Black quartz glass and its manufacturing method

Abstract

To provide black quartz glass that has excellent light shielding property, is less in probability of causing contamination in a process used, has sufficient uniformity of a color when formed into a large size, and can form a large-sized ingot, a method of capable of manufacturing with excellent productivity even the black quartz glass irrespective of a large-sized ingot, and a black quartz glass product using the black quartz glass.SOLUTION: Black quartz glass composed of 63 to 65 mass% of SiO2, 18 to 24 mass% of TiO2, and 12 to 17 mass% of Al2O3 (a total of SiO2, TiO2 and Al2O3 is 100 mass%). A method of manufacturing black quartz glass, comprising mixing 63 to 65 mass% of SiO2 powder, 18 to 24 mass% of TiO2 powder and 12 to 17 mass% of Al2O3 powder, after filling mixed powder into a mold, melting at a maximum temperature at 1700 to 1900°C in an anoxic atmosphere and cooling to room temperature to obtain the black quartz glass. A product containing a black quartz glass member using the black quartz glass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to black quartz glass, a method for producing the same, and black quartz glass products. More specifically, the present invention relates to black quartz glass that can be used for quartz glass cells for optical analysis, projector reflectors, optical fiber connectors, light-shielding materials for semiconductor manufacturing equipment and infrared heating equipment, infrared heat absorption / storage materials, etc., and to a method for efficiently producing this black quartz glass. [Background technology]

[0002] Quartz glass, with its excellent optical transparency from the ultraviolet to infrared range, low thermal expansion, and chemical resistance, is used in a variety of applications, including lighting equipment, optical instrument components, semiconductor industry components, and laboratory equipment. Among these applications, black glass, which is made by adding trace amounts of transition metal oxides to quartz glass, is used in areas where localized light blocking is required, and is used in optical instrument components such as quartz glass cells for optical analysis. However, in recent years, the miniaturization and thinning of components has led to the insufficient light blocking ability of conventional black glass, creating a demand for black quartz glass with better light blocking properties.

[0003] Furthermore, in projector applications, as bulbs become brighter to make the projection screen brighter, there is a demand for black quartz glass that can efficiently block leaked light from the reflector to prevent adverse effects on the optical system inside the projector.

[0004] In optical fiber applications, it is necessary to prevent diffuse reflection caused by leaked light from connectors that connect optical fibers, but as optical transmission density increases, there is a demand for black quartz glass with even higher light-blocking properties.

[0005] Furthermore, quartz glass has features such as high heat resistance and high chemical purity, and is often used in semiconductor manufacturing jigs, etc. However, in recent years, heat loss has become a problem in the heat treatment process of semiconductor manufacturing, and in heating processes using infrared light, there is a need for shielding materials from infrared radiation on objects other than the object to be heated, and for infrared heat absorption / heat storage materials to efficiently heat the object to be heated. For this reason, there is a need for the development of black quartz glass that effectively shields infrared rays, has excellent infrared heat absorption / heat storage properties, is capable of manufacturing large components, and does not contain metal impurities that cause process contamination.

[0006] Conventionally, the following black quartz glass containing silica as a main component has been known.

[0007] For example, Patent Document 1 proposes a method for producing black quartz glass by mixing quartz glass powder with niobium pentachloride, converting the niobium pentachloride to niobium pentoxide, and then heating the mixture to 1800°C or higher for reduction and melting.

[0008] Patent Document 2 proposes that a volatile organosilicon compound that can serve as a carbon source is subjected to a gas-phase reaction with silica porous glass, followed by heating and firing at a temperature of 1200°C or higher and 2000°C or lower to produce black quartz glass containing carbon derived from the organosilicon compound.

[0009] Patent Document 3 proposes the production of black quartz glass as a composite material having a fused silica matrix in which regions of elemental Si are embedded, by wet mixing fused silica powder, which is made by powdering fused quartz glass, with a silicon-containing powder, then molding the mixture by a casting method, drying the mixture, and heating the resulting molded body at a sintering temperature of 1350 to 1435°C, which is lower than the melting point of silicon.

