JP4647256B2 - Glass ceramics - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention can be used in a wide range of applications such as the information communication field, energy related field, and electronics field, and is an optical element used in the field of optical communication, in particular, one of members constituting a multiplexer / demultiplexer. The present invention relates to a crystallized glass having an average linear expansion coefficient and high transmittance.

  Currently, in the field of optical communication, various devices for transmitting a large amount of signals simultaneously with a single fiber at high speed are being actively researched and developed. As one of them, the wavelength division multiplexing system has been diversified.

  In this wavelength division multiplexing system, the wavelengths of adjacent channels are very close to each other in order to increase the density of information to be transmitted and received, that is, to increase the signal density. For this reason, if the wavelength of the target signal shifts depending on the environmental conditions, it becomes impossible to distinguish between adjacent wavelengths, and this becomes an erroneous signal, and it becomes easy to cause a problem that accurate signal transmission and reception cannot be performed. For this reason, various research and development have been conducted in order to perform transmission and reception accurately.

  In particular, when wavelength is multiplexed and demultiplexed by a wavelength division multiplexing multiplexer / demultiplexer, etc., because of the wavelength shift due to the environmental temperature due to the temperature dependence of the multiplexer / demultiplexer, in order to perform accurate transmission / reception Therefore, a temperature compensation member and a filter that does not cause a wavelength shift due to environmental temperature are required.

  Furthermore, not only in the field related to optical fibers but also in various devices and equipment used in energy-related fields and information fields, etc., in order to prevent the occurrence of distortion and internal stress caused by temperature differences in the usage environment There is a need for a material that can adjust the average linear expansion coefficient of a device or precision component to an appropriate value, and that can satisfy dimensional accuracy, dimensional stability, strength, thermal stability, and the like.

  Conventionally, ceramics, glass ceramics, glass, metals, and the like have been used as materials suitable for various devices in terms of temperature changes as described above because of their high heat resistance.

  However, these materials have a high average coefficient of linear expansion, i.e. they expand as the temperature increases, and many other materials used in devices with these materials also have a positive average coefficient of linear expansion. From the perspective of the entire device, it is hard to say that it is the optimal material to prevent the effects of temperature changes. In addition, conventional glass ceramics, ceramics, polymers, etc. having negative expansion characteristics are not commercialized because there are pores peculiar to ceramic materials, which are likely to cause problems such as low strength and reduced reliability due to environmental conditions. is the current situation. Therefore, as a material that can withstand temperature changes, a material that has a negative average linear expansion coefficient for canceling out a large positive average linear expansion coefficient of other members and that has high strength to withstand environmental changes is desired. ing.

Conventionally, there is a solid etalon filter as a filter used for these multiplexing / demultiplexing applications. Currently, this filter uses a Peltier element or the like because temperature control is required, but in order to reduce cost and weight, a technique that does not use a temperature controller has recently been studied. In particular, a filter material having a small change in optical path length due to temperature, that is, a material having a value of the following formula (1) close to 0 is very useful as a solid etalon filter material.
nα + dn / dt≈0 (1)
Here, n is the refractive index at the wavelength used, α is the average linear expansion coefficient, and dn / dt is the refractive index change rate with temperature.

  However, no material satisfying the formula (1) = 0 has been found so far, and research in each field is continuing. However, by using a material whose average linear expansion coefficient is negative, there is a possibility that the value of the equation (1) can be close to 0, and further, a material design that makes the value of the equation (1) negative is possible. Become.

  In addition, a substrate designed so that the value of the expression (1) is negative and a substrate having a positive value of the expression (1) are calculated so as to obtain an optimum plate thickness, and have a thickness based on these calculated values. By laminating each of the substrates with an optical contact or an adhesive having an approximate refractive index, it is possible to create a substrate material that makes the value of equation (1) as close to 0 as possible. Become.

In Patent Document 1, a negative average linear expansion of −30 to −85 (10 ⁻⁷ · K ⁻¹ ) is obtained by firing a crystal powder, a glass powder or the like and generating a large number of microcracks in the crystal grain boundary. A temperature compensating member made of a ceramic fired body having a coefficient is disclosed.

  Patent Document 2 discloses negatively expandable transparent glass ceramics.

Patent Document 3 discloses a ZnO—Al ₂ O ₃ —SiO ₂ based low thermal expansion ceramic whose main crystal phase is β-quartz solid solution and / or zinc petalite solid solution.

Patent Document 4 proposes a package in which an optical fiber having a refractive index grating is attached to a support member having a negative average linear expansion coefficient. As the negative expansion material, a composition based on Zr-tungstate (for example, ZrW ₂ O ₈ ) or Hf-tungstate (for example, HfW ₂ O ₈ ) is used. For example, −47 to −94 (10 ⁻ By using a ZrW ₂ O ₈ crystal having an average linear expansion coefficient of ⁷ · K ⁻¹ ) and adjusting the manufacturing conditions, a material having a very large negative average linear expansion coefficient is obtained. By using this material as a support member and fixing the optical fiber in a state where an appropriate stress is applied thereto, the change in wavelength due to a temperature change can be eliminated.

