Silica glass tubes by new sol-gel method

Silica glass tubes were prepared by following a new sol-gel method. The pH of the sol containing hydrolyzed Si(OC₂H₅)₄ with HCl and colloidal silica was adjusted by adding ammonia solution. Sol was poured into a cylindrical tube and gelled while rotating cylinder at 1000 rpm to form a tube-shaped gel. Then the gel was dried carefully to be tube dry-gel and finally sintered to become a clear silica glass tube.

The effects were examined of the speed of rotation before and after gelation, to form the tubular gel, upon the shape and appearance of the derived tubes. The best speed of rotation was about 1000 rpm, and an adequate long period of rotation after gelation was necessary to maintain the tube shape. One of the large silica tubes had dimensions of 26 mm outside diameter, 13 mm internal diameter and 1000 mm length, and the ovality of the silica glass tube was 0.02%.

The derived tube can be applied in a silica glass tube for an optical fiber fabrication process or in a furnace tube for IC production.