[0010] 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 the matrix of the glass sintered body.

[0011] Patent Document 5 discloses TiO2-containing silica glass. As a method for producing this silica glass, the method proposes a method in which a porous TiO2-SiO2 glass body is obtained by depositing soot obtained by flame hydrolysis of a gasifiable Si precursor and a Ti precursor, and then the body is heated to the vitrification temperature to obtain black quartz glass.

[0012] Patent Document 6 discloses a colored alumina sintered body. This sintered body is obtained by mixing Al2O3, TiO2, Cr2O3, and sintering aid components CaO, SiO2, and MgO, and firing the mixture in a reducing atmosphere. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2014-94864 A (Claims) [Patent Document 2] JP 2013-1628 A (Claims) [Patent Document 3] JP 2020-73440 A (Claims) [Patent Document 4] JP 2003-146676 A (Claims) [Patent Document 5] JP 2005-194118 A (Claims and Best Mode for Carrying Out the Invention) [Patent Document 6] JP 2000-327405 A (Claims) Summary of the Invention [Problem to be solved by the invention]

[0014] However, the black quartz glass described in Patent Document 1 sometimes lacks sufficient color uniformity when made large, posing a problem in productivity. In addition, the niobium compound contained therein may cause contamination in the process where it is used, making it difficult to apply to the semiconductor manufacturing field.

[0015] The black quartz glass described in Patent Document 2 also has problems with color uniformity, making it difficult to make it large. Furthermore, the carbon contained in the material may be generated as particles during the process of use, causing contamination, making it difficult to apply the material to the semiconductor manufacturing field.

[0016] The type of black quartz glass described in Patent Document 3 also sometimes had insufficient color uniformity when made large. Furthermore, limitations on slip casting posed problems when making it large. Furthermore, the slip casting and drying procedures were complicated, requiring a long manufacturing time, posing a problem in productivity.

[0017] The type of black quartz glass described in Patent Document 4 also has the problem that color uniformity may not be sufficient when it is made large, and furthermore, when it is made large, the risk of breakage during sintering of the molded body increases, making it difficult to obtain large black quartz glass. In addition, there is a risk that carbon particles will be generated in the process of using it and cause contamination, making it difficult to apply it to the semiconductor manufacturing field.

[0018] The TiO2-containing silica glass described in Patent Document 5 requires a soot deposition process, which makes the manufacturing process complicated and cumbersome, resulting in productivity issues. Furthermore, it is difficult to increase the size, and even if it is possible to increase the size, the color uniformity may not be sufficient.

[0019] The colored alumina sintered body described in Patent Document 6 has problems such as particle shedding during thinning in the process of use due to the presence of grain boundaries, which reduces the product yield. In addition, it is not easy to obtain high-purity powders of some of the raw materials used in the production, and furthermore, Mg and Ca, which are avoidable elements in the semiconductor production process, are essential, making it difficult to apply the product to the semiconductor production process.

[0020] The black quartz glass obtained by the above-mentioned conventional methods has problems of color uniformity and contamination when made large, and the manufacturing method of black quartz glass has problems of being difficult to make large and has problems in productivity. On the other hand, colored alumina sintered bodies have problems of reduced yield due to grain boundaries, difficulty in obtaining some raw materials, and the necessity of elements that are repulsive to the semiconductor manufacturing process.

[0021] The problem to be solved by the present invention is to provide black quartz glass that has excellent light-shielding properties, is not likely to cause contamination during the process in which it is used, has sufficient color uniformity when made large, and can be used to make large ingots.

[0022] Another problem that the present invention aims to solve is to provide a method for producing black quartz glass that solves the above problems with excellent productivity, even in the case of large ingots.

