CHESTER FRANCIS FISHER
Pilots at Dragonclaw, Columbia, MD
License number
Maryland A4904583
Issued Date
Jun 2015
Expiration Date
Jun 2017
Category
Airmen
Type
Authorized Aircraft Instructor
Address
Address
9507 Dragonclaw, Columbia, MD 21046
Professional information
Sf.sub.6 Process For Dehydration Of Fluoride Glasses
US Patent:
4539032, Sep 3, 1985
Filed:
Aug 3, 1984
Appl. No.:
6/637433
Inventors:
Danh C. Tran - Rockville MD
Chester Fisher - Columbia MD
Chester Fisher - Columbia MD
Assignee:
Geo-Centers, Inc. - Newton MA
International Classification:
C03B 5225, C03B 500, C03C 318
US Classification:
65 32
Abstract:
A method of making fluoride glasses produces fluoride glass having such low OH and low oxide content that the extrinsic optical absorbance caused by the OH vibration at 2. 9. mu. is eliminated or substantially reduced. In the method, a glass charge is placed in a capped crucible and dry argon gas is caused to flow through the capped crucible while the temperature is raised to melt the charge. Thereafter, while the dry argon gas flow is continued, the temperature in the furnace is held constant for a time sufficient to obtain a homogenous melt in which all crystalline materials are dissolved. The temperature is then lowered to a value between the glass crystalization temperature and the sublimation temperature of ZrF. sub. 4 and then, at isothermal conditions, the flow of dry argon gas is replaced by a flow of SF. sub. 6 gas or by a flow of CF. sub. 4 gas.