Seed-induced formation of fibers in a redrawn acid-soluble barium borosilicate glass

Abstract

Leaching of laminated rods composed of an acid-soluble core glass and a leachable skin glass unexpectedly resulted in the formation of pure SiO2 fibers in the space originally occupied by the core glass. Studies with the aid of light and scanning electron microscopes of the glass blank prior to and after redrawing the glass revealed that the seeds in the blank become filled with a barium borate-rich phase on redrawing. Upon leaching in hot dilute mineral acid, the nonsiliceous constituents are dissolved, leaving pure, porous SiO2 fibers in the region formerly occupied by that phase. From diametrical measurements of unleached and leached fibers it is concluded that the siliceous phase in the fibers is reinforeed by deposition of silica from the hot leachant.