Black quartz glass and its manufacturing method

Abstract

To provide: black quartz glass excellent in light-shielding, free from risk of the occurrence of contamination in a use process, and sufficient in color uniformity even when enlarged and capable of manufacturing a large-sized ingot; a method capable of manufacturing the black quartz glass with excellent productivity even in a large-sized ingot; and a product manufactured from the black quartz glass.SOLUTION: Black quartz glass includes Si in amount of 0.5-10 mass%, SiO in an amount of 0.1-5 mass%, and the remainder consisting of SiO2 and has an SCE reflectance of 10% or less at a wavelength of 350-750 nm. A method for manufacturing the black quartz glass comprises: pressure-molding powder obtained by mixing and compacting a Si powder of 0.5-10 mass% and an SiO powder of 0.1-5 mass% with (1) fumed silica, (2) the mixed powder of the fumed silica and synthetic silica powder, or (3) the mixed powder of the fumed silica, the synthetic silica powder, and spherical silica; and heating the pressure-molded product in the atmosphere to sinter the fumed silica. A product includes 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 and a manufacturing method thereof. More specifically, the present invention relates to black quartz glass that can be used for quartz glass cells for optical analysis, light shielding members for semiconductor manufacturing equipment and infrared heating equipment, infrared heat absorption / storage members, etc., and a manufacturing method for efficiently obtaining the black quartz glass. Furthermore, the present invention relates to products made of the black quartz glass of the present invention. [Background technology]

[0002] Silica glass is used in various applications such as lighting equipment, optical equipment parts, semiconductor industrial materials, and physicochemical equipment, taking advantage of its excellent light transmission from the ultraviolet to infrared regions, low thermal expansion, and chemical resistance. Among them, black glass, which is made by adding a small amount of transition metal oxide to quartz glass, is used in areas where localized light blocking is required, and is used in optical equipment parts such as quartz glass cells for optical analysis by bonding with transparent quartz glass by thermocompression bonding, etc. However, in recent years, the miniaturization and thinning of parts has progressed, and there are cases where the light blocking ability of conventional black glass is insufficient, and there is a demand for black quartz glass that has higher light blocking ability and can be easily bonded to transparent quartz glass.

[0003] Quartz glass also 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 processes, and in heating processes using infrared light, shielding materials from infrared irradiation of objects other than the object to be heated and infrared heat absorption / storage materials for efficient heating of the object to be heated are required. For this reason, there is a demand for the development of black quartz glass that effectively shields infrared rays, has excellent infrared heat absorption / storage properties, is capable of manufacturing large components, and does not contain metal impurities that cause process contamination.

[0004] Conventionally, the following black glasses containing silica as a main component have been known.

[0005] 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.

[0006] Patent Document 2 proposes a method of subjecting silica porous 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, to produce black quartz glass containing carbon derived from the organosilicon compound.

[0007] Patent Document 3 proposes wet mixing fused silica powder, which is made by powdering fused quartz glass, with a silicon-containing powder, and 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 temperature of silicon, to produce black quartz glass as a composite material having a fused silica matrix in which regions of elemental Si are embedded.

[0008] 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. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2014-94864 A (Claims and Others) [Patent Document 2] JP 2013-1628 A (Claims and Others) [Patent Document 3] JP 2020-73440 A (Claims and Others) [Patent Document 4] JP 2003-146676 A (claims and others) Summary of the Invention [Problem to be solved by the invention]

[0010] However, the black quartz glass described in Patent Document 1 may not have sufficient color uniformity when it is made large, and requires a temperature of 1800°C or higher for production, which requires high-quality furnace and heater materials, and requires a large amount of energy for heating, resulting in productivity issues.In addition, there is a risk of contamination in the process in which the niobium compound contained in the glass is used, making it difficult to apply the glass to the semiconductor manufacturing field.

[0011] The black quartz glass described in Patent Document 2 also had problems with color uniformity, making it difficult to make it large. A non-oxidizing atmosphere was also required during production, which made the furnace structure complex and the operation cumbersome, resulting in problems with productivity. It was also difficult to make it large due to the furnace structure. In addition, the carbon contained in the glass was likely to be generated as particles during the process of use, causing contamination, making it difficult to apply to the semiconductor manufacturing field.

[0012] The type of black quartz glass described in Patent Document 3 also sometimes had insufficient color uniformity when enlarged. Furthermore, there were problems with enlarging the size due to limitations in slip casting. In addition, the slip casting and drying operations were complicated, requiring a long manufacturing time, and sintering required heating at a temperature of 1350°C or higher, which required high-quality materials for the furnace and heater, and at the same time, a large amount of energy was required for heating, resulting in problems with productivity.

[0013] The type of black quartz glass described in Patent Document 4 may also have insufficient color uniformity when made large, and furthermore, when made large, there is a high risk of breakage when sintering the molded body, making it difficult to obtain large black quartz glass. In addition, carbon may be generated as particles in the process of use and cause contamination, making it unsuitable for the semiconductor manufacturing field. It was difficult to use.

[0014] The problem that the present invention aims to solve is to provide black quartz glass that has excellent light-shielding properties, is not likely to cause contamination in the processes in which it is used, has sufficient color uniformity when made large, and can be used to make large ingots.

[0015] Another object of the present invention 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.

