METHOD FOR PRODUCING SYNTHETIC QUARTZ GLASS BY DEPOSITION OF SiO2 SOOT FROM THE VAPOR PHASE ON A SUPPORT

摘要

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 largevolume cylindrical soot bodies with outer diameters of more than 300 mm of improved material homogeneity. the liquid feedstock material contains additional components comprising hexarnethylcyciotrisilxane 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 0.5 and 500 and the weight fraction mD7+is at least 20 wt. ppm.