[0023] A further object of the present invention is to provide black quartz glass products, such as optical components such as spectroscopic cells, light-shielding members for semiconductor manufacturing equipment and infrared heating equipment, and infrared heat absorption / heat storage members, which are manufactured using the black quartz glass. [Means for solving the problem]

[0024] As a result of extensive research into solving the above problems, the inventors discovered that quartz glass containing SiO2 as the main component and TiO2 and Al2O3 within specified ranges is black quartz glass with excellent light-blocking properties, and that this black quartz glass can be obtained uniformly and without cracks or bubbles in the glass by mixing and melting SiO2 powder, TiO2 powder, and Al2O3 powder in a specified composition, which led to the completion of the present invention.

[0025] The present invention is as follows. [1] Black quartz glass having a composition of 63 to 65 mass% SiO2, 18 to 24 mass% TiO2, and 12 to 17 mass% Al2O3 (however, the total of SiO2, TiO2, and Al2O3 is 100 mass%). [2] The black quartz glass according to [1], which has an SCE reflectance of 8% or less in the wavelength range of 350 nm to 750 nm. [3] L * a * b * Display brightness L * is 20 or less, saturation a * The absolute value of is 2 or less and b * The black quartz glass according to [1] or [2], wherein the absolute value of [4] The black quartz glass according to any one of [1] to [3], wherein the content of metal impurities other than Si, Ti, and Al is each 1 ppm or less. [5] Density is 2.3g / cm 3 More than 2.8g / cm 3 The black quartz glass according to any one of [1] to [4] below. [6] The black quartz glass according to any one of [1] to [5], wherein the corrosion rate obtained by the following corrosion exposure test is 1 / 5 or less of the corrosion rate of fused quartz glass obtained by the same corrosion exposure test. Corrosion exposure test: (1) A 20mm x 20mm x 2mm thick glass sample is prepared, an optical mirror surface is formed on its surface, and then a 7mm x 7mm section is masked. (2) Using a reactive ion etching device, the entire masked glass surface is etched for 4 hours at 200W with CF4 gas, O2 gas, and Ar gas flowing simultaneously, with the internal pressure set to 14Pa. (3) The mask is removed from the glass surface, and the height difference between the masked area and the corroded, unmasked area is measured. (4) The corrosion rate is calculated by dividing the height difference by the etching time. [7] The thermal expansion coefficient in the range of 30℃ to 600℃ is 20×10 -7 / ℃ or more, 30×10 -7 The black quartz glass according to any one of [1] to [6], wherein the temperature is 100°C or lower. [8] The black quartz glass according to any one of [1] to [7], which has a light transmittance of 0.1% or less at a wavelength of 200 nm to 3000 nm at a thickness of 1 mm. [9] A method for producing black quartz glass according to any one of [1] to [8], comprising mixing 63 to 65 mass% of SiO2 powder, 18 to 24 mass% of TiO2 powder, and 12 to 17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700 to 1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain the black quartz glass according to any one of [1] to [8].

[10] [9] The method for producing black quartz glass according to [9], wherein the oxygen-free atmosphere is a reduced pressure of 100 Pa or less, a N2 atmosphere, an Ar atmosphere, a He atmosphere, or a combination thereof.

[11] The method for producing black quartz glass according to [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.

[12] A product comprising a black quartz glass member using the black quartz glass according to any one of [1] to [8].

[13] The product according to

[12] , wherein the black quartz glass member is an optical component, a light-shielding component, or an infrared heat absorption / heat storage component.

[14] The product according to

[13] , wherein the optical component is a spectroscopic cell, a projector reflector, or an optical fiber connector, and the light-shielding member is a light-shielding member for semiconductor manufacturing equipment or infrared heating equipment. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide black quartz glass that is uniform, free of cracks and bubbles, and has high light-shielding properties. This black quartz glass is uniform and has excellent light-shielding properties without losing the excellent processability and low dust generation properties of transparent quartz glass. Therefore, it is suitable for use in quartz glass cells for optical analysis, projector reflectors, optical fiber connectors, light-shielding members for semiconductor manufacturing equipment and infrared heating devices, infrared heat absorption / storage members, etc. Furthermore, according to the manufacturing method of the present invention, it is possible to easily produce black quartz glass that is high in purity and does not lose the excellent processability and low dust generation properties of transparent quartz glass. DETAILED DESCRIPTION OF THE INVENTION