[0016] 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 heat absorption / storage members, made using the black quartz glass. [Means for solving the problem]

[0017] As a result of intensive research conducted by the present inventors to solve the above problems, they discovered that black quartz glass that contains substantially no metal impurities other than Si and O and is not likely to cause contamination in the processes in which it is used can be obtained in a system in which fine particles of Si and SiO are dispersed in quartz glass at a specific concentration, and further that this black quartz glass has excellent light-shielding properties, has sufficient color uniformity when made large, and can be obtained with good productivity, thereby completing the present invention.

[0018] The present invention is as follows. [1] Contains 0.5 to 10 mass% Si and 0.1 to 5 mass% SiO, with the remainder being SiO 2 (hereinafter referred to as quartz glass), which has an SCE reflectance of 10% or less in the wavelength range of 350 nm to 750 nm. [2] L * a * b * Display brightness L * is 30 or less, saturation a * The absolute value of is 3.5 or less and b * The black quartz glass according to [1], wherein the absolute value of [3] The black quartz glass according to [1] or [2], wherein the content of each of metal impurities other than Si element is 1 ppm or less. [4] The black quartz glass according to any one of [1] to [3], which satisfies any one or more of the following physical properties (a) to (f): (a) Density is 2.15 / cm 3 More than 2.3g / cm 3 Below is the (b) The specific heat at a temperature of 500°C is 1090 J / kg K or more and 1130 J / kg K or less. (c) Thermal diffusivity at 500°C is 7×10 -7 m 2 / s or more, 8×10 -7 m 2 / s or less, (d) Thermal conductivity at a temperature of 500°C is 1.5 W / mK or more and 2.1 W / mK or less. (e) The thermal expansion coefficient in the range from 30°C to 600°C is 2×10 -7 / ℃ or more, 12×10 -7 / °C or less, (f) The light transmittance at wavelengths of 200 nm to 3000 nm is 0.5% or less at a thickness of 1 mm. [5] At least a part of the Si contained in the quartz glass is in the form of particles, and the diameter of the particles is D 50 5 to 10 μm, D 10 is 1μm or more, D 95 The black quartz glass according to any one of [1] to [4], wherein the average particle diameter is 30 μm or less. [6] At least a part of the SiO contained in the quartz glass is particulate, and the diameter of the particulate matter is D 50 5 to 15 μm, D 10 1μm or more, D 90 The black quartz glass according to any one of [1] to [5], having a grain size of 35 μm or less. [7] (a)SiO 2 The part is a sintered body of fumed silica, or (b) SiO 2The part is 30 to 60 mass% fumed silica, and the rest is particle size D 50 60~100μm, D 10 is 40μm or more, D 95 A sintered body of synthetic silica powder having a particle size of 180 μm or less, or (c)SiO 2 The part is fumed silica 30 to 60 mass%, D 50 5~15μm, D 10 is 1μm or more, D 95 The spherical silica having a particle size of 70 μm or less is 5 to 25 mass%, and the rest is D 50 60~100μm, D 10 is 40μm or more, D 95 The black quartz glass according to any one of [1] to [6], which is a sintered body of synthetic silica powder having a particle size of 180 μm or less. [8] The method includes: mixing and consolidating fumed silica with 0.5 to 10 mass% Si powder and 0.1 to 5 mass% SiO powder, pressure-molding the resulting powder, and heating the pressure-molded product in air at a maximum temperature of 1200 to 1300°C to sinter the fumed silica, thereby obtaining the black quartz glass according to any one of [1] to [6] or the black quartz glass according to (a) of [7]; or (2) Fumed silica is 30 to 60 mass%, and the remainder is particle size D 50 60~100μm, D 10 is 40μm or more, D 95 a synthetic silica powder having a particle size of 180 μm or less, 0.5 to 10 mass% of Si powder and 0.1 to 5 mass% of SiO powder are mixed and consolidated to obtain a powder, the powder is pressure-molded, and the pressure-molded product is heated in air at a maximum temperature of 1250 to 1320° C. to sinter it, thereby obtaining the black quartz glass according to any one of [1] to [6] or the black quartz glass according to (b) of [7]; or (3) Fumed silica is 30 to 60% by mass, D 50 5~15μm, D 10 is 1μm or more, D 95 The spherical silica having a particle size of 70 μm or less is 5 to 25 mass%, and the rest is D 50 60~100μm, D 10 is 40μm or more, D 95a synthetic silica powder having a particle size of 180 μm or less, 0.5 to 10 mass% of Si powder and 0.1 to 5 mass% of SiO powder are mixed and consolidated to obtain a powder, the powder is pressure-molded, and the pressure-molded product is heated in air at a maximum temperature of 1250 to 1320°C to sinter it, thereby obtaining the black quartz glass according to any one of [1] to [6] or the black quartz glass of (c) in [7]. [9] Fumed silica has a tapped bulk density of 0.03 to 0.08 g / cm 3 , BET specific surface area is 50-100m 2 / g, OH group concentration of 0.5 to 1.0 mass %, and the content of metal impurities other than Si is each 1 ppm or less.

[10] The Si powder has a particle diameter of D 50 5~10μm, D 10 is 1μm or more, D 95 is 30 μm or less, and the SiO powder has a particle diameter D 50 3~15μm, D 10 is 1μm or more, D 90 The method for producing black quartz glass according to [8] or [9], wherein the grain size is 35 μm or less.

[11] The method for producing black quartz glass according to any one of [8] to

[10] , wherein the mixed compaction is carried out so that the tapped bulk density of the powder obtained by the mixed compaction is 5 to 20 times the tapped bulk density of the fumed silica.

