Black quartz glass and its manufacturing method

Abstract

The present invention relates to a black quartz glass comprising a composition having 63-65 mass% of SiO2, 18-24 mass% of TiO2, and 12-17 mass% of Al2O3 (the total of SiO2, TiO2, and Al2O3 is 100 mass%), a method for manufacturing black quartz glass comprising mixing 63-65 mass% of SiO2 powder, 18-24 mass% of TiO2 powder, and 12-17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700-1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain the black quartz glass, and a product comprising a black quartz glass member using the black quartz glass. The present invention provides black quartz glass having excellent light-blocking properties, no risk of causing contamination in the process of use, sufficient color uniformity when scaled up, and capable of producing large ingots, a method for manufacturing the black quartz glass with excellent productivity even in large ingots, and a black quartz glass product using the black quartz glass.

Description

Technology Field

[0001] The present invention relates to black quartz glass, a method for manufacturing the same, and black quartz glass products. More specifically, the present invention relates to black quartz glass that can be used in quartz glass cells for optical analysis, reflectors for projectors, connectors for optical fibers, light-shielding members for semiconductor manufacturing devices or infrared heating devices, infrared heat absorption / heat storage members, etc., and a method for manufacturing the black quartz glass efficiently.

[0002] The present application claims priority to Japanese Patent Application No. 2020-169478 filed on October 7, 2020 and Japanese Patent Application No. 2021-146784 filed on September 9, 2021, the entire contents of which are incorporated herein by reference in particular as a disclosure. Background Technology

[0003] Quartz glass is utilized for various applications, such as lighting equipment, optical instrument components, semiconductor industry components, and physicochemical instruments, by taking advantage of its good light transmittance across the ultraviolet to infrared range, low thermal expansion, and chemical resistance. Among these, black glass, which is produced by adding a small amount of transition metal oxide to quartz glass, is used in areas requiring localized light shielding and is utilized in optical instrument components, such as quartz glass cells for optical analysis. However, recently, as components have become more miniaturized and thinned, conventional black glass has shown insufficient light shielding properties, and there is a demand for black quartz glass with higher light shielding capabilities.

[0004] In addition, for projector applications, black quartz glass capable of efficiently blocking light leakage from the reflector is required to prevent adverse effects on the internal optical system of the projector due to the increased brightness of the valve to make the projected screen brighter.

[0005] In optical fiber applications, it is necessary to prevent diffuse reflection caused by leakage light in connectors that connect optical fibers; however, as optical transmission density increases, black quartz glass with higher light-blocking properties is required.

[0006] Furthermore, quartz glass possesses advantages such as high heat resistance and high chemical purity, and is widely used in jigs for semiconductor manufacturing. However, recently, heat loss has become a problem in the heat treatment processes of semiconductor manufacturing. In infrared heating processes, there is a growing need for shielding materials to block infrared irradiation from objects other than the target object, as well as infrared heat absorption and storage materials for efficient heating of the target object. In this regard, there is a demand for the development of black quartz glass that effectively shields infrared radiation, exhibits excellent infrared heat absorption and storage capabilities, enables the manufacturing of large-sized components, and is free from metal impurities that cause process contamination.

[0007] Conventionally, black quartz glass with silica as the main component is known as follows.

[0008] For example, Patent Document 1 proposes a method for producing black quartz glass by mixing quartz glass powder with niobium pentoxide, converting niobium pentoxide into niobium pentoxide, and then heating to 1800°C or higher to reduce and melt it.

[0009] In Patent Document 2, it is proposed to produce black quartz glass containing carbon derived from an organosilicon compound by reacting a volatile organosilicon compound that can serve as a carbon source with silica porous glass in the gas phase, and then heating and firing it at a temperature of 1200°C or higher and 2000°C or lower.

