Method for producing a tube consisting of quartz glass, tubular semi-finished product consisting of porous quartz glass, and the use of the same

摘要

In a known method for producing a quartz glass tube by means of flame hydrolysis of a silicon-containing start component, SiO₂-containing particles are produced, said particles are deposited on a carrier, forming a soot tube having a porous soot wall with a predetermined radial soot density profile, and the soot tube is treated in a chlorine-containing atmosphere and is then vitrified. To modify said method in such a way that a predetermined radial refractive index distribution is obtained also after dehydration treatment in a chlorine-containing atmosphere, it is suggested according to the invention that the density should be adjusted in such a way that in an inner region of the soot wall it is increased to at least 25% of the density of quartz glass, in an outer region of the soot wall the density is reduced, and in a transition region adjoining the inner region, the density decreases towards the outer region, with the proviso that the transition region extends over at least 75% of the thickness of the soot wall. The inventive tubular semi-finished product is characterized by a soot wall having, in an inner region, a density which is increased to at least 25% of the density of the quartz glass, a reduced density in an outer region, and, in a transition region adjoining the inner region, a density which decreases towards the outer region, said transition region extending over at least 75% of the thickness of the soot wall