JPH0737334B2 - Heat-resistant ceramics molded body 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 heat-resistant ceramic compact having a good surface smoothness and a method for producing the same. The present invention also relates to a reflector substrate that has good heat resistance and can be used at high temperatures.

[0002]

2. Description of the Related Art Light source lamps for lighting devices, projectors, etc., generate more heat as they become brighter, and therefore the temperature of the reflecting mirror used in combination with the lamp also rises sharply. In particular, in recent years, the brightness and the size of the lamp have been increasing in many fields, and the temperature of the reflecting mirror may exceed 550 ° C. It goes without saying that the reflector consists of a base material and a reflective film coated on the surface, and both of them control the heat resistance of the reflector, but considering the heat resistance of the base material, the maximum operating temperature and heat resistance are considered. Two of the impact properties are important. In the case of glass that is often used as a base material, the maximum operating temperature is below the transition point,
55 even Pyrex grade glass with the highest heat resistance
Since it can be used only at 0 ° C. or lower, and the thermal shock resistance is limited to a temperature difference of 250 ° C. even in a test with a solid rod (diameter 5 mm), it cannot be used safely under the severe conditions described above. Further, the heat resistance limit of the base material limits the miniaturization of the lamp and the reflecting mirror.

Quartz glass is used as a material having higher heat resistance, but this glass has the drawback that it is not easy to mold, mass production is difficult, and it is extremely expensive. Ceramics are generally excellent in heat resistance, but it is difficult to form a highly accurate curved surface necessary for manufacturing a reflecting mirror having sufficient optical characteristics, and there is a problem in surface smoothness. There is no example that has been put to practical use as a base material. Li ₂ O, Al ₂ O
_A glass having a low coefficient of thermal expansion containing 3 components of ₃ and SiO ₂ as a basic component is heat-treated to form a β-spodumene solid solution (Li ₂ O-
Al ₂ O ₃ -4SiO ₂ ) or a ceramic obtained by forming a β-eucryptite solid solution (Li ₂ O-Al ₂ O ₃ -2SiO ₂ ) (so-called crystallized glass)
Has excellent heat resistance, and the molding and polishing necessary for forming the reflector substrate can be easily performed in the stage of glass before crystallization, so that it is a preferable material for the reflector substrate. is there. However, it is a drawback when used as a reflecting mirror base material that even a smooth finished surface at the glass stage becomes rough due to crystallization. That is, since the multilayer reflective film coated on the reflector base material by means such as vacuum deposition is as thin as about 2 μm as a whole, if the surface of the base material is poor in smoothness, the reflective film will not be smooth either. Although a reflective film having a high reflectance cannot be obtained, the average roughness of the surface of the conventional crystallized glass is about 0.1 μ, and the roughness exceeds 0.5 μ in some places.
It could not be used as a base material for a high-reflectance reflecting mirror (the average roughness of the polished reflecting surface of the Pyrex glass-based reflecting mirror base material is usually about 0.001 to 0.003 μm. "Average roughness" is "center line average roughness Ra" of JIS B0601.).

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-reflectivity reflecting mirror due to insufficient surface smoothness even though it has advantageous properties as a reflecting mirror substrate as described above. The object is to improve the surface smoothness of crystallized glass products that could not be used as a base material of Another object of the present invention is to provide a crystallized glass-based heat-resistant ceramics molded article having an essentially smooth glossy surface, which is useful for applications other than the reflector substrate, and a method for producing the same.

[0005]

Means for Solving the Problems The heat-resistant ceramics molded body and the reflector substrate made of the same, which have been successfully provided by the present invention, include magnesium, calcium, zinc, lead,
And at least one metal selected from the group consisting of vanadium as an oxide in an amount of 0.3 to 7.0% (% by weight; the same applies hereinafter)
It is characterized by comprising a β-spodumen solid solution or a β-eucryptite solid solution contained therein, and having an average surface roughness of essentially 0.03 μm or less. here,
“The average roughness is essentially 0.03 μm or less” means β
-It means that the original surface which has not been subjected to any polishing treatment after the crystallization treatment for producing the Spodumene solid solution or the β-eucryptite solid solution exhibits an average roughness of 0.03 µm or less.

