Chapter 52. Sealing 304L to Lithia-Alumina-Silica (LAS) Glass-Ceramics
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1989 The American Ceramic Society, Inc.
A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10
How to Cite
Moddeman, W. E., Pence, R. E., Massey, R. T., Cassidy, R. T. and Kramer, D. P. (1989) Sealing 304L to Lithia-Alumina-Silica (LAS) Glass-Ceramics, in A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310588.ch52
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1989
Print ISBN: 9780470374870
Online ISBN: 9780470310588
- ion beam energy:;
- aluminum oxide;
- aluminum nitride
The formation of a crack-free seal between a 300 series stainless steel and a glass-ceramic has in the past been very difficult. The primary cause of this difficulty has been in obtaining glass-ceramic compositions whose coefficient of thermal expansion (CTE) approaches that of the 300 series metal piece parts. Stainless steels of the 300 series have very high CTE values that range from 180-220 × 10−7 cm/cm/°C (RT-300°C). Therefore, the corresponding glass-ceramic should have a similarly high CTE to enable the formation of stress-free seals. Both at EG&G Mound and at EG&G Electronic Components, lithia-alumina-silica (LAS) glass-ceramics have now been successfully developed and sealed to 304L stainless steel. These crack-free seals have been routinely fabricated using two techniques: by adjusting the parent glass composition or by adjusting the sealing/crystallization (or sealing/devitrification) cycle that is routinely used in forming seals between LAS glass-ceramic and nickel-based alloys. All seals were determined to be hermetic, with leak rates of <10−8 cc/sec of STP helium. Additional data on CTE values and alloy yield strengths will be given which show the feasibility of using these materials in the manufacture of various components including feedthroughs and pyrotechnic components. Metallography, SEM, and wavelength dispersive spectroscopy (WDS) results show the quality and the integrity of the glassceramic/stainless steel interface. Whenever possible, these data are compared to similar studies accomplished in the Inconel 718/LAS-glass seal system.