[0027] <Black quartz glass> The black quartz glass of the present invention will now be described. The black quartz glass of the present invention has a composition consisting primarily of 63-65 mass% SiO2, 18-24 mass% TiO2, and 12-17 mass% Al2O3, with the total of SiO2, TiO2, and Al2O3 being 100 mass%. This composition range uniquely enables the production of uniform, crack- and bubble-free black quartz glass. Outside this composition range, color unevenness and the inclusion of bubbles occur, resulting in an inconsistent glass phase and a loss of the excellent processability and low dust generation properties of transparent quartz glass. The composition range of the black quartz glass of the present invention is preferably 63.5-65.0 mass% SiO2, 18.5-23.5 mass% TiO2, and 12.5-17.0 mass% Al2O3.

[0028] The black quartz glass of the present invention preferably has an SCE reflectance of 8% or less at wavelengths of 350 nm to 750 nm. The SCE reflectance at wavelengths of 350 nm to 750 nm is measured in accordance with JIS Z 8722. An SCE reflectance of 8% or less indicates excellent light-blocking properties. From the viewpoint of excellent light-blocking properties, the SCE reflectance is preferably low, preferably 7% or less, and more preferably 5% or less. There is no particular restriction on the lower limit of the SCE reflectance, but it can be 1%.

[0029] The black quartz glass of the present invention is L* a * b * Display brightness L * is preferably 20 or less, and the saturation a * The absolute value of is 2 or less and b * It is preferable that the absolute value of is 9 or less. * By keeping the chroma a below 20, not only will color unevenness not occur, but a sufficiently black color will be obtained without causing light transmission, stray light, or scattering. * The absolute value of is 2 or less and b * When the absolute value of is 9 or less, the color tone of the glass body becomes blacker, and black quartz glass having a low SCE reflectance can be obtained. * is preferably 18 or less, and the saturation a * The absolute value of is 1.8 or less and b * It is preferable that the absolute value of is 8.5 or less, since the color tone becomes blacker.

[0030] The black quartz glass of the present invention preferably contains 1 ppm or less of each of metal impurities other than Si, Ti, and Al. Having a metal impurity content of 1 ppm or less can suppress the occurrence of process contamination in semiconductor manufacturing and the like. It can also suppress the adverse effects on accuracy due to the generation of fluorescence in fields such as optical analysis. The content of metal impurities other than Si element can be analyzed, for example, by atomic absorption spectrometry.

[0031] The black quartz glass of the present invention has a density of 2.3 g / cm 3 More than 2.8g / cm 3 The density can be in the following range. The density is almost equal to the theoretical density of transparent quartz glass melted and vitrified with TiO2 and Al2O3. The density is preferably 2.4 g / cm 3 More than 2.7g / cm 3 The range is as follows:

[0032] The corrosion rate of the black quartz glass of the present invention is less than one-fifth of that of fused quartz glass when subjected to a corrosive environment using a reactive ion etching apparatus (200 W) in which CF4 gas, O2 gas, and Ar gas are simultaneously flowed. The fused quartz glass used as a control was prepared by heating and melting natural quartz powder with an oxyhydrogen burner. Such black quartz glass, with its excellent corrosion resistance, can be used as a component for semiconductor manufacturing, liquid crystal manufacturing, MEMS manufacturing, and the like, significantly reducing particle generation and slippage even in corrosive environments.

[0033] The black quartz glass of the present invention has a thermal expansion coefficient of 20×10 -7 / ℃ or more, 25×10 -7 / °C or less. The thermal expansion coefficient of alumina ceramics is 80×10 -7 / ℃, the thermal expansion coefficient of titania ceramics is 70~100×10 -7 / °C, the expansion rate is about 1 / 3 to 1 / 4 lower than that of the conventional resin. Therefore, it can be used in environments where high temperature and dimensional accuracy are required, such as the optical system of a projector.