[12] The method for producing black quartz glass according to any one of [8] to

[11] , wherein the heating and sintering time in air is 0.5 to 5 hours.

[13] A product comprising a black quartz glass member using the black quartz glass according to any one of [1] to [7].

[14] The product according to

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

[15] The product according to

[14] , 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. Effect of the Invention

[0019] According to the present invention, there is provided black quartz glass that has excellent light-shielding properties, has sufficient color uniformity when enlarged, can be obtained with good productivity, and does not cause contamination during the process in which it is used. Furthermore, according to the present invention, there is provided a method for producing the black quartz glass with good productivity using a heating process at a relatively low temperature. In addition, since the black quartz glass of the present invention has excellent light-shielding properties, it can be suitably used for quartz glass cells for optical analysis, light-shielding members for semiconductor manufacturing equipment and infrared heating equipment, and infrared heat absorption / storage members. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] <Black quartz glass> The black quartz glass of the present invention will now be described. The black quartz glass of the present invention contains 0.5 to 10 mass% Si and 0.1 to 5 mass% SiO, with the remainder being SiO 2 At least a part of the Si is an elemental substance consisting of a plurality of Si atoms, and at least a part of the Si exists in the quartz glass as particulate matter consisting of the elemental Si. SiO is silicon monoxide, and at least a part of the SiO exists in the quartz glass as particulate matter consisting of SiO.

[0021] If the Si content is less than 0.5% by mass and the SiO content is less than 0.1% by mass, the lightness L* becomes too high, which is undesirable, and the SCE reflectance also becomes too high, which is undesirable. If the Si content exceeds 10% by mass and the SiO content exceeds 5% by mass, the sintering of the raw materials during preparation is inhibited, which causes a decrease in the mechanical strength of the quartz glass of the present invention, which is a sintered body. The Si content is preferably in the range of 0.5 to 5% by mass, more preferably 0.5 to 3% by mass. The SiO content is preferably in the range of 0.2 to 2% by mass, more preferably 0.3 to 2% by mass, with the remainder being SiO 2It is.

[0022] The black quartz glass of the present invention has an SCE reflectance of 10% 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 10% or less indicates excellent light-shielding properties. From the viewpoint of excellent light-shielding properties, the SCE reflectance is preferably low, preferably 9% or less, and more preferably 8% or less. There is no particular restriction on the lower limit of the SCE reflectance, but it can be 1%.

[0023] The black quartz glass of the present invention is L * a * b * Display brightness L * It is preferable that the lightness L is 30 or less. * By making the L value 30 or less, not only is there no color unevenness, but the black color can be presented without causing light transmission, stray light, or scattering. * a * b * Display saturation a * The absolute value of is 3.5 or less and b * It is preferable that the absolute value of the lightness L is 4 or less. * , saturation a * and b * When the lightness L is within the above range, the color tone of the black quartz glass of the present invention becomes blacker, and the black quartz glass has a low SCE reflectance. * is preferably 28 or less, and the saturation a * The absolute value of is 2.8 or less and b * It is preferable that the absolute value of is 3.7 or less, since the color tone becomes blacker.

[0024] In the black quartz glass of the present invention, the content of metal impurities other than the Si element is preferably 1 ppm or less. If the content of metal impurities other than the Si element is more than 1 ppm, there is a risk of causing process contamination in the manufacture of semiconductors, etc. Furthermore, in fields such as optical analysis, there is a risk of causing adverse effects on accuracy due to the generation of fluorescence, etc. The content of metal impurities other than the Si element can be analyzed by, for example, a method such as atomic absorption analysis.

[0025] The black quartz glass of the present invention has a density of 2.15 to 2.3 g / cm 3 The density is in the range of 2.17 to 2.27 g / cm. The density is almost equal to the theoretical density of transparent quartz glass with Si and SiO added. The density is preferably 2.17 to 2.27 g / cm. 3 More preferably, it is in the range of 2.18 to 2.25 g / cm 3 The range is.

[0026] The black quartz glass of the present invention may have a specific heat of 1090 J / kg·K or more and 1130 J / kg·K or less at a temperature of 500° C. The specific heat at a temperature of 500° C. can be measured by differential scanning calorimetry (DSC method). The specific heat is preferably in the range of 1095 J / kg·K or more and 1120 J / kg·K or less, and more preferably in the range of 1100 J / kg·K or more and 1114 J / kg·K or less.

[0027] The black quartz glass of the present invention has a thermal diffusivity of 7×10 -7 m 2 / s or more, 8×10 -7 m 2 The thermal diffusivity at a temperature of 500° C. can be measured by a flash method in accordance with JIS R 1611. The thermal diffusivity is preferably 7.2×10 -7 m 2 / s or more, 7.9×10 -7 m 2 / s or less, and more preferably 7.4 × 10 -7 m 2 / s or more, 7.6×10 -7 m 2 / s or less.

[0028] The black quartz glass of the present invention can have a thermal conductivity of 1.5 W / mK or more and 2.1 W / mK or less at a temperature of 500° C. The thermal conductivity at a temperature of 500° C. can be calculated by multiplying the density, specific heat, and thermal diffusivity of the sintered body. The thermal conductivity is preferably in the range of 1.6 W / mK or more and 2.0 W / mK or less, and more preferably in the range of 1.7 W / mK or more and 1.9 W / mK or less.