The present invention also has an oxide composition of SiO ₂ 50.
~ 65%, Al ₂ O ₃ 18-30%, Li ₂ O 3-8%,
TiO ₂ + ZrO ₂ 3-5%, P ₂ O ₅ and / or B ₂
O ₃ in a total amount of 8% by weight or less, RO (wherein R represents a metal atom selected from the group consisting of magnesium, calcium, zinc, lead, and vanadium) 0.3 to 7.0%,
R ₂ O (where R represents a potassium atom or sodium atom) 3.0% or less of glass with a predetermined shape and a smooth surface.
Molded into a molded body having a surface , the obtained glass molded body,
After heat treatment at a temperature equal to or lower than the deformation temperature of the glass to generate crystal nuclei, the temperature is raised to generate a β-spodumen solid solution or a β-eucryptite solid solution, the surface-smooth heat-resistant ceramics. The present invention provides a method for manufacturing a molded body. However, diameter 5mm, length 30
5mm glass is supported vertically with a round bar of 5mm.
The temperature at which the sample rod begins to bend when the temperature is increased at a rate of temperature increase of 5 ° C. per minute with the load applied is defined as the glass deformation temperature.

[0007]

[Function] From a β-spodumene solid solution or a β-eucryptite solid solution containing 0.3 to 7.0% of one or more metals selected from the group consisting of magnesium, calcium, zinc, lead and vanadium as oxides. In addition, the ceramic molded body of the present invention having an average surface roughness of essentially 0.03 μm or less is a β-spodumene solid solution or β-spodumene solid solution.
-It exhibits excellent heat resistance peculiar to crystallized glass made of eucryptite solid solution, and due to its inherently excellent surface smoothness, it does not require difficult polishing finish, and it has high heat resistance and It can be used in the fields where the surface smoothness is required. Hereinafter, the present invention will be described in detail while explaining the method for manufacturing the above-mentioned ceramic molded body in the order of steps.

First, the oxide composition is SiO ₂ 50-65.
%, Al ₂ O ₃ 18-30%, Li ₂ O 5-8%, TiO ₂
+ ZrO ₂ 3 to 5%, P ₂ O ₅ and / or B ₂ O ₃ in a total amount of 8% or less, RO (where R is a metal atom selected from the group consisting of magnesium, calcium, zinc, lead and vanadium). Represents 0.3 to 7.0%, R ₂ O (however, R
Represents a potassium atom or a sodium atom) 3.0%
Raw material minerals necessary for obtaining the following glass are prepared, and the raw material minerals are pulverized and mixed according to a conventional method for producing glass, and further heated and mixed in a molten state to be vitrified. The first characteristic of the above glass composition is that the melting temperature is slightly lower than that of the conventional glass of this type, and therefore, about 15
It can be melted and vitrified at a temperature of 00 ° C. or lower. The blending of the RO component is particularly important for obtaining a product having a good surface smoothness, and a crystallized glass product having a good surface smoothness that can serve as a base material for a high-reflectance reflecting mirror has an appropriate amount of the RO component. Can be produced only by blending and crystallization at a slightly lower temperature described later. Especially preferred as RO components are PbO and VO.

The proportions of the other components are also limited to the above range in order to achieve the object of the present invention. 50 for SiO ₂
If it is less than%, the glass tends to devitrify during molding, and if it exceeds 65%, melting becomes difficult. If Al ₂ O ₃ is less than 17%, the thermal expansion coefficient becomes large and the thermal shock resistance deteriorates. If it exceeds 30%, melting becomes difficult. If Li ₂ O is less than 3%, it is difficult to melt, and if it exceeds 8%, the coefficient of thermal expansion becomes too large. TiO ₂ and ZrO ₂ are components blended as a crystal nucleating agent. If the total amount of these is less than 3%, it takes too long to crystallize, but if it exceeds 5%, melting becomes difficult and the glass becomes glass. Devitrification tends to occur during molding. In addition, P ₂ O ₅ , B ₂ O ₃ , and R ₂ O are effective components for improving the meltability and workability, but if too much,
Avoid undesired blending, as it may cause devitrification, deformation of the glass molding, and other undesirable results. P ₂ O ₅ and B ₂ O
It is desirable that ₃ alone does not exceed 5%.

