The nerve center of the city of tomorrow will be underground: fiber-optic cables will connect homes, businesses, and public institutions to each other and to the rest of the world. Individual fibers are scarcely thicker than a human hair, yet can transmit information at the speed of light and across long distances with no major loss in performance.
The only way that can work, however, is if the material that goes into the fibers is as pure as humanly possible. And this is where Evonik comes into play: several of the company’s sites produce Siridion®, an ultrapure tetrachlorosilane created from what is known as metallurgical-grade silicon, which still contains many impurities. This is then reacted with hydrogen chloride and later purified. The next step is to process the raw product still further to obtain ultrapure Siridion® STC.
Glass fiber manufacturers use ultrapure tetrachlorosilane to produce preliminary quartz-glass ingots, which are heated to over 2000 °C and extruded to form glass fibers. To cool the fibers quickly, they are often flushed with helium gas, accelerating the production process to the point that a single plant can produce over two kilometers of fiber per minute.