A method for producing a solar crucible includes providing a crucible base body of transparent or opaque fused silica having an inner wall, providing a dispersion containing amorphous SiO.sub.2 particles, applying a SiO.sub.2-containing slip layer to at least a part of the inner wall by using the dispersion, drying the slip layer to form a SiO.sub.2-containing grain layer and thermally densifying the SiO.sub.2-containing grain layer to form a diffusion barrier layer. The dispersion contains a dispersion liquid and amorphous SiO.sub.2 particles that form a coarse fraction and a fine fraction with SiO.sub.2 nanoparticles. The weight percentage of the SiO.sub.2 nanoparticles based on the solids content of the dispersion is in the range between 2 and 15% by weight. The SiO.sub.2-containing grain layer is thermally densified into the diffusion barrier layer through the heating up of the silicon in the crystal growing process.

An apparatus for the continuous production of hollow quartz-glass ingots, comprising a) a crucible or refractory tank for providing a softened quartz-glass mass having a dieorifice in the bottom of the crucible or refractory tank; b) a mandrel vertically drawing off the softened quartz-glass mass through a die toprovide a hollow quartz-glass ingot; and c) a cutting section for on-line cutting of the hollow quartz-glass ingot to a specificlength, characterized in that the apparatus comprises active means for cooling the internalsurface of the hollow quartz-glass ingot prior to the cutting station.

The present invention relates a molded composite material and a method and process for creating the composite material from either recycled low grade mixed glass cullet or new glass. The composite material including; crushed glass; one or more aluminium compounds selected from oxide and hydrate at combined 0.40%-0.78% weight per weight of the glass; oxides of silicon, boron, sodium, calcium and potassium at combined 1.27%-1.90% weight per weight of the glass; zirconium silicate at 0.48%-1.3% weight per weight of the glass; and optionally tin oxide at 0%-0.45% weight per weight of the glass. The composite of the present invention can be used for making tiles, bench tops, work surfaces or other similar types of building products. The use of low grade mixed glass can also help reduce the amount of used glass being dumped in landfill or used in other low value enterprises such as providing highway aggregate or landfill cover.

The present invention relates a molded composite material and a method and process for creating the composite material from either recycled low grade mixed glass cullet or new glass. The composite material including; crushed glass; one or more aluminium compounds selected from oxide and hydrate at combined 0.40%-0.78% weight per weight of the glass; oxides of silicon, boron, sodium, calcium and potassium at combined 1.27%-1.90% weight per weight of the glass; zirconium silicate at 0.48%-1.3% weight per weight of the glass; and optionally tin oxide at 0%-0.45% weight per weight of the glass. The composite of the present invention can be used for making tiles, bench tops, work surfaces or other similar types of building products. The use of low grade mixed glass can also help reduce the amount of used glass being dumped in landfill or used in other low value enterprises such as providing highway aggregate or landfill cover.

The present invention provides a vitreous silica crucible which can suppress buckling and sidewall lowering of the crucible without fear of mixing of impurities into silicon melt. According to the present invention, provided is a vitreous silica crucible for pulling a silicon single crystal, wherein a ratio I2/I1 is 0.67 to 1.17, where I1 and I2 are area intensities of the peaks at 492 cm.sup.−1 and 606 cm.sup.−1, respectively, in Raman spectrum of vitreous silica of the region having a thickness of 2 mm from an outer surface to an inner surface of a wall of the crucible.

A method of manufacturing of a vitreous silica crucible includes: fusing silica powder under a reduced pressure of −50 kPa or more and less than −95 kPa to form a transparent vitreous silica layer as an inner layer; fusing silica powder under a reduced pressure of 0 kPa or more and less than −10 kPa to form a bubble-containing vitreous silica layer as an intermediate layer; and fusing silica powder under a reduced pressure of −10 kPa or more and less than −50 kPa to form a semi-transparent vitreous silica layer as an outer layer.

A method for measuring a three-dimensional shape of an inner surface of a vitreous silica crucible which enables the measurement of the three-dimensional shape of the inner surface of the crucible without contaminating the inner surface of the crucible, is provided. According to the present invention, a method for measuring a three-dimensional shape of a vitreous silica crucible, including a fogging step to form a fog onto an inner surface of the vitreous silica crucible, a three-dimensional shape measuring step to measure a three-dimensional shape of the inner surface, by measuring a reflected light from the inner surface irradiated with light, is provided.

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.

A production process of a polishing stone includes a glass sphere feeding step of feeding glass spheres into a mold, and a firing step of heating the mold with the glass spheres filled therein at a temperature higher than a softening point and lower than a melting point of the glass spheres, thereby forming a glass block as the polishing stone. In the firing step, the heating is stopped with air bubbles still dispersed and remaining in interstices between the glass spheres in a dispersed manner.