Patent ID: 8657957
Filing Date: 2014-02-25
Classification: C03B,C30B,Y10T

Abstract:
1. 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, comprising the steps of: arranging the electrodes in a ring shape; heating and melting the vitreous silica powder by not generating a sustainable arc between the electrodes opposed to each other through a center portion of the ring but forming a stable ring-shaped arc that connects the neighboring electrodes; 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, wherein the bubble content of a transparent layer of the bottom and a transparent layer of the wall of the manufactured crucible is equal to or less than 0.03%.