JP5629073B2 - Method for producing crystallized glass - Google Patents

Description

  The present invention relates to a production method for precisely controlling the thermal expansion characteristics of crystallized glass.

    Crystallized glass (also referred to as glass ceramics) is a material in which crystals are precipitated in a glass phase by heat-treating the glass, and develops properties that combine both the properties of the glass phase and the properties of the crystal phase. It is possible and used in various technical fields. For example, it is possible to obtain materials having various average linear expansion coefficients by controlling the types and amounts of crystals precipitated in the glass phase.

Patent Document 1 discloses a method for producing glass ceramics in which a zero crossing of a CTE-temperature curve is adjusted in a temperature range of TA ± 10 ° C. in the vicinity of application temperature TA in crystallized glass having a low thermal expansion coefficient. . However, when the slope of the CTE-temperature curve is made flatter, that is, zero expansion is obtained in a wider temperature range, or the temperature of zero crossing is to be adjusted with higher accuracy, it is disclosed in Patent Document 1. This technology was difficult to realize.
The average linear expansion coefficient α from T1 ° C. to T2 ° C. is obtained by the following equation.
α = (L _T2 −L _T1 ) / {L × (T2−T1)}
L: Length of sample at room temperature (in the present invention, room temperature is defined as 25 ° C.)
L _T1 : Length of the sample at T1 L _T2 : Length of the sample at T2 Also, the CTE-temperature curve is the above equation when the temperature range of T1 and T2 is sufficiently narrowed A curve obtained when the average linear expansion coefficient at temperature T is plotted on the y axis and the temperature is plotted on the x axis.
JP 2003-267789 A

  The object of the present invention is to solve the above problems and provide a production method for precisely controlling the thermal expansion characteristics of crystallized glass. Specifically, the slope of the CTE-temperature curve in the desired temperature range, and the average The object of the present invention is to provide a method for producing crystallized glass in which the linear expansion coefficient is precisely controlled.

  In view of the above problems, the present inventor has found that the thermal expansion characteristics of the crystallized glass can be precisely controlled by adjusting the temperature lowering rate in the process of heat treatment for crystallization as a result of intensive studies. The present invention has been completed, and its specific configuration is as follows.

(Configuration 1)
A method for producing crystallized glass comprising a step of heat-treating glass,
The step of heat treating the glass has at least a temperature raising step and a temperature lowering step,
A method for producing crystallized glass, wherein an average linear expansion coefficient in a desired temperature range is adjusted by adjusting a temperature drop rate Vr in the temperature drop step.
(Configuration 2)
A raw glass having the same composition as the product is subjected to a heat treatment step to produce at least one crystallized glass test sample, the average linear expansion coefficient α _s2 of the test sample is measured, and the desired average linear expansion coefficient α _o 2. The crystallization according to claim 1, wherein a temperature-decreasing rate Vr in the temperature-decreasing step during actual product manufacture is determined by a difference α _s2 −α _o between the average linear expansion coefficient of the test sample and the test sample, and then manufactured under the determined heat treatment conditions. Glass manufacturing method.
(Configuration 3)
If the value of α _s2 −αo is positive, the temperature decrease rate Vr of the temperature decrease process during actual product manufacture is made smaller than the temperature decrease rate Vs of the temperature decrease process during preparation of the test sample, and the value of α _s2 −α _o is The method for producing crystallized glass according to claim 1 or 2, wherein Vr is larger than Vs if negative.
(Configuration 4)
The step of heat-treating the glass includes at least a heat-retaining step, and the temperature-decreasing rate Vr is determined after determining the heat-retaining temperature Tr and the heat-retaining time Hr in the heat-retaining step during actual product manufacture. The manufacturing method of the crystallized glass in any one.
(Configuration 5)
The raw glass having the same composition as the product is subjected to a heat treatment step to produce at least one crystallized glass test sample, the average linear expansion coefficient α _s1 of the test sample is measured, and the desired average linear expansion coefficient α _o 5. The method for producing crystallized glass according to claim 4, wherein a heat retention temperature Tr and a heat retention time Hr in the heat retention step at the time of actual product manufacture are determined by a difference α _s1 −α _o between the average linear expansion coefficient of the test sample and the test sample.
(Configuration 6)
The method for producing crystallized glass according to claim 1, wherein the crystallized glass includes β-quartz and / or β-quartz solid solution.

According to the present invention, it is possible to precisely control the thermal expansion characteristics of crystallized glass. For example, it is possible to adjust an average linear expansion coefficient of 20 ppb · ° C. ⁻¹ level.

It is (DELTA) L / L-temperature graph of the Example of this invention. It is (DELTA) L / L-temperature graph of the Example of this invention. It is a CTE-temperature graph of the Example of this invention. It is a CTE-temperature gradient graph of the Example of this invention.

