A method for producing a solid body of glass is described. The method comprises providing a polymerisable composition, curing the polymerisable composition to obtain a cured body, subjecting the cured body to thermal debinding to substantially remove the organic components in the cured body, and subjecting the cured body to sintering to obtain a solid body of silica glass. The polymerisable composition one or more at least partially organic polymerisable compound(s) which form a liquid composition at operating temperature and a solid source of silica as colloidal silica particles or silica glass micro-/nanoparticles dispersed in the liquid composition. The one or more at least partially organic polymerisable compounds comprises at least one organosilicon compound as a second source of silica that is liquid or solubilisable in the liquid composition at operating temperature to thereby increase the silica loading of the cured body prior to sintering. Compositions and methods for producing solid glass objects by additive manufacturing are also described.

A method for producing a solid body of glass is described. The method comprises providing a polymerisable composition, curing the polymerisable composition to obtain a cured body, subjecting the cured body to thermal debinding to substantially remove the organic components in the cured body, and subjecting the cured body to sintering to obtain a solid body of silica glass. The polymerisable composition one or more at least partially organic polymerisable compound(s) which form a liquid composition at operating temperature and a solid source of silica as colloidal silica particles or silica glass micro-/nanoparticles dispersed in the liquid composition. The one or more at least partially organic polymerisable compounds comprises at least one organosilicon compound as a second source of silica that is liquid or solubilisable in the liquid composition at operating temperature to thereby increase the silica loading of the cured body prior to sintering. Compositions and methods for producing solid glass objects by additive manufacturing are also described.

A method for producing a pore-containing opaque quartz glass includes: (a) producing porous SiO.sub.2 granulate particles from synthetically produced SiO.sub.2, (b) thermally densifying the SiO.sub.2 granulate particles to form partly densified SiO.sub.2 granulate particles, (c) forming a dispersion from the partly densified SiO.sub.2 granulate particles, (d) comminuting the partly densified SiO.sub.2 granulate particles to form a slip containing comminuted SiO.sub.2 granulate particles, (e) shaping the slip into a shaped body and forming a porous SiO.sub.2 green body with a green density rG, and (f) sintering the SiO.sub.2 green body into opaque quartz glass. To produce opaque quartz glass that is also suited for the use of spray granulate, during step (b), partly densified SiO.sub.2 granulate particles are produced with a specific surface BET-(A) between 0.025 and 2.5 m.sup.2/g, and during step (d), comminuted SiO.sub.2 granulate particles are produced with a specific surface BET-(B) between 4 and 10 m.sup.2/g.

A method for producing a pore-containing opaque quartz glass includes: (a) producing porous SiO.sub.2 granulate particles from synthetically produced SiO.sub.2, (b) thermally densifying the SiO.sub.2 granulate particles to form partly densified SiO.sub.2 granulate particles, (c) forming a dispersion from the partly densified SiO.sub.2 granulate particles, (d) comminuting the partly densified SiO.sub.2 granulate particles to form a slip containing comminuted SiO.sub.2 granulate particles, (e) shaping the slip into a shaped body and forming a porous SiO.sub.2 green body with a green density rG, and (f) sintering the SiO.sub.2 green body into opaque quartz glass. To produce opaque quartz glass that is also suited for the use of spray granulate, during step (b), partly densified SiO.sub.2 granulate particles are produced with a specific surface BET-(A) between 0.025 and 2.5 m.sup.2/g, and during step (d), comminuted SiO.sub.2 granulate particles are produced with a specific surface BET-(B) between 4 and 10 m.sup.2/g.

A method for producing rare earth metal-doped quartz glass includes the steps of (a) providing a blank of the rare earth metal-doped quartz glass, and (b) homogenizing the blank by softening the blank zone by zone in a heating zone and by twisting the softened zone along a rotation axis. Some rare earth metals, however, show a discoloration of the quartz glass, which hints at an unforeseeable and undesired change in the chemical composition or possibly at an inhomogeneous distribution of the dopants. To avoid this drawback and to provide a modified method which ensures the production of rare earth metal-doped quartz glass with reproducible properties, during homogenization according to method step (b), the blank is softened under the action of an oxidizingly acting or a neutral plasma.

A method for producing rare earth metal-doped quartz glass includes the steps of (a) providing a blank of the rare earth metal-doped quartz glass, and (b) homogenizing the blank by softening the blank zone by zone in a heating zone and by twisting the softened zone along a rotation axis. Some rare earth metals, however, show a discoloration of the quartz glass, which hints at an unforeseeable and undesired change in the chemical composition or possibly at an inhomogeneous distribution of the dopants. To avoid this drawback and to provide a modified method which ensures the production of rare earth metal-doped quartz glass with reproducible properties, during homogenization according to method step (b), the blank is softened under the action of an oxidizingly acting or a neutral plasma.

The present invention is a method for producing a quartz glass crucible for pulling a single crystal silicon from a silicon melt held therein, including the steps of: producing a quartz glass crucible having an outer layer including an opaque quartz glass containing bubbles therein and an inner layer including a transparent quartz glass containing substantially no bubbles; roughening a region of an inner surface of the produced quartz glass crucible, the region being in contact with the silicon melt when holding the silicon melt; and heating the quartz glass crucible having the roughened inner surface to crystallize a surface of the roughened region. This can produce a quartz glass crucible for pulling a single crystal silicon which can suppress generation of a brown ring on the inner surface of the crucible during pulling the single crystal silicon and can suppress crystallinity disorder of the single crystal silicon.

The present invention is a method for producing a quartz glass crucible for pulling a single crystal silicon from a silicon melt held therein, including the steps of: producing a quartz glass crucible having an outer layer including an opaque quartz glass containing bubbles therein and an inner layer including a transparent quartz glass containing substantially no bubbles; roughening a region of an inner surface of the produced quartz glass crucible, the region being in contact with the silicon melt when holding the silicon melt; and heating the quartz glass crucible having the roughened inner surface to crystallize a surface of the roughened region. This can produce a quartz glass crucible for pulling a single crystal silicon which can suppress generation of a brown ring on the inner surface of the crucible during pulling the single crystal silicon and can suppress crystallinity disorder of the single crystal silicon.

An infrared transmissivity measurement method is for measuring an infrared transmissivity of a quartz glass crucible which includes a transparent layer made of quartz glass that does not contain bubbles, a bubble layer formed outside the transparent layer and made of quartz glass containing bubbles, and a semi-molten layer formed outside the bubble layer and made of raw material silica powder solidified in a semi-molten state. The infrared transmissivity measurement method includes processing an outer surface of the quartz glass crucible formed by the semi-molten layer to lower a surface roughness of the outer surface; and measuring an infrared transmissivity of the quartz glass crucible based on infrared light passing through the outer surface after processing the outer surface.

An infrared transmissivity measurement method is for measuring an infrared transmissivity of a quartz glass crucible which includes a transparent layer made of quartz glass that does not contain bubbles, a bubble layer formed outside the transparent layer and made of quartz glass containing bubbles, and a semi-molten layer formed outside the bubble layer and made of raw material silica powder solidified in a semi-molten state. The infrared transmissivity measurement method includes processing an outer surface of the quartz glass crucible formed by the semi-molten layer to lower a surface roughness of the outer surface; and measuring an infrared transmissivity of the quartz glass crucible based on infrared light passing through the outer surface after processing the outer surface.