The obtained glass is formed into a predetermined shape by an arbitrary method such as a blowing method, a pressing method, a roll method, a casting method or the like, as in the case of ordinary glass. Thereafter, a portion where importance is placed on molding precision and surface smoothness, for example, a reflection film coating surface in the case of using a reflecting mirror base material, is subjected to polishing finish as necessary. Then, the glass molded body is placed in a heating furnace and subjected to a two-step heat treatment for crystallization. The first stage heat treatment is β-eucryptite or β
-To uniformly generate fine crystals of spodumene,
This is a crystal nucleus forming step. Generation of uniform crystallites by performing the heat treatment in two steps is also performed in the conventional crystallized glass manufacturing method, but the first-step heat treatment in the conventional manufacturing method exclusively promotes the formation of crystal nuclei. The conditions are selected only from the viewpoint, and it is usually performed at a high temperature of 750 to 800 ° C. On the other hand, in the production method of the present invention, the treatment temperature here is lower than the deformation temperature of the glass having the above composition (about 450 to 650 ° C. for the standard composition), preferably about 50 to 100. Since the temperature is lower by ℃, the first stage heat treatment temperature does not exceed 650 ℃. This temperature condition is important for making the surface of the finally obtained crystallized glass a glossy surface with good smoothness, and the reason is not clear, but even the glass molded product of the above composition is rough if the treatment temperature is too high. It will be on the surface.

After the temperature is maintained for about 30 minutes to 2 hours to generate crystal nuclei, the temperature is raised to about 650 to 850 ° C., preferably 700 to 800 ° C., and the temperature is maintained for about 30 minutes to several hours. Upon holding, a β-eucryptite solid solution and then a β-spodumen solid solution are formed. The β-spodumen solid solution has a slightly higher coefficient of thermal expansion than the β-eucryptite solid solution, but is superior in strength. In the case of the conventional crystallized glass, heat treatment at a high temperature of about 900 to 1200 ° C. was required in the crystallization step to form the β-spodumene solid solution, but in the case of the above glass composition according to the present invention, the heat treatment temperature is Since it can be as high as 800 ° C, it consumes far less heat energy.

In the case of the β-spodumene solid solution, the obtained crystallized glass is completely devitrified with crystallization, but the surface roughness due to it is suppressed to a minimum, and the average roughness is usually 0. It is 0.03 μ or less. A reflecting mirror manufactured using a base material made of crystallized glass having an average surface roughness of 0.02μ is also a reflecting mirror manufactured using heat-resistant glass having an average roughness of 0.002 or less as a base material. It exhibits a reflectance of 90% or more of the reflectance of the above, and can be sufficiently used as a reflector substrate. The softening deformation temperature of a product made of β-spodumene solid solution is 900 ° C or higher, and it can withstand continuous use at a temperature up to 700 ° C. Excellent thermal shock resistance, 600
It was not damaged even by a test in which it was heated to ℃ and put in cold water.

[0013]