1: Test sample 1
2: Test sample 2
3: Test sample 3
4: Test sample 4
5: Test sample 5
6: Test sample 6
7: Test sample 7

  The production method according to the present invention is roughly divided into two steps, a step of producing glass and a step of heat-treating the glass. The process for producing the glass is a process for producing the original glass before the crystals are precipitated, and may be produced according to the known raw material composition, melting method and molding method depending on the desired physical properties. After the glass is molded, it may be annealed and cooled to room temperature, or may be subjected to a step of heat-treating the glass described later before cooling to room temperature.

  The step of heat-treating the glass is performed to precipitate crystals in the glass phase, and has at least a temperature raising step and a temperature lowering step. Furthermore, you may have a heat retention process. Each of the temperature raising step, the temperature lowering step, and the heat retaining step may be one step or may have a plurality of steps. For example, the step of heat-treating the glass may be three steps of a temperature raising step, a temperature keeping step, and a temperature lowering step, or a first temperature raising step, a first heat keeping step, a second temperature raising step, and a second step. There may be five stages of a heat retaining process and a first temperature lowering process. The first heat retaining step is preferably a heat retaining step for nucleation, and the second heat retaining step is preferably a heat retaining step for nucleus growth. Moreover, it is preferable that the temperature of a 2nd heat retention process is higher than the temperature of a 1st heat retention process.

  In the present invention, the average linear expansion coefficient in a desired temperature range is adjusted by adjusting the temperature decrease rate Vr in the temperature decrease step, preferably in the last temperature decrease step. By adjusting the temperature drop rate Vr, the average linear expansion coefficient in a desired temperature range can be strictly adjusted.

  In order to obtain crystallized glass that is more strictly controlled with respect to a desired average linear expansion coefficient, a heat retention step is provided in the step of heat-treating the glass, and the heat retention temperature Tr in the heat retention step during actual product manufacture After determining the heat retention time Hr, it is preferable to determine the temperature drop rate Vr during actual product manufacture.

For this purpose, first, an original glass having the same composition as that of the target product is prepared, and heat treatment is performed under initial conditions to precipitate crystals, thereby preparing at least one test sample.
Next, this average linear expansion coefficient α _s1 is measured. Here, the heat retention temperature Tr and the heat retention time Hr in the heat retention step of actual product manufacture may be determined based on the difference α _s1 −α _o between the target average linear expansion coefficient α _o and the average linear expansion coefficient of the test sample.
The heat retention temperature Tr and the heat retention time Hr adjusted by the difference α _s1 −α _o between the target average linear expansion coefficient α _o and the average linear expansion coefficient of the test sample are the heat retention temperature Tr and the heat retention time Hr in the nuclear growth process. Is preferred.
When the absolute value of α _s1 −α _o is large, a new test sample is prepared by changing the heat retention temperature Tr and / or the heat retention time Hr from the initial condition, and the average linear expansion coefficient α _s1 ′ is measured. Based on the change from α _s1 to α _s1 ′, a new condition is repeatedly set, and the heat retention temperature Tr and the heat retention time Hr in the heat retention process of actual product manufacture are determined so as to approach the desired average linear expansion coefficient. Just do it.

  The operation of the heat retention temperature and the heat retention time in the heat retention step can control the slope of the CTE-temperature curve as well as the adjustment of the average linear expansion coefficient.

Next, at least one test sample of crystallized glass is produced by performing a heat treatment process using Tr and Hr determined on the original glass having the same composition as the product, and the average linear expansion coefficient α of the test sample is prepared. _s2 is measured. Here, the temperature decrease rate Vr in the temperature decreasing step at the time of actual product manufacture may be determined based on the target average linear expansion coefficient α _o and the average linear expansion coefficient α _s2 −α _{o of the} test sample.
For example, in a crystallized glass whose crystal phase has a negative average linear expansion coefficient, when α _s1 −α _o is positive and is 0.2 × 10 ⁻⁷ ° C. ⁻¹ or less, the desired average can be obtained by decreasing Vr. A linear expansion coefficient can be obtained.
When the absolute value of α _s2 −α _o is large, a new test sample is prepared by changing the temperature drop rate in the temperature drop process from the conditions for producing the test sample, and the average linear expansion coefficient α _s2 ′ is measured. , By repeating the setting of a new condition based on the change from α _s1 to α _s2 ′, Vr for actual product manufacture may be determined so as to approach the desired average linear expansion coefficient.

  The operation of the temperature lowering rate in the temperature lowering process can control the average linear expansion coefficient while maintaining the slope of the CTE-temperature curve in a desired temperature range.

