Buckling of a vitreous silica crucible 12 or inward fall of a sidewall 15 is effectively suppressed. The vitreous silica crucible 12 includes the cylindrical sidewall 15 having an upward-opening rim, a mortar-shaped bottom 16 including a curve, and a round portion 17 connecting the sidewall 15 and the bottom 16. In the vitreous silica crucible 12 the per-unit area thermal resistance in the thickness direction of the sidewall 15 is higher than that of the round portion 17.

The present invention provides a vitreous silica crucible which inhibits a deformation even when used under a high temperature condition for a long time, and a method for manufacturing the same. The vitreous silica crucible comprises: a substantially cylindrical straight body portion having an opening on the top end and extending in a vertical direction, a curved bottom portion, and a corner portion connecting the straight body portion with the bottom portion and a curvature of which is greater than that of the bottom portion, wherein, the vitreous silica crucible comprises a transparent layer on the inside and a bubble layer on the outside thereof, a compressive stress layer in which compressive stress remains in the inner surface side of the transparent layer, and a tensile stress layer in which tensile stress remains and is adjacent to the compressive stress layer at a gradual rate of change of stress.

An object is to provide an apparatus and a method for manufacturing a silica glass crucible, both allowing a stable silica powder layer to be formed in a mold in a short period of time.

One embodiment of the present invention is an apparatus for manufacturing a silica glass crucible, by forming a silica powder layer on the inside of a rotating mold, which comprises a rotating means for rotating the mold as well as a supply means for feeding a silica powder to the inside of the mold. In this manufacturing apparatus, the supply means has a feeding part for feeding the silica powder in a manner releasing it to fall to a position away from the inner wall surface of the mold on the inside of the mold, as well as a dispersing part for changing, to one toward the inner wall surface side, at the fall position, the direction in which the silica powder fed from the feeding part moves, while also widening the angle at which the silica powder disperses toward the inner wall surface at the fall position.

A quartz glass crucible 1 having a cylindrical side wall portion 10a, a bottom portion 10b, and a corner portion 10c connecting the side wall portion 10a and the bottom portion 10b to each other includes a transparent layer 11 made of quartz glass, and a bubble layer 12 made of quartz glass and formed outside the transparent layer 11. A ratio of an infrared transmittance of the corner portion 10c at a maximum thickness position of the corner portion 10c to an infrared transmittance of the side wall portion 10a is 0.3 or more and 0.99 or less, and an absolute value of a rate of change in infrared transmittance in a height direction along a wall surface of the crucible from a center of the bottom portion 10b toward an upper end of the side wall portion 10a is 3%/cm or less.

A quartz glass crucible 1 having a cylindrical side wall portion 10a, a bottom portion 10b, and a corner portion 10c includes a transparent layer 11 as an innermost layer made of quartz glass, a semi-molten layer 13 as an outermost layer made of raw material silica powder solidified in a semi-molten state, and a bubble layer 12 made of quartz glass interposed therebetween. An infrared transmissivity of the corner portion 10c in a state where the semi-molten layer 13 is removed is 25 to 51%, the infrared transmissivity of the corner portion 10c in the state where the semi-molten layer 13 is removed is lower than an infrared transmissivity of the side wall portion 10a, and the infrared transmissivity of the side wall portion 10a in the state where the semi-molten layer 13 is removed is lower than an infrared transmissivity of the bottom portion 10b.

A quartz glass crucible including a bottom portion, a curved portion, and a straight body portion, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles therein, and an inner layer including transparent quartz glass, the outer layer includes a plurality of layers in a part of the straight body portion, out of the plurality of layers, one layer having a devitrification spot number of 50/cm.sup.3 or more and 70/cm.sup.3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours, and a layer positioned inwards of the devitrifiable layer in a thickness direction of the quartz glass crucible is a low devitrification layer having a spot number of 2/cm.sup.3 or less when the quartz glass crucible is heated at 1600° C. for 24 hours. This provides a quartz glass crucible suppressed from deformation due to heating and excessive progression of devitrification.

A quartz glass crucible including bottom, curved, and straight body portions, where the quartz glass crucible includes an outer layer including opaque quartz glass containing bubbles, and an inner layer including transparent quartz glass, the outer layer fabricated from different types of raw material powder, the outer layer having regions sectioned by bubble content densities, and bubble content densities of two outer layer adjacent regions, when d.sub.a (pcs/mm.sup.3) is defined as content density of a region “a” having a greater content density, and d.sub.b (pcs/mm.sup.3) is defined as content density of a region “b” having a smaller content density, a difference D=(d.sub.a−d.sub.b)/d.sub.b between content densities of the two regions is 10% or more.

This disclosure relates to fabrication of quartz hollow cylinder with reduced bubbles using atmospheric control. An example horizontal rotating arc furnace includes a housing, supports, and a rotary union. The housing defines an interior configured to receive silica particles and electrodes that generate a plasma arc and includes a plurality of first ports on an exterior of the housing fluidly connected to the interior and supply pipes fluidly coupled to the first ports. The supports mechanically couple the housing to a drive system to provide rotational motion to the housing. The rotary union is coupled to the housing includes second ports to fluidly connect to a vacuum supply. The second ports are fluidly connected to the first ports via the supply pipes. The horizontal rotating arc furnace is configured to apply a vacuum to the interior of the housing via the first ports when the housing is spinning.

A mold for manufacturing a quartz glass crucible by a rotary molding method, having a plurality of grooves that are concentric with respect to a mold rotation axis in at least a straight body portion of an inner surface of the mold, wherein the plurality of concentric grooves are non-penetrating grooves that do not penetrate the mold. This provides a mold for manufacturing a quartz glass crucible by a rotary molding method, having an inner surface made so that it is difficult for quartz powder to slide down when forming a quartz powder compact.

A silica glass crucible includes a cylindrical side wall portion, a curved bottom portion, and a corner portion that is provided between the side wall portion and the bottom portion and has a higher curvature than a curvature of the bottom portion, in which a first region provided from a crucible inner surface to a middle in a thickness direction, a second region that is provided outside the first region in the thickness direction and has a different strain distribution from the first region, and a third region that is provided outside the second region in the thickness direction and up to the crucible outer surface and has a different strain distribution from the second region, are provided, and internal residual stresses of the first region and the third region are compressive stresses, whereas an internal residual stress of the second region includes a tensile stress.