[0034] The black quartz glass of the present invention preferably has a light transmittance of 0.1% or less at a thickness of 1 mm in the wavelength range of 200 nm to 3000 nm. The light transmittance in the wavelength range of 200 nm to 3000 nm is measured using a spectrophotometer. A light transmittance of 0.1% or less indicates excellent light-blocking properties. From the viewpoint of excellent light-blocking properties, the light transmittance is preferably low, preferably 0.07% or less, and more preferably 0.05% or less. There is no particular restriction on the lower limit of the light transmittance, but it can be 0.01%.

[0035] <For manufacturing black quartz glass> The method for producing the black quartz glass of the present invention will now be described. The method for producing the black quartz glass of the present invention comprises mixing 63 to 65 mass% of SiO2 powder, 18 to 24 mass% of TiO2 powder, and 12 to 17 mass% of Al2O3 powder, filling the mixed powder into a mold, melting it at a maximum temperature of 1700 to 1900°C in an oxygen-free atmosphere, and cooling it to room temperature to obtain the black quartz glass of the present invention.

[0036] The SiO2 powder, TiO2 powder, and Al2O3 powder are preferably high-purity powders, from the viewpoint of obtaining black quartz glass with a low impurity content. High-purity SiO2 powder, TiO2 powder, and Al2O3 powder are readily available as commercial products. The high-purity powder preferably contains metal impurities other than Si, Ti, and Al at a content of 1 ppm or less. While there are no particular restrictions on the particle size or shape of the raw material powders, it is preferable to appropriately select the particle size and shape of each raw material so that the three components are uniformly mixed and dispersed. Furthermore, from the viewpoint of easy melting of the mixed powder, a relatively small particle size is preferable, and the average particle size can be, for example, in the range of 0.1 to 300 μm.

[0037] The raw materials are mixed in a dry powder state to obtain a 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, melts of SiO2, TiO2, and Al2O3 exhibit phase separation, cracks, and a large number of visible bubbles, making the resulting glass unsuitable for practical use. However, the inventors' investigations have revealed that within the composition range of the present invention, a surprisingly uniform, black quartz glass is obtained, free of phase separation, cracks, and bubbles. Furthermore, the resulting quartz glass exhibits high opacity without losing its excellent processability and low dust generation. The raw material powders can be mixed using common mixing devices such as agitator mixers, ball mills, rocking mixers, cross mixers, and V-type mixers.

[0038] 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 shape similar to the shape after machining and a volume 1.01 times or more larger, from the viewpoint of efficiently obtaining a product close to the shape of the product after machining. There are no particular restrictions on the mold, but it can be, for example, a mold made of carbon.

[0039] The raw material powder is melted by heating the powder raw material filled into a mold in an oxygen-free atmosphere to a maximum temperature of 1700 to 1900°C, preferably 1750 to 1850°C. A maximum temperature lower than 1700°C results in insufficient vitrification. A temperature higher than 1900°C is undesirable because SiO2 vaporization begins. The oxygen-free atmosphere can be, 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 can be reduced to 100 Pa or less and then replaced with an N2, Ar, or He atmosphere, or the pressure can be further reduced to a reduced pressure N2, Ar, or He atmosphere. Black quartz glass can be obtained by melting and vitrifying the raw material in an oxygen-free atmosphere. Heating and melting and vitrifying the raw material in an oxygen-containing atmosphere can be difficult to blacken, or no blackened quartz glass can be obtained. The melting time is not particularly limited, but is, for example, 0.1 to 10 hours. However, it is not intended to be limited to this range. After melting, the ingot of black quartz glass of the present invention is obtained by cooling it to room temperature and removing it from the mold.

[0040] The black quartz glass ingot obtained through the above steps can be processed using a processing machine such as a band saw, wire saw, or core drill that is used to manufacture quartz components, to obtain a black quartz glass product.

[0041] The black quartz glass thus obtained has a sufficiently black color without color unevenness and does not transmit light, cause stray light, or scatter light, making it useful in the optical field in general.

