Using porous grains in powder-in-tube (pit) process
AssigneeOFS Fitel, LLC
InventorDennis J Trevor
Life of this patent
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Abstract
The embodiments disclosed herein seek to ameliorate the 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, instead of using fully densified silica particulate, the disclosed process uses mesoporous silica grains that have a substantially monodisperse size distribution as the starting materials for a powder-in-tube preform manufacturing process.
Claims18
A powder-in-tube preform manufacturing process, comprising:
- sealing a thin-walled silica tube with a grain-sealed bottom, the grain-sealed bottom being gas-permeable, the silica tube having a wall thickness of approximately 2.5 millimeters (mm), the silica tube having an inner diameter that is between approximately 25 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;
- filling the silica tube with mesoporous silica grains, the mesoporous silica grains being substantially monodisperse in size, the mesoporous silica grains being smaller than refractory particles;
- 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 1700° C.;
- and
- consolidating the silica tube substantially concurrently with the sintering of the mesoporous silica grains.
A preform manufacturing process, comprising:
- filling a silica tube with substantially homogeneous mesoporous silica grains;
- applying a vapor-phase purification process to the mesoporous silica grains;
- sintering the mesoporous silica grains;
- and
- consolidating the silica tube.
A preform manufacturing system, comprising:
- substantially homogeneous mesoporous silica grains;
- a silica tube holding the mesoporous silica grains;
- an input port to introduce gases into the silica tube;
- an output vent to evacuate impurities from the silica tube;
- and
- a heating element to heat the mesoporous silica grains.
Dependencies are inferred from the claim text.