[0010] In Patent Document 3, it is proposed to produce black quartz glass as a composite material having a matrix of molten silica in which regions of elemental Si are embedded by wet mixing molten silica powder obtained by pulverizing molten quartz glass and silicon-containing powder, then molding by casting and drying, and heating the obtained molded body at a sintering temperature below the melting temperature of silicon, 1350 to 1435°C.

[0011] Patent document 4 proposes a colored glass sintered body in which carbon is dispersed as colored particles in a volume ratio of 0.1% to 30% in a matrix of the glass sintered body.

[0012] Patent document 5 discloses a TiO2-containing silica glass. As a method for manufacturing this silica glass, a method is proposed in which soot obtained by flame hydrolysis of a gasifiable Si precursor and a Ti precursor is deposited, and then fluorine is added to a porous TiO2-SiO2 glass body, and finally the temperature is raised to a vitrification temperature to obtain black quartz glass.

[0013] Patent document 6 discloses a colored alumina sintered body. This sintered body is obtained by mixing Al2O3, TiO2, Cr2O3, and CaO, SiO2, and MgO as sintering aid components, and firing in a reducing atmosphere. Prior art literature

[0014] The entire description of Japanese Patent Publication No. 2014-94864, Japanese Patent Publication No. 2013-1628, Japanese Patent Publication No. 2020-73440, Japanese Patent Publication No. 2003-146676, Japanese Patent Publication No. 2005-194118, and Japanese Patent Publication No. 2000-327405 is incorporated herein by reference as a particular disclosure. The problem to be solved

[0015] However, the black quartz glass described in Patent Document 1 sometimes lacked sufficient color uniformity when scaled up and faced challenges in productivity. In addition, there was difficulty in applying it to the semiconductor manufacturing field because the niobium compound it contained could cause contamination during the process in which it is used.

[0016] The black quartz glass described in Patent Document 2 also had issues with color uniformity and was difficult to scale up. In addition, there was a concern that the carbon contained therein would be generated as a particle during the process of use and cause contamination, making it difficult to apply to the semiconductor manufacturing field.

[0017] There were cases where the color uniformity was insufficient even with the type of black quartz glass described in Patent Document 3 when it was scaled up. Furthermore, there were challenges regarding scaling up due to limitations in casting molding. In addition, the casting molding and drying operations were cumbersome, requiring a long time for manufacturing, and there were challenges regarding productivity.

[0018] There was a problem in that the black quartz glass of the type described in Patent Document 4 also had insufficient color uniformity when enlarged, and when enlarged, the risk of breakage during sintering of the molded body increased, making it impossible to obtain large black quartz glass. In addition, there was difficulty in applying it to the semiconductor manufacturing field because there was a risk of contamination caused by carbon being generated in the process where it is used as a particle.

[0019] The TiO2-containing silica glass described in Patent Document 5 required a process for depositing soot, and its manufacturing was complex and required cumbersome operations, which presented challenges regarding productivity. In addition, it was difficult to increase the size, and even if it could be increased in size, there were cases where the color uniformity was insufficient.

[0020] The colored alumina sintered body described in Patent Document 6 has grain boundaries, which causes problems such as particle detachment during thinning in the process of use, thereby lowering the product yield. Additionally, some of the raw materials for manufacturing are difficult to obtain as high-purity powder, and Mg and Ca, which are undesirable elements in the semiconductor manufacturing process, are essential, so there was also a problem that it is difficult to apply to the semiconductor manufacturing process.

[0021] The black quartz glass obtained by the aforementioned conventional methods has issues with color uniformity and contamination when scaled up, and the manufacturing method for black quartz glass faces challenges in scaling up and productivity. Meanwhile, colored alumina sintered bodies have challenges such as reduced yield caused by grain boundaries, difficulty in obtaining certain raw materials, and the necessity of elements avoided in semiconductor manufacturing processes.

[0022] The problem that the present invention aims to solve is to provide black quartz glass that has excellent light-blocking properties, is not likely to cause contamination during the process of use, has sufficient color uniformity when scaled up, and allows for the production of large ingots.

