JPS6028605A - Manufacture of infrared ray transmitting material - Google Patents

Abstract

PURPOSE:To form an IR transmitting material into granules or a flaky powder by filtering it in a molten state to remove impurities and successively dropping it to solidify it through rapid cooling. CONSTITUTION:High purity CsBr power available on the market is solidified in advance into ingot 3 and placed in a filtration device as a starting material. H2 is introduced in a flow rate of 200cc/min through a gas inlet 6 at the bottom of the device for one hr, and the temp. is raised to 500 deg.C in an atmospheric pressure. The ingot 3 begins to melt on reaching the m.p. and gradually passes through a quartz glass filter 1 to remove impurities. Then, it drops through the outlet end 2b of the filter 1 as liquid droplets, and collides with the bottom of a crucible 5 made of transparent quartz having the bottom 30cm below the lower end of an electric heater 4. The droplets are scattered and solidified by rapid cooling into granules or a flaky powder in a state easily capable of being taken out without crushing the crucible 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing an infrared transmitting material (more particularly, it relates to a method for producing an infrared transmitting material whose main component is an alkali halide or a metal halide!).

[Technical background of the invention and its problems]

An example of an infrared transmitting material that transmits or transmits high power infrared laser light such as CO or laser light is CsI.

CsBr, kgcl, TlBr, T/I, etc. are known.

However, optical fibers made of these infrared-transmissive materials (
=, When a high-energy laser beam with a power density of several Kwlcd1 or more is transmitted through the optical fiber, the optical fiber is often melted and damaged. For this phenomenon C two,
One reason for this is that impurities contained in C2 in the material absorb light and generate heat. Also, if there are impurities,
Problems have arisen, such as an increase in light loss during laser beam transmission due to light absorption by impurities, and an increase in light scattering loss due to the roughening of the optical fiber surface. An infrared transmitting method that solves the above problem by heating and melting an infrared transmitting material containing impurities in a dry gas atmosphere, filtering the material through a quartz glass filter, and then solidifying the obtained filtrate. However, since the filtrate is solidified in a transparent quartz glass crucible, the infrared transmitting material and the transparent quartz glass crucible may stick together, making it difficult to take out the infrared transmitting material. In this case, it is relatively easy to destroy the transparent quartz crucible and take it out, but in addition to the disadvantage that the quartz crucible cannot be reused,
Impurities such as quartz glass powder are mixed into the infrared transmitting material C:
If high-energy laser light is transmitted through it, it is possible that it will be melted and damaged. Therefore, there is a need for a method of taking out an infrared transmitting material without destroying a transparent quartz glass crucible.

[Purpose of the invention]

The object of the present invention is to improve the above-mentioned drawbacks and provide a method for easily producing a high-purity infrared transmitting material without destroying a transparent quartz glass crucible.

[Summary of the invention]

The method for producing an infrared transmitting material of the present invention is characterized by filtering and removing impurities from the infrared transmitting material in a molten state, and then rapidly cooling and solidifying the melt by dropping it (thereby producing a powder in the form of granules or flakes). .

The present invention will be explained in detail below.

The infrared transmitting material that is the object of the present invention includes KCI
, KB'r , alkali halides such as CsBr and CsI, AgCl! , AgBr, TlCl and Tl
Metal halides such as Br are exemplified, but in addition to C2, any material that can be used as an infrared transmitting material can be used.

Examples of filters that filter impurities in the infrared transmitting material in a molten state include sintered quartz glass particles and quartz glass fibers. When a quartz glass filter is used, StO, which is an impurity, is efficiently removed.

An example of a filter using a sintered silica glass body is shown in FIG. 1L. The filter has a structure in which a filter L is formed by crushing quartz glass and arranging the granules into a disk shape (secondary sintering) and fixing it to a quartz glass row 1z (alt 2) welding. The smaller the pore diameter of the shaped filter 1 is, the better, in terms of removing impurities, and for practical purposes, it is preferably several μm or less.