Patent Document 5 and Patent Document 6 describe liquid crystal polymers as other substances having a negative average linear expansion coefficient.
JP 2000-313654 A US Pat. No. 4,507,392 JP-A-2-208256 US Pat. No. 5,694,503 WO 97/14983 Japanese Patent Laid-Open No. 10-90555

By the way, as a material having a negative average linear expansion coefficient, β-eucryptite, β-eucryptite solid solution, β-quartz and β-quartz solid solution, or two or more kinds of crystals selected from these are generally used. Inorganic materials such as Li ₂ O—Al ₂ O ₃ —SiO ₂ based ceramics, ZnO—Al ₂ O ₃ —SiO ₂ based ceramics, lead titanate, hafnium titanate, zirconium tungstate, tantalum tungstate are known. Yes.

  General fired ceramics made of the above crystals are in a porous state compared to glass ceramics. When this ceramic material is impregnated with a substance having a low average viscosity and a positive average linear expansion characteristic, temperature change, humidity change, etc. Due to the effect of expansion of the impregnated material due to environmental changes, the expansion characteristics of this material differ from the inherent expansion characteristics of fired ceramics. Since it changes, problems are likely to occur in terms of long-term stability.

  However, since the fired ceramic disclosed in Patent Document 1 has a relatively large particle size, it does not have optical transparency and has a large number of microcracks. When the agent or the like is impregnated, the average linear expansion coefficient is greatly changed, so that practical application is difficult.

Further, the glass ceramic disclosed in Patent Document 2 contains a large amount of TiO ₂ and ZrO ₂ as crystal nucleation materials. If a large amount of TiO ₂ or ZrO ₂ is contained as a nucleation material, the temperature at which the raw glass is melted must be increased, and a homogeneous raw glass cannot be obtained. Further, devitrification is likely to occur during glass forming, which causes problems in terms of productivity and practicality.

Moreover, since the ceramic disclosed in Patent Document 3 contains a large amount of ZnO component that easily sublimes at high temperatures, it is described that long-time melting when forming the original glass (parent glass) is not preferable. In the examples, the melting time is as extremely short as 10 minutes. However, in such a short time, the SiO ₂ and Al ₂ O ₃ components are not sufficiently melted and remain at a high temperature, so that a homogeneous raw glass cannot be obtained. Even if it is crystallized, homogeneous ceramics cannot be obtained.

  If the glass is melted for several hours as usual, the remaining melt can be eliminated, but the composition of the original glass fluctuates due to sublimation of the ZnO component, and a homogeneous ceramic is stably obtained. I can't. In addition, the melting temperature of the example is as high as 1620 ° C., which increases the manufacturing cost.

Further, in the negative expansion material used in the package disclosed in Patent Document 4, Al ₂ O ₃ , SiO ₂ , ZrO ₂ , MgO, CaO, Y ₂ O in powder state is used in order to adjust the average linear expansion coefficient. A complicated procedure in which a material having a positive average linear expansion coefficient such as ₃ is appropriately added and the mixture is made into a sintered body must be taken, which is not suitable for mass production. Moreover, since different materials must be mixed, it requires appropriate technology and equipment, and it is difficult to obtain a homogeneous material. In addition to this, ZrW ₂ O ₈ and HfW ₂ O ₈ undergo a phase transition around 157 ° C., so that the average linear expansion curve is bent, and therefore cannot be said to be thermally stable in a wide temperature range. .

Furthermore, since the liquid crystal polymer as disclosed in Patent Document 5 and Patent Document 6 is a crystalline resin, it has a strong crystal orientation. For example, an injection molded product causes problems such as warping. In addition, when the average linear expansion coefficient in the orientation direction has a very large negative value of about −100 (10 ⁻⁷ · K ⁻¹ ), the average linear expansion coefficient other than the orientation direction has a large positive value. Therefore, physical properties such as bending strength and elastic modulus vary greatly depending on the direction, and are difficult to put into practical use for devices.

  As described above, conventional materials having a negative average linear expansion coefficient have some problems, so they are not widely used in the optical communication field, energy-related field, information field, and other various fields. There is no actual situation.

  In view of the above situation, the object of the present invention is to achieve its denseness, i.e., in a general environmental temperature range of −40 ° C. to + 80 ° C. when used in the fields of optical communication, energy, and information. By having very high density without pores, voids or cracks, it is not impregnated with grinding fluid, adhesives, etc., yet has high light transmittance and desired negative average linear expansion. An object of the present invention is to provide a glass ceramic having a coefficient, obtained at low cost, and capable of being stably produced in terms of composition and physical properties.

As a result of repeating various test studies to achieve the above object, the present inventors heat-treat Li ₂ O—Al ₂ O ₃ —SiO ₂ glass having a specific composition range to precipitate fine crystal particles. As a result, a glass ceramic having high transmittance and no anisotropy was successfully obtained, and this led to the present invention.

