Electric lamp and discharge devices – With gas or vapor – Envelope composition
Patent
1986-01-08
1987-09-15
Bell, Mark L.
Electric lamp and discharge devices
With gas or vapor
Envelope composition
313624, 313638, 501 15, 501 17, 501 63, 501 64, 501 66, 501 67, 501 69, H01J 6122, H01J 6130, H01J 6136, C03C 824
Patent
active
046942190
ABSTRACT:
An arc discharge lamp is provided using sealing compositions comprising mainly Al.sub.2 O.sub.3 --SiO.sub.2 --MgO. Preferred compositions include between 25 to 28% by weight of MgO and 13 to 21% by weight of Al.sub.2 O.sub.3 since these have lower melting points than others in the group. The sealing compositions are used to seal end closure members of alumina or cermet to ceramic arc tubes for use in discharge lamps. The compositions are selected to have linear expansion co-efficients compatible with the materials of the end closures and arc tubes. The methods described give sealing times of between 3 and 4 minutes.
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Rankin, G. A., et al., "The Ternary System MgO--Al.sub.2 O.sub.3 --SiO.sub.2 ", Am. J. of Science, vol. LXV, Apr. 1918, pp. 301-325.
Bell Mark L.
Thorn Emi plc
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