Browse Prior Art Database

Self Aligning Metal Ceramic Metal Structure

IP.com Disclosure Number: IPCOM000074261D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Wardly, GA: AUTHOR

Abstract

This is a metal-ceramic-metal seal structure that maintains alignment after repeated bakeout. Many different configurations employing the concept can be made, and a cross-sectional view of a representative structure is shown.

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Self Aligning Metal Ceramic Metal Structure

This is a metal-ceramic-metal seal structure that maintains alignment after repeated bakeout. Many different configurations employing the concept can be made, and a cross-sectional view of a representative structure is shown.

An upper metal piece 10 sits on a ceramic tube 12 which in turn sits on the lower metal support piece 14. Also shown are two KOVAR* rings 16 and 18 and two ceramic rings 20 and 22 which are used to connect the metal pieces to the ceramic tube. The drawing shows the relative positions of the seat, the ceramic to KOVAR seal, and the KOVAR to metal seal. The upper ring 16 is internal to the ceramic tube 12 while the seat 24 is external to the tube. This allows for the larger thermal expansion of the metal piece 10 and a radial gap 26 will exist at the seat 24 at elevated temperatures. On cooling down the radial gap disappears and again centers the metal piece on the ceramic tube 12. The internal ring 16 maintains the mechanical connection between the upper metal piece 10 and the ceramic tube 12 by flexing. The position of the metal to ring brazed joint 28 is higher than the ring to ceramic brazed joint 30.

The function of this is to raise the upper metal piece 10 as it expands at elevated temperatures. Thus an axial gap would appear at the seat 24 between the ceramic tube 12 and the upper metal piece. Alternatively, if there is no axial gap at the seat 24 at elevated temperature, then as the assembly cools, the strains on the ring 16 force the upper metal piece 10 tightly against the axial seat
24. The axial seat 24 is shown about at the same elevation as the metal brazed joint 28. If the ax...