【Example】

Example 1 SiO ₂ 60%, Al ₂ O ₃ 21%, Li ₂ O 5.5%, Ti
O ₂ + ZrO ₂ 4%, P ₂ O ₅ 5%, B ₂ O ₃ 2.5%, Z
nO + MgO 4%, to prepare a raw material so that the K ₂ O + Na ₂ O1.5% of the composition, and vitrified by melting at 1500 ° C., and molded into a substrate shape of the reflecting mirror having a diameter of 80mm by this pressing. This glass molded body having a deformation temperature of 660 ° C. was held at 570 ° C. for 1 hour, then heated to 770 ° C. at a heating rate of 3 ° C./min, held at this temperature for 1 hour, and then cooled. The molded body that was transparent before the heat treatment was milky white, and it was confirmed from the X-ray diffraction pattern that it became a β-spodumen solid solution. The coefficient of thermal expansion (average value from room temperature to 400 ° C.) was 6 × 10 ⁻⁷ / ° C., and the bending strength was 900 kgf / cm ² . Further, it was confirmed that even if it was heated to 600 ° C. and put into cold water, it was not damaged and the thermal shock resistance was excellent. The surface was a beautiful glossy surface, and the average roughness was 0.03 μm or less. The reflectance of the reflecting mirror obtained by depositing the Ta ₂ O-SiO ₂ alternating multilayer film on the predetermined position of the product is the same as the above, and the same reflecting film is deposited on the reflecting mirror base material of glass without heat treatment. When the reflectance of the reflecting mirror thus obtained was 100, it was 90 or more over the entire visible light region.

Example 2 SiO ₂ 53%, Al ₂ O ₃ 25%, Li ₂ O 6%, TiO ₂
+ ZrO ₂ 4.3%, P ₂ O ₅ 3%, B ₂ O ₃ 3%, PbO
+ MgO 3.5%, K ₂ O + Na ₂ O 1.4% are mixed and the raw materials are mixed and melted at 1470 ° C to be vitrified, which is then pressed into a base material of a reflector with a diameter of 80 mm. did. The glass molded body having a deformation temperature of 650 ° C. was held at 600 ° C. for 1 hour, then heated to 750 ° C. at a heating rate of 5 ° C./min, held at this temperature for 1 hour, and then cooled. The molded body which was transparent before the heat treatment was translucent and milky white, and it was confirmed from the X-ray diffraction pattern that it was a β-spodumen solid solution. Thermal expansion coefficient is 15 × 10
^The bending strength was ^-7 / ° C and the bending strength was 950 kgf / cm ² . Also, 60
It was confirmed that even if it was heated to 0 ° C. and put into cold water, it did not break and had excellent thermal shock resistance. The surface was a beautiful glossy surface, and the average roughness was 0.025 μm or less. The reflectance of the reflecting mirror obtained by depositing the Ta ₂ O—SiO ₂ alternating multilayer film at a predetermined position on the product is the same as that described above, but the same reflecting film is deposited on the reflecting mirror base material of glass without heat treatment. If the reflectance of the obtained reflector is 100, it is 90 over the entire visible light range.
That was all.

Comparative Example 1 The same raw material as in Example 2 except that PbO and MgO were not included, that is, SiO ₂ 53%, Al ₂ O ₃ 25
%, Li ₂ O 6%, TiO ₂ + ZrO ₂ 4.3%, P ₂ O ₅ 3
%, B ₂ O ₃ 3%, K ₂ O + Na ₂ O 1.4% as a raw material
It was melted at 470 ° C. to be vitrified, and this was molded into a substrate shape of a reflecting mirror having a diameter of 80 mm in the same manner as in Example 2. This glass molding with a deformation temperature of 650 ℃ is 600 ℃
After the temperature was maintained for 1 hour, the temperature was raised to 750 ° C. at a temperature rising rate of 5 ° C./min, and the temperature was maintained for 1 hour and then cooled. The molded body which was transparent before the heat treatment was translucent milky white, and the formation of β-spodumene solid solution was confirmed,
The surface roughness of the product was uneven, and the roughness was over 0.3 μm. In addition, it was confirmed that it was deformed as a whole. As a result, the reflectance of the reflecting mirror obtained by vapor-depositing the multilayer reflecting film thereon in the same manner as in Example 2 is the reflectance of the reflecting mirror obtained by vapor-depositing the same reflecting film on the polished glass surface. 1
When it was set to 00, it did not reach 90 in the entire visible light region.