[0023] Another problem that the present invention aims to solve is to provide a method for manufacturing black quartz glass that solves the above problem with excellent productivity, even in large ingots.

[0024] Another objective of the present invention is to provide black quartz glass products, such as optical components for spectroscopic cells, light-shielding members for semiconductor manufacturing devices or infrared heating devices, or infrared heat-absorbing / heat-storing members, manufactured using the black quartz glass. means of solving the problem

[0025] The inventors, having conducted a thorough examination to solve the above problem, discovered that a quartz glass having SiO2 as the main component and containing TiO2 and Al2O3 within a predetermined range is a black quartz glass with excellent light-blocking properties, and that this black quartz glass is obtained in a uniform state without cracks or bubbles in the glass by mixing and melting SiO2 powder, TiO2 powder, and Al2O3 powder in a predetermined composition, and thus completed the present invention.

[0026] The present invention is as follows.

[0027] [1]

[0028] Black quartz glass having a composition of 63–65 mass% SiO2, 18–24 mass% TiO2, and 12–17 mass% Al2O3 (provided that the total of SiO2, TiO2, and Al2O3 is 100 mass%).

[0029] [2]

[0030] Black quartz glass described in [1], having an SCE reflectance of 8% or less at wavelengths of 350 nm to 750 nm.

[0031] [3]

[0032] Black quartz glass as described in [1] or [2], having a lightness L* of the L*a*b* display system of 20 or less, an absolute value of saturation a* of 2 or less, and an absolute value of b* of 9 or less.

[0033] [4]

[0034] A black quartz glass described in any one of [1] to [3], having a content of metal impurities other than Si, Ti, and Al of 1 ppm or less.

[0035] [5]

[0036] Black quartz glass described in any one of [1] to [4], having a density of 2.3 g / cm³ or more and 2.8 g / cm³ or less.

[0037] [6]

[0038] Black quartz glass is a black quartz glass described in any one of [1] to [5], wherein the corrosion rate obtained by the following corrosion exposure test is 1 / 5 or less compared to the corrosion rate of fused quartz glass obtained by the same corrosion exposure test.

[0039] Corrosion Exposure Test: (1) Prepare a glass sample with a thickness of 20 mm × 20 mm × 2 mm, form an optical mirror surface on its surface, and then mask a 7 mm × 7 mm area. (2) Use a reactive ion etching device, simultaneously flow CF4 gas, O2 gas, and Ar, set the pressure inside the device to 14 Pa, and etch the entire masked glass surface at 200 W for 4 hours. (3) Remove the mask from the glass surface and measure the step difference between the masked area and the etched non-masked area. (4) Calculate the corrosion rate as step difference / etching time.

[0040] [7]

[0041] The coefficient of thermal expansion in the range of 30℃ to 600℃ is 20×10 -7 / ℃ or higher, 30×10 -7 Black quartz glass described in any one of [1] to [6] with a temperature of / ℃ or lower.

[0042] [8]

[0043] A black quartz glass described in any one of [1] to [7], having a light transmittance of 0.1% or less at a thickness of 1 mm at a wavelength of 200 nm to 3000 nm.

[0044] [9]

[0045] A method for manufacturing black quartz glass comprising mixing 63-65 mass% of SiO2 powder, 18-24 mass% of TiO2 powder, and 12-17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700-1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain black quartz glass as described in any one of [1] to [8].

[0046]

[10]

[0047] The method for manufacturing black quartz glass described in [9] is an oxygen-free atmosphere, reduced pressure of 100 Pa or less, N2 atmosphere, Ar atmosphere, He atmosphere, or a combination thereof.

[0048]

[11]

[0049] A method for manufacturing black quartz glass as described in [9] or

[10] , wherein the shape of the mold into which the mixed powder is filled is similar to the shape after machining, and the volume is 1.01 or more of the shape after machining.

[0050]

[12]

[0051] A product comprising a black quartz glass member using black quartz glass as described in any one of [1] to [8].