That is, the invention described in claim 1
% By mass
SiO ₂ 40~59%
Al ₂ O ₃ 10-30%
Li ₂ O 1-5.4%
ZnO 3-10%
TiO ₂ + ZrO ₂ 1.0-5.0%
P ₂ O ₅ less than 4%
Containing
The main crystal phase, beta-eucryptite _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2), β- eucryptite solid solution _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2 solid solution), beta -At least one selected from quartz (β-SiO ₂ ) and β-quartz solid solution (β-SiO ₂ solid solution), and an average linear expansion coefficient in the temperature range of -40 ° C to + 80 ° C is -25. less than exceeded ^{~-15 (10 -7 · K} -1), and the spectral transmittance in 1000~1700nm wavelength band is a glass ceramic, characterized in that at least 85.0%.

The invention according to claim 2 is the glass ceramic according to claim 1,
S iO ₂ / (Al ₂ O ₃ + Li ₂ O) ≧ 1.5
It is characterized by being.

The invention according to claim 3 is characterized in that, in the glass ceramic according to claim 1 or 2, the content of the Li ₂ O component is 12.0% or less in mol%.

The invention according to claim 4 is the glass ceramic according to any one of claims 1 to 3,
% By mass
B aO + SrO 0.5~6%
It is characterized by containing.

The invention according to claim 5 is the glass ceramic according to any one of claims 1 to 4,
% By mass
B ₂ O ₃ 0-5%
B aO 0-4%
S rO 0~4%
C aO 0-2%
Z rO ₂ 0.5~3%
T iO ₂ 0.5~3%
H fO ₂ 0-3%
As ₂ O ₃ + Sb ₂ O ₃ 0 to 2%
It is characterized by containing.

The invention according to claim 6 is characterized in that the glass ceramic according to any one of claims 1 to 5 does not substantially contain MgO.

The invention described in claim 7 is characterized in that the glass ceramic according to any one of claims 1 to 6 does not substantially contain PbO, Na ₂ O and K ₂ O.

The invention described in claim 8 is characterized in that the Young's modulus is 60 GPa or more in the glass ceramic according to any one of claims 1 to 7 .

The invention according to claim 9 is characterized in that, in the glass ceramic according to any one of claims 1 to 8 , the hysteresis of the thermal expansion curve is 15 ppm or less.

A tenth aspect of the present invention is the glass ceramic according to any one of the first to ninth aspects, wherein the crystal phase does not contain Al ₂ TiO ₅ crystals.

The invention according to claim 11 is the glass ceramic according to any one of claims 1 to 10 , wherein the original glass is melted, molded, and slowly cooled, then at 650 to 750 ° C. for 0.5 to 50 hours, It is obtained by performing the first heat treatment and then performing the second heat treatment at 700 to 850 ° C. for 0.5 to 100 hours.

The glass ceramic of the present invention exceeds -25 in a temperature range of -40 ° C to + 80 ° C by heat-treating and crystallizing Li ₂ O-Al ₂ O ₃ -SiO ₂ glass having a specific composition range. A material having a negative average linear expansion coefficient of less than −15 (10 ⁻⁷ · K ⁻¹ ) and having a spectral transmittance of 85.0% or more at a wavelength of 1000 to 1700 nm can be stably produced. In addition, because it has good mechanical strength, it does not require a step for strength improvement such as chemical strengthening, and therefore it does not cause problems such as elution of alkali ions. is there. Therefore, the optical device in the optical communication field can be applied in combination with a material having a positive average linear expansion coefficient.

  In addition to the optical communication field, it can be used in a wide range of applications such as energy-related fields, information communication fields, and electronics fields.

  In addition, the glass ceramic of the present invention can be produced by melting the original glass at a relatively low temperature as compared with the prior art, and can be produced at a low cost because the heat treatment temperature for crystallization is low. In addition, since the composition does not contain unstable components and the composition ratio can be easily controlled, it can be stably produced in terms of composition and physical properties.

Hereinafter, the negative thermal expansion glass ceramic of the present invention will be described in detail.
In the present invention, the glass ceramic is a material obtained by precipitating a crystal phase in a glass phase by heat-treating the glass, and crystallizes not only the glass phase and the crystal phase but also all the glass phase. It includes a material that has undergone a phase transition into a phase, that is, a material whose crystal content (crystallinity) in the material is 100% by mass. Further, the composition of the constituent components is all by mass unless otherwise specified. Further, in the present specification, “substantially does not contain” means that at least “an amount that does not substantially change the characteristics of the present invention may be included”. However, in the case described in this way, “an amount that may be mixed as an impurity may be included, but it should not be included up to an amount that is intentionally added”. preferable.

  In this specification, the main crystal phase refers to all crystal phases having a relatively large precipitation ratio. That is, in the X-ray chart in X-ray diffraction (the vertical axis is the X-ray diffraction intensity, the horizontal axis is the diffraction angle), the X-ray diffraction intensity of the main peak (highest peak) of the crystal phase with the highest precipitation ratio is 100. In this case, all the crystals having a ratio of X-ray diffraction intensities (hereinafter referred to as X-ray intensity ratios) of the main peaks (the highest peaks in the respective crystal phases) of the respective precipitated crystal phases are referred to as main crystal phases. Here, the X-ray intensity ratio of the crystals other than the main crystal phase is preferably less than 20, more preferably less than 10, and most preferably less than 5.

