Preparation and structure-sensitive investigations on silica glass fibers

Abstract

Fused silica fibers (6–25 μm) (Herasil I, HSQ 100 and Suprasil II) were prepared by rod pulling. The optimum range of the rod pulling parameters and also the connections to the drawing parameters of nozzle drawing method are given. Three silica glass fiber types were investigated by optical birefringence and apparent (frozen-in) stress optical constant, by density changes as compared to the bulk glass and by the expansion and shrinkage behaviour on heating and annealing. Results of apparent stress optical constant and Poisson ratio calculated from density and shrinkage data of the silica glass fibers compared with the corresponding results obtained from other investigations on metasilicate-, metaphosphate- and E-glass fibers indicate the existence of asymmetric hollows in the open silica glass structure deformed and oriented by the fiber drawing process. The different concentrations of hydroxyl in the three glass types and the density anomaly clearly reflect the different mechanical and optical properties.