A pre-sintered porcelain block for dental restoration; the pre-sintered porcelain block does not contain crystal phases and has a Vickers hardness of 0.5-2 GPa. Due to a hardness which is significantly lower than that of the porcelain block containing a lithium metasilicate crystal phase, the pre-sintered porcelain block may be processed by using dry machining and can simultaneously be processed by using wet machining when being mechanically processed into a dental restoration shape.

A pre-sintered porcelain block for dental restoration; the pre-sintered porcelain block does not contain crystal phases and has a Vickers hardness of 0.5-2 GPa. Due to a hardness which is significantly lower than that of the porcelain block containing a lithium metasilicate crystal phase, the pre-sintered porcelain block may be processed by using dry machining and can simultaneously be processed by using wet machining when being mechanically processed into a dental restoration shape.

Disclosed is a pre-sintered ceramic block for a dental restoration, which has a low pre-sintering temperature, contains a silica main crystal phase, but does not contain or contains a small amount of lithium metasilicate crystal phase. The pre-sintered ceramic block has a low hardness, with a Vickers hardness of 0.5-3 GPa, which is significantly lower than that of a ceramic block containing a lithium metasilicate crystal phase, and same is suitable for dry machining and also wet machining when being machined into a dental restoration. (FIG. 2)

A method of forming an optical component includes depositing slurry that includes glass powder material onto a facesheet and fusing the glass powder material to a facesheet to form a first core material layer on the facesheet. The method also includes successively fusing glass powder material in a plurality of additional core material layers to build a core material structure on the facesheet. The method can include selectively depositing slurry including glass powder material over only a portion of at least one of the facesheet, the first core material layer, and/or the one of the additional core material layers. Depositing the slurry can include extruding the slurry from an extruder.

A method of forming an optical component includes depositing slurry that includes glass powder material onto a facesheet and fusing the glass powder material to a facesheet to form a first core material layer on the facesheet. The method also includes successively fusing glass powder material in a plurality of additional core material layers to build a core material structure on the facesheet. The method can include selectively depositing slurry including glass powder material over only a portion of at least one of the facesheet, the first core material layer, and/or the one of the additional core material layers. Depositing the slurry can include extruding the slurry from an extruder.

Methods for forming a sintered patch on a silicon-based substrate are disclosed. The methods include applying a patch slurry on the silicon-based substrate, drying the patch slurry on the silicon-based substrate to form a dried patch material, and sintering the dried patch material in an oxidizing atmosphere to form a sintered patch on the silicon-based substrate. The patch slurry includes a patch material containing silicates in a fluid carrier.

Methods for forming a sintered patch on a silicon-based substrate are disclosed. The methods include applying a patch slurry on the silicon-based substrate, drying the patch slurry on the silicon-based substrate to form a dried patch material, and sintering the dried patch material in an oxidizing atmosphere to form a sintered patch on the silicon-based substrate. The patch slurry includes a patch material containing silicates in a fluid carrier.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate I prepared from a pyrogenically produced silicon dioxide powder, treating the silicon dioxide granulate I with a reactant at a temperature in a range from 1000 to 1300° C., and making a glass melt out of the silicon dioxide granulate. A quartz glass body is made out of at least a part of the glass melt. Furthermore, one aspect relates to a quartz glass body obtainable by this process. Furthermore, one aspect relates to a light guide, an illuminant, and a formed body, each of which is obtainable by further processing of the quartz glass body. One aspect additionally relates to a process for the preparation of a silicon dioxide granulate II.

Doped quartz glass components for use in a plasma-assisted manufacturing process contain at least one dopant which is capable of reacting with fluorine to form a fluoride compound, and the fluoride compound has a boiling point higher than that of SiF.sub.4. The doped quartz glass component has high dry-etch resistance and low particle formation, and has uniform etch removal when used in a plasma-assisted manufacturing process. The doped quartz glass has a microhomogeneity defined by (a) a surface roughness with an R.sub.a value of less than 20 nm after the surface has been subjected to a dry-etching procedure as specified in the description, or (b) a dopant distribution with a lateral concentration profile in which maxima of the dopant concentration are at an average distance apart of less than 30 μm.

The invention proposes a device for three-dimensional printing of a glass object, by applying and solidifying successive layers of a material constituting the glass, in locations corresponding to the section of the object to be produced in the corresponding layer, by means of a laser producing a beam whose wavelength allows the direct fusion in the core of the material.

The device comprises: means for supplying the material to a support on which the successive layers are formed; means for thermal regulation of the successive layers for holding their temperature during the production of the object and for cooling them after the production of the object; a central unit controlling the laser.

The printing device comprises means for servo-controlling the power and the speed of the laser in real time.