Patent ID: 9487428
Filing Date: 2016-11-08
CPC Classification: C03B

Claim Text:
1. A powder-in-tube preform manufacturing process, comprising: sealing a bottom of a thin-walled silica tube, the silica tube having a wall thickness of approximately 7 millimeters (mm), the silica tube having an inner diameter that is between approximately 35 mm to approximately 90 mm, the silica tube having a tube length of approximately 1.2 meters (m); inserting a core rod into the silica tube, the inserted core rod being substantially centered within the silica tube; coating the silica tube with a layer of a nucleating compound selected from the group consisting of: aluminum containing salts, calcium, magnesium, and barium; filling the silica tube with mesoporous silica grains, the mesoporous silica grains being substantially monodisperse in size; applying a vapor-phase purification process to the mesoporous silica grains, the vapor-phase purification process being applied at a temperature that is less than approximately 1300 degrees Celsius (° C.); applying a vacuum to the silica tube to decrease the pressure within the silica tube; sintering the mesoporous silica grains in the presence of the vacuum and at a temperature that is greater than approximately 1000° C.; consolidating the silica tube to form a preform; and cooling the preform to below approximately 280° C.