JPH0737335B2 - Crystallized glass and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystallized glass and a method for producing the same, and more specifically, it is suitable as a reinforcing component for reinforcing a connecting portion when a fused silica optical fiber is connected. The present invention relates to crystallized glass and a method for manufacturing the same.

[0002]

2. Description of the Related Art As one of the methods of permanently connecting quartz optical fibers, there is a method of fusing the exposed portions of their ends. In that case, in order to enhance the reliability of the connecting portions, they are reinforced. Reinforcement parts are used.

In order to prevent the reliability of the connecting portion from being impaired by external force, the reinforcing material of this optical fiber is
According to the test method specified in ISR 1601 (1981), it has a high bending strength of 2500 kgf / cm ² or more, and the thermal expansion coefficient of silica glass (5.9 × 10 ^{− 7} /
℃) -3 ~ 10 × 10 ^-7 / ℃ has a coefficient of thermal expansion, when used in the manhole or the sea floor, excellent corrosion resistance so as not to deteriorate by groundwater, seawater or other external environment Properties such as having properties are required, and conventionally, as materials thereof, metals, ceramics, quartz glass, and crystallized glass have been used, but none of them satisfy all the above properties.

[0004]

That is, metal has a high flexural strength, but has a drawback that the coefficient of thermal expansion is too high and is corrosive, and ceramic has a high flexural strength.
It has corrosion resistance, but has the drawback of having a too high coefficient of thermal expansion. Quartz glass has good thermal expansion coefficient and corrosion resistance, but the bending strength is too low.
Further, although crystallized glass has corrosion resistance and a thermal expansion coefficient similar to that of quartz glass exists, it still has a drawback that the bending strength is too low.

By the way, with respect to crystallized glass, various proposals have been made to strengthen it by ion exchange. For example, Japanese Patent Publication No. 47-49299 discloses that
A method of strengthening alkali ions in the crystalline phase of crystallized glass by replacing them with ions of larger ionic radius is disclosed. However, in this method, since it is necessary to raise the temperature of the molten salt used for ion exchange,
There is a problem that the workability is poor and the equipment is severely deteriorated. Further, in the case of a material having a low degree of crystallinity, there is a problem that the glass phase is cracked, and conversely the strength is easily lowered.

An object of the present invention is to have a coefficient of thermal expansion close to that of quartz glass, while maintaining a coefficient of 2500 kgf /
It is an object of the present invention to provide a crystallized glass having a high bending strength of not less than cm ² and satisfying all the properties required for a reinforcing component of an optical fiber, and a manufacturing method thereof.

[0007]

The crystallized glass of the present invention comprises a Li ₂ O--Al ₂ O ₃ --SiO ₂ -based glass phase,
20-70% by volume of β-quartz solid solution crystals are deposited, and
Li ⁺ ions only in the surface glass phase are replaced by ions having a larger ionic radius,
Coefficient of thermal expansion at 380 ° C to -3 to 10 × 10 ^-7 /
It is characterized by having a bending strength of 2500 kgf / cm ² or more at ℃.

The method for producing crystallized glass of the present invention is
The Li ₂ O—Al ₂ O ₃ —SiO ₂ based glass is subjected to a primary heat treatment in a temperature range other than the temperature at which the crystal nucleation rate is maximized, and then is further treated in a temperature range other than the temperature at which the crystal growth rate is maximized. By the subsequent heat treatment, β-in the glass phase
Crystallized glass is prepared by precipitating 20 to 70% by volume of quartz solid solution crystal, and then the crystallized glass is immersed in a molten salt containing ions having a larger ionic radius than Li ⁺ ions and having a temperature of 600 ° C. or less. By doing so, Li ⁺ ions only in the glass phase of the surface layer are replaced with ions having a larger ionic radius.

Further, another method for producing crystallized glass of the present invention is one in which a Li ₂ O--Al ₂ O ₃ --SiO ₂ -based glass is provided between the temperatures at which the crystal nucleation rate and the crystal growth rate are maximized. By heat treatment in the temperature range of 10 to prepare a crystallized glass in which β-quartz solid solution crystals are precipitated in the glass phase in an amount of 20 to 70% by volume, and then the crystallized glass is treated with ions having an ion radius larger than that of Li ⁺ ions. Including and 60
By immersing in a molten salt at a temperature of 0 ° C. or lower, Li ⁺ ions only in the glass phase of the surface layer are replaced with ions having a larger ionic radius.

[0010]

In the present invention, the reason why the β-quartz solid solution crystal precipitation ratio and the crystallinity in the glass phase are set to 20 to 70% by volume is as described below.