[0029] The black quartz glass of the present invention has a thermal expansion coefficient of 2×10 at temperatures between 30°C and 600°C. -7 / ℃ or more, 12×10 -7 The thermal expansion coefficient at temperatures of 30°C to 600°C can be measured by thermomechanical analysis (TMA method). The thermal expansion coefficient is preferably 4×10 -7 / ℃ or more, 11×10 -7 / °C or less, more preferably 6×10 -7 / ℃ or more, 10×10 -7 / ℃ or less.

[0030] The black quartz glass of the present invention may have a light transmittance of 0.5% or less at a thickness of 1 mm at wavelengths of 200 nm to 3000 nm. The light transmittance at wavelengths of 200 nm to 3000 nm is measured by a spectrophotometer. A light transmittance of 0.5% or less indicates excellent light blocking properties. From the viewpoint of excellent light blocking properties, the light transmittance is preferably low, preferably 0.4% or less, and more preferably 0.3% or less. There is no particular restriction on the lower limit of the light transmittance, but it may be 0.01%.

[0031] The black quartz glass of the present invention contains Si as particulate matter, and the particle diameter of the Si particulate matter is, for example, D 50 5 to 10 μm, D 10 is 1μm or more, D 95 The black quartz glass of the present invention contains SiO as particulate matter, and the particle diameter of the SiO particulate matter is, for example, D 50 3 to 15 μm, D 10 1μm or more, D 90The particle diameter of the Si particles is D 50 The particle diameter of the SiO particulate matter is D 50 3μm or more, saturation a * and b * The absolute value of is smaller, and the color tone becomes blacker, which is preferable. 50 The particle size of the SiO particulate matter is D 50 The lightness L is 15μm or less. * The SCE reflectance is below a predetermined value, resulting in a black quartz glass with excellent light-shielding properties. In addition, the raw material silica is easily sintered during preparation of the black quartz glass, and black quartz glass with excellent mechanical strength tends to be obtained. 10 and the particle diameter of the SiO particulate matter is D 10 If it is 1μm or more, saturation a * and b * The absolute value of tends to be small, which is preferable. 50 The particle size of the SiO particulate matter is D 50 If the particle size is 15 μm or less, the sintering of the raw material silica proceeds well during the preparation of the black quartz glass, and black quartz glass that is a sintered body having excellent mechanical strength tends to be obtained.

[0032] The black quartz glass of the present invention is manufactured using fumed silica as a sintering material, as described below. Fumed silica is fine powder of silica obtained by burning silicon tetrachloride gas or the like in a gas phase. Fumed silica has a small particle diameter of 10 to 30 nm, so that it generally has a very low bulk density and is not suitable for granulation or molding. Usually, the density of the sintered body obtained by sintering is low and is not satisfactory as quartz glass. However, in the present invention, (1) fumed silica, in which Si particulate matter and SiO particulate matter are dispersed at a specific concentration, or (2) a mixed powder of fumed silica and synthetic silica powder, or (3) a mixed powder of fumed silica, synthetic silica powder, and spherical silica, is sintered, and surprisingly, quartz glass having a density almost equal to the theoretical density of quartz glass with Si and SiO added thereto is obtained. Moreover, the obtained quartz glass is black quartz glass having an SCE reflectance of 10% or less. As described later, the fumed silica used as the raw material has a tap bulk density of 0.03 to 0.08 g / cm 3 , BET specific surface area 50~100m 2 Fumed silica having a molecular weight of 0.1 to 0.5 wt %, a molecular weight of 0.5 to 1.0 wt %, and / or a content of metal impurities other than Si element of 1 ppm or less is preferred from the viewpoints that quartz glass having a density nearly equal to the theoretical density obtained by adding Si and SiO to quartz glass can be obtained, and further, black quartz glass having satisfactory properties such as SCE reflectance can be produced even in large ingots.

[0033] <Manufacturing method of 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 includes pressurizing and compacting (1) fumed silica, or (2) a mixed powder of fumed silica and synthetic silica powder, or (3) a mixed powder of fumed silica, synthetic silica powder, and spherical silica with 0.5 to 10 mass% of Si powder and 0.1 to 5 mass% of SiO powder, and heating the pressurized molded product in air to sinter the fumed silica. The maximum temperature of this heating is in the range of 1200 to 1300°C in the case of (1), and in the range of 1250°C to 1320°C in the cases of (2) and (3). The black quartz glass of the present invention can be obtained by this production method.

[0034] Synthetic silica powder is a high-purity powdered silica obtained by hydrolyzing, drying, pulverizing, and calcining chemically purified silicon alkoxide. Spherical silica powder is a high-purity synthetic fused spherical silica obtained by reacting silicon tetrachloride gas in the gas phase. By adding synthetic silica powder or synthetic silica powder and spherical silica to fumed silica, the structure of the sintered body can be made more uniform and the heating time to the maximum temperature can be shortened.

[0035] In the manufacturing method of the present invention, a predetermined amount of Si powder and SiO powder are made to coexist with (1) fumed silica, or (2) fumed silica and synthetic silica powder, or (3) fumed silica, synthetic silica powder, and spherical silica powder, and the Si particles and SiO particles are uniformly mixed with (1) fumed silica, or (2) fumed silica and synthetic silica powder, or (3) fumed silica, synthetic silica powder, and spherical silica powder in a dry powder state without substantial aggregation. In this mixing, consolidation proceeds simultaneously with mixing to obtain a powder for pressure molding. In this specification, the consolidation operation proceeding simultaneously with mixing is defined as mixing and consolidation.