[0052]

[13]

[0053] The product described in

[12] , which is an optical component, a light-blocking component, or an infrared heat-absorbing / heat-storing component.

[0054]

[14]

[0055] The product described in

[13] , in which the optical component is a spectroscopic cell, a reflector of a projector, or a connector of an optical fiber, and the light-blocking member is a light-blocking member of a semiconductor manufacturing device or an infrared heating device. Effects of the invention

[0056] According to the present invention, it is possible to provide black quartz glass that is uniform, free of cracks or bubbles, and possesses high light-blocking properties. This black quartz glass is uniform and has excellent light-blocking properties without losing the good processability and low dust emission characteristics of transparent quartz glass. Therefore, it can be advantageously utilized in quartz glass cells for optical analysis, reflectors for projectors, connectors for optical fibers, light-blocking members for semiconductor manufacturing devices or infrared heating devices, and infrared heat absorption / heat storage members. Furthermore, according to the manufacturing method of the present invention, black quartz glass can be easily produced with high purity without losing the good processability and low dust emission characteristics of transparent quartz glass. Specific details for implementing the invention

[0057] Black Quartz Glass

[0058] The black quartz glass of the present invention is described. The black quartz glass of the present invention has a composition in which SiO2 is 63 to 65 mass% as the main component, TiO2 is 18 to 24 mass%, and Al2O3 is 12 to 17 mass%, and the total of SiO2, TiO2, and Al2O3 is 100 mass%. By being within this compositional range, a uniform black quartz glass without cracks or bubbles can be specifically obtained. If the compositional range is exceeded, color stains or the inclusion of bubbles occur, and a uniform glass phase is not formed, resulting in the loss of the good processability and low oscillation properties of transparent quartz glass. The compositional range of the black quartz glass of the present invention is preferably 63.5 to 65.0 mass% for SiO2, 18.5 to 23.5 mass% for TiO2, and 12.5 to 17.0 mass% for Al2O3.

[0059] The black quartz glass of the present invention preferably has an SCE reflectance of 8% or less at a wavelength of 350 nm to 750 nm. The SCE reflectance at a wavelength of 350 nm to 750 nm is measured in accordance with JIS Z 8722. Excellent light-blocking properties are exhibited by having an SCE reflectance of 8% or less. From the perspective of excellent light-blocking properties, it is preferable for the SCE reflectance to be low, preferably 7% or less, and more preferably 5% or less. There is no particular limit on the lower limit of the SCE reflectance, but it is possible for it to be 1%.

[0060] The black quartz glass of the present invention preferably has a lightness L* of the L*a*b* indicator system of 20 or less, and preferably has an absolute value of chroma a* of 2 or less and an absolute value of b* of 9 or less. By having a lightness L* of 20 or less, not only is color staining not occurring, but a sufficient black color can be obtained that does not cause light transmission, stray light, or scattering. Furthermore, by having an absolute value of chroma a* of 2 or less and an absolute value of b* of 9 or less, the hue of the glass becomes blacker, and a black quartz glass having a low SCE reflectance is obtained. It is preferable that the lightness L* is 18 or less, and that the absolute value of chroma a* is 1.8 or less and the absolute value of b* is 8.5 or less, as this results in a blacker hue.

[0061] In the black quartz glass of the present invention, it is preferable that the content of metal impurities other than Si, Ti, and Al be 1 ppm or less for each. By having a metal impurity content of 1 ppm or less, the occurrence of oscillation contamination in semiconductor manufacturing, etc. can be suppressed. In addition, adverse effects on precision caused by fluorescence generation, etc., in fields such as optical analysis can be suppressed. The content of metal impurities other than the Si element can be analyzed, for example, by methods such as atomic absorption spectroscopy.

[0062] The black quartz glass of the present invention may have a density in the range of 2.3 g / cm³ or higher and 2.8 g / cm³ or lower. The density is approximately consistent with the theoretical density of transparent quartz glass obtained by melting and vitrifying TiO2 and Al2O3. The density is preferably in the range of 2.4 g / cm³ or higher and 2.7 g / cm³ or lower.

