Paper Number
GG29
Session
Out of Equilibrium Systems: Gels and Glasses
Title
Rheology of glass-ceramics for sealing applications
Presentation Date and Time
October 23, 2019 (Wednesday) 9:50
Track / Room
Track 7 / Room 306C
Authors
- Grillet, Anne M. (Sandia National Laboratories, Engineering Sciences Division)
- Dai, Steve X. (Sandia National Laboratories, Materials Science Division)
- Elisberg, Brenton (Sandia National Laboratories, Engineering Sciences Division)
Author and Affiliation Lines
Anne M. Grillet1, Steve X. Dai2, and Brenton Elisberg1
1Engineering Sciences Division, Sandia National Laboratories, Albuquerque, NM 87185; 2Materials Science Division, Sandia National Laboratories, Albuquerque, NM 87185
Speaker / Presenter
Grillet, Anne M.
Text of Abstract
Glass to metal seals are commonly used to manufacture hermetic electrical pass-throughs. A common concern is cracking of the glass which can compromise the hermiticity because even smalls differences in thermal expansion coefficient (CTE) can result in large residual stresses in the glass. Glass-ceramics contain an embedded crystalline phase surrounded by a glassy matrix. The crystals form a space filling “gel-like” structure which supports a stress above the melting temperature of the glassy matrix. The morphology, thermal and mechanical properties can be manipulated both by composition and thermal history. In particular, the thermal expansion coefficient can be carefully matched to that of the metals in a sealing application to minimize thermal expansion stresses. This study will focus on a class of lithium silicate glass-ceramics of interest for sealing applications.
The viscoelastic rheology of a traditional glass and the glass ceramic will be presented from room temperature through the matrix glass transition and beyond. The measured mechanical properties of a glass-ceramic are sensitive to the internal microstructure of the glassy and ceramic phases. By varying the cooling rate, the microstructure can be manipulated as evidenced by qualitative changes in the behavior through the glass transition. We will also show additional data on the crystalline phase make up and evidence for dynamic restructuring well below the melting temperature of the glass-ceramic. Measurements of the mechanical properties of the glass-ceramic contribute to continuing efforts to develop and calibrate material models to predict stress development and cracking of glass to metal seals.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2019-5398 A