[0036] To obtain powder for compaction by mixing and consolidation, the particle size must be D 50 5 to 10 μm, D 10 is 1μm or more, D95 is 300.5 to 10 mass% of Si powder with a particle size of D 50 3 to 15 μm, D 10 1μm or more, D 90 It is preferable to use SiO powder having a particle size of 35 μm or less at a ratio of 0.1 to 5 mass %. In addition, to obtain a powder for pressure molding by mixing and consolidating, a tap bulk density of 0.03 to 0.08 g / cm3 is required. 3 , BET specific surface area 50~100m 2 / g, OH group concentration 0.5 to 1.0 mass%, content of metal impurities other than Si is 1 ppm or less, and the particle size is D 50 60~100μm, D 10 is 40μm or more, D 95 Synthetic silica powder with a particle size of 180 μm or less, 50 5 to 15 μm, D 10 is 1μm or more, D 95 It is preferable to use spherical silica having a diameter of 70 μm or less. The use of fumed silica, synthetic silica powder, or spherical silica is also preferable from the viewpoint of obtaining quartz glass having a density almost equal to the theoretical density obtained by adding Si and SiO to quartz glass.

[0037] Furthermore, the particle size is D 50 60~100μm, D 10 is 40μm or more, D 95 Synthetic silica powder with a particle size of 180 μm or less, and 50 5 to 15 μm, D 10 is 1μm or more, D 95The use of spherical silica having a diameter of 70 μm or less is also preferred from the viewpoint of making the structure of the sintered body more uniform and shortening the heating time to the maximum temperature during sintering. Furthermore, when the raw silica is fumed silica and synthetic silica powder, it is preferred that the fumed silica is 30 to 60 mass% and the remainder is synthetic silica powder from the viewpoint of making the structure of the sintered body more uniform and shortening the heating time to the maximum temperature during sintering. In addition, when the raw silica is fumed silica, synthetic silica powder and spherical silica powder, it is preferred that the fumed silica is 30 to 60 mass%, the spherical silica is 5 to 25 mass%, and the remainder is synthetic silica powder from the viewpoint of making the structure of the sintered body more uniform and shortening the heating time to the maximum temperature during sintering.

[0038] Generally, fumed silica is not suitable for sintering. However, by pressing the powder for pressure molding obtained by mixing and consolidating in this way and heating it in air at a maximum temperature of 1200 to 1320°C, the density of the obtained sintered body can reach almost the theoretical density, and black quartz glass with excellent properties such as SCE reflectance can be obtained.

[0039] The mixed compaction is preferably carried out so that the tapped bulk density of the powder obtained by compaction is 5 to 20 times that of the fumed silica. When the tapped bulk density of the powder for pressure molding is 5 times or more that of the fumed silica, the density of the sintered body tends to be high. When the tapped bulk density of the powder for pressure molding is 20 times or less that of the fumed silica, the strength of the molded body does not decrease. The tapped bulk density of the powder for pressure molding is preferably 6 to 15 times, more preferably 7 to 10 times that of the fumed silica. The mixed compaction can be carried out using a general mixing device such as an agitation type mixer, a ball mill, a rocking mixer, a cross mixer, or a V-type mixer.

[0040] The mixed compacted powder can be molded into a desired shape. As a molding method, a dry method such as die press molding or cold isostatic pressing, which is usually used for molding ceramics, can be used. For example, a pressing pressure of 10 to 300 MPa is appropriate. If it is 10 MPa or more, the molded body will not collapse and the yield during molding can be maintained. If it is 300 MPa or less, it is desirable because it does not require large-scale equipment, has good productivity, and can reduce production costs.

[0041] When the raw silica is fumed silica, sintering is carried out in air at a maximum sintering temperature of 1200 to 1300°C, preferably 1240 to 1260°C, and more preferably 1240 to 1250°C. If the sintering temperature exceeds 1300°C, the lightness L * If the sintering temperature is less than 1200°C, it tends not to be possible to obtain a sintered body with good density and bending strength.

[0042] When the raw silica is fumed silica and synthetic silica powder, sintering is carried out in air at a maximum sintering temperature of 1250 to 1320°C, preferably 1280 to 1310°C, and more preferably 1290 to 1300°C. If the sintering temperature exceeds 1320°C, the lightness L * If the sintering temperature is less than 1250°C, it tends not to be possible to obtain a sintered body with good density and bending strength.

[0043] When the raw silica is fumed silica, synthetic silica powder, and spherical silica powder, sintering is carried out in air at a maximum sintering temperature of 1250 to 1320°C, preferably 1280 to 1310°C, and more preferably 1290 to 1300°C. If the sintering temperature exceeds 1320°C, the lightness L * If the sintering temperature is less than 1250°C, it tends not to be possible to obtain a sintered body with good density and bending strength.

[0044] In any of the heating and sintering steps, the sintering time at the maximum temperature in an atmospheric furnace can be, for example, in the range of 0.5 to 5 hours. However, it can be appropriately adjusted in consideration of the physical properties of the sintered body. If the sintering time is short, the density and bending strength tend to decrease. If the sintering time is too long, it will result in a decrease in productivity and an increase in production costs.