[0063] The black quartz glass of the present invention can have a corrosion rate of 1 / 5 or less of the corrosion rate of molten quartz glass under a corrosive environment in which CF4 gas, O2 gas, and Ar are simultaneously flowed using a reactive ion etching device (200W). The molten quartz glass used as a control is produced by heating and melting natural quartz powder with an oxyhydrogen burner. By using such black quartz glass with excellent corrosion resistance as a component for semiconductor manufacturing, a component for liquid crystal manufacturing, a component for MEMS manufacturing, etc., it is possible to significantly reduce particle generation or slip even in a corrosive environment.

[0064] The black quartz glass of the present invention has a thermal expansion coefficient of 20×10 -7 / ℃ or higher, 25×10 -7 It may be / ℃ or lower. The thermal expansion coefficient of alumina ceramics is 80×10 -7 / ℃, the coefficient of thermal expansion of titania ceramics is 70–100×10 -7 Compared to / ℃, the expansion rate is about 1 / 3 to 1 / 4 smaller. Therefore, it can be preferably used in environments where dimensional accuracy is required at high temperatures, such as the optical system of a projector.

[0065] The black quartz glass of the present invention preferably has a light transmittance of 0.1% or less at a wavelength of 200 nm to 3000 nm at a thickness of 1 mm. The light transmittance at a wavelength of 200 nm to 3000 nm is measured by a spectrophotometer. Excellent light-blocking properties are exhibited by having a light transmittance of 0.1% or less. From the perspective of excellent light-blocking properties, it is preferable for the light transmittance to be low, preferably 0.07% or less, and more preferably 0.05% or less. There is no particular limit on the lower limit of the light transmittance, but it may be 0.01%.

[0066] Method for manufacturing black quartz glass

[0067] The method for manufacturing black quartz glass of the present invention is described.

[0068] The method for manufacturing black quartz glass of the present invention comprises mixing 63-65 mass% of SiO2 powder, 18-24 mass% of TiO2 powder, and 12-17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700-1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain the black quartz glass of the present invention.

[0069] From the perspective of obtaining black quartz glass with low impurity content, it is desirable that SiO2 powder, TiO2 powder, and Al2O3 powder be high-purity powders. High-purity powders of SiO2 powder, TiO2 powder, and Al2O3 powder can be easily obtained as commercially available products. For high-purity powders, it is desirable that the content of metal impurities other than Si, Ti, and Al is 1 ppm or less for each. Although there are no particular restrictions on the particle size or shape of the raw powders, it is desirable to appropriately select the particle size or shape of each raw material so that the three components are uniformly mixed and dispersed. In addition, from the perspective of facilitating the melting of the mixed powder, it is desirable that the particle size be relatively small, and for example, the average particle size may be in the range of 0.1 to 300 μm.

[0070] Raw materials are mixed in the state of dry powder to obtain raw material powder. The ratios of SiO2 powder, TiO2 powder, and Al2O3 powder are selected from the ranges of 63–65 mass%, 18–24 mass%, and 12–17 mass%, respectively, depending on the composition of the black quartz glass. Typically, molten SiO2, TiO2, and Al2O3 generate a large amount of fragmentation, cracks, and visible bubbles, and the resulting glass is not suitable for practical use. However, the inventors' investigation revealed that within the compositional range of the present invention, a black quartz glass is obtained that is surprisingly uniform, free of fragmentation, cracks, and bubbles. Furthermore, the obtained quartz glass was a black quartz glass with high shielding properties that did not lose good processability and low oscillation properties. Mixing of raw material powders can be achieved using general mixing devices such as a stirred mixer, ball mill, rocking mixer, cross mixer, and V-mixer.

