Abstract: A method for evaluating a quartz glass crucible constituted by an outer layer formed of an opaque quartz glass containing a bubble, and an inner layer formed of a transparent quartz glass. The method includes steps of preparing a quartz glass crucible to be evaluated, irradiating the quartz glass crucible to be evaluated with ultraviolet rays as an excitation light, detecting a blue fluorescence emitted from the quartz glass crucible irradiated with the ultraviolet rays, and evaluating a state of oxygen deficiency defects in the outer layer of the quartz glass crucible on the basis of existence or non-existence of the blue fluorescence. The method allows hydrogen doping and water vapor introduction to attain nondestructive and easy evaluation on the state of the oxygen deficiency defects generated in the quartz glass crucible.

Abstract: A quartz glass plate has a quartz glass plate body and a quartz glass member adhered to the quartz glass plate body through an adhesive layer, where the adhesive layer contains silica, and a sum of concentrations of Li, Na, and K ions, being alkali metal ions and Ca ions, being alkaline earth metal ions contained in the adhesive layer is 10 ppm by mass or less. Consequently, a step with a uniform thickness can be formed, and a quartz glass plate is not easily damaged by irradiation with a light containing an ultraviolet ray.

Abstract: A mold for manufacturing a quartz glass crucible by a rotary molding method, having a plurality of grooves that are concentric with respect to a mold rotation axis in at least a straight body portion of an inner surface of the mold, wherein the plurality of concentric grooves are non-penetrating grooves that do not penetrate the mold. This provides a mold for manufacturing a quartz glass crucible by a rotary molding method, having an inner surface made so that it is difficult for quartz powder to slide down when forming a quartz powder compact.

Abstract: One aspect is a method for producing a multilayered silica glass body. The method involves producing a multilayered silica glass body in which a transparent silica glass layer is provided on the surface of a siliceous substrate made of a siliceous material. The method includes preparing the siliceous substrate, preparing a silica slurry in which silica particles are dispersed in a liquid, applying the silica slurry to the surface of the siliceous substrate, leveling the silica slurry applied to the surface of the siliceous substrate by applying vibration to the siliceous substrate, drying the leveled silica slurry, and vitrifying the dried silica slurry by heating to form a transparent silica glass layer. As a result, a transparent silica glass layer of uniform thickness is obtained at excellent yield, and a method for producing a multilayered silica glass body easily in a short time is provided.

Abstract: A quartz glass crucible including a bottom portion, a curved portion, and a straight body portion, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles therein, and an inner layer including transparent quartz glass, the outer layer includes a plurality of layers in a part of the straight body portion, out of the plurality of layers, one layer having a devitrification spot number of 50/cm3 or more and 70/cm3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours, and a layer positioned inwards of the devitrifiable layer in a thickness direction of the quartz glass crucible is a low devitrification layer having a spot number of 2/cm3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours. This provides a quartz glass crucible suppressed from deformation due to heating and excessive progression of devitrification.

Abstract: Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm.

Abstract: A CZ crucible for growing a single crystal silicon ingot by a CZ method, where the CZ crucible includes a closed-end cylindrical graphite crucible and a closed-end cylindrical quartz glass crucible disposed inside the graphite crucible, and the CZ crucible includes a gap between an inner surface of a bottom portion of the graphite crucible and an outer surface of a bottom portion of the quartz glass crucible on a central axis of the CZ crucible, the gap keeping the inner surface of the bottom portion of the graphite crucible and the outer surface of the bottom portion of the quartz glass crucible contactless with each other. This provides a CZ crucible that ensures that a closed-end cylindrical quartz glass crucible for growing a single crystal silicon ingot by a CZ method can be stable and self-supporting when disposed inside a closed-end cylindrical graphite crucible.

