JP7722875B2 - Black quartz glass and its manufacturing method - Google Patents

Description

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 for quartz glass cells for optical analysis, projector reflectors, optical fiber connectors, light-shielding materials for semiconductor manufacturing equipment and infrared heating equipment, and infrared heat absorption/storage materials, and a method for efficiently obtaining this black quartz glass.

Quartz glass is used in a variety of applications, including lighting equipment, optical equipment components, semiconductor industry materials, and scientific and laboratory equipment, thanks to its excellent optical transparency from the ultraviolet to infrared ranges, low thermal expansion, and chemical resistance. Among these, black glass, 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 equipment components such as quartz glass cells for optical analysis. However, in recent years, as components have become smaller and thinner, the light blocking ability of conventional black glass has sometimes become insufficient, and black quartz glass with better light blocking properties is in demand.

In addition, 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 light leaking from the reflector to prevent adverse effects on the optical system inside the projector.

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 better light-blocking properties.

Furthermore, quartz glass has features such as high heat resistance and high chemical purity, and is often used in semiconductor manufacturing jigs and other applications. However, in recent years, heat loss has become an issue 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 being heated, as well as infrared heat absorption/heat storage materials for efficient heating of the object being heated. For this reason, there is a demand for the development of black quartz glass that effectively shields infrared rays, has excellent infrared heat absorption/heat storage properties, is capable of producing large components, and does not contain metal impurities that cause process contamination.

The following types of black quartz glass, primarily composed of silica, have been known to date:

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 1,800°C or higher for reduction and melting.

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

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

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

Patent Document 5 discloses TiO ₂ -containing silica glass. As a method for producing this silica glass, the method proposes a method in which fluorine is incorporated into a porous TiO ₂ -SiO ₂ glass body obtained by depositing soot obtained by flame hydrolysis of a gasifiable Si precursor and a Ti precursor, and then the temperature is finally raised to the vitrification temperature to obtain black quartz glass.

Patent Document 6 discloses a colored alumina sintered body, which is obtained by mixing _Al2O3 , _TiO2 , _Cr2O3 , and _sintering aid components _CaO , _SiO2 , and MgO, and firing the mixture in a reducing atmosphere.

JP 2014-94864 A (Claims) JP 2013-1628 A (Claims) JP 2020-73440 A (Claims) JP 2003-146676 A (Claims) JP 2005-194118 A (Claims and Best Mode for Carrying Out the Invention) JP 2000-327405 A (Claims)

However, the black quartz glass described in Patent Document 1 sometimes lacks sufficient color uniformity when enlarged, posing productivity issues. Furthermore, the niobium compounds contained in it could cause contamination in processes where they are used, making it difficult to apply to the semiconductor manufacturing field.

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.

The type of black quartz glass described in Patent Document 3 also sometimes lacked sufficient color uniformity when enlarged. Furthermore, limitations on slip casting posed challenges when enlarging the glass. Furthermore, the slip casting and drying procedures were cumbersome, requiring a long manufacturing time, posing productivity challenges.

The type of black quartz glass described in Patent Document 4 also sometimes lacks sufficient color uniformity when made large. Furthermore, when made large, the risk of breakage increases when the compact is sintered, making it difficult to obtain large black quartz glass. In addition, carbon particles are generated during the process of use, which can cause contamination, making it difficult to apply to the semiconductor manufacturing field.

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.

The colored alumina sintered body described in Patent Document 6 has grain boundaries, which causes particle shedding during thinning during use, resulting in reduced product yield. Furthermore, it is difficult to obtain high-purity powders of some of the raw materials used in production, and the body requires Mg and Ca, elements that are avoided in semiconductor manufacturing processes, making it difficult to apply to semiconductor manufacturing processes.

Black quartz glass and other products obtained using the above-mentioned conventional methods have problems with color uniformity and contamination when produced in large sizes, making it difficult to produce large-scale products using this method, and posing productivity challenges. On the other hand, colored alumina sintered bodies have issues with reduced yields due to grain boundaries, difficulty in obtaining some raw materials, and the need for elements that are repulsive to the semiconductor manufacturing process.

The problem that this invention aims to solve is to provide black quartz glass that has excellent light-blocking properties, is not likely to cause contamination during the processes in which it is used, has sufficient color uniformity when made large, and can be used to produce large ingots.

