Method for producing silica glass
Patent 4317668 Issued on March 2, 1982. Estimated Expiration Date: 
January 21, 2001. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 21, 2001. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesProcess for increasing the annealing point of 96% silica glass Method of making dry optical waveguides Granular quartz glass product Patent #: 4243422 InventorsAssigneeApplicationNo. 06/226876 filed on 01/21/1981US Classes:65/17.2, Sol-gel or liquid phase route utilized264/332, Fusing or melting inorganic material501/12, Made by gel route501/54, More than 90 percent by weight silica65/30.1, With chemically reactive treatment of glass preform65/32.2, With bonding or sealing65/901LIQUID PHASE REACTION PROCESSExaminersPrimary: McCarthy, Helen M.Attorney, Agent or FirmInternational ClassesC03C 3/06 (20060101)C03B 19/12 (20060101) C03B 37/016 (20060101) Foreign Application Priority Data1980-01-21 JPAbstractA method for producing silica glass wherein a dry silica gel subjected to a water desorption treatment and a carbon removal treatment is heated and has its temperature raised in an atmosphere containing chlorine, to perform a hydroxyl group removal treatment, the resultant silica gel is thereafter heated to a temperature of approximately 1,000° C.-1,100° C. in an atmosphere containing at least 1% of oxygen, to perform a chlorine removal treatment, and the resultant silica gel is further heated to a temperature of 1,050° C.-1,300° C. in He or in vacuum, to perform a sintering treatment. The silica glass thus produced does not form bubbles even when heated to high temperatures of or above 1,300° C. Therefore, it is easily worked and it is free from the lowering of transparency attributed to the bubble formation.Other References
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