JP2000143257A - Production of glass article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the heat resistance by incorporating concentrated nitrogen and to increase the viscosity by incorporating silazane into a porous vitreous body and then converting the silazane into nitrogen-contg. silica and further vitrifying the silica. SOLUTION: Silazane having an Si-N coupling is previously incorporated into a porous vitreous body. The body is heated under the conditions where nitrogen is not desorbed from the silazane-contg. porous vitreous body, concretely in the atmosphere contg. a reducing gas contg. an inert gas and nitrogen, and the silazane is converted into nitrogen-contg. silica. The nitrogen-contg. porous vitreous body obtained by the conversion is heated and vitrified to obtain a nitrogen-contg. glass article. The vitrification is also performed in an inert as atmosphere, preferably in an atmosphere contg. nitrogen gas, to secure nitrogen in the glass. Nitrogen is advantageously added in the nitrogen-contg. reducing gas atmosphere before the vitrification to increase the nitrogen content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass article manufacturing technique, and more particularly to a method for manufacturing a nitrogen-containing high-purity glass article.

[0002]

2. Description of the Related Art Glass articles are widely used as building materials, various chemical equipment materials, semiconductor substrate materials, optical parts, optical transmission media such as optical fibers, and the like. Recently, glass containing nitrogen has been receiving attention for the purpose of improving the devitrification resistance and heat deformation resistance of glass articles.

For example, Japanese Patent Publication Nos. 7-64580 and 7-64
No. 581 discloses a method for producing a nitrogen-containing high-purity heat-resistant synthetic quartz glass member that can be used for a container for heat-treating a semiconductor wafer or the like. Porous silica body
A method has been proposed in which a partial denitrification is performed by heat treatment in an atmosphere containing an oxygen gas containing not less than mol% or an inert gas containing water vapor, and then a vitrification is performed. Also, Japanese Unexamined Patent Publication No.
No. 279049, JP-A-7-300341, JP-T-Hei-1
Japanese Patent Publication No. 0-502324 also discloses a method for producing a nitrogen-containing glass in which a porous body is subjected to heat treatment in an ammonia-containing atmosphere or a reducing atmosphere containing nitrogen to dope the porous body with nitrogen, and then to heat and sinter the porous body. Has been proposed.

[0004]

In the above prior art,
There is a problem that the amount of added nitrogen in the obtained glass is small. That is, the amount of nitrogen added by the prior art is 0.1 at most.
% By weight, and if this amount can be increased, the effect of increasing the high-temperature viscosity and improving the heat resistance can be expected. Further, addition of nitrogen increases the refractive index of the glass, so that it is widely used for optical components such as rod lenses and glass for optical fibers. An object of the present invention is to provide a method for producing a glass article capable of increasing the amount of added nitrogen.

[0005]

According to the present invention, there is provided (1) a method in which silazane is contained in a porous glass body, and thereafter, the silazane in the porous glass body is converted into nitrogen-containing silica. A method for producing a glass article, characterized in that the nitrogen-containing porous glass body is heated and transparently vitrified, and (2) after impregnating the porous glass body with liquid silazane, the solution of the silazane solution in the porous glass body The solvent is volatilized, and then a conversion treatment of silazane in the porous glass body to nitrogen-containing silica is performed,
The method for producing a glass article according to the above (1), wherein the obtained nitrogen-containing porous glass body is heated and transparently vitrified, (3) after impregnating the porous glass body with a silazane solution, Volatilizing the solvent of the silazane solution in the porous glass body, then performing a conversion treatment of the silazane in the porous glass body to nitrogen-containing silica, and heating and vitrifying the obtained nitrogen-containing porous glass body. The method according to any one of (1) to (3), wherein the method for producing a glass article according to (1), wherein the silazane contains a carbon atom. Glass article manufacturing method, (5)
The method for producing a glass article according to any one of the above (1) to (4), wherein heating is performed under an inert gas atmosphere as the silazane conversion treatment. (6) Nitrogen is used as the silazane conversion treatment. The method for producing a quartz glass article according to any one of the above (1) to (4), wherein heating is performed under an atmosphere of a reducing compound gas containing (7) a reduction including a nitrogen atom as the silazane conversion treatment. The method for producing a quartz glass article according to any one of claims 1 to 4, wherein the heating is performed in an atmosphere containing a reactive compound gas and an inert gas, (8) the inert gas atmosphere is at least The method for producing a glass article according to the above (5) or (7), wherein the method further comprises a nitrogen gas, and (9) the reducing compound gas containing a nitrogen atom is ammonia. Or the quartz gas described in (7) Method for producing a scan article, a method, the manufacture of glass articles (3), wherein the performed under an atmosphere that no oxygen volatilization of (10) wherein the solvent.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present inventors differ from the conventional method in which nitrogen is added in the gas phase in that the porous glass body contains silazane and the porous glass body containing this silazane. To convert it to nitrogen-containing silica,
The present invention has been reached. Silazane is H ₃ Si [NHSiH ₂ ] _n NHSiH ₃
And are called disilazane or trisilazane / polysilazane depending on the number of silicon atoms. In addition, those whose side chains are all hydrogen are perhydrosilazane (for example, perhydropolysilazane existing in the form of an inorganic polymer: [SH ₂ NH] _x, etc.), and those in which hydrogen is substituted with an organic group (for example, hexamethyldisilazane) : NH [Si (CH ₃ ) ₃ ]
Etc.) are referred to as organosilazanes. (Poly) silazane is converted to silicon nitride (Si ₃ N ₄ ) when baked in ammonia or an inert gas such as N ₂ or Ar, or in vacuum, and converted to silica (SiO ₂ ) when heated in air or steam. It is known to (Poly) silazane is soluble in most organic solvents such as aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and octane, ethers and esters, and can be handled in the form of a solution. There are advantages.