That is, when the crystallinity is 70% by volume or more, the glass layer to be subjected to ion exchange becomes too small, and it becomes impossible to obtain a desired bending strength.
Since the crystal phase having a negative coefficient of thermal expansion becomes too predominant, the coefficient of thermal expansion at 30 to 380 ° C. is −3 × 10 ^−7.
/ ° C or less. On the other hand, when the crystallinity is 20% by volume or less, the glass phase having a positive coefficient of thermal expansion becomes too predominant, so that the coefficient of thermal expansion becomes 10 × 10 ⁻⁷ / ° C. or more.

In the present invention, the primary heat treatment is performed in a temperature range other than the temperature at which the crystal nucleation rate is maximized, and then the secondary heat treatment is performed in a temperature range other than the temperature at which the crystal growth rate is maximized. Since the heat treatment is performed only once at a temperature between the maximum of the production rate and the maximum of the crystal growth rate, the nucleation is performed slowly, and after the arbitrary number of crystal nuclei are produced, the crystal growth is also slow. Then, crystals of any size can be deposited. As a result, the crystallinity can be controlled to a desired value of 20 to 70% by volume. That is, when heat treatment is performed at a temperature at which the crystal nucleation rate or the crystal growth rate is maximized, the crystallization rate is too fast,
It is not preferable because the crystallinity cannot be controlled to a desired value.

The specific conditions for the primary heat treatment are as follows:
Suitable for 0.25 to 4 hours at a temperature 20 ° C. or more away from the temperature at which the crystal nucleation rate is maximum, and as the condition for the secondary heat treatment, 20 ° C. or more from the temperature at which the crystal growth rate is maximum. Suitable for remote temperatures of 0.25-4 hours. Further, when crystallization is performed by one heat treatment, it is suitable that the temperature is within 20 ° C. from the intermediate temperature of the temperatures at which the crystal nucleation rate and the crystal growth rate are maximized for 1 to 10 hours.

Further, in the present invention, ion exchange is performed at 60
When using a molten salt of 0 ° C or lower, when the ion exchange is performed at a high temperature of 600 ° C or higher, the deterioration of the apparatus is fast, the workability is poor, and the surface of the glass phase is excessively ionized and cracks easily occur. Because. KNO ₃ or NaNO ₃ can be used as the molten salt for ion exchange, but KN ₃ or NaNO ₃ can be used in order to obtain high strength in a short time.
O ₃ is preferably used, and by immersing the crystallized glass in these molten salts for 1 to 20 hours, a strengthening layer is formed up to a depth of several tens of microns of the glass phase of the crystallized glass.

More specifically, the molten salt will be described.
When KNO ₃ is used, ion exchange can be performed at 600 ° C. or lower, but it is preferably performed at 550 ° C. or lower in consideration of workability and deterioration of equipment. Also NaNO
_{When 3} is used, ion exchange can be performed at 500 ° C or lower, but considering workability, 450 ° C
It is preferable to perform the following.

The Li ₂ O--A used in the present invention
The l ₂ O ₃ -SiO ₂ based glass, in weight percent,
_{Li 2 O 3~5%, Al 2} O 3 20~35%, Si
O ₂ 55 to 70%, TiO ₂ 1 to 3%, ZrO ₂ 1
_{~4%, P 2 O 5 1~5} %, Na 2 O 0~4%, K
₂ O 0 to 4%, the glass having a composition of _{Na 2 O + K 2 O 0.5~4} % is preferred. That is, since this glass contains both TiO ₂ and ZrO ₂ as the nucleating material, it is possible to easily adjust the crystal nucleation rate and the crystal growth rate.

[0017]

EXAMPLES The present invention will be described in detail below based on examples.

In weight percentage, SiO₂ 66%, Al₂ O
₃ 23%, Li₂ O 4%, TiO ₂ 2%, ZrO₂ Three
%, P₂ O_Five 1%, Na₂ O 0.5%, K₂ O 0.
Mix the raw materials so that the composition becomes 5%, and put it in a platinum crucible.
After melting for 16 hours at 1580 ° C, a plate with a thickness of 6 mm
And then into a 3x4x50mm prism.
It was

The temperature at which the crystal nucleation rate of this glass is maximized is 750 ° C., and the temperature at which the crystal growth rate is maximized is 840 ° C.

Next, as shown in Table 1, this glass molded body was heat-treated under various conditions to be crystallized, its crystallinity and coefficient of thermal expansion were measured, and further ion exchanged under various conditions, Its bending strength is JIS R 1601 (198
It measured according to 1).

[0021]

[Table 1]

No. Each of the samples 1 to 6 was subjected to the primary heat treatment in a temperature range other than the temperature at which the crystal nucleation rate was maximized, and was further subjected to the secondary heat treatment in a temperature range other than the temperature at which the crystal growth rate was maximized. Sample No. 7 was heat-treated only once in a temperature range between the maximum temperatures of the crystal nucleation rate and the crystal growth rate, and the crystallinity and thermal expansion coefficient of each sample were measured. Bending strength was measured after ion exchange at ˜500 ° C. for 3 to 6 hours.

