Abstract: A known method for producing synthetic quartz glass comprises the method steps of: forming a stream of a SiO2 feedstock material which contains octamethylcyclotetrasiloxane (D4) as the main component which has a reference molecular mass assigned to it, feeding the stream to a reaction zone in which the feedstock material is converted under formation of amorphous SiO2 particles by pyrolysis or hydrolysis into SiO2, depositing the amorphous SiO2 particles on a deposition surface while forming a porous SiO2 soot body, and vitrifying the SiO2 soot body while forming the synthetic quartz glass.

Abstract: The present invention relates to a method for producing synthetic quartz glass, comprising the steps of: providing a liquid SiO2 feedstock material (105), which comprises more than 70% by wt. of the octamethylcyclotetrasiloxane D4, vaporizing the SiO2 feedstock material (105) into a gaseous SiO2 feedstock vapor (107), converting the SiO2 feedstock vapor (107) into SiO2 particles, depositing the SiO2 particles on a deposition surface (160) while forming a SiO2 soot body (200), vitrifying the SiO2 soot body (200) while forming the synthetic quartz glass. According to the invention it is provided that vaporizing the heated SiO2 feedstock material (105) comprises an injection phase in an expansion chamber (125) in which the heated SiO2 feedstock material (105) is atomized into droplets, the droplets having a mean diameter of less than 5 pm, preferably less than 2 ?m.

Abstract: A method for producing synthetic quartz glass comprises providing a liquid SiO2 feedstock material containing mainly octamethylcyclotetrasiloxane D4, vaporizing the SiO2 feedstock material into a feedstock vapor, converting the feedstock vapor into SiO2 particles, depositing the SiO2 particles on a deposition surface while forming a porous SiO2 soot body, and vitrifying the SiO2 soot body while forming the synthetic quartz glass. To produce large-volume cylindrical soot bodies with outer diameters of more than 300 mm of improved material homogeneity, the liquid feedstock material contains additional components comprising hexamethylcyclotrisiloxane D3 and its linear homolog with a weight fraction mD3, dodecamethylcyclohexasiloxane D6 and its linear homolog with a weight fraction mD6, and tetradecamethylcycloheptasiloxane D7 and/or hexadecamethylcyclooctasiloxane D8 and its linear homologs with a weight fraction mD7+. The weight ratio mD3/mD6 is in a range between 0.

Abstract: A known method for producing synthetic quartz glass comprises the method steps of: forming a stream of a SiO2 feedstock material which contains octamethylcyclotetrasiloxane (D4) as the main component which has a reference molecular mass assigned to it, feeding the stream to a reaction zone in which the feedstock material is converted under formation of amorphous SiO2 particles by pyrolysis or hydrolysis into SiO2, depositing the amorphous SiO2 particles on a deposition surface while forming a porous SiO2 soot body, and vitrifying the SiO2 soot body while forming the synthetic quartz glass.

Abstract: The present invention relates to a method for producing synthetic quartz glass, comprising the steps of: (A) providing a liquid SiO2 feedstock material (105), which comprises more than 70% by wt. of the polyalkylsiloxane D4, (B) vaporizing the SiO2 feedstock material (105) into a gaseous SiO2 feedstock vapor (107), (C) converting the SiO2 feedstock vapor (107) into SiO2 particles, (D) depositing the SiO2 particles on a deposition surface (160) while forming a SiO2 soot body (200), (E) vitrifying the SiO2 soot body (200) while forming the synthetic quartz glass, According to the invention it is provided that vaporizing the heated SiO2 feedstock material (105) comprises an injection phase in an expansion chamber (125) in which the SiO2 feedstock material (105) is atomized into fine droplets, the droplets having a mean diameter of less than 5 ?m, preferably less than 2 ?m.

Abstract: A method for producing synthetic quartz glass comprises providing a liquid SiO2 feedstock material containing octamethylcyclotetrasiloxane D4, vaporizing the SiO2 feedstock material into vapor, converting the vapor into SiO2 particles, depositing the particles to form a porous SiO2 soot body, and vitrifying the soot body, forming the synthetic quartz glass. To produce cylindrical soot bodies with outer diameters above 300 mm and improved material homogeneity, the liquid feedstock material contains additional components comprising hexamethylcyclotrisiloxane D3 and the linear homolog thereof with a weight fraction mD3, decamethylcyclohexasiloxane D6 and the linear homolog thereof with a weight fraction mD6, and tetradecamethylcycloheptasiloxane D7 and/or hexadecamethylcyclooctasiloxane D8 and the linear homologs thereof with a weight fraction mD7+, wherein the weight ratio mD3/mD6 is between 0.5 and 500 and the weight fraction mD7+ is at least 20 wt. ppm.

Abstract: Method for producing a semifinished product from synthetic quartz glass Methods for producing a semifinished product from synthetic quartz glass by plastic deformation of a softened SiO2 mass in a melt mold are known. Starting from this, to avoid fusion defects as much as possible and to obtain semifinished products of quartz glass in a reproducibly high quality, a method is suggested that comprises the following steps: (a) providing a porous SiO2 soot body, (b) zonewise sintering of the SiO2 soot body in the melt mold at a sintering temperature and during a sintering period with formation of a completely sintered transparent quartz glass body, and directly thereafter (c) shaping the sintered quartz glass body by softening in the melt mold with formation of a viscous quartz glass mass which fills the volume of the melt mold entirely or partly, and (d) cooling the quartz glass mass and removing the mass from the melt mold with formation of the semifinished product.

Abstract: Method for producing a semifinished product from synthetic quartz glass Methods for producing a semifinished product from synthetic quartz glass by plastic deformation of a softened SiO2 mass in a melt mold are known. Starting from this, to avoid fusion defects as much as possible and to obtain semifinished products of quartz glass in a reproducibly high quality, a method is suggested that comprises the following steps: (a) providing a porous SiO2 soot body, (b) zonewise sintering of the SiO2 soot body in the melt mold at a sintering temperature and during a sintering period with formation of a completely sintered transparent quartz glass body, and directly thereafter (c) shaping the sintered quartz glass body by softening in the melt mold with formation of a viscous quartz glass mass which fills the volume of the melt mold entirely or partly, and (d) cooling the quartz glass mass and removing the mass from the melt mold with formation of the semifinished product.

Abstract: In a known method for producing a hollow cylinder from synthetic quartz glass, a compound containing silicon is flame-hydrolyzed and SiO2 particles are deposited in layers on a rotating carrier to produce an elongated porous soot body with a central inner bore. Said body is subjected to a dehydration treatment and is then sintered vertically in a vitrification furnace, the body being held in the vitrification furnace by a retaining device. The retaining device comprises an elongated retaining body, which contains graphite and protrudes into the inner bore of the soot body, said soot body collapsing onto the retaining body to form the quartz glass tube. The aim of the invention is to develop said method to prevent the contamination of the quartz glass tube and to optimize the service life of the retaining device and the production costs.

Abstract: In a known process for the manufacture of an elongated porous SiO2 preform, SiO2 particles are deposited on the mantle surface of a cylindrical carrier rotating about its longitudinal axis. The SiO2 particles are formed by means of a plurality of deposition burners which are arranged, at a distance from one another, in at least one burner row extending parallel to the longitudinal axis of the carrier. The burners are moved in a repeated cycle back and forth along the forming preform and between turnaround points where the direction of their motion is reversed. Measures are taken in the process to prevent or reduce overheating of the preform in the turnaround point regions. These measures can lead to variations in the rate of deposition.