[0071] The raw material powder obtained by mixing is filled into a mold of the desired shape. There are no particular restrictions on the shape of the mold, but it is desirable to have a volume of at least 1.01 times that of the shape after machining, and to efficiently obtain a product close to the shape of the product after machining. There are no particular restrictions on the mold, but for example, a carbon-based mold is possible.

[0072] Melting of the raw material powder is performed by heating the powder raw material filled in a mold in an oxygen-free atmosphere at a maximum temperature of 1700 to 1900°C, preferably 1750 to 1850°C. If the maximum temperature is lower than 1700°C, vitrification becomes insufficient. If it exceeds 1900°C, vaporization of SiO2 begins, which is undesirable. An oxygen-free atmosphere is, for example, a reduced pressure of 100 Pa or less, an N2 atmosphere, an Ar atmosphere, a He atmosphere, or a combination thereof. For example, the pressure may be reduced to 100 Pa or less followed by an N2, Ar, or He atmosphere, or the pressure may be further reduced to a reduced pressure N2, Ar, or He atmosphere. By heating and melting in an oxygen-free atmosphere to vitrify, black quartz glass can be obtained. Even if vitrification is performed by heating and melting in an oxygen-containing atmosphere, it is difficult to achieve blackening, or blackened quartz glass cannot be obtained. There is no particular limit to the heating and melting time, but for example, it is 0.1 to 10 hours. However, it is not intended to be limited to this range. After melting, the black quartz glass ingot of the present invention is obtained by cooling to room temperature and separating from the mold.

[0073] The black quartz glass ingot obtained through the aforementioned process can be processed by a processing machine such as a band saw, wire saw, or core drill used to manufacture quartz components to obtain a black quartz glass product.

[0074] The black quartz glass obtained in this way has a sufficient black color that is free of color stains and does not cause light transmission, stray light, or scattering, and is useful in the field of optics in general.

[0075] <Product containing black quartz glass components>

[0076] The present invention comprises a product including a black quartz glass member using the black quartz glass of the present invention. The black quartz glass member may be, for example, an optical component, a light-shielding member, or an infrared heat-absorbing / heat-storing member. The optical component is, for example, a spectroscopic cell, a reflector of a projector, or a connector of an optical fiber, and the light-shielding member is, for example, a light-shielding member of a semiconductor manufacturing device or an infrared heating device. However, it is not intended to be limited to these members.

[0077] The black quartz glass of the present invention does not contain repulsive elements in the semiconductor manufacturing process and is preferred for use in components of heat treatment devices used in semiconductor manufacturing. For example, in a wafer heat treatment device, by configuring the portion other than the surface transmitting infrared rays for heating with the black quartz glass of the present invention, heat radiated outside the furnace can be efficiently shielded, thereby enabling improvements in the energy industry and uniformity of the temperature distribution inside the furnace.

[0078] [Example]

[0079] The present invention will be specifically described below by way of examples, but the present invention is not limited to examples.

[0080] Sample characteristics were measured as follows.

[0081] (1) The density of the sample was measured by the Archimedes method.

[0082] (2) The SCE reflectance was measured in accordance with JIS Z 8722 using a spectrophotometer after processing the sample to a thickness of 7 mm. The highest value was recorded in the wavelength range of 360 to 740 nm.

[0083] (3) The lightness L* and saturation a*,b* of the L*a*b* display system were measured using a spectrophotometer in accordance with JIS Z 8722.

[0084] (4) The thermal expansion coefficient was measured by thermomechanical analysis (TMA method) under conditions of 30 to 600°C after processing the sample into 3×4×20 mmL.

[0085] (5) Light transmittance was measured in the range of 200 to 3000 nm using a spectrophotometer after processing the sample to a thickness of 1 mm.

