealed part has not yet been logically elucidated, but the glass composition range of the present invention has a small surface tension at high temperatures and a dependence of the viscosity coefficient on temperature. There are characteristics such as large sex,
It is thought that these features are working effectively.

The glass composition of the present invention also has a heat resistance higher by about 100°C or more than the glass composition having the above-mentioned composition range, and a thermal expansion coefficient in the range of 67×IF7 to 75×10-7°C. Close to that of porcelain, especially high pressure NaI-I
It is ideal as a sealant for J-luminium lamp arc tubes, but it can also be applied to products other than the high-pressure sodium lamps shown in this example, and it can also be used to seal porcelain other than alumina porcelain and metals. is also valid.

As explained above, the sealing glass composition according to the present invention has excellent heat resistance and is characterized by significantly less bubbles generated during sealing, and is of great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the end of the arc tube of a high-pressure sodium lamp, and FIG. 2 is a composition diagram of glass. In FIG. 1, 1 is a porcelain pipe, 2 is a cap, 4 is a metal pipe, and 5 is a sealing glass. The shaded area in FIG. 2 shows the composition range of the sealing glass according to the present invention.

Claims (1)

[Claims] I Consists of four components: MgO-BaO-CaO-A7203, the proportions of each component are Mg08-12 weight ratio, Ba0
2 to 6 weight ratio, (CaO + Al203) 82 to 90 weight ratio, and the ratio of CaO and Al203 is Al20
A heat-resistant sealing glass composition characterized by containing 070 to 95 parts by weight of Ca to 3,100 parts by weight.