Glass-to-Metal Seals, with Particular Reference to Current Lead-In Seals in Vacuum Devices

JSGT 1945 V29 T092-T110

It is shown experimentally for a seal of practical dimensions that the stress due to differential expansion of metal and glass approximates that derived by A. W. Hull & E. E. Burger for a very long seal. Further, the stress in a glass-metal seal arising from differential expansion is shown to be considerably modified both by the thermal history of the seal during the manufacture and the operating conditions of the device in which· the seal is used. A procedure is described and illustrated by which a suitable compromise in the dimensions of the glass-metal seal and its heat treatment during manufacture can be determined to ensure absence of extreme stresses at any time during manufacture or subsequently.

R. W. Douglas