In addition, an example of a filter using silica glass fiber is shown in the second example.
It is shown in Figs. In both filters, glass fibers are placed near the inlet of the filtrate leakage part of funnel 2 (a) (two-packed (two-packed), and this is used as filter 1. The diameter of the glass fiber is The smaller the better,
Practically speaking, the thickness is preferably several μm or less.

The filling amount and packing density of the glass fibers are determined by taking into account the size of the filter, the amount of the filter, etc., but it is a good idea to increase the filling amount and density of the glass fiber. .

On the other hand, the structure of the filter is not particularly limited, and is usually made of quartz glass.In order to increase the recovery rate of the excess sample, the volume of the filter part should be small and the filtration rate should be low. It is preferable to do so. The molten liquid of the infrared transmitting material, which has been filtered in a molten state and impurities removed, then falls gently from the open end provided at the lower end of the filter, and the droplets are transferred to the bottom of a quartz glass crucible or to the bifurcated crucible C. When it is dispersed on the quartz glass Shahei plate (2), it is rapidly cooled and assimilated (2) and becomes an ungranular or flake-like powder. It is necessary to maintain a low temperature at.In other words, it is desirable that the bottom position is at least about 30 CI!L away from the lower end of the core.
As an example of a crucible, if a method such as using a water-cooled structure for cooling is used, the bottom of the crucible will be at a position of approximately 30° (even if it is higher than It is shown in a schematic diagram. In the figure, 3 is low) 2 (a
), 4 is an electric furnace that heats and melts the sample from the surroundings, 5 is a quartz glass crucible that houses the filtrate,
6 is a drying gas inlet, 7 is a drying gas outlet, 8 is a thermocouple for measuring the temperature of the filter, 9Vi quartz glass furnace tube,
10 is a support for the crucible 5 made of quartz glass, 11 is a disk made of quartz glass, and 12 is a silicone rubber stopper inserted into the upper and lower parts of the furnace core tube 9.

The following sections: The manufacturing method of the present invention using the apparatus! I will talk about two things. First, when applying the method of the present invention, it is desirable to remove the remaining organic substances in advance.1 Normally, it is difficult to remove them, so the filtered sample is heated in advance to remove the remaining organic substances. It is desirable to decompose and carbonize it.

First, a predetermined amount of the filtered sample 3 containing impurities is placed inside the filter (
Two storage. Next, introduction of dry gas from which dust has been removed is started from the gas inlet 6 at the bottom of the device. Examples of the drying gas used here include hydrogen and inert gases such as alkone and methane. Incidentally, since the full-length halide has high reactivity, it is preferable that these gases do not contain moisture and oxygen.

Therefore, for τ:, a high-purity residue may be used. Furthermore, if an inert gas such as argon is used, the carbon particles in the sample will aggregate and become easier to filter, so it is preferable to use an inert gas as the introduced gas.

Next, after the air in the furnace tube 9 has been sufficiently replaced with dry gas, the sample 3 is heated to a temperature higher than its melting temperature by C2 while continuing to introduce the gas. Although the heating rate is not particularly limited, it is preferable to raise the temperature quickly depending on the performance of the apparatus. Filtration is usually carried out under atmospheric pressure, and the molten sample is filtered under its own weight (from the second to the bottom).The appropriate filtration time is usually
It takes about several minutes per 00 t.

Note that the equipment used in the present invention is not limited to those shown in the figure, and any equipment can be used as long as it is capable of heating, melting, and filtering a sample in a dry gas atmosphere. It is possible.

As mentioned above (2. Impurities such as organic substances and carbon particles.

It is removed by filtration using a filter (2). Note that the S-sulfur in the infrared transmitting material cannot be removed by simply using a filter; it is removed only by using a quartz glass filter (2). Although the removal mechanism of Sin is not clear, it is thought that in addition to the usual mechanical removal mechanism, some kind of chemical reaction mechanism with the quartz glass that constitutes the filter is at work. Although the reason is not clear, when the filtration operation is performed while introducing an inert gas, the carbon particles coagulate and the filtration rate of the particles increases.

According to the above filtration operation, the filtered filtrate falls in a molten state as droplets from the lower open end 2(b) of the filter, collides with the bottom of the transparent quartz glass crucible 5, and scatters.
Rapid cooling and solidification (thus forming a powder in the form of granules or flakes).

