| 摘要 |
The invention relates to a method for producing a blank of Fe-doped silica glass for use as heat protection glass. The ratio of Fe2+ / Fe3+ is influenced in the method in favour of Fe2+. In addition, no further dopants are required. According to the invention, the method comprises the following steps: (a) producing an iron-doped SiO2 soot body by means of flame hydrolysis of a silicon-containing and an iron-containing starting substance, (b) drying the soot body such that a mean hydroxyl group content of less than 10 ppm by weight is achieved, (c) vitrifying the soot body, which contains iron in a first oxidation state Fe3+, under a reducing atmosphere that is suitable for reducing the iron at least partially from the first oxidation state Fe3+ to a second, lower oxidation state Fe2+, so as to form the blank of iron-doped glass with a high silicic acid content. A blank is obtained having an iron content in the range between 0.1 and 1% by weight, which exhibits an internal transmission of at most 40% in the infrared wavelength range and an internal transmission of at least 85% in the visible spectral range. |
