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Sealing glass‐ceramics with near‐linear thermal strain, part III : Stress modeling of strain and strain rate matched glass‐ceramic to metal seals
Author(s) -
Dai Steve,
Elisberg Brenton,
Calderone James,
Lyon Nathan
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14821
Subject(s) - materials science , ceramic , seal (emblem) , thermal expansion , composite material , glass ceramic , stress (linguistics) , glass transition , ultimate tensile strength , deformation (meteorology) , strain (injury) , metallurgy , polymer , medicine , art , visual arts , linguistics , philosophy
Thermal mechanical stresses of glass‐ceramic to stainless steel ( GC t SS ) seals are analyzed using finite element modeling over a temperature cycle from a set temperature ( T set ) 500°C to −55°C, and then back to 600°C. Two glass‐ceramics having an identical coefficient of thermal expansion ( CTE ) at ~16 ppm/°C but very different linearity of thermal strains, designated as near‐linear NL 16 and step‐like SL 16, were formed from the same parent glass using different crystallization processes. Stress modeling reveals much higher plastic strain in the stainless steel using SL 16 glass‐ceramic when the GC t SS seal cools from T set . Upon heating tensile stresses start to develop at the GC ‐ SS interface before the temperature reaches T set . On the other hand, the much lower plastic deformation in stainless steel accumulated during cooling using NL 16 glass‐ceramic allows for radially compressive stress at the GC ‐ SS interface to remain present when the seal is heated back to T set . The qualitative stress comparison suggests that with a better match of thermal strain rate to that of stainless steel, the NL 16 glass‐ceramic not only improves the hermeticity of the GC t SS seals, but would also improve the reliability of the seals exposed to high‐temperature and/or high‐pressure abnormal environments.