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 method of manufacturing a fused silica crucible by heating and melting a vitreous silica powder compact shaped into a mold using arc discharge of electrodes arranged around a rotation shaft of the mold, includes the steps of: arranging the electrodes in a ring shape, and setting a ratio W/R of a horizontal distance W between the electrode front end and the surface of the vitreous silica powder compact to a vitreous silica powder compact opening radius R, for at least a predetermined time during arc heating, to be in the range of 0.002 to 0.98.

Abstract: An arc discharge method of the present invention includes the steps of: heating and melting a non-conductive object by arc discharge using a plurality of carbon electrodes in an output range of 300 to 12,000 kVA; and setting a ratio of the distance between a contact position at which the carbon electrodes come in contact with each other and a front end to the diameter of the carbon electrode during the start of the arc discharge to be in the range of 0.001 to 0.9.

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: A silica glass crucible causing fewer pinholes in silicon single crystals is provided by a method of preventing pinholes by performing the pulling up of a silicon single crystal while restraining the dissolution rate of the crucible inner surface to 20 ?m/hr or less, using a silica glass crucible for the pulling up of silicon single crystals, wherein the area of crystalline silica formed by crystallization of amorphous silica is restricted to 10% or less of the crucible inner surface area, or the density of pits formed from open bubbles on the crucible inner surface is restricted to 0.01 to 0.2 counts/mm2.

Abstract: A method of producing a quartz glass crucible by arc melting a quartz powder molded product loaded on the inner side of a mold while performing vacuum suction, includes initiating the melting of quartz powder from the rim edge of a quartz powder molded product, subsequently lowering the arc electrode or raising the mold to heat and melt the sections on the downside of the rim edge. The method is preferably carried out such that the inner surface of the crucible is sealed within a time corresponding to 10% of the total arc time starting from the initiation of arc melting, and the seal thickness is 3 mm or less. The quartz glass crucible thus produced is useful for the pulling up of silicon single crystals and has a uniform glass layer with fewer internal bubbles.

Abstract: A method is provided for producing a vitreous silica crucible having excellent shape formability and fewer internal bubbles without excessively heating the curved portion and the bottom part. The method comprises arc melting a quartz powder molded product loaded in a rotating mold while performing vacuum suction, wherein the electrode is moved sideways with respect to the mold center line upon the initiation of arc melting or during the arc melting, and the arc melting is performed at an eccentric position, and preferably the time for total heating is limited to 60% or less of the total arc melting time. A vitreous silica crucible produced by this method is also provided.

Abstract: A silica glass crucible for pulling up a silicon crystal related to the present invention includes a roundness Sx of an interior surface of the silica glass crucible and a roundness Sy of an exterior surface of the silica glass crucible in at least a wall part of the silica glass crucible both being 0.4 or less (Sx/M?0.4, Sy/M?0.4) to a maximum thickness M in the same measurement height as the roundness.

Abstract: A crucible lift device for taking a crucible out of a mold is provided with a lid member which closely contacts a limb portion defining an opening of a crucible; a decompressing mechanism which decompresses an internal space of the crucible sealed with the lid member; and a vertically-moving mechanism for the lid member. The crucible lift device includes a stand, and the vertically-moving mechanism includes a crane device which is fixed to a beam provided on an upper end of the stand and vertically moves the lid member. The decompressing mechanism includes a suction duct which penetrates the lid member to open into the internal space of crucible, and a decompressor which is connected to the suction duct. The vertically-moving mechanism can integrally lift the crucible in which the internal space is decompressed together with the lid member.

Abstract: A silica glass crucible having a sidewall portion and a bottom portion is provided with a first synthetic silica glass layer constituting an inner layer at least in the sidewall portion, a second synthetic silica glass layer constituting an inner layer at least in a region including a center of the bottom portion, and a natural silica glass layer constituting an outer layer in the sidewall portion and the bottom portion. A melting rate of the second synthetic silica glass layer with respect to a silicon melt is higher than that of the first synthetic silica glass layer. An aluminum concentration of the second synthetic silica glass layer is higher than that of the first synthetic silica glass layer.

