Using silicon tetraflouride during 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 crystals, the disclosed process uses porous silica grains that have a substantially monodisperse size distribution as the starting materials for a powder-in-tube preform manufacturing process and utilize silicon tetrafloride doping to promote silica dehydration.
Claims18
A powder-in-tube perform manufacturing process, comprising:
- sealing a bottom of a thin-walled silica tube;
- 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;
- removing impurities by heating the mesoporous silica grains to a temperature that is less than approximately 800 degrees Celsius (° C.);
- adding silicon tetrafluoride gas (SiF4) to the purified mesoporous silica grains;
- heating the purified mesoporous silica grains in the presence of the SiF4 gas at a temperature of greater than approximately 1000° C., which results in dehydration of the purified mesoporous silica and fluorine doping of silica;
- sintering the purified mesoporous silica grains in the presence of SiF4;
- and
- consolidating the silica tube.
A preform manufacturing process, comprising:
- filling a silica tube with substantially homogeneous mesoporous silica grains;
- purifying the mesoporous silica grains in the presence of silicon tetrafluoride (SiF4) gas;
- sintering the mesoporous silica grains;
- and
- consolidating the silica tube.
A preform manufacturing system, comprising:
- mesoporous silica grains;
- silicon tetrafluoride (SiF4) gas;
- a silica tube to hold the mesoporous silica grains and the SiF4 gas;
- 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.