Manufacture of silica bodies using sol-gel techniques
AssigneeFitel USA Corp.
InventorsSuhas Bhandarkar, Yoram De Hazan, John Burnette MacChesney, Thomas Edward Stockert
Life of this patent
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Abstract
The use of silica powders having large particle sizes in making sol-gel silica bodies has been found to have important advantages. Among these are higher gel strength, higher silica loading, more rapid aging and drying of the gel, a reduction in the amount of organic additives leading to reduced process time required for organic burn-off, and easier removal of contaminant particles due to their larger size. It was also discovered that spherical particle morphology contributes to the improved properties.
Claims14
Process for the manufacture of a silica glass body comprising:
- (a) preparing a sol by mixing silica particles and water, the silica particles having a surface area defined by the range 5-25 m2 per gram, and containing at least 85% spherical particles, with the ratio by weight of silica particles to water being greater than 65%,
- (b) adding a water soluble base to adjust the pH of the sol to a value in the range 10-13,
- (c) adding a gelling agent to the sol,
- (d) casting the sol into a mold,
- (e) gelling the sol in the mold to form a gelled body in the shape of the mold,
- (f) removing the gelled body from the mold, and
- (g) firing the gelled body to consolidate the gelled body into a vitreous silica body.
Process for the manufacture of optical fiber preforms comprising:
- (a) preparing a porous silica body of silica particles, said porous silica body having a weight greater than 5 kg, by the steps of:
- (i) preparing a sol by mixing silica particles and water, the silica particles having a surface area defined by the range 5-25 m2 per gram, with at least 85% of the silica particles being spherical, and the ratio by weight of silica particles to water being greater than 65%,
- (ii) adding a water soluble base to adjust the pH of the sol to a value in the range 10-13,
- (iii) adding a gelling agent to the sol,
- (iv) casting the sol into a mold,
- (v) gelling the sol in the mold to form a gelled body in the shape of the mold, and
- (vi) removing the gelled body from the mold,
- (b) heating the porous silica body at a temperature greater than 1300° C. to consolidate the porous silica body into a preform.
Process for the manufacture of optical fiber comprising:
- (a) preparing a porous silica body of silica particles, said porous silica body having a weight greater than 5 kg, by the steps of:
- (i) preparing a sol by mixing silica particles and water, the silica particles having a surface area defined by the range 5-25 m2 per gram, with at least 85% of the silica particles being spherical, and the ratio by weight of silica particles to water being greater than 65%,
- (ii) adding a water soluble base to adjust the pH of the sol to a value in the range 10-13,
- (iii) adding a gelling agent to the sol,
- (iv) casting the sol into a mold,
- (v) gelling the sol in the mold to form a gelled body in the shape of the mold, and
- (vi) removing the gelled body from the mold,
- (b) heating the porous silica body at a temperature greater than 1300° C. to consolidate the porous silica body into a preform,
- (c) mounting the preform in a fiber draw apparatus, and
- (d) drawing optical fiber from the preform.
Dependencies are inferred from the claim text.