Abstract: A quartz glass crucible for growing a single crystal silicon ingot by a CZ method, where the crucible has a closed-end cylindrical shape including a cylindrical straight body portion, a first curved portion continuous with a lower end of the straight body portion and having a first curvature R1, a second curved portion continuous with the first and having a second curvature R2, and a bottom portion continuous with the second curved portion, R1 and R2 have a relationship of R1<R2, and an outer surface of the bottom portion forms a flat surface perpendicular to a central axis of the crucible or a concave surface concave with respect to the flat surface. This provides a closed-end cylindrical quartz glass crucible for growing a single crystal silicon ingot by a CZ method that can be stable and self-supporting when it is disposed inside a closed-end cylindrical graphite crucible.

Abstract: There is provided a technique that includes a first annealing step of annealing the reaction tube; a first cleaning step of cleaning an inner surface of the reaction tube, after the first annealing step, with a liquid including a fluorine compound having a first concentration; a first rinsing step of washing away the fluorine compound used in the first cleaning step with pure water; a second annealing step of annealing the reaction tube; a second cleaning step of cleaning the inner surface of the reaction tube, after the second annealing step, with a liquid including a fluorine compound having a second concentration higher than the first concentration; and a second rinsing step of washing away the fluorine compound used in the second cleaning step with pure water.

Abstract: A quartz glass crucible including bottom, curved, and straight body portions, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles, and an inner layer including transparent quartz glass, the outer layer fabricated from different types of raw material powder, the outer layer having regions sectioned by bubble content densities, and bubble content densities of two outer layer adjacent regions, when da (pcs/mm3) is defined as content density of a region “a” having a greater content density, and db (pcs/mm3) is defined as content density of a region “b” having a smaller content density, a difference D=(da?db)/db between content densities of the two regions is 10% or more.

Abstract: Provided is a heat reflective member, which is prevented from braking even in a high-temperature environment. It generates no dust in use, and can be washed with a chemical liquid. The heat reflective member has a laminated structure in which quartz glass layers are formed on an upper surface and a lower surface of a siliceous sintered powder layer. The heat reflective member includes: an impermeable layer which is formed at a portion of the siliceous sintered powder layer at an end portion of the heat reflective member, which has a thickness at least larger than half of a thickness of the siliceous sintered powder layer, and through which a gas or a liquid is prevented from penetrating; and a buffer layer which is formed between the impermeable layer and the siliceous sintered powder layer, and which changes in density from the impermeable layer toward the sintered powder layer.

Abstract: One aspect is a reflective member, which has a laminated structure in which transparent quartz glass members are formed on an upper surface and a lower surface of an opaque siliceous sintered powder layer. The opaque siliceous sintered powder layer has a thickness of 0.1 mm or more and a thickness distribution of ±0.05 mm or less. When a load is applied to each of the transparent quartz glass members on an upper surface and a lower surface of the laminated structure in a direction parallel to the laminated structure, the reflective member is fractured at a load of 5 N or more per square centimeter. The laminated structure includes a semi-transparent portion having a width of 0.01 mm or less, which has an intermediate opacity between an opacity of the opaque siliceous sintered powder layer and an opacity of each of the transparent quartz glass members.

Abstract: One aspect is a method for producing a hollow porous quartz glass base material. Even when the hollow porous quartz glass base material is produced in large weight and high bulk density, the ease of target extraction is maintained and target extraction is performed stably. The method includes preparing a heat resistant substrate, which has an outer surface on which SiO2 particles are deposited, the outer surface having a surface roughness in which the maximum height Rz is less than 9 ?m and the arithmetic average roughness Ra is less than 1 ?m. The heat resistant substrate is rotated and SiO2 particles are deposited on the outer surface of the heat resistant substrate to form a glass particulate deposit. The heat resistant substrate is extracted from the glass particulate deposit to produce the base material.

Abstract: Provided is a titanium-containing quartz glass having excellent UV absorption. The quartz glass absorbs ultraviolet rays having a wavelength of 250 nm or less, ozone generation-related adverse effects on the human body, are prevented, a decrease in transmittance of the quartz glass in the range from near-ultraviolet to visible light due to being colored when irradiated with ultraviolet rays does not occur, absorption build-up or lamp burst-inducing deformation build-up, which is caused by a structural change in the quartz glass that occurs in the range of 200-300 nm when irradiated with ultraviolet rays, is suppressed, and a decrease in transmittance at intended wavelength ranges does not occur even when exposed to ultraviolet rays. The titanium-containing quartz glass having excellent UV absorption is colorless, wherein the average concentration of titanium is 10-500 ppm, the concentration of OH group is 10-350 ppm.

