Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB890260A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Philips Electrical Industries Ltd
Original Assignee
Philips Electrical Industries Ltd
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Filing date
Publication date
Application filed by Philips Electrical Industries LtdfiledCriticalPhilips Electrical Industries Ltd
Publication of GB932184ApublicationCriticalpatent/GB932184A/en
C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
C03C23/007—Other surface treatment of glass not in the form of fibres or filaments by thermal treatment
Abstract
A method of manufacturing quartz crystals having an absorption coefficient not exceeding 0,4 in the wavelength range between 2,000 and 35,000 comprises selecting smoky quartz crystals exhibiting at a wavelength of 4,500 an absorption of from 5-40% per cm. thickness and a coefficient of absorption between 0,05 and 0,5 and subsequently thermally bleaching the crystals at a temperature which exceeds 300 DEG C. In examples thermal bleaching is effected at 500 DEG C. for 20 hours.
GB890260A1959-03-171960-03-14Improvements relating to the manufacture of quartz crystals
ExpiredGB932184A
(en)