[0086] (6) Corrosion exposure test for measuring corrosion rate:

[0087] (1) Prepare a glass sample with a thickness of 20 mm × 20 mm × 2 mm, form an optical mirror surface on its surface, and then cover a 7 mm × 7 mm area. (2) Using a reactive ion etching device, simultaneously flow CF4 gas, O2 gas, and Ar, set the pressure inside the device to 14 Pa, and etch the entire masked glass surface at 200 W for 4 hours. (3) Remove the mask from the glass surface and measure the step difference between the masked area and the etched non-masked area. (4) Calculate the etching rate as step difference / etching time. The fused quartz glass used as a control is made by heating and melting natural quartz powder with an oxyhydrogen burner.

[0088] (Example 1)

[0089] SiO2 powder with a metal impurity content other than Si of 1 ppm or less, TiO2 powder with a metal impurity content other than Ti of 1 ppm or less, and Al2O3 powder with a metal impurity content other than Al of 1 ppm or less were prepared. 64.5 mass% of SiO2 powder, 18.6 mass% of TiO2 powder, and 16.9 mass% of Al2O3 powder were mixed using a ball mill without the use of a solvent. The obtained raw powders were filled into a mold and melted by heating at a maximum temperature of 1800°C for 20 minutes in a nitrogen atmosphere. After melting, the mixture was cooled to room temperature to obtain black quartz glass. The physical properties of the obtained black quartz glass were as follows: density 2.6 g / cm³, SCE reflectance 3.3% or less, light transmittance 0.05% or less in the range of 200–3000 nm, and thermal expansion coefficient 25 × 10⁻⁶ -7In the L*a*b* indicator system at / ℃, the lightness L* was 8.9, the chroma a* was 1.1, and b* was -6.8. The corrosion rate in the corrosion exposure test was 9.55 nm / min, which was 1 / 5.4 compared to 51.79 nm / min of fused quartz glass. The obtained black quartz glass was visually confirmed to have a sufficient black color that does not cause light transmission, stray light, or scattering, and to be aesthetically excellent with no bubbles, cracks, or color stains.

[0090] (Example 2)

[0091] The same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1 were used, and 63.9 mass% of SiO2 powder, 23.2 mass% of TiO2 powder, and 12.9 mass% of Al2O3 powder were mixed using a ball mill without the use of a solvent. The obtained raw powder was filled into a mold and melted by heating at a maximum temperature of 1800°C for 20 minutes in a nitrogen atmosphere. After melting, it was cooled to room temperature to obtain black quartz glass. The physical properties of the obtained black quartz glass were as follows: density 2.6 g / cm³, SCE reflectance 4.1% or less, light transmittance 0.06% or less in the range of 200–3000 nm, and thermal expansion coefficient 28 × 10⁻⁶ -7 In the L*a*b* indicator system at / ℃, the lightness L* was 13.1, the chroma a* was 0.6, and the b* was -7.1. The corrosion rate in the corrosion exposure test was 9.92 nm / min, which was 1 / 5.2 compared to 51.79 nm / min of fused quartz glass. The obtained black quartz glass was visually confirmed to have a sufficient black color that does not cause light transmission, stray light, or scattering, and to be aesthetically excellent with no bubbles, cracks, or color stains.

[0092] (Comparative Example 1)

[0093] The same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1 were used, and 85.4 mass% of SiO2 powder, 11.2 mass% of TiO2 powder, and 3.4 mass% of Al2O3 powder were mixed in a ball mill without using a solvent. The obtained raw powder was filled into a mold and melted by heating at a maximum temperature of 1800°C for 20 minutes in a nitrogen atmosphere. After melting, it was cooled to room temperature. The occurrence of color stains, bubbles, and cracks in the obtained molten material was visually confirmed.

[0094] (Comparative Example 2)

[0095] The same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1 were used, and 51.0 mass% of SiO2 powder, 24.0 mass% of TiO2 powder, and 25.0 mass% of Al2O3 powder were mixed in a ball mill without using a solvent. The obtained raw powder was filled into a mold and melted by heating at a maximum temperature of 1800°C for 20 minutes in a nitrogen atmosphere. After melting, it was cooled to room temperature. The occurrence of color stains, bubbles, and cracks in the obtained molten material was visually confirmed.