[0042] <Products containing black quartz glass components> The present invention encompasses products containing black quartz glass members made from the black quartz glass of the present invention. The black quartz glass member can be, for example, an optical component, a light-shielding component, or an infrared heat absorption / heat storage component. Examples of optical components include spectroscopic cells, projector reflectors, and optical fiber connectors, and examples of light-shielding components include light-shielding components for semiconductor manufacturing equipment or infrared heating equipment. However, the present invention is not intended to be limited to these components.

[0043] The black quartz glass of the present invention does not contain any elements that are harmful to semiconductor manufacturing processes, making it suitable for use in heat treatment equipment used in semiconductor manufacturing. For example, in wafer heat treatment equipment, by constructing the entire equipment except for the surfaces that transmit infrared rays used for heating out of the black quartz glass of the present invention, it is possible to efficiently block heat radiated outside the furnace, improving energy efficiency and achieving a uniform temperature distribution within the furnace. [Example]

[0044] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. It's not that.

[0045] The sample properties were measured as follows. (1) The density of the samples was measured by the Archimedes method. (2) The SCE reflectance was measured by cutting the sample to a thickness of 7 mm and using a spectrophotometer in accordance with JIS Z 8722. The highest value in the wavelength range of 360 to 740 nm was recorded. (3)L * a * b * Display brightness L * and saturation a * , b * was measured using a spectrophotometer in accordance with JIS Z 8722. (4) The thermal expansion coefficient was measured by processing the sample into 3 × 4 × 20 mmL and measuring it at 30 to 600°C by thermomechanical analysis (TMA). (5) The 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.

[0046] (6) Corrosion exposure test for measuring corrosion rate: (1) A 20mm x 20mm x 2mm thick glass sample is prepared, and after forming an optical mirror surface on its surface, a 7mm x 7mm section is masked. (2) Using a reactive ion etching device, the entire masked glass surface is etched for 4 hours at 200W with CF4 gas, O2 gas, and Ar gas flowing simultaneously, with the internal pressure set to 14Pa. (3) The mask is removed from the glass surface, and the step between the masked area and the corroded, unmasked area is measured. (4) The corrosion rate is calculated as the step difference divided by the etching time. The fused silica glass used as a control was made by heating and melting natural quartz powder with an oxyhydrogen burner.

[0047] Example 1 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% SiO2 powder, 18.6 mass% TiO2 powder, and 16.9 mass% Al2O3 powder were mixed in a ball mill without using a solvent. The resulting raw material powder was filled into a mold and melted by heating in a nitrogen atmosphere at a maximum temperature of 1800°C for 20 minutes. After melting, it was cooled to room temperature to obtain black quartz glass. The physical properties of the resulting black quartz glass were as follows: density: 2.6 g / cm 3 , SCE reflectance is 3.3% or less, light transmittance is 0.05% or less in the range of 200 to 3000 nm, and thermal expansion coefficient is 25 × 10 -7 / ℃、L * a * b * Display brightness L * is 8.9, saturation a * is 1.1, b * The corrosion rate in the corrosion exposure test was 9.55 nm / min, which was 51.79 nm / min, 1 / 5.4 of that of fused silica glass. The black silica glass obtained exhibited a sufficiently dark color that did not transmit light, generate stray light, or scatter, and was visually confirmed to be free of bubbles, cracks, or color unevenness, and to have an excellent aesthetic appearance.

[0048] Example 2 Using the same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1, 63.9 mass% of SiO2 powder, 23.2 mass% of TiO2 powder, and 12.9 mass% of Al2O3 powder were mixed in a ball mill without using a solvent. The obtained raw material powder was filled into a mold and melted by heating in a nitrogen atmosphere at a maximum temperature of 1800°C for 20 minutes. 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 / cm 3 , SCE reflectance is 4.1% or less, light transmittance is 0.06% or less in the range of 200 to 3000 nm, and thermal expansion coefficient is 28 × 10 -7 / ℃, L * a * b * Display brightness L * is 13.1, saturation a * is 0.6, b * The corrosion rate in the corrosion exposure test was 9.92 nm / min, which was 51.79 nm / min, 1 / 5.2 of that of fused silica glass. The black silica glass obtained exhibited a sufficiently dark color that did not transmit light, generate stray light, or scatter, and was visually confirmed to be free of bubbles, cracks, or color unevenness, and to have an excellent aesthetic appearance.