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 large ingots.

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/storage members, all made using the black quartz glass.

As a result of intensive research to solve 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, thereby completing the present invention.

The present invention is as follows.
[1]
Black quartz glass having a composition of 63 to 65 mass % of SiO ₂ , 18 to 24 mass % of TiO ₂ , and 12 to 17 mass % of Al ₂ O ₃ (provided that the total of SiO ₂ , TiO ₂ , and Al ₂ O ₃ is 100 mass %).
[2]
The black quartz glass according to [1], having an SCE reflectance of 8% or less in the wavelength range of 350 nm to 750 nm.
[3]
The black quartz glass according to [1] or [2], wherein the lightness L ^* of the L ^* a ^* b ^* display system is 20 or less, the absolute value of ^the chroma a ^* is 2 or less, and the absolute value of the chroma b* is 9 or less.
[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]
The black quartz glass according to any one of [1] to [4], having a density of 2.3 g/cm ³ or more and 2.8 g/cm ³ or less.
[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 20 mm x 20 mm x 2 mm thick glass sample is prepared, an optical mirror surface is formed on its surface, and then a 7 mm x 7 mm portion is masked. (2) Using a reactive ion etching device, the entire masked glass surface is etched for 4 hours at 200 W with _CF4 gas, _O2 gas, and Ar simultaneously flowing, with the internal pressure set to 14 Pa. (3) The mask is removed from the glass surface, and the height difference between the masked portion and the corroded unmasked portion is measured. (4) The corrosion rate is calculated by height difference/etching time.
[7]
The black quartz glass according to any one of [1] to [6], which has a thermal expansion coefficient in the range of 30°C to 600°C of 20 x 10 ^-7 /°C or more and 30 x 10 ^-7 /°C or less.
[8]
The black quartz glass according to any one of [1] to [7], 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.
[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]
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 N ₂ 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 member, or an infrared heat absorption/heat storage member.
[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.

The present invention makes it possible to provide black quartz glass that is uniform, free of cracks and bubbles, and has high light-blocking properties. This black quartz glass is uniform and has excellent light-blocking properties without losing the excellent processability and low dust generation properties of transparent quartz glass. As a result, it is suitable for use in quartz glass cells for optical analysis, projector reflectors, optical fiber connectors, light-blocking materials for semiconductor manufacturing equipment and infrared heating devices, infrared heat absorption/storage materials, and more. Furthermore, the manufacturing method of the present invention makes it possible to easily produce high-purity black quartz glass without losing the excellent processability and low dust generation properties of transparent quartz glass.

<Black quartz glass>
The black quartz glass of the present invention is described below. The black quartz glass of the present invention has a composition consisting primarily of 63-65% by mass of _SiO2 , 18-24% by mass of _TiO2 , and 12-17% by _mass of _Al2O3 , with the total of _SiO2 , _TiO2 , and _Al2O3 being 100% by mass. This composition range uniquely enables the production _of uniform, crack- and bubble-free black quartz glass. Outside this composition range, color unevenness and bubble inclusions 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% by mass of _SiO2 , 18.5-23.5% by mass of _TiO2 , and 12.5-17.0% by _mass of _Al2O3 .

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 perspective of excellent light-blocking properties, a low SCE reflectance is preferable, 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 can be 1%.

The black quartz glass of the present invention preferably has a lightness L ^* of 20 or less in the L ^* a ^* b ^* display system, and preferably has an absolute value of 2 or less for chroma a ^* and an absolute value of 9 or less for b ^* . A lightness L ^* of 20 or less not only prevents color unevenness but also provides a sufficiently black color that does not cause light transmission, stray light, or scattering. Furthermore, an absolute value of chroma a ^* of 2 or less and an absolute value of b ^* of 9 or less results in a blacker color tone of the glass body, and black quartz glass with low SCE reflectance can be obtained. The lightness L ^* is preferably 18 or less, and an absolute value of chroma a ^* of 1.8 or less and an absolute value of b ^* of 8.5 or less are preferred for a blacker color tone.

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 other processes. It can also suppress the adverse effects on accuracy caused by fluorescence generation in fields such as optical analysis. The content of metal impurities other than Si element can be analyzed, for example, by atomic absorption analysis.

