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AssigneeToshiba Ceramics Co., Ltd.
InventorsHirotaka Hagihara, Takakazu Mori, Atsuro Miyao, Kiyoaki Misu, Shinya Wagatsuma, Shunichi Suzuki
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The invention is to offer such a carbon electrode of less consumption and a long useful life and a method of fabricating the same which prevents particles from falling from carbon electrodes into a melting quartz glass, checks occurrence of bubbles in the quartz glass, and avoids lowering of single crystallizing yield by bubbles existing in a transparent layer formed in the vicinity of an inside surface of a quartz glass crucible when lifting silicon single crystal by using the quartz glass crucible made by using the carbon electrodes. The carbon electrode to be used for melting quartz glass by an arc discharge, is characterized in that an electrode material is composed of carbon of bulk density being 1.80 g/cm3 or higher and a three-point bending strength being 35 MPa or higher.
A carbon electrode to be used for melting quartz glass by an arc discharge, wherein an electrode base material comprises carbon of bulk density being 1.80 g/cm3 or higher and three-point bending strength being 35 MPa or higher.
A method of fabricating a carbon electrode for melting quartz glass, wherein a kneaded material is obtained by heating and kneading a carbonaceous raw material and a binding material, and is pulverized, said carbonaceous raw material having a maximum particle diameter of 150 μm or less, and 90 wt % or more thereof being 75 μm or less of the particle diameter and said binding material having residual carbon of 50% or more, and thereafter a secondary particle is sieved such that the maximum particle diameter is 500 μm or less, and 50 wt % or more is 38 to 500 μm of the particle diameter, and pressing said secondary particle by cold isostatic pressing, followed by, after baking said pressed secondary particle, processing an isotropic graphite material graphitized at 2900 to 3100° C. and carrying out a purifying process on said isotropic graphite material.
A method of fabricating carbon electrode for melting quartz glass, wherein a kneaded material is obtained by heating and kneading the carbonaceous raw material and the binding material, and is extruded at 130 to 200° C., said carbonaceous raw material having a maximum particle diameter of 150 μm or less, and 90 wt % or more thereof being 75 μm or less of the particle diameter and said binding material having residual carbon of 50% or more, and the extruded material is baked and processed into a graphite material graphitized at 2900 to 3100° C. and further carried out with a purifying process.
Dependencies are inferred from the claim text.