  In this specification, the hysteresis of the thermal expansion curve is the average linear expansion coefficient measured when the ΔL / L curve is drawn from low temperature to high temperature and from high temperature to low temperature. The difference in ΔL / L value at the temperature at which the curve is farthest (that is, the maximum value of the difference in thermal expansion coefficient during temperature rise and temperature drop).

The main crystal phase of the negative thermal expansion glass ceramics of the present invention, beta-eucryptite _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2), β- eucryptite solid solution (β-Li ₂ O · Al ₂ O ₃ .2SiO ₂ solid solution), β-quartz (β-SiO ₂ ), and β-quartz solid solution (β-SiO ₂ solid solution). Here, the solid solution means that in each crystal of β-eucryptite or β-quartz, a part of the crystal is substituted with an element other than the element constituting the crystal, or an atom has entered between the crystals. .

  These main crystal phases are important elements contributing to the negative average linear expansion coefficient in the glass ceramics of the present invention. By heat-treating the original glass having a specific composition under predetermined conditions, the main crystal phase having a negative average linear expansion coefficient is precipitated in the glass phase having a positive average linear expansion coefficient, or all the glass phases Phase transition to a crystal phase including the main crystal phase, thereby making it possible to control the average linear expansion coefficient within a desired negative numerical range as a whole glass ceramic.

  In particular, in the present application, a large negative average linear expansion has been conventionally achieved by diversifying the composition, selection of the type of precipitated crystal phase, precipitation ratio of the precipitated crystal phase = crystallinity, precipitated crystal grain size, etc. Using these precipitated crystals, for which only a coefficient was obtained, glass ceramics having a desired negative average linear expansion coefficient, which was lower than before, could be obtained for the first time.

Note that the types of these main crystal phases and the crystallinity of the entire glass ceramic are the contents of Li ₂ O, Al ₂ O ₃ and SiO ₂ within a specific composition range, and all heat treatments for crystallization described later. It is determined by temperature.

In the glass ceramic of the present invention, it is important to set a negative average linear expansion coefficient within a specific range, and in order to realize this, a crystalline phase having a positive average linear expansion coefficient, that is, lithium disilicate, silicate Lithium, α-quartz, α-cristobalite, α-tridymite, petalite including Zn-petalite, Al ₂ TiO ₅ , β-spodumene, cordierite, spinel crystals including garnite, wollastonite, forsterite , Diopsite, nepheline, clinoenstatite, anorcite, celsian, gelenite, felsper, willemite, mullite, corundum, lanquinite, larnite and their solid solutions are preferably not included. To maintain mechanical strength, tungstates including f-tungstate and Zr-tungstate, titanates including magnesium titanate, aluminum titanate, barium titanate, manganese titanate and lead titanate, mullite, 3 It is preferable not to contain 2 barium acid, Al ₂ O ₃ .5SiO _2, or a solid solution thereof.

  Regarding the average linear expansion coefficient, as described above, in the optical device, it is a major purpose to make the expression (1) substantially zero, and for this purpose, the change in the optical path length due to the material having the positive average linear expansion coefficient is reduced. That is, it is necessary to combine materials having a negative average linear expansion coefficient to compensate for temperature.

  The average linear expansion coefficient is affected by various factors such as the type of precipitated crystals / crystallinity / crystal grain size / average linear expansion coefficient of the glass matrix portion, and these factors are mechanical. The strength (for example, Young's modulus, rigidity, hardness, etc.) is also closely influenced.

  In glass ceramics used as optical device members, performance related to temperature compensation is important, but mechanical strength is also important in terms of durability. It becomes important.

As a result of examining various optimizations in order to satisfy these in a balanced manner, the negative average linear expansion coefficient of the glass ceramic of the present invention is more than −25 and less than ⁻¹⁵ (10 ⁻⁷ · K ⁻¹ ). Has been found to be suitable. More preferably, the upper limit is −16 (10 ⁻⁷ · K ⁻¹ ) and / or the lower limit is −24 (10 ⁻⁷ · K ⁻¹ ), and most preferably the upper limit is −17 (10 ^−7). · K ^-1) and / or the lower limit is ^{-23 (10 -7 · K -1)} .

  The transmittance or light transmittance in the present invention indicates the spectral transmittance at a light wavelength of 1000 to 1700 nm in a sample having a thickness of 10 mm. In the optical communication field, the higher the transmittance in a generally used wavelength band, the lower the loss when used as a filter material. As a result of various examinations on the transmittance, it has a transmittance of 85% or more, so that it can be easily applied as a filter material. A more preferable transmittance is 88% or more, and most preferably 90% or more.

  Regarding the hysteresis (ΔL / L) of the thermal expansion curve, the glass ceramic member of the present invention has a purpose of providing a temperature compensation effect of an optical communication device in combination with a positive member. If the hysteresis is large, the temperature compensation effect is lowered. Therefore, the hysteresis of the thermal expansion curve should be low and is preferably 15 ppm or less. In addition, More preferably, it is 10 ppm or less, Most preferably, it is 8 ppm or less.

