Method of making fused silica by decomposing siloxanes

Abstract

This invention relates to the production of high purity fused silica glass through oxidation or flame hydrolysis of a vaporizable silicon-containing compound. More particularly, this invention is directed to the use of vaporizable, halide-free compounds in said production. In the preferred practice, a polymethylsiloxane comprises said vaporizable, halide-free compound.

1. In a method for making a non-porous body of high purity fused silica glass comprising the steps of:
 (a) producing a gas stream containing a silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO 2 ;    (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO 2 ;    (c) depositing said amorphous particles onto a support; and    (d) either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non-porous body;    
       the improvement comprising utilizing as said silicon-containing compound in vapor form, a halide-free polymethylsiloxane, whereby no halide-containing vapors are emitted during the making of said non-porous body of high purity fused silica glass. 
     
     
       2. A method according to  claim 1  wherein said polymethylsiloxane is hexamethyldisiloxane. 
     
     
       3. A method according to  claim 1  wherein said polymethylsiloxane is a polymethylcyclosiloxane. 
     
     
       4. A method according to  claim 3  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       5. A method according to  claim 1  wherein said gas stream is comprised of an inert gas. 
     
     
       6. A method according to  claim 5  wherein said inert gas is nitrogen. 
     
     
       7. In a method for making a non-porous body of high purity fused silica glass doped with at least one oxide dopant comprising the steps of:
 (a) producing a gas stream containing a silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO 2  and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;    (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO 2  doped with an oxide dopant;    (c) depositing said amorphous particles onto a support; and    (d) either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non-porous body;    
       the improvement comprising utilizing as said silicon-containing compound in vapor form a halide-free polymethylsiloxane, whereby no halide-containing vapors from said silicon-containing compound are emitted during the making of said non-porous body of high fused silica glass. 
     
     
       8. A method according to  claim 7  wherein said polymethylsiloxane is hexamethyldisiloxane. 
     
     
       9. A method according to  claim 7  wherein said polymethylsiloxane is a polymethylcyclosiloxane. 
     
     
       10. A method according to  claim 9  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       11. A method according to  claim 7  wherein said compound in vapor form capable of being converted to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table is a halide-containing compound. 
     
     
       12. A method according to  claim 7   In a method for making a non- porous body of high purity fused silica glass doped with at least one oxide dopant comprising the steps of:  
 ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table,  wherein said compound in vapor form capable of being converted to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VB A, and the rare earth series of the Periodic Table is a halide-free compound;  
 ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant;    
 ( c )  depositing said amorphous particles onto a support; and    
 ( d )  either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non - porous body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said non - porous body of high purity fused silica glass.    
 
     
     
       13. In a method for making optical waveguide fibers of high purity fused silica through the outside vapor deposition process comprising the steps of:
 (a) producing a gas stream containing a silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO 2 ;  
 (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO 2 ;  
 (c) depositing said amorphous particles onto a mandrel;  
 (d) consolidating said deposit of amorphous particles into a non-porous, transparent glass body; and  
 (e) and  drawing optical waveguide fiber from said body;  
 
       the improvement comprising utilizing as said silicon-containing compound in vapor form a halide-free polymethylsiloxane  polymethylcyclosiloxane, whereby no halide-containing vapors are emitted during the making of said optical waveguide fibers. 
     
     
       14. A method according to  claim 13  wherein said polymethylsiloxane is hexamethyldisiloxane. 
     
     
       15. A method according to  claim 13  wherein said polymethylsiloxane is a polymethylcyclosiloxane. 
     
     
       16. A method according to  claim 15  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       17. In a method for making optical waveguide fibers of high purity fused silica glass doped with an oxide dopant comprising the steps of:
 (a) producing a gas stream containing a silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO 2  and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;    (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO 2  doped with an oxide dopant;    (c) depositing said amorphous particles onto a mandrel;    (d) consolidating said deposit of amorphous particles into a non-porous transparent glass body; and    (e) drawing waveguide fiber from said body;    
       the improvement comprising utilizing as said silicon-containing compound in vapor form a halide-free polymethylsiloxane, whereby no halide-containing vapors from said silicon-containing compound are emitted during the making of said optical waveguide fibers. 
     
     
       18. A method according to  claim 17  wherein said polymethylsiloxane is hexamethyldisiloxane. 
     
     
       19. A method according to  claim 17  wherein said polymethylsiloxane is a polymethylcyclosiloxane. 
     
     
       20. A method according to  claim 19  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       21. A method according to  claim 17  wherein said compounding vapor form capable of being converted to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table is a halide-containing compound. 
     