Comparative Example 2 A glass molded body obtained in the same manner as in Example 2 was replaced with 650
After holding at ℃ for 1 hour, it was heated to 830 ℃ and heat-treated for 1 hour. The molded body that was transparent before heat treatment was milky white, and it was confirmed from the X-ray diffraction pattern that it was a β-spodumene solid solution. The bending strength was high at 1400 kgf / cm ² , but the thermal expansion coefficient was 20 ×. The thermal shock resistance was 10 ^-7 / ° C and 500 ° C or less. The average roughness of the surface was 0.05 μm or more, and there were wrinkles visually observed. The reflectance of the reflecting mirror obtained by depositing the multilayer reflecting film on this molded body in the same manner as in Example 2 is the reflectance of the reflecting mirror obtained by depositing the same reflecting film on the polished glass surface. When it was 100, it was around 80 in the entire visible light region.

[0017]

As described above, the ceramic molded body of the present invention which has excellent heat resistance, thermal shock resistance and mechanical strength, and which has an extremely smooth glossy surface, which is different from conventional crystallized glass, is Not only is it excellent as a reflector substrate, but it can also be used for many applications such as various optical materials, electrical insulators, electronic component materials, etc., by making use of its features. Further, according to the production method of the present invention, crystallization can be performed at a much lower temperature than that in the case of producing a conventional crystallized glass, and the product can be provided at a low cost, and the product usually does not need a polishing finish. Since the surface has a relatively high degree of smoothness, the present invention makes it possible to utilize a heat-resistant material having a high degree of smoothness in many fields more easily than conventional ones.

Claims (4)

[Claims] 1. Magnesium, calcium, zinc, lead,
And β-spodumen solid solution or β-eucryptite solid solution containing 0.5 to 7.0% by weight of one or more metals selected from the group consisting of vanadium and oxide as an oxide, and the average surface roughness is essentially A heat-resistant ceramics compact characterized by having a particle size of 0.03 μm or less. 2. The oxide composition of SiO _{2 is} 50-65 wt%, Al ₂ O ₃ 18-30 wt%, Li ₂ O 3-8 wt%, TiO ₂ + ZrO ₂ 3-5 wt%, P ₂ O ₅ And / or B ₂ O ₃ in a total amount of 8% by weight or less, RO (however, R
Represents a metal atom selected from the group consisting of magnesium, calcium, zinc, lead, and vanadium) 0.3-
Specified glass is 7.0 wt% and R ₂ O (where R represents potassium atom or sodium atom) 3.0 wt% or less.
To form a molded body having a smooth surface, and the glass molded body obtained is heat-treated at a temperature not higher than the deformation temperature of the glass to generate crystal nuclei, and then heated to a β-spodumene solid solution. Alternatively, a β-eucryptite solid solution is produced, and the average roughness is 0.03 μm or less.
A method for producing a heat-resistant ceramic compact having a certain smooth surface . 3. Magnesium, calcium, zinc, lead,
And β-spodumen solid solution or β-eucryptite solid solution containing 0.3 to 7.0% by weight of one or more metal oxides selected from the group consisting of vanadium and the average surface roughness is essentially A reflecting mirror substrate having a thickness of 0.03 μm or less. 4. The oxide composition of SiO _{2 is} 50-65 wt%, Al ₂ O ₃ 18-30 wt%, Li ₂ O 3-8 wt%, TiO ₂ + ZrO ₂ 3-5 wt%, P ₂ O ₅ And / or B ₂ O ₃ in a total amount of 8% by weight or less, RO (however, R
Represents a metal atom selected from the group consisting of magnesium, calcium, zinc, lead, and vanadium) 0.3-
7.0 wt%, R ₂ O (where R represents a potassium atom or sodium atom) 3.0 wt% or less of glass is molded into a molded product having a predetermined shape and a smooth surface, and the obtained glass molding The body should be 50 to 1 above the deformation temperature of the glass.
After heat treatment at a low temperature of 00 ° C. to generate crystal nuclei, the temperature is raised to generate β-spodumen solid solution or β-eucryptite solid solution, and the average roughness is 0.03 μm or less. A method for producing a heat-resistant ceramic molded body having a smooth surface.