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 high-purity vitreous silica crucible which has high strength and is used for pulling a large-diameter single-crystal silicon ingot, includes a double laminated structure constituted by an outer layer composed of amorphous silica glass with a bubble content of 1 to 10% and a purity of 99.99% or higher and an inner layer composed of amorphous silica glass with a bubble content of 0.6% or less and a purity of 99.99% or higher, and in the portion between the upper opening end of the high-purity vitreous silica crucible and the ingot-pulling start line of a silicon melt surface in the step of pulling a single-crystal silicon ingot, a portion corresponding to 40 to 100 volume % from the upper opening end of the crucible is in a crystalline structure free from the crystallization promoter.

Abstract: A vitreous silica crucible for pulling single-crystal silicon, which is formed of vitreous silica and has a bottomed cylindrical shape, wherein, in a liquid-level movement range in the inner surface of the crucible, ranging from a position corresponding to the liquid surface level of a silicon melt at the time of stating the pulling of single-crystal silicon to a position corresponding to the liquid surface level of a silicon melt at the time of finishing the pulling of single-crystal silicon, the concentration of an OH group included in the vitreous silica is higher in an erosion thickness portion of the inner surface of the crucible than that in the range lower than the liquid surface level which is positioned below the liquid-level movement range

Abstract: A vitreous silica crucible for pulling single-crystal silicon, comprising a surface glass layer having a thickness of 100 ?m from an inner surface of the crucible, and a glass layer provided below the surface glass layer in a thickness direction of the crucible and extending to a depth of 1 mm from the inner surface of the crucible. The concentration of OH groups in the surface glass layer is 90 ppm or less, and the concentration of OH groups in the glass layer is equal to or more than 90 ppm and equal to or less than 200 ppm. The bubble content in the glass layer is 0.1% or less.

Abstract: A high-purity vitreous silica crucible used for pulling a large-diameter single-crystal silicon ingot, includes a double layered structure constituted by an outer layer composed of high-purity amorphous vitreous silica with a bubble content of 1 to 10% and a purity of 99.99% or higher, and an inner layer composed of high-purity amorphous vitreous silica s with a bubble content of 0.6% or less and a purity of 99.99% or higher, wherein, at least for an inner surface of the vitreous silica crucible between ingot-pulling start line and ingot-pulling end line of a silicon melt surface, a longitudinal section of the inner surface is shaped into a waveform, and depth and width of the ring grooves constituting the multi ring-groove patterned face are set in the range of 0.5 to 2 mm and 10 to 100 mm, respectively.

Abstract: The present invention relates to a vitreous silica crucible for pulling up silicon single crystals by a pulling-up process having a first stage and a second stage after the first stage. The crucible comprises a transparent inner layer containing inner layer bubbles, and an outer layer containing outer layer bubbles. The second stage expansion coefficient X2 of the inner-layer bubbles during the second stage is set to ? or less of the first stage expansion coefficient X1 of the inner-layer bubbles during the first stage.

Abstract: A vitreous silica member of the present invention is characterized by being formed of vitreous silica exhibiting the easily crystallizable property in the absence of a crystallization accelerator. The vitreous silica having the easily crystallizable property is obtained preferably by heating and melting crystalline quartz at a temperature in the range of 1,710° C. or more to 1,780° C. or less for vitrification, and controlling the fictive temperature of the glass to be in the range of 1,100° C. or more to 1,400° C. or less. The invention also includes a vitreous silica crucible and a method of pulling single-crystal silicon using this vitreous silica crucible.

Abstract: A crucible has a structure where a layer containing a crystallization accelerating component such as aluminum or the like (a crystallization accelerating layer) is inserted inside a quartz glass layer of a crucible straight body part excepting a crucible bottom part. The crucible does not deform and fall inwardly at the straight body part since a part containing a crystallization accelerating component advances to crystallize so as to increase strength at a high temperature when the crucible is used in pulling up silicon single crystal. Therefore, a single crystallization rate can be increased. Further, since the crystallization accelerating layer is inserted inside the quartz glass layer, the crystallization accelerating component, such as aluminum or barium, does not contact with silicon melt or a carbon susceptor, contamination by eluting these metals does not occurs.

Abstract: A process reinforcing a silica glass substance, such as a silica glass crucible, is provided without intermixing an impurity. The process comprises forming a silica glass powder layer on a surface of the silica glass substance, and crystallizing said silica glass powder layer under high temperature. As for a silica glass crucible, the process for reinforcing the silica glass crucible and the reinforced silica glass crucible are provided, wherein the silica glass powder layer on the whole or a part of the surface of the crucible is formed and then, crystallized under a temperature at the melting of a silicon raw material being charged into said quartz glass crucible.

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.