JPH09125186A - Functionally gradient material, sealing member for electric discharge lamp using functionally gradient material, and production of functionally gradient material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high strength, transparent functionally gradient material by using slurry consisting of mixture of crystalline SiO2 and amorphous SiO2 , metals or metal oxides, and solvent and subjecting this slurry to casting, molding, and burning. SOLUTION: A slurry 4, consisting of SiO2 , one or more metals or metal oxides, and solvent, is cast in an acrylic tube 3 disposed on a gypsum mold 2. The metals, etc., are gathered downward by specific gravity difference to form concentration distribution, and the solvent is removed via the gypsum mold 2 to carry out molding. Then, the resultant molding is drawn from the mold and burnt, by which the functionally gradient material is obtained. At this time, a mixture of crystalline SiO2 and amorphous SiO2 , preferably a mixture in which amorphous SiO2 comprises <=10wt.%, is used as the SiO2 . Further, preferred viscosity of the slurry 3 is 10-24cp. By using this amorphous SiO2 as an inorganic binder, a transparent, high strength sintered compact can be obtained without forming cavities at the time of sintering. The resultant functionally gradient material is suitably used, e.g. for sealing member for electric discharge lamp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functionally graded material, a sealing member for a discharge lamp using the functionally graded material, and a method for manufacturing the functionally graded material.

[0002]

2. Description of the Related Art A functionally graded material has been conventionally known as a heat-resistant material for locations where the temperature difference between the inside and the outside is extremely large. A conventional functionally graded material is manufactured by casting a slurry containing a plurality of types of substances having different specific gravities and then firing the slurry. To the slurry used for the above-mentioned cast molding, a dispersant (peptizing agent) for preventing agglomeration of particles, a resin for ensuring the strength of a green body (green body), and an organic binder such as a saccharide are added.

[0003]

In the above-mentioned prior art, when a dispersant or an organic binder is added when a functionally gradient material is produced from a slurry containing SiO ₂ , an organic binder is formed. After the sintering, after the sintering, a void is formed in the place where the organic binder was interposed and the strength is lowered, and the SiO ₂ portion of the sintered body made of the functionally gradient material is not sufficiently sintered and becomes cloudy.

Therefore, the present applicant prepared a slurry excluding the above organic binder and cast-molded it, but the strength of the green formed body was insufficient and the shape could not be maintained.

[0005]

In order to solve the above problems, the present invention provides a functionally graded material obtained by casting and molding a slurry of SiO ₂ and one or more metals or metal oxides and a solvent, followed by firing. and the SiO ₂ and a mixture of crystalline SiO ₂ and amorphous SiO _2. Further, a hole is formed from the end face of the layer containing a large amount of SiO ₂ to a position reaching the layer containing a large amount of metal or metal oxide, and a rod-shaped electrode is inserted into the hole to form a sealing member for a discharge lamp. it can.

Here, the mixture of crystalline SiO ₂ and amorphous SiO ₂ preferably contains 10 wt% or less of amorphous SiO _2, and the viscosity of the slurry is 10 in consideration of moldability and the like. It is preferably set to 24 cp. Amorphous Si
If O ₂ is not mixed, the strength of the green body is weak, and the area of SiO ₂ becomes cloudy during sintering. On the other hand, if the content of amorphous SiO ₂ is 10 wt% or more, the viscosity is too high and it is not suitable for the casting slurry.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a schematic view of an experimental manufacturing apparatus used for manufacturing the functionally gradient material according to the present invention. The manufacturing apparatus 1 is a container in which a plaster mold (porous mold) 2 is coated with wax on its inner surface. , For example acrylic tube 3
It is configured by setting.

In order to obtain a desired functionally graded material using this manufacturing apparatus 1, first, as shown in FIG. 1A, crystalline SiO ₂ , amorphous SiO ₂ , Mo (molybdenum) is placed in an acrylic tube 3. And a slurry 4 composed of water is poured.
In the present invention, a part of the crystal SiO ₂ is replaced by amorphous SiO _2, utilizes the amorphous SiO ₂ as a binder for inorganic. The raw material analysis was performed by fluorescent X-ray and X-ray diffraction microscopy.