  The Young's modulus is as high as possible because it will reduce the durability of the device when it is used if it does not have a certain value for the purpose of using it for optical communication devices. However, if it is too high, the hardness of the glass ceramic itself is too high, and the workability is likely to be significantly reduced. In addition, if an attempt is made to obtain a glass having an excessively high Young's modulus, the meltability of the original glass tends to be lowered, and this tends to be an impediment to obtaining a homogeneous glass ceramic.

  For these reasons, at least the lower limit of the Young's modulus is preferably 60 GPa, more preferably 70 GPa, even more preferably 80 GPa, while the upper limit is preferably 140 Pa, more preferably 125 GPa, and even more preferably 110 GPa.

  The rigidity is positively proportional to the Young's modulus, and as described above, it is preferable that the rigidity is high when considered as a device member for optical communication. However, it is easy to form a homogeneous glass ceramic with good workability. If it is going to obtain, there exists a preferable range like Young's modulus, and as the range, the lower limit is 20 GPa, more preferably 25 GPa, more preferably 30 GPa, while the upper limit is 50 GPa, more preferably 45 GPa, More preferably, it is 40 GPa.

The SiO ₂ component is the main component of the main crystal having a negative average linear expansion coefficient. However, when the amount is less than 40%, a desired main crystal phase is not easily precipitated, and exceeds 59%. In addition, since it becomes difficult to melt and clarify the glass, and a crystal phase other than the desired main crystal phase is likely to precipitate, the preferable lower limit of the SiO ₂ component amount is 40%, more preferably 45%. More preferably, it is 50%, while the upper limit is 59%, more preferably 58.9%, still more preferably 58.8%.

Al ₂ O ₃ component is an important component constituting β-eucryptite in the main crystal having a negative average linear expansion coefficient or a solid solution thereof, or a β-quartz solid solution in which the Al component is substituted and / or invaded. However, if it is less than 10%, the homogeneity of the original glass is lowered, and it becomes difficult to produce a desired main crystal phase up to a necessary amount, and the chemical durability of the glass is also deteriorated. On the other hand, if it exceeds 30%, the melting point of the original glass becomes too high, and it becomes difficult to melt and clarify the glass. Therefore, as a preferable range of the Al ₂ O ₃ component, the lower limit is 10%, more preferably 13%, More preferably, it is 15%, while the upper limit is 30%, more preferably 28.5%, still more preferably 27%.

The Li ₂ O component is an important component constituting β-eucryptite or a solid solution thereof in the main crystal having a negative average linear expansion coefficient, and a β-quartz solid solution in which the Li component is substituted and / or invaded. However, if it is less than 1%, it becomes difficult to melt the original glass, and it becomes difficult to obtain a required amount of a desired main crystal phase up to a required amount. Moreover, when it exceeds 5.4%, it will become difficult to vitrify and the intensity | strength and the transmittance | permeability of the glass ceramics after heat processing will fall. A preferred range is 1 to 5%. More preferably, the lower limit is 2%, and most preferably the lower limit is 3%. However, since the Li ₂ O component has a small molecular weight, a very large proportion is shown in a multi-component system when converted to a molar ratio. Therefore, it is preferable to calculate the molar ratio in the whole glass. When the Li ₂ O ratio exceeds 12 mol%, damage to the platinum crucible and a desired thermal expansion coefficient cannot be obtained. Therefore, the amount is preferably 12 mol% or less, more preferably 11.5 mol% or less, and 11 mol % Or less is most preferable.

Further, when SiO ₂ / (Al ₂ O ₃ + Li ₂ O) is less than 1.5, the number of stable SiO ₂ formers after crystallization is reduced, so that glass ceramic breaks due to abnormal crystal growth, cans and low transmission Increasing the rate is a problem. Therefore, it is desirable that SiO ₂ / (Al ₂ O ₃ + Li ₂ O) is 1.5 or more. In addition, More preferably, it is 1.6 or more, Most preferably, it is 1.7 or more.

ZnO component, Zn component is replaced and / or intrusion β- Yuktobanian descriptor components tight solid solution _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2 solid solution) and β- quartz solid solution (β-SiO ₂ solid solution) However, if it is less than 3%, it is difficult to obtain a desired average linear expansion coefficient after crystallization. On the other hand, if it exceeds 10%, devitrification is likely to occur during molding, and productivity becomes difficult. As the range of the content of the ZnO component, the lower limit is 3%, more preferably 3.5%, most preferably 4%, while the upper limit is 10%, more preferably 8%, most preferably 7%. is there.

The B ₂ O ₃ component can be arbitrarily added for the purpose of improving the meltability of the original glass, and when added, the B ₂ O ₃ component constitutes the glass phase portion of the negative thermal expansion glass ceramic of the present invention. When the amount exceeds 5%, the formation of a desired main crystal phase is hindered, and the heat resistance of the glass ceramic is deteriorated. In addition, Preferably it is 3.5% or less, More preferably, it is 2% or less, Most preferably, it is preferable not to contain substantially.