〔Effect of the invention〕

According to the present invention, the infrared transmitting material after impurities have been removed is placed in a transparent quartz glass crucible. It can be taken out. In addition, since the microscopic mixing of atoms becomes complete by rapidly cooling the melt, it becomes an extremely effective means for homogenizing materials containing a trace amount of amorphous materials or solid solution materials.

[Embodiments of the invention]

As a filtration raw material, commercially available high-purity CaBr test powder (purity 9
9.59! Inkotsuto, in which n was melted and solidified in advance, was used.

This melting and solidification was carried out as follows.

That is, the CsBr powder of about 150 f described above was filled into a quartz glass boat, placed in a horizontal electric furnace, and then heated under high-purity 1 yr gas flow (the linear velocity of gas flow was about 20 m at the port). The heating rate was 200 to 200 bt (1/min).In the middle section of the ingot, many scale-like precipitates of about several μm in size were observed, which were aggregates of carbon fine particles, which were carbides of residual organic matter. Furthermore, a cyclic impurity (about a few micrometers) was also observed.

Next, it was filtered using the apparatus shown in FIG. The filter was filled with about 0.3 f of straight quartz glass fibers of 1 to 6 μm. The filter C
The inner diameter of the upper part of the funnel is 44mm, the inner diameter of the filter part is 10m and the length is 20mm, and the inner diameter of the nozzle part at the bottom of the funnel is 3mm.Furthermore, the furnace tube 9 has an inner diameter of 52mm. It is made of quartz glass.The electric furnace 4 uses a Kanthal wire heating element, and is heated within the range of 680 to 700°C (the width of one isothermal zone is approximately 150 m.The sample temperature is measured at the top of the filter. did.

The filtration operation was carried out in two steps using the above device as follows.

First, the ingot was placed in a filter, and hydrogen gas was passed through the gas inlet 6 at the bottom of the device at a flow rate of 200 cC/min (linear density of 9 to 7 min at the funnel) for about 1 hour, and then heated under atmospheric pressure. The temperature was raised at 500°/hour.

When the ingot reaches its melting point, it begins to melt and becomes a molten liquid (=
Impurities are removed by sequentially passing through filters. Then, the droplets fall from the open end 2(b) at the lower end of the filter, collide with the bottom of the transparent quartz glass crucible 5 whose bottom is 30cm below the lower end of the electric furnace 4, and are scattered and rapidly solidified. This resulted in ungranular or flaky powder. The powder could be easily taken out (2) without destroying the transparent quartz glass crucible.

The purity of the fcCsBr material obtained in this way is 99.9%.
Met. Sin has a C2 absorption band near the wavelength 10.6 μm of the CO2 laser, and the amount of impurities is filter 1:: 0.
What was 2 ppm decreased by 0.11) pIn or less (detection limit).

The structure of the material was observed using an optical microscope, but no impurities were found. Also, using this material, diameter 1 order, length 1 order
10 single-crystal light guide fibers of m are made, and this is l: 1
00 W CO, laser light was transmitted.

8 No damage was observed at all.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a filter using a sintered silica glass particle filter, Figures 2, 3, and 4 are perspective views of a filter using a silica glass fiber filter, and Figure 5 is a perspective view of a filter using a silica glass fiber filter. is a schematic cross-sectional view of the filtration device. l: quartz glass filter, 2(a): funnel, 2(b): funnel opening end, 3: filtration sample,
4... Electric furnace, 5... Quartz glass Rutsuho, 6...
...Gas inlet, 7...Gas outlet. 8... Thermocouple for temperature measurement, 9... Quartz glass furnace core tube, 10... Quartz glass crucible support. 11... Quartz glass disc, 12... Silicone rubber stopper. Agent Patent attorney Kensuke Norichika (1 other person) Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] The method for producing an infrared transmitting material is characterized in that impurities are removed by filtration from the infrared transmitting material in a molten state, and then the melt is dropped and rapidly solidified to produce a powder in the form of granules or flakes. A method for producing an infrared transmitting material.