Abstract: A fluid-cooled mold for the production of a quartz crucible provided in its interior with a space for flowing of cooling fluid comprises an outer mold section made from a heat-conductive metal or alloy material and an inner mold section closely arranged to an inner surface of the outer mold section and made from a heat-resistant material.

Abstract: In an apparatus for the production of a silica crucible comprising a carbon mold suitable for producing the silica crucible by the rotating mold method, the carbon mold has a thermal conductivity of not more than 125 W/(m·K).

Abstract: Provided is a method of calculating a temperature distribution with higher accuracy than a conventional method, which calculates a temperature distribution of an inner surface of a silica powder molded body during manufacturing based on boundary conditions corrected in accordance with the actually measured temperature in consideration of plasma radiation by arc discharge and heat radiation of arc discharge.

Abstract: In a mold for use in the production of a silica crucible, a cylindrical rim member is engagedly supported through hooks to an inner side of an upper opening portion of the mold corresponding to an upper part of a silica crucible and an outer diameter of the rim member is smaller than an inner diameter of the mold but larger than an inner diameter of the silica crucible.

Abstract: A modification process of the synthetic quartz powder, which can make a quartz glass product hardly having bubbles at the time of fusing, is provided, along with a modification process of the synthetic quartz powder and a glass product using said modified quartz powder are provided, wherein the synthetic quartz powder is kept in helium atmosphere at least in the temperature falling process, when the amorphous synthetic quartz powder produced by the sol-gel method is carried out by heat treatment in a vacuum furnace at more than the degas temperature and less than the baking temperature, wherein the highest temperature in the helium atmosphere is preferably set to from more than 700° C. to less than 1400° C., and the helium atmosphere is kept to less than 400° C.

Abstract: The method of producing a vitreous silica crucible, comprises deposition step of depositing silica powder on an inner wall surface of a cylindrical rotation mold having a bottom while rotating the mold; and a fusion step to obtain a vitreous silica crucible by heating and fusing the silica powder deposited on the inner wall surface of the mold and thereby vitrifying the silica powder. In the deposition step, a density of the deposited silica powder layer on the inner wall surface of the mold is controlled within a predetermined range by controlling the electrostatic charging voltage of the silica powder to be in a range of 1.0 kV or less in absolute value, and supplying the thus controlled silica powder to the inner wall surface of the mold. Thus, a wall thickness of the vitreous silica crucible is controlled.

Abstract: A method of manufacturing a carbon electrode for melting an object to be melted by arc discharge, includes: a rubbing step of rubbing the surface of the carbon electrode before power is supplied with a rubbing material of the same type as the object to be melted.

Abstract: Provided is a method of manufacturing a vitreous silica crucible, including: an arc fusing process for fusing the silica powder molded body by using arc flames generated from the plurality of carbon electrodes, wherein the arc fusing process is performed in a state of disposing tips of at least a pair of carbon electrodes of the plurality of carbon electrodes closer to a target surface of the silica powder molded body than other carbon electrode tips, and setting distances from each of the tips of the closer carbon electrodes to the target surface, to be equal, and the arc fusing process is performed by heating and fusing the silica powder molded body while performing fire polishing, which partially removes an inner surface of the silica powder molded body by using arc flames generated by the closer carbon electrodes.

Abstract: A surface modified quartz glass crucible and a process for modifying the crucible includes a layer of a metal oxide on the whole or a part of the inside and/or outside of the crucible, and baking it. At least an inside surface of the crucible is coated with a said metal oxide of magnesium, calcium, strontium or barium. The coated layer of the crucible does not abrade easily and provides a high dislocation free ratio of silicon single crystals pulled by using the crucible.

Abstract: [Problems] To provide a treatment method having excellent purification effect, in which impurities having high ionicity in a silica powder can be removed in a short time, a apparatus thereof, and a purified silica powder. [Means for Solving the Problems] A purification method of a silica powder comprises: making a silica powder into a fluid state; contacting a purified gas to the silica powder in the fluid state at high temperature; and thereby removing impurity components of the silica powder. In the method, the silica powder in the fluid state is positioned in a magnetic field region. Further, the silica powder is contacted with the purified gas, while applying voltage to the silica powder by an electric field generated by moving of the silica powder. Preferably, the silica powder in a fluid state is positioned in the magnetic region of 10 gausses or more, and contacted with the purification gas at a temperature of 1000° C. or more.

Abstract: [Problems] To provide a treatment method having excellent purification effect, in which impurities having high ionicity in a silica powder can be removed in a short time, a apparatus thereof, and a purified silica powder. [Means for Solving the Problems] A purification method of a silica powder comprises: making a silica powder into a fluid state; contacting a purified gas to the silica powder in the fluid state at high temperature; and thereby removing impurity components of the silica powder. In the method, the silica powder in the fluid state is positioned in a magnetic field region. Further, the silica powder is contacted with the purified gas, while applying voltage to the silica powder by an electric field generated by moving of the silica powder. Preferably, the silica powder in a fluid state is positioned in the magnetic region of 10 gausses or more, and contacted with the purification gas at a temperature of 1000° C. or more.