BaO component, Ba component is replaced and / or intrusion β- Yuktobanian descriptor components tight solid solution _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2 solid solution) and β- quartz solid solution (β-SiO ₂ solid solution) It is a component which can be added arbitrarily. This component has the effect of preventing the platinum of the crucible and other metal elements in the raw glass from alloying when the raw glass is melted, and maintaining the devitrification resistance of the raw glass. It may be preferable to utilize this effect. When it is desired to obtain the effect, it is preferably 0.5% or more. However, if it exceeds 4%, the average linear expansion coefficient of the glass becomes too large, and as a result, the average linear expansion coefficient as glass ceramics tends to increase, making it difficult to obtain the desired average linear expansion coefficient. A more preferred upper limit is 2.5%, and a most preferred upper limit is 2.0%.

SrO component, Sr component is replaced and / or intrusion β- Yuktobanian descriptor components tight solid solution _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2 solid solution) and β- quartz solid solution (β-SiO ₂ solid solution) It is a component which can be added arbitrarily. This component has the effect of reducing the hysteresis of the average linear expansion coefficient by combining with other RO (metal oxide) components, and it may be preferable to utilize this effect depending on the composition of the glass ceramic. When it is desired to obtain the effect, it is preferably 0.5% or more. However, if it exceeds 4%, in addition to being a constituent component of the main crystal phase, it will also be present in the glass matrix a lot, and this will increase the average linear expansion coefficient of the glass matrix, resulting in glass The average linear expansion coefficient as ceramics tends to be large, and it becomes difficult to obtain glass ceramics having a desired average linear expansion coefficient. A preferred upper limit is 3.0%, a more preferred upper limit is 2.5%, and a most preferred upper limit is 2.0%.

  Since the BaO component and the SrO component have a more preferable effect as described above for the glass ceramic as described above, the total amount of these components is preferably 0.5% or more. However, if it is contained in a large amount, the above-described problem that the average linear expansion coefficient falls outside the desired range is likely to occur. Therefore, the total amount is preferably 6% or less. A more preferred upper limit is 5.5%, and a most preferred upper limit is 4.5%.

  The CaO component has an effect of improving the melting and clarifying of the glass, but if it exceeds 2%, a sufficient negative average linear expansion coefficient cannot be obtained, so 2% or less is preferable. A more preferable upper limit is 1.8%, and a most preferable upper limit is 1.5%.

Since the ZrO ₂ component acts as a crystal nucleating agent, addition of 0.5% or more is preferable. However, if it exceeds 3%, melting and refining of the original glass tends to be difficult, and as a result, unmelted products are likely to be generated. A more preferable upper limit is 2.8%, and a most preferable upper limit is 2.5%.

Since the TiO ₂ component also acts as a crystal nucleating agent, addition of 0.5% or more is preferable. If it exceeds 3%, it tends to be devitrified at the time of glass molding, so 3% or less is preferable. A more preferable upper limit is 2.8%, and a most preferable upper limit is 2.5%.

Further, for the total amount of the TiO ₂ component and the ZrO ₂ component, by adding both components in combination, the Young's modulus is improved, and the crystal grain size of the main crystal phase can be easily controlled to a desired particle size, As a result, since high light transmittance can be easily realized, the total amount of the TiO ₂ component and the ZrO ₂ component is preferably 1.0% or more. However, if it exceeds 5.0%, it becomes difficult to obtain a desired average linear expansion coefficient. Therefore, the total amount of these components is preferably 5.0% or less. A more preferred lower limit is 1.5%, and a most preferred lower limit is 2.0%.

The HfO ₂ component is a component that reduces the average linear expansion coefficient of the original glass, but if it exceeds 3%, the meltability tends to deteriorate, so 3% or less is preferable. In addition, a more preferable upper limit is 2%, and it is most preferable not to contain substantially.

The As ₂ O ₃ and Sb ₂ O ₃ components can be added as fining agents during glass melting to obtain a homogeneous product, but a total amount of these components up to 2% is sufficient.

In addition to the above components, F ₂ , La ₂ O ₃ , Ta ₂ O ₅ , GeO ₂ , Bi ₂ O ₃ , WO ₃ , Y ₂ O ₃ , Gd can be used as long as the desired characteristics of the glass ceramics of the present invention are not impaired. ₂ O ₃ , SnO ₂ , TeO ₂ , CoO, NiO, CuO, AgO, MoO, MnO ₂ , Fe ₂ O ₃ , Cr ₂ O ₃ , Nb ₂ O ₅ , V ₂ O ₅ , Yb ₂ O ₃ , CeO ₂ , Cs ₂ O, rare earth elements other than the above, and the like can be added up to 3% each. However, since it tends to cause an influence on crystallization promotion or a tendency to decrease the transmittance, it is preferably not substantially contained if possible.

The P ₂ O ₅ component is preferably less than 4% because it tends to bring the average linear expansion coefficient of the glass ceramic after crystallization in a positive direction and the meltability tends to deteriorate. More preferably, it is 3% or less, and most preferably it is not substantially contained.

  It is preferable that the MgO component is not substantially contained since it tends to cause a tendency to increase the crystal grain size.