In particular, in the case of crystallized glass containing β-quartz and / or β-quartz solid solution, it is easy to obtain crystallized glass having desired low thermal expansion characteristics by the production method of the present invention.
The crystallized glass containing β-quartz and / or β-quartz solid solution is in mass% based on oxide, SiO ₂ : 47 to 65%, Al ₂ O ₃ : 17 to 29%, Li ₂ O: 1 to 8%. _{, P 2 O 5: 1~13%} , MgO: 0.5~5%, ZnO: 0.5~5.5%, TiO 2: 1~7%, ZrO 2: 1~7%, Na 2 O _{: 0~4%, K 2 O:} 0~4%, CaO: 0~7%, BaO: 0~7%, SrO: 0~4%, As 2 O 3: 0~2%, Sb 2 O 3 : It can produce by including each component of 0 to 2% of range.

Note that test samples are manufactured only once at the lab level before actual product manufacture, and are included in the present invention even after the actual product is manufactured in accordance with the determined conditions. A case where a product is extracted from a line and manufacturing conditions are fed back to an actual product manufacturing line based on the measured value is also included in the present invention.

Examples of the present invention will be described below. In the examples, a desired average linear expansion coefficient α _o from 0 ° C. to 50 ° C. is 0.01 × 10 ⁻⁷ ° C ⁻¹ , and a ΔL / L-temperature curve within a temperature range of 0 ° C. to 50 ° C. The objective was to produce crystallized glass having a maximum value-minimum value of 5 × 10 ⁻⁷ or less and a main crystal phase containing β-quartz and / or β-quartz solid solution.

SiO ₂ : 55.40%, P ₂ O ₅ : 7.60%, Al ₂ O ₃ : 24.50%, Li ₂ O: 3.95%, MgO: 0.80% by mass% based on oxide _{, ZnO: 0.70%, CaO:} 0.95%, BaO: 1.10%, TiO 2: 2.30%, ZrO 2: 2.00%, as 2 O 3: 0.70% become so After mixing raw materials such as oxides, carbonates or nitrates as raw materials, they are melted at a temperature of about 1450 to 1550 ° C. using a normal melting apparatus, homogenized with stirring, and then molded, cooled, and molded into glass. Obtained.

The obtained glass molded body was crystallized under several initial conditions to prepare test samples 1 to 4. Specifically, the temperature is maintained after raising the temperature from the room temperature to the nucleation heat retention temperature at the first temperature increase rate, the temperature is maintained after the temperature is increased to the nucleus growth heat retention temperature at the second temperature increase rate, and then the temperature is decreased to room temperature at the first temperature decrease rate. . Heat treatment conditions at this time, average linear expansion coefficient α _s1 between 0 ° C. and 50 ° C., difference between α _s1 and α _o , maximum value of ΔL / L-temperature curve within the temperature range of 0 ° C. to 50 ° C.−minimum Values are shown in Table 1.

The average linear expansion coefficient was measured using a Fizeau interferometric precise expansion coefficient measuring device. The shape of the measurement sample is a cylindrical shape having a diameter of 6 mm and a length of about 80 mm. As a measuring method, an optical flat plate is brought into contact with both ends of the sample so that interference fringes by a He—Ne laser can be observed, and the sample is placed in a temperature-controllable furnace. Next, by changing the temperature of the measurement sample and observing the change in interference fringes, the amount of change in the measurement sample length due to temperature is measured. In the present invention, the temperature is raised or lowered at 0.5 ° C./min ⁻¹ in the temperature range from 0 ° C. to 50 ° C., the amount of change in the measured sample length is plotted every 5 seconds, and a fifth order approximate curve Then, the average linear expansion coefficient from 0 ° C. to 50 ° C. and the maximum value-minimum value of ΔL / L within the temperature range of 0 ° C. to 50 ° C. were calculated. Note that the average linear expansion coefficient and the maximum value-minimum value of the ΔL / L-temperature curve are both average values during temperature rise and temperature drop.

As a result of measurement, in order to lower the average linear expansion coefficient based on the heat treatment conditions of the test sample 1 in which the maximum value-minimum value of the ΔL / L-temperature curve in the temperature range of 0 ° C. to 50 ° C. is the minimum. The heat treatment conditions were reconsidered.
Since β-quartz and / or β-quartz solid solution has a negative expansion coefficient, in order to lower the average linear expansion coefficient, increase the crystal growth degree by increasing the nuclear growth heat retention temperature or lengthening the nuclear growth heat retention time. Therefore, on the basis of the heat treatment conditions of the test sample 1, the nucleation heat retention time was increased by 20 hours to prepare the test sample 5. The average linear expansion coefficient from 0 ° C. to 50 ° C. and the maximum value-minimum value of the ΔL / L-temperature curve in the temperature range from 0 ° C. to 50 ° C. were measured in the same manner as in test samples 1 to 4.

