The present invention relates to a moldable nanocomposite for producing a transparent article made of multicomponent fused silica glass, the moldable nanocomposite comprising: an organic binder; and a fused silica glass powder dispersed in the organic binder, the fused silica glass powder comprising fused silica glass particles having a diameter in the range from 5 nm to 500 nm, wherein the fused silica glass powder is pre-modified with a dopant and/or wherein at least one non-crystalline modifying agent is contained in the moldable nanocomposite and one or more dopant reagents selected from organoelement compounds, metal complexes and salts are contained in the moldable nanocomposite as the at least one non-crystalline modifying agent, and wherein the content of the fused silica glass powder in the moldable nanocomposite is at least 5 parts per volume based on 100 parts per volume of the organic binder. Further, the present invention relates to a method of producing a transparent article made of multicomponent fused silica glass.

The present invention relates to a method of manufacturing a metal mold for replicating a component having a predetermined three-dimensional shape, the manufacturing method comprising: (a) fabricating a glass-based mold by using a moldable nanocomposite comprising an organic binder and glass particles dispersed therein, the glass-based mold having the predetermined three-dimensional shape; and (b) replicating the glass-based mold obtained in step (a) by melting a metal inside the glass-based mold or by melting a metal outside the glass-based mold and pouring it onto or into the glass-based mold, followed by cooling, or by pressing the glass-based mold into a malleable metal substrate, thereby obtaining the metal mold for replicating the component, the metal mold having the predetermined three-dimensional shape inverted. Further, the present invention relates to a method of replicating a component having a predetermined three-dimensional shape, wherein the metal mold obtained by the manufacturing method is used for replicating the component, wherein the glass particles of the moldable nanocomposite comprise a first type of glass particles having a diameter in the range from 5 nm to 500 nm.

A method for preparing quartz glass with low content of hydroxyl and high purity, includes providing silica powders including hydroxyl groups. The silica powders are dehydroxylated, which includes drying the silica powders at a first temperature, heating the silica powders up to a second temperature and introducing a first oxidizing gas including halogen gas, thereby obtaining first dehydroxylated powders, and heating the first dehydroxylated powders up to a third temperature and introducing a second oxidizing gas including oxygen or ozone, thereby obtaining second dehydroxylated powders. The second dehydroxylated powders are heated up to a fourth temperature to obtain a vitrified body. The vitrified body is cooled to obtain the quartz glass with low content of hydroxyl and high purity. The quartz glass prepared by the above method has low content of hydroxyl and high purity. A quartz glass with low content of hydroxyl and high purity is also provided.

A porous cellular body comprising primarily a porous sintered glass material is disclosed. The porous sintered glass material primarily includes a first phase and a second phase, the first phase primarily comprising amorphous fused silica and the second phase comprising amorphous fused silica and a sintering aid.

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 of manufacturing a crucible assembly having a shell and a liner is disclosed. The method includes forming the shell using a casting process. The shell includes silica and has an inner surface and an outer surface. The method also includes forming the liner on the inner surface of the shell. The liner is formed of synthetic silica.

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 large sized opaque quartz glass ingot having an excellent heat ray shielding property, an outstanding light blocking property, high mechanical strength and small roughness of a baked finished smooth surface. The shape of bubbles inside the quartz glass are almost complete spheres and the average particle size of the bubbles is 1 ?m or less, such that the strength of the opaque quartz glass ingot is increased as the stress concentration at the edges of the bubbles is eliminated and an increase of surface roughness caused by baking is alleviated.

An object of the present invention is to provide an opaque quartz glass containing pores with irregular shapes and having sufficient heat ray reflecting, heat ray blocking and light shielding properties, and further to provide a method for producing the opaque quartz glass. The opaque quartz glass of the present invention is an opaque quartz glass containing pores with irregular shapes dispersed in a glass body, wherein the opaque quartz glass has a pore size distribution of the pores having D.sub.50 of 4 to 30 ?m, a proportion of pores with pore sizes of 5 ?m or less of 1 to 50%, and a proportion of pores with pore sizes of 15 ?m or less of 30 to 90%, and an area ratio of pores in a microscopic image at a cross section of 5% or more. The opaque quartz glass of the present invention is obtained by mixing a plurality of types of the specific silica powders having different particle size distributions from each other at a predetermined formulation, and sintering a pressure-molded article of the mixed powder.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in an oven, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the oven comprises a hanging sinter crucible. The invention also relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body which are each obtainable by further processing the quartz glass body.