[0045] The black quartz glass ingot obtained through the above-mentioned steps can be processed using a processing machine such as a band saw, wire saw, or core drill that is used in manufacturing quartz components to obtain a black quartz glass product.

[0046] The black quartz glass thus obtained is free of color unevenness and has a sufficiently black color that does not transmit light, cause stray light, or scatter light, making it useful in the optical field in general. In addition, it not only has extremely high light shielding performance, but can also be bonded to transparent quartz glass, making it suitable for producing optical analysis cells made of quartz glass.

[0047] The present invention encompasses products that include black quartz glass members using the black quartz glass of the present invention. When used in high-temperature environments that require dimensional accuracy, the black quartz glass of the present invention has a thermal expansion coefficient as small as that of quartz glass, and other thermal properties are also equivalent to those of quartz glass. Therefore, the black quartz glass member of the present invention is useful, for example, as an optical component, a light-shielding member, or an infrared heat absorption / storage member. Examples of optical components include spectroscopic cells, projector reflectors, or optical fiber connectors, and light-shielding members include light-shielding members for semiconductor manufacturing equipment or infrared heating equipment. However, it is not intended to be limited to these members.

[0048] The black quartz glass of the present invention does not contain metal impurities and is particularly suitable for use as a component of heat treatment equipment used in semiconductor manufacturing. For example, in a wafer heat treatment equipment, by constructing the parts other than the surface that transmits infrared rays for heating with the black quartz glass of the present invention, it is possible to efficiently block the heat radiated outside the furnace, improve energy efficiency, and make the temperature distribution inside the furnace uniform. EXAMPLES

[0049] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0050] The sample properties were measured as follows. (1) The density of the sintered body 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 * Lightness L* and chroma a of the display system * , b * was measured in accordance with JIS Z 8722 using a spectrophotometer. (4) The specific heat was measured by differential scanning calorimetry (DSC) at 500℃ using a sample cut to φ6×1mmt. (5) Thermal diffusivity was measured by machining the specimen to φ10×1 mmt and measuring it at 500℃ using the flash method in accordance with JIS R1611. (6) Thermal conductivity was calculated using the following formula at a temperature of 500°C. Thermal conductivity = specific heat × thermal diffusivity × density of sintered body (7) The thermal expansion coefficient was measured by processing the sample into 3 × 4 × 20 mmL and using thermomechanical analysis (TMA) at temperatures between 30 and 600°C. (8) The light transmittance was measured by cutting the sample to a thickness of 1 mm and using a spectrophotometer in the range of 200 to 3000 nm.

[0051] Example 1 Tapped density: 0.06g / cm 3 , BET specific surface area 85m 2 / g, OH group concentration 0.7 mass%, metal impurity content other than Si is 1 ppm or less, and the particle size is D 50 7μm, D 10 is 4μm, D 95 2.0 mass% of Si powder with a particle size of 11 μm and 5010μm, D 10 5 μm, D 90 SiO powder having a particle size of 20 μm was added at a rate of 0.5 mass %, and the mixture was mixed and consolidated in a ball mill without using a solvent. The resulting tapped bulk density was 0.45 g / cm 3 The powder for pressure molding was press molded at 90 MPa and sintered in air at 1250°C for 3 hours.

[0052] The density of the resulting black quartz glass was 2.20 g / cm 3 , SCE reflectance is 5.3% or less, L * a * b * Display brightness L * is 20.6, saturation a * is 1.9, b * is -0.6, the specific heat at a temperature of 500 is 1103 J / kg K, and the thermal diffusivity at a temperature of 500°C is 7.5×10 -7 m 2 / s, the thermal conductivity at 500°C is 1.82 W / mK, and the thermal expansion coefficient at temperatures from 30 to 600°C is 9.4 × 10 -7 / °C, and the light transmittance was 0.12% or less in the range of 200 to 3000 nm. The obtained black quartz glass had no color unevenness and exhibited a sufficiently black color that did not transmit light, cause stray light, or scatter light. It was confirmed to be uniform by visual inspection, and was also aesthetically excellent.

[0053] Example 2 Tapped density: 0.06g / cm 3 , BET specific surface area 85m 2 / g, OH group concentration 0.7 mass%, metal impurity content other than Si is 1 ppm or less, and the particle size is D 50 8μm, D 10 3μm, D 95 1.0 mass% of Si powder with a particle diameter of 20 μm and 50 10μm, D 10 5 μm, D 90 SiO powder having a particle size of 20 μm was added at a ratio of 1.0 mass %, and the mixture was mixed and consolidated in a ball mill without using a solvent. The resulting tapped bulk density was 0.45 g / cm 3The powder for pressure molding was press molded at 90 MPa and sintered in air at 1250°C for 3 hours.

[0054] The density of the resulting black quartz glass was 2.19 g / cm 3 ,SCE reflectance is 7.6% or less,L * a * b * Display brightness L * is 25.2, saturation a * is 2.6, b * is 3.3, the specific heat at a temperature of 500 is 1108 J / kg K, and the thermal diffusivity at a temperature of 500°C is 7.5×10 -7 m 2 / s, the thermal conductivity at 500°C is 1.83 W / mK, and the thermal expansion coefficient at temperatures from 30 to 600°C is 8.3 × 10 -7 / °C, and the light transmittance was 0.17% or less in the range of 200 to 3000 nm. The obtained black quartz glass had no color unevenness and exhibited a sufficiently black color that did not transmit light, cause stray light, or scatter light. It was confirmed to be uniform by visual inspection, and was also aesthetically excellent.