[0049] (Comparative Example 1) Using the same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1, 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 resulting raw material powder was filled into a mold and melted by heating in a nitrogen atmosphere at a maximum temperature of 1800°C for 20 minutes. After melting, it was cooled to room temperature. The resulting melt was visually inspected for color unevenness, bubbles, and cracks.

[0050] (Comparative Example 2) Using the same SiO2 powder, TiO2 powder, and Al2O3 powder as in Example 1, 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 resulting raw material powder was filled into a mold and melted by heating in a nitrogen atmosphere at a maximum temperature of 1800°C for 20 minutes. After melting, it was cooled to room temperature. The resulting melt was visually inspected for color unevenness, bubbles, and cracks.

[0051] [Table 1] [Industrial Applicability]

[0052] The present invention is useful in fields related to the use and production of black quartz glass. According to the method for producing black quartz glass of the present invention, large, uniform, and highly light-shielding black quartz glass can be produced economically and efficiently without losing the excellent processability and low dust generation properties of transparent quartz glass. The black quartz glass of the present invention can be suitably used for optical components such as quartz glass cells for optical analysis, projector reflectors, and optical fiber connectors, as well as light-shielding materials for semiconductor manufacturing equipment and infrared heating devices, and infrared heat absorption / storage materials.

Claims

1. SiO 2 63 to 65 mass %, TiO 2 18 to 24 mass % of Al 2 O 3 A composition containing 12 to 17 mass % of SiO 2 , TiO 2 and Al 2 O 3 The total of these is 100% by mass, A black quartz glass having a lightness L* of 20 or less, an absolute value of chroma a* of 2 or less, and an absolute value of chroma b* of 9 or less in the L*a*b* display system.

2. The black quartz glass according to claim 1, having an SCE reflectance of 8% or less in the wavelength range of 350 nm to 750 nm.

3. 3. The black quartz glass according to claim 1, wherein the content of metal impurities other than Si, Ti, and Al is each 1 ppm or less.

4. Density is 2.3 g / cm 3 Above, 2.8g / cm 3 The black quartz glass according to any one of claims 1 to 3, wherein:

5. The thermal expansion coefficient in the range of 30°C to 600°C is 20 x 10 -7 / ℃ or more, 30 x 10 -7 The black quartz glass according to any one of claims 1 to 4, wherein the temperature is 100°C or lower.

6. The black quartz glass according to any one of claims 1 to 5, having a light transmittance of 0.1% or less at a thickness of 1 mm in the wavelength range of 200 nm to 3000 nm.

7. SiO 2 Powder 63-65% by mass, TiO 2 Powder 18 to 24% by mass and Al 2 O 3 7. A method for producing black quartz glass, comprising: mixing 12 to 17 mass% of a powder containing 12 to 17 mass% of a crystalline silica powder; filling the mixed powder into a mold; melting the powder at a maximum temperature of 1700 to 1900°C in an oxygen-free atmosphere; and cooling to room temperature to obtain the black quartz glass according to any one of claims 1 to 6.

8. The oxygen-free atmosphere is a reduced pressure of 100 Pa or less, N 2 The method for producing black quartz glass according to claim 7, wherein the atmosphere is a nitrogen atmosphere, an Ar atmosphere, a He atmosphere, or a combination thereof.

9. 9. The method for producing black quartz glass according to claim 7, 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 times the shape after machining.

10. A product comprising a black quartz glass member made of the black quartz glass according to any one of claims 1 to 6.

11. 11. The product according to claim 10, wherein the black quartz glass member is an optical component, a light-shielding component, or an infrared heat absorption / storage component.

12. The product according to claim 11, wherein the optical component is a spectroscopic cell, a projector reflector, or an optical fiber connector, and the light-shielding member is a light-shielding member for semiconductor manufacturing equipment or infrared heating equipment.

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