Abstract: A method of manufacturing a carbon electrode for melting an object to be melted by arc discharge, includes: a rubbing step of rubbing the surface of the carbon electrode before power is supplied with a rubbing material of the same type as the object to be melted.

Abstract: A silica glass crucible used for pulling up silicon single crystal at a high temperature. The silica glass crucible may have at least an outer surface of a wall part of the crucible covered with fine grooves having a length of less than 200 ?m, a width of less than 30 ?m and a depth of from more than 3 ?m to less than 30 ?m. The fine groves may be formed by carrying out a sand-blast treatment and a hydrofluoric acid etching and may exist on more than 10% of the outer surface of the crucible, and a sliding frictional coefficient of the outer surface of the crucible to a carbon at 1500° C. is more than 0.6.

Abstract: An object of the present invention is to provide a crane device suitable for handling a wrapped crucible, which crane device is capable of realizing mechanical handling of the wrapped crucible by way of a machine without manual work. In view of this, the present invention provides a crane device adapted to be capable of making reciprocal movements along a path between a position above a lifting-up point where a wrapped quartz glass crucible is placed and another position above a putting-down point where a packing container is placed and ascending to/descending from the path at each of the lifting-up point and the putting-down point, the crane device having: four arms extending in the ascend-descend direction and disposed at apexes of a quadrangle such that two arms paired on a diagonal line of the quadrangle are movable to advance to/separate from each other; and a claw provided at a rear end of each arm to extend in the advancing direction of the arm.

Abstract: To provide a treatment method having excellent purification effect, in which impurities having high ionicity in a silica powder can be removed in a short time, a apparatus thereof, and a purified silica powder. A purification method of a silica powder comprises: making a silica powder into a fluid state; contacting a purified gas to the silica powder in the fluid state at high temperature; and thereby removing impurity components of the silica powder. In the method, the silica powder in the fluid state is positioned in a magnetic field region. Further, the silica powder is contacted with the purified gas, while applying voltage to the silica powder by an electric field generated by moving of the silica powder. Preferably, the silica powder in a fluid state is positioned in the magnetic region of 10 gausses or more, and contacted with the purification gas at a temperature of 1000° C. or more.

Abstract: Provided are an apparatus and a method for manufacturing a vitreous silica crucible, which enable accurate measurement of a fume generation amount, prevention of deterioration of an inner surface property, and real-time control of a raw material melting state. Provided is an apparatus for manufacturing a vitreous silica crucible 50 by supplying silica powder into a mold 10 to form a silica powder layer 11, and heating and melting the silica powder layer 11 by arc discharge. The apparatus includes the mold 10 for defining an outer shape of a vitreous silica crucible, an arc discharge unit having a plurality of carbon electrodes 13 and a power-supply unit 40, and a fume-amount measurement unit 30 for detecting an amount of fumes 80 generated in the mold 10.

Abstract: A reforming process of a quartz glass crucible in which the quartz glass crucible is reformed by an arc discharge generated by electrodes positioned around a rotational axis and configured to heat an inside surface of the crucible while the crucible is rotated. The process includes arranging electrodes in an electrode structure such that neighboring electrodes are positioned at regular intervals in a ring-like configuration; forming a stable ring-like arc between the neighboring electrodes, without generating a continuous arc between electrodes facing each other across a central portion of the ring-like configuration; heating the inside surface of the crucible; and removing a foreign substance located on the inside surface of the crucible or a bubble located under the inside surface of the crucible.

Abstract: Provided is a vitreous silica crucible for pulling a silicon single crystal, having an inner surface layer which is excellent in uniformity and has a low bubble content rate, and a method of manufacturing the same. Provided is a method of manufacturing a vitreous silica crucible for pulling a silicon single crystal comprising the step of forming an inner surface layer 30 made of synthetic silica powder, wherein the inner surface layer 30 comprises an inner side portion 31 of the inner surface layer 30, the inner side portion 31 made of a first synthetic silica powder; and a surface side portion 32 of the inner surface layer 30, the surface side portion made of a second synthetic silica powder having a smaller average particle size than that of the first synthetic silica powder.

Abstract: An object of the present invention is to provide a crucible handling device that can firmly sandwich and reliably move a quartz glass crucible under a clean environment and a method of handling a quartz glass crucible using the crucible handling device.

Abstract: There is provided a silica crucible for pulling a silicon single crystal, comprising silica glass and having a two-layer structure of an outer layer and an inner layer, wherein the inner layer, in a sectional side view of the crucible, has a wavy inner surface shape having mountain parts and valley parts at least between a start position and an end position for the pulling of a silicon single crystal in a silicon melt surface, and when a distance from an upper opening end of the crucible to the start position for the pulling of the silicon single crystal is 100, only a crucible portion from the upper opening end to a position within a range of 40 to 100 is crystalline.