[0055] Example 3 Tapped density: 0.06g / cm 3 , BET specific surface area 85m 2 / g, OH group concentration 0.7 mass%, metal impurity content other than Si is 1 ppm or less, 50 mass% of fumed silica, particle diameter D 50 is 80μm, D 10 48μm, D 95 The silica mixed powder is 50 mass % of a synthetic silica powder having a particle diameter of 160 μm and a content of metal impurities other than Si of 1 ppm or less. 50 6μm, D 10 is 4μm, D 95 2.0 mass% of Si powder with a particle size of 10 μm and 50 10μm, D 10 5 μm, D 90 SiO powder having a particle size of 20 μm was added at a ratio of 0.5 mass %, and the mixture was mixed and consolidated in a ball mill without using a solvent. The resulting tapped bulk density was 0.60 g / cm 3The powder for pressure molding was press molded at 90 MPa and sintered in air at 1300°C for 3 hours.

[0056] The density of the resulting black quartz glass was 2.20 g / cm 3 , SCE reflectance is 5.3% or less, L * a * b * Display brightness L * is 18.2, saturation a * is 3.2, b * is 2.1, the specific heat at a temperature of 500 is 1105 J / kg K, and the thermal diffusivity at a temperature of 500°C is 7.5×10 -7 m 2 / s, the thermal conductivity at 500°C is 1.81 W / mK, and the thermal expansion coefficient at temperatures from 30 to 600°C is 9.0 × 10 -7 / °C, and the light transmittance was 0.14% or less in the range of 200 to 3000 nm. The obtained black quartz glass had no color unevenness and exhibited a sufficiently black color that did not transmit light, cause stray light, or scatter light. It was confirmed to be uniform by visual inspection, and was also aesthetically excellent.

[0057] Example 4 Tapped density: 0.06g / cm 3 , BET specific surface area 85m 2 / g, OH group concentration 0.7 mass%, metal impurity content other than Si is 1 ppm or less, fumed silica is 40 mass%, particle diameter is D 50 is 80μm, D 10 48μm, D 95 The synthetic silica powder has a particle size of 160 μm, and the content of metal impurities other than Si is 1 ppm or less. 50 is 11μm, D 10 3μm, D 95 The silica mixed powder contains 18 mass% spherical silica, the particle diameter of which is 52 μm and the content of metal impurities other than Si is 1 ppm or less. 50 6μm, D 10 3μm, D 95 1.0 mass% of Si powder with a particle diameter of 13 μm and 50 5 μm, D 102μm, D 90 SiO powder having a particle size of 9 μm was added at a rate of 0.5 mass %, and the mixture was mixed and consolidated in a ball mill without using a solvent. The resulting tapped bulk density was 0.79 g / cm 3 The powder for pressure molding was press molded at 90 MPa and sintered in air at 1300°C for 3 hours.

[0058] The density of the resulting black quartz glass was 2.20 g / cm 3 ,SCE reflectance is 5.2% or less,L * a * b * Display brightness L * is 19.0, saturation a * is 2.2, b * is 3.6, the specific heat at a temperature of 500 is 1112 J / kg K, and the thermal diffusivity at a temperature of 500°C is 7.5×10 -7 m 2 / s, the thermal conductivity at 500°C is 1.83 W / mK, and the thermal expansion coefficient at temperatures from 30 to 600°C is 7.6 × 10 -7 / °C, and the light transmittance was 0.22% or less in the range of 200 to 3000 nm. The obtained black quartz glass had no color unevenness and exhibited a sufficiently black color that did not transmit light, cause stray light, or scatter light. It was confirmed to be uniform by visual inspection, and was also aesthetically excellent.

[0059] Comparative Example 1 Tapped density: 0.06g / cm 3 , BET specific surface area 85m 2 / g, OH group concentration 0.7 mass%, metal impurity content other than Si is 1 ppm or less, and the particle size is D 50 7μm, D 10 is 4μm, D 95 The powder was mixed and consolidated in a ball mill without using a solvent. The powder for pressure molding was press molded at 90 MPa and sintered at 1250°C for 3 hours in air.

[0060] The density of the obtained black quartz glass was 2.09 g / cm 3The SCE reflectance is small, and the SCE reflectance is large, less than 13.0%, and the L * a * b * Display brightness L * The saturation is also large at 36.2, * is 1.1, b * The color was uneven, and the prevention of light transmission, stray light, and scattering was insufficient.

[0061] [Table 1]

[0062] [Table 2] [Industrial Applicability]

[0063] The present invention is useful in the field of black quartz glass. According to the present invention, a large black quartz glass ingot with excellent light-shielding properties can be economically and efficiently provided. The black quartz glass of the present invention can be suitably used for quartz glass cells for optical analysis, light-shielding members for semiconductor manufacturing equipment and infrared heating equipment, and infrared heat absorption / storage members.

Claims

1. Contains 0.5 to 10 mass % Si and 0.1 to 5 mass % SiO, with the remainder being SiO 2 (hereinafter referred to as quartz glass) having an SCE reflectance of 10% or less in the wavelength range of 350 nm to 750 nm.

2. L * a * b * Display brightness L * is 30 or less, saturation a * The absolute value of b is 3.5 or less and * The black quartz glass according to claim 1, wherein the absolute value of is 4 or less.