The density of the black quartz glass of the present invention can be in the range of 2.3 g/ ^cm3 or more and 2.8 g/ ^cm3 or less. This density is approximately equal to the theoretical density obtained by fused quartz glass with _TiO2 and _Al2O3 . The density is preferably in the range of 2.4 g/ _cm3 or ^more and 2.7 g/ ^cm3 or less.

The corrosion rate of the black quartz glass of the present invention can be reduced to one-fifth or less of that of fused quartz glass in a corrosive environment using a reactive ion etching apparatus (200 W) in which _CF4 gas, _O2 gas, and Ar 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 excellent corrosion resistance can be used as a component for semiconductor manufacturing, liquid crystal manufacturing, MEMS manufacturing, etc., to significantly reduce particle generation and slippage even in corrosive environments.

The black quartz glass of the present invention can have a thermal expansion coefficient of 20×10 ⁻⁷ /°C or more and 25× ^{10 −7 /} °C or less. This is about one-third to one-quarter of the thermal expansion coefficient of alumina ceramics, which is 80×10 ⁻⁷ /°C, and the thermal expansion coefficient of titania ceramics, which is 70 to 100×10 −7 /°C. As a result, it can be suitably used in environments requiring dimensional accuracy at high temperatures, such as in the optical systems of projectors.

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 wavelengths of 200 nm to 3000 nm. The light transmittance in wavelengths 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 perspective of excellent light-blocking properties, a low light transmittance is preferable, preferably 0.07% or less, and more preferably 0.05% or less. There is no particular limit on the lower limit of light transmittance, but it can be 0.01%.

<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 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.

The _SiO2 powder, _TiO2 powder, and _{Al2O3 powder} are preferably high-purity powders from the viewpoint of obtaining black quartz glass with low impurity content. High-purity _SiO2 powder, _TiO2 powder, and _Al2O3 powder are readily available commercially. 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; for example, the average particle size can be in the range of 0.1 to 300 μm.

The raw materials are mixed in a dry powder state _to obtain a raw material powder. The proportions 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.

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, with a volume at least 1.01 times larger, from the perspective of efficiently obtaining a product that is close to the shape of the product after machining. There are no particular restrictions on the mold, but it can be made of carbon, for example.

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 below 1700°C results in insufficient vitrification. A temperature above 1900°C is undesirable because SiO2 vaporizes. Examples of oxygen-free atmospheres include a reduced pressure of 100 Pa or less, an _N2 atmosphere, an Ar atmosphere, a He atmosphere, or a combination thereof. For example, the atmosphere can be reduced to 100 Pa or less and then replaced with an _N2 , Ar, or He atmosphere, or the atmosphere 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-containing atmosphere. Black quartz glass is difficult to obtain when melting and vitrifying the raw material in an oxygen-containing atmosphere, or black quartz glass cannot 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.

The black quartz glass ingot obtained through the above process can be processed using processing machines such as band saws, wire saws, and core drills that are used to manufacture quartz components to obtain black quartz glass products.

The black quartz glass obtained in this way has no color unevenness and exhibits a sufficiently black color that does not transmit light, cause stray light, or scatter, making it useful in the optical field in general.

<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/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 devices. However, the present invention is not intended to be limited to these components.

The black quartz glass of the present invention does not contain elements that are repulsive 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 all surfaces other than those that transmit infrared rays used for heating from 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 more uniform temperature distribution within the furnace.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The sample properties were measured as follows.
(1) The density of the sample was measured by the Archimedes method.
(2) The SCE reflectance was measured by processing the sample into 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) The lightness L ^* and chroma a ^* , b ^* of the ^{L *a*} b ^* display system were measured in accordance with JIS Z 8722 using a spectrophotometer.
(4) The thermal expansion coefficient was measured by processing the sample into a size of 3×4×20 mmL and measuring it by thermomechanical analysis (TMA) at temperatures of 30 to 600°C.
(5) The light transmittance was measured by processing the sample to a thickness of 1 mm and using a spectrophotometer in the range of 200 to 3000 nm.

(6) Corrosion exposure test for measuring corrosion rate:
(1) A 20 mm x 20 mm x 2 mm thick glass sample is prepared, an optical mirror surface is formed on its surface, and then a 7 mm x 7 mm portion is masked. (2) Using a reactive ion etching device, the entire masked glass surface is etched for 4 hours at 200 W with _CF4 gas, _O2 gas, and Ar simultaneously flowing, with the internal pressure set to 14 Pa. (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/etching time. The fused silica glass used as a control was prepared by heating and melting natural quartz powder with an oxyhydrogen burner.