The PbO component is an environmentally unfavorable component, and the Na ₂ O and K ₂ O components are diffused in the negative thermal expansible glass ceramics of the present invention by diffusing these ions in subsequent processes such as film formation and cleaning. It is preferable that the PbO, Na ₂ O and K ₂ O components are not substantially contained because the physical properties are easily changed.

  Regarding the precipitated crystal grain size of the glass ceramic, if the difference in the refractive index between the glass matrix portion and the precipitated crystal phase and / or the precipitated crystal grain size is large, the light transmittance decreases. In this respect, the glass ceramics of the present application are all very fine particles having an average crystal grain size of 0.3 μm or less, and therefore have good light transmittance. A preferred average crystal grain size is 0.2 μm or less, a more preferred average crystal grain size is 0.15 μm or less, and a most preferred average crystal grain size is 0.1 μm or less.

  The glass ceramics obtained by the present application are homogeneous. For example, various alkali components (ions) such as Li, Na, and K have no difference in concentration between the surface phase and the inside. Further, the occurrence of cracks is extremely small, and there are no cracks having a size exceeding 5 μm, and moreover, there are no cracks exceeding 1 μm. The most preferred glass ceramics are those without any cracks.

The glass ceramic of the present invention containing the above composition is produced by the following method.
First, glass materials such as oxides, carbonates, hydroxides, and nitrates are weighed and prepared so as to have the above-described composition, put in a crucible, and stirred at about 1300 to 1550 ° C. for about 6 to 8 hours. While melting, a clear original glass is obtained.

  After the raw glass is melted as described above, it is formed into a plate shape and slowly cooled by an operation such as casting into a mold.

  Next, heat treatment for forming glass ceramics is performed. In general, glass ceramics having negative expansion characteristics tend to generate large cracks at the interface between the residual matrix glass and the precipitated crystal phase. This is because a stress caused by a large difference in thermal expansion occurs between the residual glass matrix having positive thermal expansion characteristics and the precipitated crystal phase having negative thermal expansion characteristics. There was a problem that could not be produced. However, in this application, the crystal grain size was controlled by the crystallization conditions, and a material capable of stable production was successfully created. First, the temperature is maintained at 650 to 750 ° C. to promote nucleation (first heat treatment). When this nucleation temperature is lower than 650 ° C., crystal nucleation is impossible. Conversely, when the temperature is higher than 750 ° C., nuclei are generated and grown early. Therefore, the crystal grows greatly in the second heat treatment stage, causing cracks in the material.

  The heat treatment time is preferably set to 0.5 to 50 hours in order to obtain desired characteristics. From the viewpoint of more preferable characteristics and productivity / cost, the lower limit is 1 hour and / or the upper limit is More preferably, it is 30 hours.

  After nucleation, the crystal grain size is controlled by optimizing the heating process up to the nucleus growth temperature. In the case of a large size product, if the rate of temperature rise is fast, at this point, the crystallinity degree of the precipitated crystal phase is still low and there is a large number of glass matrix parts having a positive average linear expansion coefficient. Distortion may occur and the product may break. For this reason, temperature control to make the speed as slow as possible becomes important. In order to obtain the desired characteristics, 10 ° C./Hr. The following is preferable.

  After nucleation, crystallization is performed at a temperature of 700 to 850 ° C. (second heat treatment). When the crystallization temperature is lower than 700 ° C., the main crystal phase is difficult to grow sufficiently, and when higher than 850 ° C., the original glass is softened. This is not desirable because it easily deforms or re-dissolves. Preferably, the lower limit is 750 and / or the upper limit is 850 ° C. After crystallization, 50 ° C./Hr. Hereinafter, more preferably 25 ° C./Hr. It is desirable to slowly cool at the following rate.

  The heat treatment time for the nucleus growth is preferably set to 0.5 to 100 hours, and for the same reason as the first heat treatment, it is more preferable that the lower limit is 1 hour and / or the upper limit is 30 hours. When the temperature raising rate is slow, a shorter time is possible from the viewpoint of productivity.

  Next, examples of the negative thermal expansion glass ceramic of the present invention will be described. The present invention is not limited to these examples.

  Tables 1 and 2 show Example Nos. Of glass ceramics of the present invention. 1-No. For 6, the composition ratio, dissolution temperature, nucleation temperature, nucleation time, nucleation growth temperature, nucleation growth time, average linear expansion coefficient, specific gravity, average crystal particle diameter, thermal expansion hysteresis, Young's modulus, rigidity, transmittance Indicated.

[Examples 1 to 6]
The glass ceramics of Examples 1 to 6 were manufactured as follows. First, glass raw materials such as oxides, carbonates, hydroxides, and nitrates are weighed and prepared so as to have the compositions shown in Tables 1 and 2, and placed in a platinum crucible. The mixture was melted and stirred at the dissolution temperature shown in Table 2 for 6 to 8 hours.