[0096] [Table 1]

[0097]

[0098] [Industrial Applicability]

[0099] The present invention is useful in fields related to the use and manufacture of black quartz glass. According to the method for manufacturing black quartz glass of the present invention, large black quartz glass with uniform and excellent light-blocking properties can be manufactured economically and efficiently without losing the good processability and low emission properties of transparent quartz glass. The black quartz glass of the present invention can be preferably used in optical components such as quartz glass cells for optical analysis, reflectors for projectors, and optical fiber connectors, as well as in light-blocking members for semiconductor manufacturing devices or infrared heating devices, and infrared heat absorption / heat storage members.

Claims

Claim 1 A black quartz glass having a composition of 63–65 mass% SiO2, 18–24 mass% TiO2, and 12–17 mass% Al2O3 (provided that the total of SiO2, TiO2, and Al2O3 is 100 mass%), wherein the lightness L* of the L*a*b* indicator system is 20 or less, the absolute value of the chroma a* is 2 or less, and the absolute value of the b* is 9 or less. Claim 2 Black quartz glass according to claim 1, having an SCE reflectance of 8% or less at a wavelength of 350 nm to 750 nm. Claim 3 Black quartz glass according to claim 1 or 2, wherein the content of metal impurities other than Si, Ti, and Al is 1 ppm or less for each. Claim 4 Black quartz glass according to claim 1 or 2, having a density of 2.3 g / cm³ or more and 2.8 g / cm³ or less. Claim 5 In claim 1 or 2, the black quartz glass is a black quartz glass in which the corrosion rate obtained by the following corrosion exposure test is 1 / 5 or less compared to the corrosion rate of fused quartz glass obtained by the same corrosion exposure test: Corrosion exposure test: (1) Prepare a glass sample with a thickness of 20 mm × 20 mm × 2 mm, form an optical mirror surface on its surface, and then mask a 7 mm × 7 mm portion, (2) use a reactive ion etching device to simultaneously flow CF4 gas, O2 gas, and Ar, set the pressure inside the device to 14 Pa, and etch the entire masked glass surface at 200 W for 4 hours, (3) remove the mask from the glass surface and measure the step difference between the masked portion and the corroded non-masked portion, and (4) calculate the corrosion rate as step difference / etching time. Claim 6 In claim 1 or 2, the coefficient of thermal expansion in the range of 30℃ to 600℃ is 20×10 -7 / ℃ or higher, 30×10 -7 Black quartz glass at / ℃ or lower. Claim 7 Black quartz glass according to claim 1 or 2, wherein the light transmittance at a wavelength of 200 nm to 3000 nm is 0.1% or less at a thickness of 1 mm. Claim 8 A method for manufacturing black quartz glass comprising mixing 63-65 mass% of SiO2 powder, 18-24 mass% of TiO2 powder, and 12-17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700-1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain the black quartz glass described in claim 1 or 2. Claim 9 A method for manufacturing black quartz glass according to claim 8, wherein the oxygen-free atmosphere is a reduced pressure of 100 Pa or less, an N2 atmosphere, an Ar atmosphere, a He atmosphere, or a combination thereof. Claim 10 A method for manufacturing black quartz glass according to claim 8, wherein the mold for filling the mixed powder has a shape similar to the shape of the black quartz glass obtained from the mold after mechanical processing, and the mold has a volume of at least 1.01 times the volume of the black quartz glass obtained from the mold after mechanical processing. Claim 11 A product comprising a black quartz glass member using the black quartz glass described in paragraph 1 or 2. Claim 12 In paragraph 11, the product, wherein the black quartz glass member is an optical component, a light-shielding member, or an infrared heat-absorbing / heat-storing member. Claim 13 A product according to Clause 12, wherein the optical component is a spectroscopic cell, a projector reflector, or a fiber optic connector, and the light-shielding member is a light-shielding member of a semiconductor manufacturing device or an infrared heating device. Claim 14 delete

Images