(Operation) The problem that the amount of added nitrogen is small in the conventional technique of adding nitrogen in a gas phase to a porous glass body can be considered as follows. The Si-O-Si bond is stable in the porous glass body, and the bond of Si-N mainly formed by adding nitrogen in the gas phase to silica glass is due to Si-OH or defects such as defects in the glass. Mainly formed only in.
Therefore, the amount of nitrogen added to the glass is limited. On the other hand, in the present invention, a silazane having a Si—N bond is contained in advance, and the silazane-containing porous glass body is free from nitrogen, and specifically contains an inert gas and / or a nitrogen atom. Is converted to silica containing nitrogen by heating in an atmosphere containing a reducing gas, so that nitrogen is easily added to the porous glass regardless of the amount of Si-OH bonds and defects in the porous glass. The amount of addition can be increased. When nitrogen gas and / or a nitrogen-containing reducing compound gas (for example, ammonia or the like) is used as a heating atmosphere in this conversion step, the conversion of silazane to nitrogen-containing silica and the effect of nitrogen addition in the gas phase are also secondary. It is thought that it can be obtained.

More specifically, when silazane is heated in an oxidizing atmosphere, Si—H bonds and Si—N bonds in the silazane change into Si—O bonds, and SiO ₂ is generated. On the other hand, when heated in a non-oxidizing atmosphere, Si-H bonds are broken and Si ₃ N ₄ is generated. When heat treatment is performed in an intermediate atmosphere between the _two, a mixture of SiO _{2 and} Si ₃ N ₄ is obtained. At that time, it is considered that the reaction proceeds even between SiO _{2 and} Si ₃ N ₄ , and N atoms are taken into the SiO ₂ network, resulting in a nitrogen-containing silica glass. That is, when converting from silazane according to the present invention, before complete silicon nitride (Si ₃ N ₄ ) is formed, it further reacts with the porous glass particles themselves (SiO ₂ ),
It is believed that nitrogen atoms enter the glass network.

After the above conversion step, the obtained nitrogen-containing porous glass body is heated and vitrified to obtain a nitrogen-containing glass article. Also in this heating transparent vitrification step, heating is performed in an inert gas atmosphere, preferably in an atmosphere containing nitrogen gas, in order to secure nitrogen in the glass. Further, when the nitrogen addition treatment in a nitrogen atom-containing reducing gas atmosphere is used in combination before the heating and vitrification, it is more advantageous to increase the nitrogen content. The nitriding (addition of nitrogen) action in the gas phase is possible only in a reducing atmosphere containing a nitrogen atom or an atmosphere composed of a reducing compound gas containing a nitrogen atom and an inert gas. Simply using an inert gas atmosphere, even if a nitrogen gas is used, hardly provides an effect of nitrogen addition. The effect of using nitrogen gas is mainly to prevent desorption of nitrogen in glass (silazane). Therefore, in order to increase the nitrogen content, it is preferable to use an atmosphere containing at least a nitrogen-containing reducing compound gas.