     
       22. A method according to  claim 17   In a method for making optical waveguide fibers of high purity fused silica glass doped with an oxide dopant comprising the steps of:
 ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;    
 ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant,  wherein said compound in vapor form capable of being converted to at least one member of the group consisting of P 2 O 5  and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rear earth series of the Periodic Table is a halide-free compound;  
 ( c )  depositing said amorphous particles onto a mandrel;    
 ( d )  consolidating said deposit of amorphous particles into a non - porous transparent glass body; and    
 ( e )  drawing waveguide fiber from said body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said optical waveguide fibers.    
 
     
     
       23. In a method for making high purity fused silica glass through the outside vapor deposition process comprising the steps of:
 (a) producing a gas stream containing a silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO 2 ;    (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO 2 ;    (c) depositing said amorphous particles onto a mandrel; and    (d) consolidating said deposit of amorphous particles into a non-porous, transparent glass body;    
       the improvement comprising utilizing as said silicon-containing compound in vapor form a halide-free polymethylsiloxane, whereby no halide-containing vapors from said silicon-containing compound are emitted during the making of said high purity fused silica glass. 
     
     
       24. A method according to  claim 23  wherein said polymethylsiloxane is hexamethyldisiloxane. 
     
     
       25. A method according to  claim 23  wherein said polymethylsiloxane is a polymethylcyclosiloxane. 
     
     
       26. A method according to  claim 25  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       27. A method according to  claim 12 , wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       28. A method according to  claim 12 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane. 
     
     
       29. A method according to  claim 13 , wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       30. A method according to  claim 13 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane. 
     
     
       31. A method according to  claim 22 , wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       32. A method according to  claim 22 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane. 
     
     
       33. In a method for making a non- porous body of high purity fused silica glass comprising the steps of:    ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2 ;    ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2 ;    ( c )  depositing said amorphous particles onto a support; and      ( d )  either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non - porous body;        the improvement comprising utilizing as said silicon - containing compound in vapor form, a halide - free polymethylcyclosiloxane selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof, whereby no halide - containing vapors are emitted during the making of said non - porous body of high purity fused silica glass.     
     
     
       34. A method according to  claim 33  wherein said gas stream is comprised of an inert gas. 
     
     
       35. A method according to  claim 34  wherein said inert gas is nitrogen. 
     
     
       36. A method according to  claim 33 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane. 
     
     
       37. In a method for making a non- porous body of high purity fused silica glass doped with at least one oxide dopant comprising the steps of:    ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;      ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant;      ( c )  depositing said amorphous particles onto a support; and      ( d )  either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non - porous body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said non - porous body of high fused silica glass.     
     
     
       38. A method according to  claim 37  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       39. A method according to  claim 37 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane. 
     
     
       40. In a method for making a non- porous body of high purity fused silica glass doped with at least one oxide dopant comprising the steps of:    ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a halide - containing compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;      ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant;      ( c )  depositing said amorphous particles onto a support; and      ( d )  either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a non - porous body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said non - porous body of high fused silica glass.     
     
     
       41. In a method for making optical waveguide fibers of high purity fused silica glass doped with an oxide dopant comprising the steps of:
 ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;      ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant;      ( c )  depositing said amorphous particles onto a mandrel;      ( d )  consolidating said deposit of amorphous particles into a non - porous transparent glass body; and      ( e )  drawing waveguide fiber from said body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said optical waveguide fibers.     
     
     
       42. A method according to  claim 41  wherein said polymethylcyclosiloxane is selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof. 
     
     
       43. In a method for making optical waveguide fibers of high purity fused silica glass doped with an oxide dopant comprising the steps of:
 ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO   2    and a halide containing compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P   2   O   5    and a metal oxide which has a metallic component selected from Group IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;      ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2    doped with an oxide dopant;      ( c )  depositing said amorphous particles onto a mandrel;      ( d )  consolidating said deposit of amorphous particles into a non - porous transparent glass body; and      ( e )  drawing waveguide fiber from said body; the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said optical waveguide fibers.     
     
     
       44. In a method of making high purity fused silica glass through the outside vapor deposition process comprising the steps of:
 ( a )  producing a gas stream containing a silicon - containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis of SiO   2 ;    ( b )  passing said gas stream into the flame of a combustion burner to form amorphous particles of fused SiO   2 ;    ( c )  depositing said amorphous particles onto a mandrel; and      ( d )  consolidating said deposit of amorphous particles into a non - porous, transparent glass body;        the improvement comprising utilizing as said silicon - containing compound in vapor form a halide - free polymethylcyclosiloxane selected from the group consisting of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethylcyclotrisiloxane, and mixtures thereof, whereby no halide - containing vapors from said silicon - containing compound are emitted during the making of said high purity fused silica glass.     
     
     
       45. A method according to  claim 44 , wherein said polymethylcyclosiloxane is octamethylcyclotetrasiloxane.