Method of manufacturing carbon electrode

1. A method of manufacturing a carbon electrode for melting a vitreous silica object to be melted by arc discharge, wherein the levels of impurities of the vitreous silica are set to be in the ranges of 0.001 to 1.0 ppm of Fe, 0.001 to 1.3 ppm of Na, 0.001 to 1.0 ppm of K, 0.001 to 1.0 ppm of Li, 0.001 to 0.05 ppm of Cu, and 0.001 to 1.0 ppm of Ca, or in the ranges at lower levels than these ranges, the method comprising:

rubbing the surface of the carbon electrode before power is supplied, with a vitreous silica of the same type as the vitreous silica object to be melted, by at least one of:

inserting a front end side of the carbon electrode into a storage tank storing powdered vitreous silica, by at least one of rotating and reciprocating in an axial direction the storage tank and the carbon electrode relative to each other;

rubbing the surface of the carbon electrode by ejecting powdered vitreous silica from a nozzle onto the surface of the carbon electrode;

rubbing the surface of the carbon electrode with a grinder made of vitreous silica; and

rubbing the surface of the carbon electrode against a rotating surface of at least a portion of a fused vitreous silica crucible.

2. The method according to claim 1 , wherein the rubbing step is performed after a grinding step of shaping the front end of the carbon electrode.

3. The method according to claim 1 , wherein the average particle size D 50 of the vitreous silica powder is in the range of 100 to 250 μm.

4. The method according to claim 1 , wherein in the rubbing step, when the front end side of the carbon electrode is rubbed, the levels of impurities on the surface of a holding device for holding the base end side of the electrode are maintained in the ranges of 0.001 to 1.0 ppm of Fe, 0.001 to 1.3 ppm of Na, 0.001 to 1.0 ppm of K, 0.001 to 1.0 ppm of Li, 0.001 to 0.05 ppm of Cu, and 0.001 to 1.0 ppm of Ca.