In the present invention, as a specific means for incorporating silazane in the porous glass body, there is firstly a method of immersing the porous glass body in liquid silazane or a solution in which silazane is dissolved in a solvent. Since the silazane can be contained in the porous glass body in a liquid state, it is easy to handle, and the amount to be impregnated can be adjusted by selecting the bulk density, the silazane concentration, the solution viscosity, and the like of the porous glass body. Further, in the present invention, it is conceivable to mix the powdery silazane with the glass fine powder and to add and process it as a glass porous body by applying a powder compaction method. However, it should be noted that the reaction of the silazane powder with oxygen in the air is likely to proceed.

The details will be described below. The porous glass body of the present invention refers to a state in which glass particles are densely packed and pores inside the glass body are connected. As a method for producing such a porous glass body, for example, a VAD method,
Glass particles are synthesized by subjecting glass materials such as OVD method to oxidation reaction or flame hydrolysis reaction in the gas phase,
A sol-gel method, a compacting method, and the like can be used in addition to a gas phase synthesis method of depositing this to obtain a porous body. In the sol-gel method, a silicon alkoxide is used as a starting material, and gelation is performed by hydrolysis and polymerization to obtain a porous body. In the compacting method, glass fine particles (fine powder) are filled in a container, and pressure is applied from the surroundings to form a porous molded body. The bulk density of the porous glass body used in the present invention is, for example, about 0.1 to 0.8 g / cm ³ ,
It is preferably 0.15 to 0.7 g / cm ³ , particularly preferably 0.2 to 0.6 g / cm ³ . The reason for this is that if the bulk density is too low, there is a risk of collapse during impregnation into the liquid silazane or silazane solution, while if the bulk density is too high, it is not possible to sufficiently impregnate the inside of the porous material. .

The silazane used in the present invention may be any of the aforementioned inorganic perhydro (poly) silazane and organosilazane. The use of organosilazane (silazane containing a carbon atom) is advantageous in increasing the amount of nitrogen added by a reduction action by carbon and a substitution reaction between a carbon atom and a nitrogen atom. Specific examples of the silazane include perhydrosilazane, hexamethyldisilazane, hexamethylcyclotrisilazane, and octamethylcyclotetrasilazane.

As the solvent for preparing the silazane solution, as described above, it can be used because it is soluble in most solvents such as aromatic hydrocarbons, aliphatic hydrocarbons, ethers and esters, but alcohols are It is not preferable because it reacts. Specific examples include xylene, toluene, hexane, octane, dibutyl ether and the like. The concentration of the silazane solution when impregnating the solution is not particularly limited, but is preferably from 10 to 100% by weight. The time for immersion is not particularly limited, and is appropriately selected according to the state of the porous glass body.
About 20 hours is enough. Furthermore, it is also possible to impregnate a powdery silazane dissolved in a solvent, or to mix the powdery silazane and glass fine particles and then mold.

After the porous glass body is immersed in a silazane (solution) for a predetermined time, the porous glass body is taken out. When a solution is used, the solvent is removed by volatilization or the like. Specifically, the gas is volatilized by, for example, reduced pressure or heating. However, in order to prevent elimination of nitrogen atoms in the silazane, the reaction is performed in the absence of oxygen and in a dry atmosphere, more preferably in a reducing atmosphere. More specifically, the reaction is performed in an inert gas atmosphere containing an inert gas such as a nitrogen gas, an argon gas, a helium gas, or a reducing gas such as an ammonia gas. The temperature for volatilization is selected according to the solvent, but is usually about 20 to 100 ° C. If the temperature is lower than 20 ° C., it takes a long time to evaporate and the efficiency is poor.
In addition, if the temperature exceeds 100 ° C, there is a danger of ignition or ignition depending on the solvent, which is not suitable.

Next, a treatment for converting the silazane contained in the porous glass into nitrogen-containing silica (hereinafter referred to as "conversion treatment")
May be abbreviated). The conversion treatment is performed in an atmosphere in which silazane is not oxidized. Specifically, inert gas such as nitrogen gas, argon gas, helium gas and / or
Alternatively, an atmosphere including a nitrogen-containing reducing compound gas may be used. Examples of the nitrogen-containing reducing compound gas include ammonia (NH ₃ ), nitric oxide (NO), and nitrous oxide (N ₂ O)
And the like. Ammonia gas is particularly preferred because it is the most easily available among the nitrogen-containing reducing compound gases and has excellent handling properties. In particular, when heating is performed in an atmosphere containing nitrogen gas and / or a nitrogen-containing reducing compound gas, silazane is converted into nitrogen-containing silica, nitrogen is prevented from being desorbed, and nitrogen is added to the porous glass body in the gas phase. An addition effect can also be expected.
The heating temperature in the conversion treatment of the present invention is desirably 300 ° C to 1200 ° C. If the temperature is lower than 300 ° C., the conversion process takes a long time and the efficiency is poor. If the temperature exceeds 1200 ° C., sintering of the porous glass body starts to proceed, and desorption of nitrogen also starts to occur, making it difficult to obtain a transparent glass.

