Abstract: 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 SiO2 particles, applying a SiO2-containing slip layer to at least a part of the inner wall by using the dispersion, drying the slip layer to form a SiO2-containing grain layer and thermally densifying the SiO2-containing grain layer to form a diffusion barrier layer. The dispersion contains a dispersion liquid and amorphous SiO2 particles that form a coarse fraction and a fine fraction with SiO2 nanoparticles. The weight percentage of the SiO2 nanoparticles based on the solids content of the dispersion is in the range between 2 and 15% by weight. The SiO2-containing grain layer is thermally densified into the diffusion barrier layer through the heating up of the silicon in the crystal growing process.

Abstract: A method for producing a coated component consisting of transparent or opaque fused silica comprises a method step in which a SiO2 granulation layer is applied to a coating surface of a substrate, which in the area of the free surface has a relatively great granulation fine fraction. Starting from this, in order to achieve a smooth, preferably also dense surface layer, it is suggested according to the invention that the application of the SiO2 granulation layer comprises (i) providing a dispersion containing a dispersion liquid and amorphous SiO2 particles which form a coarse fraction with particle sizes ranging between 1 ?m and 50 ?m and a fine fraction of SiO2 nanoparticles having particle sizes of less than 100 nm, wherein the solids content of the dispersion is between 70 and 80 wt.-%, and of which between 2 wt.-% and 15 wt.

Abstract: In a known composite material with a fused silica matrix there are regions of silicon-containing phase embedded. In order to provide a composite material which is suitable for producing components for use in high-temperature processes for heat treatment even when exacting requirements are imposed on impermeability to gas and on purity, it is proposed in accordance with the invention that the composite material be impervious to gas, have a closed porosity of less than 0.5% and a specific density of at least 2.19 g/cm3, and at a temperature of 1000° C. have a spectral emissivity of at least 0.7 for wavelengths between 2 and 8 ?m.

Abstract: The invention relates to a process for producing a paste-like SiO2 composition using an SiO2 slip which allows simple intermediate storage and transport conditions without the processability of the slip to give the paste-like SiO2 composition being impaired thereby. According to the invention, it is for this purpose proposed that a homogeneous SiO2 base slip be subjected to a drying step to form a dry SiO2 composition and subsequently be processed further by means of a remoistening step to give the paste-like SiO2 composition, where the remoistening step comprises the addition of liquid to the dry SiO2 composition to form a paste-like kneadable SiO2 composition having a solids content of more than 85% by weight. The invention further relates to the use of a paste-like SiO2 composition as repair composition.

Abstract: In a known method, a SiO2 slip layer is applied to a basic quartz glass body by means of spraying on an SiO2 slip, the slip layer is dried and sintered to form an SiO2-containing functional layer.

Abstract: In a known method, a SiO2 slip layer is applied to a basic quartz glass body by means of spraying on an SiO2 slip, the slip layer is dried and sintered to form an SiO2-containing functional layer.