Fine silica tube and process for making same

摘要

A fine silica tube composed of silica gel and having an outer diameter of 0.05 to 2 mu m wherein the cylindrical wall portion of the tube has a cross-section defined by a substantially square outer periphery and a substantially square vacant center, or by a circular outer periphery and a substantially square vacant center; and a fine silica tube composed of silica glass and having an outer diameter of 0.05 to 1.4 mu m wherein the cylindrical wall portion of the tube has a cross-section defined by a substantially square outer periphery and a substantially square vacant center. The fine silica gel tube is made by treating a tetraalkoxysilane with ammonia or aqueous ammonia in a water-soluble alcohol medium in the presence of tartaric acid, citric acid, a tartaric acid salt or a citric acid salt, whereby the tetraalkoxysilane is hydrolyzed. The fine silica glass tube is made by calcining the fine silica gel tube at 800 DEG to 1,400 DEG C.