Method of manufacturing vitreous silica crucible, vitreous silica crucible
The present invention provides a method of manufacturing a vitreous silica crucible having a transparent layer by use of waste vitreous silica. According to the present invention, there is provided a method of manufacturing a vitreous silica crucible for manufacturing a monocrystalline or polycrystalline silicon ingot, including a process of vitrifying a silica powder sintered body having a crucible shape in the whole or part of the thickness direction by arc fusing the silica powder sintered body from the inner surface side, wherein the method further includes at least one means of (1) depressurizing the silica powder sintered body from the outer surface side during the arc fusing, and (2) forming a synthetic vitreous silica layer on the inner surface by spraying synthetic silica powder onto the inner surface of the silica powder sintered body during the arc fusing.
1. A method of manufacturing a vitreous silica crucible for manufacturing a monocrystalline or polycrystalline silicon ingot, comprising:
vitrifying an amorphous silica powder sintered body having a crucible shape in at least part of a thickness direction by arc fusing the amorphous silica powder sintered body from an inner surface side;
depressurizing the amorphous silica powder sintered body from an outer surface side during the arc fusing; and
forming a synthetic vitreous silica layer on the inner surface side by spraying synthetic silica powder onto an inner surface of the amorphous silica powder sintered body during the arc fusing, wherein:
the spraying of the synthetic silica powder is started just after the inner surface side of the amorphous silica powder sintered body has started to be fused, and the arc fusing is terminated when half of the amorphous silica powder sintered body in a thickness direction is fused,
the arc fusing is carried out such that a temperature on the inner surface of the amorphous silica powder sintered body is 1700 to 2600 degrees C.,
the amorphous silica powder sintered body is manufactured by mixing silica powder obtained by pulverizing vitreous silica with a dispersion medium to obtain a slurry, and then forming the slurry into a crucible shape, followed by firing,
the vitreous silica is waste vitreous silica generated in a manufacturing process of a vitreous silica crucible, and
the firing is carried out at 800 to 1500 degrees C.
2. The method of claim 1 , wherein an average particle diameter of the silica powder defining the amorphous silica powder sintered body is 1 to 250 μm.
3. The method of claim 1 , wherein the forming of the synthetic vitreous silica layer comprises forming a transparent vitreous silica layer.
4. The method of claim 3 , wherein the transparent vitreous silica layer substantially does not contain bubbles.