After a nitrogen-containing porous glass body is obtained by the above treatment, it is heated and made transparent to obtain a nitrogen-containing glass article. The heating and clearing temperature can be performed under ordinary conditions. For example, a temperature of 14
Heat to about 00 ° C to 1700 ° C. If the temperature is lower than 1400 ° C., sintering cannot be performed sufficiently, and voids remain inside. On the other hand, when the temperature exceeds 1700 ° C., nitrogen is rapidly desorbed, foaming occurs, and it becomes difficult to obtain a transparent glass. For example, helium, argon, and nitrogen can be used as the inert gas. The use of helium is advantageous in preventing the generation of bubbles. When a nitrogen gas atmosphere is used as an inert gas, desorption of nitrogen from the glass can be prevented. In addition, if the heating is performed in a nitrogen atom-containing reducing compound gas atmosphere before the heating / clearing treatment, the same effect as the nitrogen addition in the related art can be obtained, so that the nitrogen addition amount in the glass can be further increased. If the heat treatment is performed in the presence of oxygen, water vapor, or the like as proposed in the above publications before the heat clearing treatment, the added nitrogen can be removed. It is also possible to adjust the distribution of the quantities.

The glass article according to the present invention obtained as described above can realize a high nitrogen concentration of up to 1000 ppm or more. Such a high concentration of nitrogen is one of the indexes indicating the heat resistance. In addition, the annealing point (the viscosity of the glass
2.51 × 10 ¹³ Poise temperature (also called slow cooling temperature) is 12
It can be set to 00 ° C. or higher.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

[Example 1] Argon (A) containing silicon tetrachloride (SiCl ₄ ) vapor in a flame formed by oxygen and hydrogen gas
r) Introduce gas, VAD method, diameter 80mmφ, length 300m
m of a porous glass body (bulk density: 0.3 g / cm ³ ). The porous glass body was immersed in a xylene solution containing 20% by weight of perhydropolysilazane (trade name: N110, manufactured by Tonen Corp.) for 5 hours to impregnate the porous glass body with the perhydropolysilazane solution. Thereafter, the porous glass body was taken out of the solution, and kept at a temperature of 100 ° C. in a stream of nitrogen (N ₂ ) to completely vaporize xylene as a solvent. Next, the inside of the heating furnace is maintained in a mixed gas atmosphere in which ammonia (NH ₃ ) and nitrogen are at a volume ratio of 50:50, and the porous glass body is maintained in the heating furnace at a temperature of 950 ° C. for 3 hours. The perhydropolysilazane in the body was converted to nitrogen-containing silica. Next, the inside of the furnace was set to a 100% nitrogen atmosphere, the temperature was maintained at 1450 ° C. for 5 hours, and the porous glass body was turned into a transparent glass, whereby a nitrogen-containing silica glass was produced. The nitrogen concentration in this glass was 1.8% by weight (18%
000 ppm), and the annealing point was 1270 ° C. In addition, the nitrogen concentration in glass is described in Literature: Mio Sakuhana, "Oxynitride Glass-Breakthrough of Oxide Glass-", Nos. 47-49.
Page, published by Uchida Lao Tsuruho (1989): Kjeldahl method.

Example 2 A porous glass body produced by the VAD method in the same manner as in Example 1 was used in the same manner as in Example 1 in an amount of 20% by weight.
After being immersed in a perhydropolysilazane-containing xylene solution for 5 hours, it was taken out of the solution, and kept at a temperature of 100 ° C. in a nitrogen stream in a heating furnace to completely volatilize xylene as a solvent. Next, the porous glass body was kept in a heating furnace maintained at 100% nitrogen atmosphere at a temperature of 1000 ° C. for 2 hours to convert perhydropolysilazane in the porous glass body into nitrogen-containing silica. Next, the inside of the heating furnace was set to a 100% helium atmosphere, kept at a temperature of 1450 ° C. for 5 hours, and the porous glass body was turned into a transparent glass, thereby producing a nitrogen-containing silica glass. When the nitrogen concentration in this glass was measured by the Kjeldahl method in the same manner as in Example 1, the weight was 1.4% by weight (14000 ppm), and the annealing point was 1250 ° C.
Met.