Abstract: One aspect is a process to producing a synthetic quartz glass, including an annealing treatment that includes: putting a synthetic quartz glass as a parent material into a heat treatment furnace; elevating a temperature in the heat treatment furnace to a prescribed keeping temperature that is equal to or higher than the annealing point; keeping the keeping temperature; annealing the synthetic quartz glass; and taking the synthetic quartz glass out of the heat treatment furnace. The process includes determining an annealing rate v [° C./h] of the annealing step based on a value of S/V [mm2/mm3], wherein S [mm2] is the surface area of the synthetic quartz glass as a parent material and V [mm3] is the volume thereof and a target birefringence Re [nm/cm] for the synthetic quartz glass after the annealing, and the annealing step is performed at the determined annealing rate v.

Abstract: One aspect is a method for producing a multilayered silica glass body. The method involves producing a multilayered silica glass body in which a transparent silica glass layer is provided on the surface of a siliceous substrate made of a siliceous material. The method includes preparing the siliceous substrate, preparing a silica slurry in which silica particles are dispersed in a liquid, applying the silica slurry to the surface of the siliceous substrate, leveling the silica slurry applied to the surface of the siliceous substrate by applying vibration to the siliceous substrate, drying the leveled silica slurry, and vitrifying the dried silica slurry by heating to form a transparent silica glass layer. As a result, a transparent silica glass layer of uniform thickness is obtained at excellent yield, and a method for producing a multilayered silica glass body easily in a short time is provided.

Abstract: A quartz glass crucible including a bottom portion, a curved portion, and a straight body portion, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles therein, and an inner layer including transparent quartz glass, the outer layer includes a plurality of layers in a part of the straight body portion, out of the plurality of layers, one layer having a devitrification spot number of 50/cm3 or more and 70/cm3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours, and a layer positioned inwards of the devitrifiable layer in a thickness direction of the quartz glass crucible is a low devitrification layer having a spot number of 2/cm3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours. This provides a quartz glass crucible suppressed from deformation due to heating and excessive progression of devitrification.

Abstract: There is provided a technique that includes a first annealing step of annealing the reaction tube; a first cleaning step of cleaning an inner surface of the reaction tube, after the first annealing step, with a liquid including a fluorine compound having a first concentration; a first rinsing step of washing away the fluorine compound used in the first cleaning step with pure water; a second annealing step of annealing the reaction tube; a second cleaning step of cleaning the inner surface of the reaction tube, after the second annealing step, with a liquid including a fluorine compound having a second concentration higher than the first concentration; and a second rinsing step of washing away the fluorine compound used in the second cleaning step with pure water.

Abstract: A quartz glass plate has a quartz glass plate body and a quartz glass member adhered to the quartz glass plate body through an adhesive layer, where the adhesive layer contains silica, and a sum of concentrations of Li, Na, and K ions, being alkali metal ions and Ca ions, being alkaline earth metal ions contained in the adhesive layer is 10 ppm by mass or less. Consequently, a step with a uniform thickness can be formed, and a quartz glass plate is not easily damaged by irradiation with a light containing an ultraviolet ray.

Abstract: A quartz glass crucible including bottom, curved, and straight body portions, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles, and an inner layer including transparent quartz glass, the outer layer fabricated from different types of raw material powder, the outer layer having regions sectioned by bubble content densities, and bubble content densities of two outer layer adjacent regions, when da (pcs/mm3) is defined as content density of a region “a” having a greater content density, and db (pcs/mm3) is defined as content density of a region “b” having a smaller content density, a difference D=(da?db)/db between content densities of the two regions is 10% or more.