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

4. The black quartz glass according to any one of claims 1 to 3, which satisfies any one or more of the following physical properties (a) to (f): (a) Density is 2.15 / cm 3 2.3g / cm or more 3 Below is the (b) the specific heat at a temperature of 500°C is 1090 J / kg K or more and 1130 J / kg K or less; (c) Thermal diffusivity at a temperature of 500°C is 7 x 10 -7 m 2 / s or more, 8×10 -7 m 2 / s or less, (d) the thermal conductivity at a temperature of 500°C is 1.5 W / mK or more and 2.1 W / mK or less; (e) The coefficient of thermal expansion in the range from 30°C to 600°C is 2×10 -7 / ℃ or more, 12 x 10 -7 / ° C. or less, (f) The light transmittance at wavelengths of 200 nm to 3000 nm is 0.5% or less at a thickness of 1 mm.

5. At least a part of the Si contained in the quartz glass is in the form of particles, and the diameter of the particles is D 50 5 to 10 μm, D 10 is 1 μm or more, D 95 The black quartz glass according to any one of claims 1 to 4, wherein the thickness is 30 μm or less.

6. At least a part of the SiO contained in the quartz glass is particulate, and the diameter of the particulate matter is D 50 5 to 15 μm, D 10 1 μm or more, D 90 The black quartz glass according to any one of claims 1 to 5, having a thickness of 35 μm or less.

7. (a) SiO 2 The portion (b) is a sintered body of fumed silica, or (b) is SiO 2 The portion is 30 to 60 mass% fumed silica, and the remainder is particle size D 50 is 60 to 100 μm, D 10 is 40 μm or more, D 95 (c) a sintered body of a synthetic silica powder having a particle size of 180 μm or less, or (b) a sintered body of a synthetic silica powder having a particle size of 180 μm or less, 2 The portion is 30 to 60 mass% fumed silica, D 50 is 5 to 15 μm, D 10 is 1 μm or more, D 95 The spherical silica having a particle size of 70 μm or less is 5 to 25 mass %, and the remainder is D 50 is 60 to 100 μm, D 10 is 40 μm or more, D 95 The black quartz glass according to any one of claims 1 to 6, which is a sintered body of synthetic silica powder having a particle size of 180 μm or less.

8. (1) A method of producing the black quartz glass according to any one of claims 1 to 6 or the black quartz glass according to claim 7 (a) by mixing and consolidating fumed silica with 0.5 to 10% by mass of Si powder and 0.1 to 5% by mass of SiO powder, pressure-molding the powder obtained, and heating the pressure-molded product in air at a maximum temperature of 1200 to 1300°C to sinter the fumed silica, or (2) Fumed silica is 30 to 60 mass %, and the remainder is D in particle size. 50 is 60 to 100 μm, D 10 is 40 μm or more, D 95 a synthetic silica powder having a particle size of 180 μm or less, 0.5 to 10 mass% of Si powder and 0.1 to 5 mass% of SiO powder are mixed and consolidated to obtain a powder, the powder is pressurized and the pressurized molded product is heated in air at a maximum temperature of 1250 to 1320° C. to sinter it, thereby obtaining the black quartz glass according to any one of claims 1 to 6 or the black quartz glass according to (b) of claim 7; or (3) 30 to 60% by mass of fumed silica, D 50 is 5 to 15 μm, D 10 is 1 μm or more, D 95 The spherical silica having a particle size of 70 μm or less is 5 to 25 mass %, and the remainder is D 50 is 60 to 100 μm, D 10 is 40 μm or more, D 95 7. A method for producing black quartz glass, comprising: mixing and consolidating a synthetic silica powder having a particle size of 180 μm or less with 0.5 to 10 mass % of Si powder and 0.1 to 5 mass % of SiO powder, pressure molding the powder obtained, and heating and sintering the pressure molded product at a maximum temperature of 1250 to 1320° C. in air to obtain the black quartz glass according to any one of claims 1 to 6 or the black quartz glass according to (c) of claim 7.

9. Fumed silica has a tap bulk density of 0.03 to 0.08 g / cm 3 , BET specific surface area is 50-100m 2 / g, OH group concentration of 0.5 to 1.0 mass%, and the content of metal impurities other than Si is each 1 ppm or less.

10. The Si powder has a particle diameter D 50 is 5 to 10 μm, D 10 is 1 μm or more, D 95 is 30 μm or less, and the SiO powder has a particle diameter D 50 is 3 to 15 μm, D 10 is 1 μm or more, D 90 The method for producing black quartz glass according to claim 8 or 9, wherein the thickness is 35 μm or less.

11. The method for producing black quartz glass according to any one of claims 8 to 10, wherein the mixed compaction is carried out so that the tapped bulk density of the powder obtained by the mixed compaction is 5 to 20 times the tapped bulk density of the fumed silica.

12. The method for producing black quartz glass according to any one of claims 8 to 11, wherein the time for heat sintering in air is 0.5 to 5 hours.

13. A product comprising a black quartz glass member using the black quartz glass according to any one of claims 1 to 7.

14. 14. The article of claim 13, wherein the black quartz glass member is an optical component, a light shielding component, or an infrared heat absorbing / storing component.

15. The product according to claim 14, wherein the optical component is a spectroscopic cell, a reflector of a projector, or a connector of an optical fiber, and the light-shielding member is a light-shielding member of a semiconductor manufacturing device or an infrared heating device.

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