When the slurry 4 is poured, as shown in FIG. 1 (b), Mo having a large specific gravity gathers downward and a difference in distribution occurs between it and SiO ₂ having a small specific gravity. Then, after the water content in the slurry 4 is removed from the gypsum mold 2 and the inking has grown, the gypsum mold is demolded and dried to obtain a green shaped body. After this, this green form is 1100-
Preliminarily calcined at 1350 ° C, then processed into a cylindrical shape, and finally 17
The intended functionally gradient material is obtained by firing in a vacuum or reducing atmosphere at 00 to 1750 ° C.

Next, the viscosity of the slurry when changing the mixing ratio of amorphous SiO ₂ with respect to the entire SiO ₂ (unit: c
Table 1 shows the results of examining p), the appearance of the green body, the strength and the transparency of the sintered body. In Table 1, the unit of each component is g (gram), and the ratio in parentheses is the ratio (wt%) to the total weight of the slurry. In addition,
₂ (C) is crystalline SiO ₂ and SiO ₂ (A) is amorphous SiO _2.
Are respectively shown.

[0011]

[Table 1]

The crystalline SiO ₂ has a purity of 3N or more,
Amorphous SiO ₂ having an average particle size of 0.8 μm (manufactured by Kojundo Chemical Laboratory Co., Ltd.) having a purity of 3N or more (manufactured by Wako Pure Chemical Industries, Ltd.) is used as Mo (molybdenum). ) As powders, those having an average particle size of 1.5 μm were used.

Next, referring to Table 1, the appearance of the green molded body, the strength and the transparency of the sintered body in the above experiment will be described. The mixing ratio of amorphous SiO ₂ is 0 w with respect to the entire SiO _2.
When it is t%, that is, when there is no binder, it has an appropriate viscosity (10 cp), but cracks occur in the green body, and the strength of the sintered body is insufficient, and the SiO ₂ region becomes cloudy. (Experimental example 1). Since this is not a satisfactory result, it is indicated by x.

Further, when the mixing ratio of amorphous SiO _{2 to} the entire SiO ₂ was 50 wt%, the binder action was so strong that the viscosity could not be measured (Experimental Example 5). Therefore, it is shown here by −.

On the other hand, amorphous S with respect to the entire SiO ₂
The mixing ratio of iO ₂ is 1.2 wt% (Experimental Example 2), 5.0
In the case of wt% (Experimental example 3) and 13.0 wt% (Experimental example 4), a formed product having an appropriate viscosity (10 to 24 cp) due to the binder action of amorphous SiO ₂ and having no crack is obtained. be able to. Since these are satisfactory results, they are marked with a circle.

Further, when the green body was fired, the sintered body was sufficiently sintered in the SiO ₂ region, so that the sintered body became transparent with high strength and no cloudiness. Since these are satisfactory results, they are marked with a circle.

In the present invention, the functionally graded material manufactured as described above is applied to a sealing member (sealing cap) of a discharge lamp. FIG. 2 is a sectional view of a discharge lamp provided with a sealing cap made of a functionally graded material.

The discharge lamp has openings 11 and 12 formed at both ends of a translucent arc tube 10 made of polycrystalline alumina or the like, and sealing caps 20 and 30 are fitted into the openings 11 and 12, and a glass solder or the like is used. The sealing materials 13 and 14 are hermetically sealed by heating with high frequency or infrared rays.

The sealing caps 20 and 30 are formed by using the functionally graded material obtained above, and have a hole 21 extending from the end portions 20a and 30a of the SiO ₂ -rich layer to the middle of the Mo-rich layer 21. , 31 are cut, the rod-shaped electrodes 22, 32 are inserted through these holes 21, 31, and the tips of the electrodes are M-shaped.
Inserted in a layer containing a lot of o.

By inserting the tips of the electrodes 22 and 32 into a layer containing a large amount of Mo, electrical conduction can be established with the outside, and M
By connecting the ends 20b and 30b of the layer containing a large amount of o to a power source, the electrodes 22 and 3 are connected via the part where Mo is mostly occupied.
2 can be supplied with electric power.