Example 1
_SiO2 powder, containing 1 ppm or less of each metal impurity other than Si, _TiO2 powder, containing 1 ppm or less of each metal impurity other than Ti, and _Al2O3 powder, containing 1 ppm or less of each metal impurity other than _Al , 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, the mixture was cooled to room temperature to obtain black quartz glass. The physical properties of the resulting black quartz glass were as follows: The density was 2.6 g/cm ³ , the SCE reflectance was 3.3% or less, the light transmittance was 0.05% or less in the range of 200 to 3000 nm, the thermal expansion coefficient was 25×10 ^-7 /°C, the lightness L ^* in the L ^* a ^* b ^* display system was 8.9, the chroma a ^* was 1.1, and the b ^* was -6.8. The corrosion rate in the corrosion exposure test was 9.55 nm/min, which was 1/5.4 of the 51.79 nm/min of fused silica glass. The obtained black quartz glass exhibited a sufficient black color that did not transmit light, generate stray light, or scatter, and it was visually confirmed that it was free of bubbles, cracks, and color unevenness, and had an excellent aesthetic appearance.

Example 2
The same _SiO2 powder, _TiO2 powder, and _{Al2O3 powder} as in Example 1 were used. 63.9% by weight of _SiO2 powder, 23.2% by weight of _TiO2 powder, and 12.9% by weight of _{Al2O3 powder} were mixed in a ball mill without the use of a solvent. The resulting raw powder was filled into a mold and heated to a maximum temperature of 1800°C for 20 minutes in a nitrogen atmosphere to melt it. 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/ ^cm3 , SCE reflectance: 4.1% or less, light transmittance: 0.06% or less in the range of 200 to 3000 nm, coefficient of thermal expansion: 28 x ^10-7 /°C, and lightness (L* ⁾ of 13.1 in the L ^* a ^* b ^* display system, chroma (a ^*) : 0.6, and b ^* : -7.1. The corrosion rate in the corrosion exposure test was 9.92 nm/min, which was 1/5.2 of the 51.79 nm/min of fused silica glass. The obtained black quartz glass exhibited a sufficiently black color that did not transmit light, generate stray light, or scatter, and it was visually confirmed that it was free of bubbles, cracks, and color unevenness, and had an excellent aesthetic appearance.

(Comparative Example 1)
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 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, the mixture was cooled to room temperature. The resulting melt was visually inspected for color unevenness, bubbles, and cracks.

(Comparative Example 2)
Using the same _SiO2 powder, _TiO2 powder, and _{Al2O3 powder} as in Example 1, 51.0 mass% _SiO2 powder, 24.0 mass% _TiO2 powder, and 25.0 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. The resulting melt was visually inspected for color unevenness, bubbles, and cracks.

The present invention is useful in fields related to the use and production of black quartz glass. The method for producing black quartz glass of the present invention makes it possible to economically and efficiently produce large, uniform, and highly light-shielding black quartz glass 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 in 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 (12)

The composition is 63 to 65 mass% of _SiO2 , 18 to 24 mass% of _TiO2 , and 12 to 17 mass% _{of Al2O3} (provided that the total _{of SiO2} , _TiO2 , and _Al2O3 is 100 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. The black quartz glass of claim 1, having an SCE reflectance of 8% or less at wavelengths of 350 nm to 750 nm. 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. The black quartz glass according to any one of claims 1 to 3 , having a density of 2.3 g/cm ³ or more and 2.8 g/cm ³ or less. 5. The black quartz glass according to claim 1, which has a thermal expansion coefficient in the range of 30°C to 600°C of 20 x 10 ^-7 /°C or more and 30 x 10 ^-7 /°C or less. The black quartz glass according to any one of claims 1 to 5 , having a light transmittance of 0.1% or less at a wavelength of 200 nm to 3000 nm at a thickness of 1 mm. A method for producing black quartz glass according to any one of claims 1 to 6, 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 claims 1 to 6 . 8. The method for producing black quartz glass according to claim 7 , 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. 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. A product comprising a black quartz glass member made of the black quartz glass according to any one of claims 1 to 6 . 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. 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.