The average linear expansion coefficient of the test sample 5 was 0.03 × 10 ⁻⁷ · ° C.− ¹ , which was closer to the desired average linear expansion coefficient than the test sample 1, so the first temperature increase during the preparation of the sample 5 The rate, the nucleation temperature, the nucleation temperature, the second heating rate, the nucleation temperature, and the nucleation temperature were determined as the heat treatment conditions during product manufacture.

Furthermore, adjustment of the temperature drop rate Vr was attempted in order to bring it closer to the target thermal expansion characteristic. For the prepared test samples, the average linear expansion coefficient at 0 ° C. to 50 ° C., the maximum value of the ΔL / L-temperature curve within the temperature range of 0 ° C. to 50 ° C., as in Test Samples 1 to 4. Was measured. In addition, an average linear expansion coefficient every 5 ° C. from 0 ° C. to 50 ° C. was plotted, and a CTE-temperature curve was drawn.
Table 3 shows the variation of the average linear expansion coefficient by adjusting the cooling rate. In test sample 6, when the treatment was performed at 0.01 ° C./min ^{−1 which} is 1/10 of the first temperature decrease rate of test sample 5, the average linear expansion coefficient was −0.04 × 10 ^−7. · ° C.- ¹ and α _s2 −α _o was too large in the negative direction to be −0.05 × 10 ⁻⁷ · ° C.− ^1. When heat treatment was performed from the original glass at min ⁻¹ , the average linear expansion coefficient was 0.01 × 10 ⁻⁷ · ° C. ⁻¹ , and the maximum value−minimum value of the ΔL / L-temperature curve was 1. Therefore, the first temperature drop rate of the test sample 7 was adopted as an actual manufacturing condition. As shown in FIG. 3, the CTE-temperature curve of test sample 7 is negative compared to the CTE-temperature curve of test sample 5 while maintaining the slope of the CTE-temperature curve, that is, the temperature dependence of CTE. By translating in the direction, the target average linear expansion coefficient could be brought closer to the value.

Further, as shown in FIG. 4, the CTE value changes almost proportionally to the logarithm of the temperature decrease gradient, and other than the average linear expansion coefficient shown in the embodiment, a desired average can be obtained by selecting an appropriate temperature decrease gradient. A linear expansion coefficient can be obtained.

According to the present invention, the average linear expansion coefficient and the maximum value-minimum value of the ΔL / L-temperature curve can be adjusted by the nuclear growth heat retention temperature and the nuclear growth heat retention time for producing the crystallized glass, and the temperature decrease gradient By adjusting the speed, it is possible to precisely control the average linear expansion coefficient while maintaining the temperature dependence of the CTE.

Claims (5)

A method for producing crystallized glass comprising a step of heat-treating glass,
The step of heat-treating the glass has at least a temperature raising step and a temperature lowering step of lowering the temperature to room temperature ,
Adjusting the average linear expansion coefficient within the temperature range of 0 to 50 ° C. by adjusting the temperature decrease rate Vr in the temperature decrease step;
A method for producing crystallized glass containing β-quartz and / or β-quartz solid solution in a main crystal phase . A raw glass having the same composition as the product is subjected to a heat treatment step to produce at least one crystallized glass test sample, the average linear expansion coefficient α _s2 of the test sample is measured, and the desired average linear expansion coefficient α _o 2. The crystallization according to claim 1, wherein a temperature-decreasing rate Vr in the temperature-decreasing step at the time of actual product manufacture is determined by a difference α _s2 −α _o between the average linear expansion coefficient of the test sample and the test sample, and then manufactured under the determined heat treatment conditions. Glass manufacturing method. If the value of α _s2 −α _o is positive, the temperature drop rate Vr in the temperature drop step during actual product manufacture is made smaller than the temperature drop rate Vs in the temperature drop step during preparation of the test sample, and the value of α _s2 −α _o The method for producing crystallized glass according to claim 1 or 2, wherein Vr is larger than Vs if is negative.   The step of heat-treating the glass includes at least a heat-retaining step, and the temperature-decreasing rate Vr is determined after determining the heat-retaining temperature Tr and the heat-retaining time Hr in the heat-retaining step during actual product manufacture. The manufacturing method of the crystallized glass in any one. The raw glass having the same composition as the product is subjected to a heat treatment step to produce at least one crystallized glass test sample, the average linear expansion coefficient α _s1 of the test sample is measured, and the desired average linear expansion coefficient α _o 5. The method for producing crystallized glass according to claim 4, wherein the heat retention temperature Tr and the heat retention time Hr in the heat retention step at the time of actual product manufacture are determined by the difference α _s1 −α _o between the average linear expansion coefficient of the test sample and the test sample.