JPS61122130A - Processing of fused quartz article - Google Patents

Abstract

PURPOSE:To carry out the processing of a fused quartz article without increasing the OH-concentration in the fused quartz article, by applying a gas generated by the combustion of CO gas and O2 gas to the fused quartz article to be processed, and processing the softened article. CONSTITUTION:CO gas and O2 gas are supplied to the center channel 5 and the outer channel 6 from the bombs 7, 10 via the valves 8, 11 and the connecting pipes 9, 12, respectively, and burnt at the tip 13 of the burner 4 to form the flame 14 of 1,600-2,000 deg.C. The flame 14 is applied to the surface 3 of a hole 2 bored to a fused quartz article 1 to effect the softening of the article and the softened article is processed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of processing fused silica articles.

As used herein, processing a fused silica article refers to heating at least a portion of the fused silica article to a temperature of one or more softening points, which is on the order of about 1650°C, to change the geometry of the softened portion. means. Further, the fused quartz article refers to an article made of fused quartz, that is, quartz glass, or an article made of fused quartz and other materials.

[Prior Art] Conventionally, when processing a fused quartz article, the fused quartz article was softened and processed by applying an oxyhydrogen flame formed by burning hydrogen gas with oxygen gas to the fused quartz article.

[Problems to be Solved by the Invention] However, in the conventional method, when a fused quartz article is processed, the processed portion of the article is exposed to an oxyhydrogen flame.
Processed fused silica articles inevitably contain a high concentration of OH groups as impurities.

The temperature of this OH group is so high that the fused silica article is
Compared to fused silica products with low hemp, it is not only difficult to use at high temperatures due to its low viscosity at high temperatures, but also is used as optical components that utilize infrared light due to its low transmittance of infrared light. It may be difficult to do so.

The present invention has been made in view of the above-mentioned points, and its object is to provide a method for processing a fused silica article without the risk of increasing the concentration of O) in the fused silica article.

[Means for Solving the Problems] According to the present invention, the object is to soften and process the fused quartz article by applying a flame formed by burning carbon oxide gas with oxygen gas to the fused quartz article. This is achieved by a method of processing a fused silica article comprising:

[Operations and Effects] According to the present invention, a flame formed by burning carbon oxide gas with oxygen gas is applied to the processed part of the fused silica article to be processed, and the processed part is exposed to the flame formed by burning carbon oxide gas with oxygen gas. It is softened by the heat of the flame, and the geometry of the softened part can be changed as desired.

Therefore, according to the present invention, there is no risk of increasing the concentration of OH groups in the fused silica article during processing of the fused silica article, and
When conventional quartz glass containing a high concentration of OH groups is treated according to the present invention, some of the OH groups on the surface of the quartz glass are diffused into the combustion gas, so that the O near the surface of the quartz glass is
The number of stitches containing H bases decreases.

Next, a preferred embodiment of the present invention will be described based on the drawings.

In FIG. 1, 1 is a fused silica tube made by drilling holes 2 in a fused silica ingot produced by, for example, a flame melting method using a suitable drilling means such as an ultrasonic drilling machine. For example, the surface of the hole 2 formed during drilling is processed to eliminate minute cracks and irregularities on the surface 3 of the hole 2 so that it can be used as a cladding of an optical fiber by being fitted into a core glass and drawn. .

In addition, when producing a fused quartz ingot by the flame melting method, instead of using an oxyhydrogen flame obtained by burning hydrogen gas with oxygen gas, for example, a flame obtained by burning carbon oxide gas with l hydrogen gas is used. is preferable. 4 is a burner for processing the surface 3 of the hole 2 of the quartz glass tube 1, and the burner 4 has a central passage 5 and a cylindrical passage 6 coaxial with the passage 5. As long as the burner 4 is constructed in such a way that the two gases carbon monoxide and oxygen can be delivered to its tip either separately or in a mixture in a predetermined proportion, as described below.
The structure of the burner 4 may be different. For example, burner 4
The tube may be made of a triple pipe instead of a double pipe, or it may have flow passages arranged substantially parallel to each other or in one plane instead of coaxial flow passages. In the central passage 5 of the burner 4,
For example - carbon monoxide gas is fed from a carbon oxide cylinder 7 via a valve 8 and a connecting line 9, and oxygen gas is fed into the outer channel 6 from an oxygen cylinder 10 via a valve 11 and a connecting line 12. It will be done.

Carbon monoxide gas and oxygen gas from the flow path 5.6 are reacted on the tip 13 side of the burner 4, and the temperature reaches 1.
An oxygen/carbon oxide flame 14 of about 600 to 2000°C is applied to the surface 3 of the hole 2 of the quartz glass tube 1. The surface 3 of the hole 2 in the quartz glass tube 1 is heated and softened by the flame 14, the minute cracks caused by the boring of the hole are eliminated, and the irregularities are smoothed out using a suitable tool if desired. The carbon monoxide gas inlet and the oxygen gas flow m supplied to the tip 13 of the burner 4 can be adjusted, for example, by changing the opening degree of the valves 8, 11; The ratio with the outlet is preferably adjusted to 0.5/4:1.

A quartz glass rod for forming a core portion is inserted into the hole 2 of the quartz glass tube 1 whose surface 3 has been flattened in this way,
An optical fiber can be formed by softening the tube 1 and the rod and drawing them together.

The measurement results of the transmission loss characteristics of the optical fiber thus formed are shown as a solid curve 15 in FIG. 0H near the inner surface of the quartz glass tube before drawing
The IIa degree was about 1 ppm.

In FIG. 2, the horizontal axis is the wavelength λ(*) of the light to be transmitted through the optical fiber, and 1 NIC in the vertical direction is the transmission loss in units of dB/1.

FIG. 2 further shows the same procedure as in the previous embodiment except that an oxyhydrogen flame was used instead of the oxygen-carbon oxide flame 14 when processing the inner surface 3 of the hole 2 of the fused silica tube 1. The transmission loss characteristics of the optical fiber formed by the method are shown as a curve 16 consisting of a chain double-dashed line. The OH group srg near the inner surface of the quartz glass tube before drawing was about 200 ppm. Note that this WJ@quartz tube 1 was manufactured from a fused silica ingot manufactured by a flame melting method using a flame obtained by burning carbon monoxide with oxygen.

Further, a carbon monoxide monooxygen flame according to the present invention was used for heating during the drawing to obtain an optical fiber.

As is clear from the results shown by curves 15 and 16 in FIG. 2, the optical fiber 15 processed using a carbon monoxide/oxygen flame according to the present invention is different from the optical fiber processed using an oxyhydrogen flame. 16 in the near-infrared region, especially about 12
The transmission loss was reduced for light having a wavelength of about p to about 1.61 IIR.

It should be noted that if the concentration of OH groups in the fused silica article is reduced, the viscosity of the fused silica article at elevated temperatures will be increased, so that the molten I! In addition to the above-mentioned optical applications, Ei arrow products are also suitable for applications requiring heat resistance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a fused silica processing method according to a preferred embodiment of the present invention, and FIG. 2 is a graph showing the transmission loss characteristics of an optical fiber using the fused silica tube manufactured by the method shown in FIG. 1 for its cladding. It is. 1... Fused quartz tube, 3... Surface, 4...
...Burner, 5.6...Flow path, 7...
...-Carbon oxide cylinder, 10...Oxygen cylinder, 14...Flame.

Claims (1)

[Claims] A method for processing a fused quartz article, which comprises softening and processing the fused quartz article by applying a flame formed by burning carbon monoxide gas with oxygen gas to the fused quartz article.