On the other hand, No. Sample No. 8 was subjected to a primary heat treatment at a temperature at which the crystal nucleus generation rate was a maximum, that is, 750 ° C., and a secondary heat treatment at a temperature at which the crystal growth rate was a maximum, that is, 840 ° C. The thermal expansion coefficient was measured, and then the ion exchange was performed at 550 ° C. for 6 hours, and then the bending strength was measured. Furthermore, No. The sample of No. 9 is No. After heat treatment under the same conditions as for the sample of No. 1, the crystallinity and the coefficient of thermal expansion were measured, and then a molten salt containing 48% by weight of K ₂ SO ₄ and 52% by weight of KCl was used to obtain 720 ° C. After ion exchange for 5 hours,
Bending strength is measured.

As is clear from Table 1, No. Each of the samples 1 to 7 has a crystallinity of 35 to 60% and a crystallinity of -1.0 to
Good thermal expansion coefficient of 6.5 × 10 ^-7 / ° C and 3000 kg
It had a high bending strength of f / cm ² or more.

On the other hand, No. Sample No. 8 had a thermal expansion coefficient of -6.0 × 10 ^-7 / ° C, which was too low, and a bending strength of 1500 kgf / cm ² . Furthermore, No. Sample No. 9 had a thermal expansion coefficient of 6.5 × 10 ⁻⁷ / ° C., but had a low bending strength of 1100 kgf / cm ² .

Table 2 shows No. Sample No. 1 and No. 1 9 shows the results of investigating at which site in the crystallized glass the ion exchange of the sample 9 was performed.

As is clear from Table 2, No. In the sample of No. 1, the volume of the crystal unit cell hardly changed before and after the ion exchange, therefore, K ⁺ ions did not enter into the crystal phase, and the ion exchange reaction occurred only in the glass phase. Be understood.

On the other hand, No. In the sample of No. 9, the volume of the crystal unit cell was increased after the ion exchange, and therefore it is clear that K ⁺ ions have entered the crystal phase. In addition, No.
The bending strength of the sample No. 9 is 1100 Kgf / cm ² What is low is that the ion exchange temperature is as high as 720 ° C., so a large amount of K ⁺ also enters the glass phase, destroying the structure of the glass phase,
It is thought that it was because of cracks.

The crystallinity is measured by an X-ray diffraction method, and the thermal expansion coefficient is measured by a dilatometer. Furthermore, the bending strength is JIS R 1
It was measured according to the method defined in 601 (1981).

[0030]

As described above, the crystallized glass of the present invention is
It has a high flexural strength of 2500 kgf / cm ² or more, a coefficient of thermal expansion of -3 to 10 x 10 ^-7 / ° C, which is similar to that of silica glass and is also excellent in corrosion resistance. According to the manufacturing method of the present invention, it can be manufactured with good workability and without causing severe deterioration of equipment.

[Table 2]

Claims (3)

[Claims] 1. A β-quartz solid solution crystal is precipitated in a Li ₂ O-Al ₂ O ₃ -SiO ₂ -based glass phase in an amount of 20 to 70% by volume, and Li ⁺ ions only in the surface glass phase are It is replaced by ions having a larger ionic radius than that, and has a thermal expansion coefficient of -3 to 10 at 30 to 380 ° C.
A crystallized glass characterized by having a bending strength of 2500 kgf / cm ² or more at × 10 ^-7 / ° C. 2. A Li ₂ O—Al ₂ O ₃ —SiO ₂ based glass is subjected to primary heat treatment in a temperature range other than the temperature at which the crystal nucleation rate is maximized, and then at a temperature other than the temperature at which the crystal growth rate is maximized. The second heat treatment in the temperature range of 10 to prepare a crystallized glass in which β-quartz solid solution crystals are precipitated in the glass phase in an amount of 20 to 70% by volume, and then the crystallized glass is mixed with L
An ion having an ion radius larger than that of the Li ⁺ ion only in the glass phase of the surface layer is contained by immersing in a molten salt at a temperature of 600 ° C. or less and containing an ion having an ion radius larger than that of i ⁺ ion. And a method for producing crystallized glass, the method comprising: 3. Li ₂ O—Al ₂ O ₃ —SiO ₂ -based glass is heat-treated in a temperature range between temperatures at which the crystal nucleation rate and the crystal growth rate reach their respective maximums, whereby a glass phase is formed. To prepare a crystallized glass in which 20 to 70% by volume of β-quartz solid solution crystal is deposited, and then the crystallized glass is mixed with L
An ion having an ion radius larger than that of the Li ⁺ ion only in the glass phase of the surface layer is contained by immersing in a molten salt at a temperature of 600 ° C. or less and containing an ion having an ion radius larger than that of i ⁺ ion. And a method for producing crystallized glass, the method comprising: