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US 9,487,428 B2Granted
Easy removal of a thin-walled tube in a powder-in-tube (PIT) process
AssigneeOFS Fitel, LLC
InventorDennis J Trevor
Life of this patent
Estimating the term…
Abstract
The embodiments disclosed herein seek to ameliorate high costs associated with the use of ultra-pure silica by using a lower-cost starting material and purifying the lower-cost starting material to an acceptable level of purity during the preform manufacturing process. In one embodiment, a nucleating compound is coated on a thin-walled silica tube, which upon cooling, forms cristobalite allowing for easy removal of the thin-walled silica tube.
Claims9
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.
8 more elements
A preform manufacturing process, comprising:
- coating a silica tube with a nucleating compound;
- filling the silica tube with silica grains;
- applying a vapor-phase purification process to the silica grains;
- forming an α-cristobalite layer on the silica tube from the nucleating compound;
- sintering the silica grains;
- consolidating the silica tube to form a preform;
- and
- cooling the preform to convert the α-cristobalite into β-cristobalite.
5 more elements
Dependencies are inferred from the claim text.