Example 3 A porous glass body produced by the VAD method in the same manner as in Example 1 was replaced with hexamethyldisilazane.
After immersion in a 20 wt% xylene solution for 5 hours, take out
In a heating furnace maintained in a 100% nitrogen atmosphere at a temperature of 950 ° C
Hold for hours. Next, the inside of the heating furnace was kept in a mixed gas atmosphere in which the volume ratio of ammonia and nitrogen was 50:50, and the porous glass body was kept at a temperature of 950 ° C. for 3 hours. After converting hexamethyldisilazane in the porous glass body to nitrogen-containing silica as described above, the furnace was set to a 100% helium atmosphere, and kept at a temperature of 1450 ° C. for 5 hours to make the porous glass body transparent. Nitrogen-containing silica glass was produced by vitrification. When the nitrogen concentration in this glass was measured by the Kjeldahl method in the same manner as in Example 1, it was 1.7% by weight (17000 pp).
m), and the annealing point was 1265 ° C.

Comparative Example 1 As in Example 1, a porous glass body prepared by the VAD method was placed in a heating furnace in a mixed gas atmosphere in which ammonia and nitrogen had a volume ratio of 50:50. It was kept at 950 ° C. for 3 hours to perform a nitrogen conversion treatment. Next, the inside of the furnace was changed to a 100% nitrogen atmosphere, and the temperature was changed to 1450 ° C.
For 5 hours to make the porous glass body transparent, thereby producing a nitrogen-containing silica glass. When the nitrogen concentration in this glass was measured by the Kjeldahl method in the same manner as in Example 1, it was 0.7% by weight (7000 ppm) and the annealing point was 1195 ° C.

[0022]

As described above, according to the present invention, it is possible to produce a glass article containing nitrogen at a high concentration, having high heat resistance and having increased viscosity and improved performance. Further, the present invention makes it easy to adjust the amount of nitrogen added, and makes it possible to add a large amount of nitrogen as an additive for increasing the refractive index of glass with good controllability of the amount of addition. Therefore, the present invention is very advantageous when applied widely to the field of using glass such as a crucible for semiconductor production as an apparatus material, and to the field of manufacturing optical parts such as rod lenses and glass for optical fibers.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Ishikawa 1st Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Taku Yamazaki 1st Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industry Co., Ltd. Yokohama Works F term (reference) 4G014 AH15 4G021 CA15

Claims (10)

[Claims] 1. A method for converting a silazane in a porous glass body to nitrogen-containing silica after the silazane is contained in the porous glass body, and heating the resulting nitrogen-containing porous glass body to a transparent vitrification. A method for producing a glass article. 2. After impregnating the porous glass body with liquid silazane, the solvent of the silazane solution in the porous glass body is volatilized, and then the silazane in the porous glass body is converted into nitrogen-containing silica. 2. A conversion treatment is performed, and the obtained nitrogen-containing porous glass body is heated to be transparent and vitrified.
A method for producing the glass article according to the above. 3. After impregnating the porous glass body with the silazane solution, the solvent of the silazane solution in the porous glass body is volatilized, and then the silazane in the porous glass body is converted into nitrogen-containing silica. The method for producing a glass article according to claim 1, wherein the treatment is performed, and the obtained nitrogen-containing porous glass body is heated and made vitrified. 4. The method for producing a glass article according to claim 1, wherein the silazane contains a carbon atom. 5. The method for producing a glass article according to claim 1, wherein the conversion of the silazane is performed under an inert gas atmosphere. 6. The method for producing a quartz glass article according to claim 1, wherein the step of converting the silazane is performed in an atmosphere of a reducing compound gas containing a nitrogen atom. 7. The quartz according to claim 1, wherein the conversion of the silazane is carried out in an atmosphere containing a reducing compound gas containing a nitrogen atom and an inert gas. A method for manufacturing a glass article. 8. The method according to claim 5, wherein the inert gas atmosphere contains at least nitrogen gas. 9. The method for producing a quartz glass article according to claim 6, wherein the reducing compound gas containing a nitrogen atom is ammonia. 10. The method for producing a glass article according to claim 3, wherein the evaporation of the solvent is performed in an atmosphere in which oxygen does not exist.