  Next, the melted original glass was cast into a mold and molded and slowly cooled to obtain glass molded bodies, respectively. Thereafter, the glass molded body was directly put into a crystallization furnace, heated and heated, and crystal nuclei were formed at the nucleation temperatures and nucleation times shown in Tables 1 and 2. Subsequently, the mixture was heated and heated, and crystallized at the same nucleus growth temperature and nucleus growth time as shown in Tables 1 and 2, followed by 50 ° C./Hr. The glass ceramic was obtained by slow cooling at the following rate.

  Samples having a diameter of 5 mm and a length of 20 mm were cut out from the glass ceramics of each example obtained as described above, and average lines in a temperature range of −40 ° C. to + 80 ° C. were measured with a TAS200 thermomechanical analyzer manufactured by Rigaku Corporation. The expansion coefficient and thermal expansion hysteresis were measured.

Further, the glass ceramic obtained as described above was polished with CeO ₂ and the specific gravity, Young's modulus, rigidity, and transmittance were measured.

  Furthermore, the average crystal grain size was measured by a TEM photograph. For taking a TEM photograph, a thin sample of several μm was obtained by ion milling, and the sample was observed at an acceleration voltage of 75 kV and a magnification of 50,000 times. From this observation, it was confirmed that the average crystal particle size was less than about 0.1 μm for Examples 1 and 4 and less than 0.05 μm for Example 3.

[Comparative Examples 1-3]
In the glass ceramics of Comparative Examples 1 to 3, glass raw materials such as oxides, carbonates, hydroxides, and nitrates are weighed and prepared so as to have the composition shown in Table 3, and put in a platinum crucible, and a normal melting apparatus is used. The mixture is stirred at 1400 to 1550 ° C. for 6 to 8 hours to form crystal nuclei at the nucleation temperature and nucleation time shown in Table 3, and crystallized at the nucleation temperature and nucleation time shown in Table 3. Except that, it was obtained in the same manner as in Examples 1-6.

In Comparative Example 1, the amount of Li ₂ O or Al ₂ O ₃ component is very large. The β-eucryptite solid solution with fast crystal growth grows further by bonding to each other after crystal growth from the crystal nucleus. By repeating this phenomenon, the precipitated crystal grain size is large and the crystallinity is high, so that the light transmittance at a desired wavelength is low.

In Comparative Example 2, since Li ₂ O component as compared with the embodiment in the present invention is large, is increased crystallinity in the same manner as in Comparative Example 1, it is difficult to obtain the desired average linear thermal expansion coefficient.

In Comparative Example 3, since the amount of SiO ₂ is larger than the amount limited in the present invention, the degree of crystallinity becomes high as in Comparative Example 1, and it is difficult to obtain a desired average linear expansion coefficient.

2 is a TEM photograph of Example 1. 4 is a TEM photograph of Example 3. 4 is a TEM photograph of Example 4.

Claims (11)

% By mass
SiO ₂ 40~59%
Al ₂ O ₃ 10-30%
Li ₂ O 1-5.4%
ZnO 3-10%
TiO ₂ + ZrO ₂ 1.0-5.0%
P ₂ O ₅ less than 4%
Containing
The main crystal phase, beta-eucryptite _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2), β- eucryptite solid solution _{(β-Li 2 O · Al} 2 O 3 · 2SiO 2 solid solution), beta -At least one selected from quartz (β-SiO ₂ ) and β-quartz solid solution (β-SiO ₂ solid solution), and an average linear expansion coefficient in the temperature range of -40 ° C to + 80 ° C is -25. Glass ceramics characterized by having a spectral transmittance of 85.0% or more in a wavelength range of 1000 to 1700 nm and exceeding to less than −15 (10 ⁻⁷ · K ⁻¹ ). S iO ₂ / (Al ₂ O ₃ + Li ₂ O) ≧ 1.5
The glass ceramic according to claim 1, wherein: The glass ceramic according to claim 1, wherein the content of the Li ₂ O component is 12.0% or less in terms of mol%. % By mass
B aO + SrO 0.5~6%
The characterized in that it contains a glass ceramic according to any one of claims 1 to 3. % By mass
B ₂ O ₃ 0-5%
B aO 0-4%
S rO 0~4%
C aO 0-2%
Z rO ₂ 0.5~3%
T iO ₂ 0.5~3%
H fO ₂ 0-3%
As ₂ O ₃ + Sb ₂ O ₃ 0 to 2%
The glass ceramic according to claim 1, comprising: The glass ceramic according to any one of claims 1 to 5 , which is substantially free of MgO. PbO, glass ceramic according to any one of claims 1 to 6, characterized in that does not substantially contain Na ₂ O and K ₂ O. The glass ceramic according to any one of claims 1 to 7 , wherein Young's modulus is 60 GPa or more. The glass ceramics according to any one of claims 1 to 8 , wherein the hysteresis of the thermal expansion curve is 15 ppm or less. Crystal phase, glass ceramic according to any one of claims 1-9, characterized in that it does not contain the Al ₂ TiO ₅ crystal. After melting, forming, and slowly cooling the original glass, the first heat treatment is performed at 650 to 750 ° C. for 0.5 to 50 hours, and then the second heat treatment is performed at 700 to 850 ° C. for 0.5 to 100 hours. The glass ceramic according to claim 1 , wherein the glass ceramic is obtained.