A gap S is formed between the electrodes 22 and 32 and the holes 21 and 31. This gap S is equal to or larger than the difference in thermal expansion between the electrodes 22 and 32 and the sealing caps 20 and 30 during lighting, that is, the inner diameter of the holes 21 and 31 is increased by the expansion of the electrodes 22 and 32 during discharge lighting. The inner surface of the hole does not come into contact with the inner surface of the hole to prevent cracking of the sealing caps 20 and 30.

When the sealing caps 20 and 30 are fixed to the arc tube 10, the sealing caps 20 and 30 are fixed.
The part where 30 contacts the openings 11 and 12 of the arc tube 10 is
The ends 20a and 30a are occupied by the quartz particles so that the thermal expansion coefficient thereof is substantially the same as the thermal expansion coefficient of the material forming the arc tube 10. This prevents leakage of the luminescent material from the connecting portion between the sealing caps 20 and 30 and the quartz arc tube 10 due to the difference in thermal expansion.

[0023]

As described above, the present invention is based on SiO ₂
When molded casting a slurry comprising one or more metal or metal oxide and a solvent, in the functionally gradient material obtained by firing, because the SiO ₂ was a mixture of crystalline SiO ₂ and the amorphous SiO _2, organic Like when using a binder,
After firing, no cavities are formed in the places where the organic binder was present, and the firing of the SiO ₂ region can be performed sufficiently.

Further, since the mixture of crystalline SiO ₂ and amorphous SiO ₂ contains 10% or less of amorphous SiO ₂ , the sintered body can secure high strength, and the transparent portion of the SiO 2 region is transparent. Can be realized. The viscosity of the slurry is 10 to 24.
Since it is set to cp, when the slurry is cast-molded, the green molded body can have sufficient strength to maintain its shape.

Furthermore, the sealing member for a discharge lamp using the functionally gradient material according to the present invention is obtained by casting a slurry of a mixture of crystalline SiO ₂ and amorphous SiO ₂ and one or more metals or metal oxides and a solvent. Since the functionally graded material is formed into a cylindrical shape and then fired and the electrodes are inserted in the compositional gradient direction of the functionally graded material, it is possible to easily provide a long-life discharge lamp.

[Brief description of the drawings]

FIG. 1 is a schematic view of an experimental manufacturing apparatus used for manufacturing a functionally gradient material according to the present invention.

FIG. 2 is a cross-sectional view of a discharge lamp with a sealing cap made of a functionally graded material attached.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus, 2 ... Gypsum type (porous type), 3 ... Acrylic tube, 4 ... Slurry, 10 ... Arc tube, 11, 12 ...
Recesses, 13, 14 ... Sealing material, 20, 30 ... Sealing caps 21, 31 ... Electrodes, 22, 32 ... Electrode insertion cavities, 2
3, 33 ... Recesses.

Claims (4)

[Claims] 1. A functionally gradient material obtained by casting and molding a slurry comprising SiO ₂ and one or more metals or metal oxides and a solvent, followed by firing, wherein the SiO ₂ is crystalline S.
A functionally graded material, which is a mixture of SiO ₂ and amorphous SiO ₂ . 2. A functionally graded material according to claim 1, non proportion of amorphous SiO ₂ in the mixture of the crystalline SiO ₂ and the amorphous SiO ₂ are inclined to equal to or less than 10 wt% Functional material. 3. A sealing member for a discharge lamp using the functionally graded material according to claim 1, wherein the sealing member reaches a layer containing a large amount of metal or a metal oxide from an end face of the layer containing a large amount of SiO _2. A sealing member for a discharge lamp using a functionally gradient material, wherein a hole is formed up to a position and a rod-shaped electrode is inserted into this hole with a gap. 4. A method for producing a functionally graded material, which comprises casting a slurry of SiO ₂ and one or more metals or metal oxides and a solvent and then firing the slurry, wherein the viscosity of the slurry is 10 to 24 cp. Of manufacturing a functionally graded material to be used.