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Title: Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability

Abstract

The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li 2O–SiO 2–Al 2O 3–K 2O–B 2O 3–P 2O 5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain, as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed tomore » the transition behavior of quartz crystals embedded in the glass-ceramics.« less

Authors:
 [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1329625
Alternate Identifier(s):
OSTI ID: 1400786
Report Number(s):
SAND-2016-10170J
Journal ID: ISSN 0002-7820; 648181
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Name: Journal of the American Ceramic Society; Journal ID: ISSN 0002-7820
Publisher:
American Ceramic Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; glass-ceramics; crystals/crystallization; thermal expansion; X-ray methods

Citation Formats

Rodriguez, Mark A., Griego, James J. M., and Dai, Steve. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability. United States: N. p., 2016. Web. doi:10.1111/jace.14438.
Rodriguez, Mark A., Griego, James J. M., & Dai, Steve. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability. United States. doi:10.1111/jace.14438.
Rodriguez, Mark A., Griego, James J. M., and Dai, Steve. Mon . "Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability". United States. doi:10.1111/jace.14438. https://www.osti.gov/servlets/purl/1329625.
@article{osti_1329625,
title = {Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability},
author = {Rodriguez, Mark A. and Griego, James J. M. and Dai, Steve},
abstractNote = {The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain, as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass-ceramics.},
doi = {10.1111/jace.14438},
journal = {Journal of the American Ceramic Society},
number = ,
volume = ,
place = {United States},
year = {Mon Aug 22 00:00:00 EDT 2016},
month = {Mon Aug 22 00:00:00 EDT 2016}
}

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  • Here, the sequence of crystallization in a re-crystallizable lithium silicate sealing glass-ceramic Li 2O-SiO 2-Al 2O 3-K 2O-B 2O 3-P 2O 5-ZnO was analyzed by in situ high temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a 2-stage heat treatment schedule, including rapid cooling from sealing temperature to a 1st hold temperature 650 °C, following by heating to a 2nd hold temperature of 810 °C. Notable growth and saturation of Quartz was observed at 650 °C (1st hold).
  • Cited by 1
  • Here, a widely adopted approach to form matched seals in metals having high coefficient of thermal expansion (CTE), e.g. stainless steel, is the use of high CTE glass-ceramics. With the nucleation and growth of Cristobalite as the main high-expansion crystalline phase, the CTE of recrystallizable lithium silicate Li 2O-SiO 2-Al 2O 3-K 2O-B 2O 3-P 2O 5-ZnO glass-ceramic can approach 18 ppm/°C, matching closely to the 18 ~ 20 ppm/°C CTE of 304L stainless steel.
  • A widely adopted approach to form matched seals in metals having high coefficient of thermal expansion (CTE), e.g. stainless steel, is the use of high CTE glass-ceramics. With the nucleation and growth of Cristobalite as the main high-expansion crystalline phase, the CTE of recrystallizable lithium silicate Li 2O–SiO 2–Al 2O 3–K 2O–B 2O 3–P 2O 5–ZnO glass-ceramic can approach 18 ppm/°C, matching closely to the 18 ppm/°C–20 ppm/°C CTE of 304L stainless steel. However, a large volume change induced by the α-β inversion between the low- and high- Cristobalite, a 1 st order displacive phase transition, results in a nonlinearmore » step-like change in the thermal strain of glass-ceramics. The sudden change in the thermal strain causes a substantial transient mismatch between the glass-ceramic and stainless steel. In this study, we developed new thermal profiles based on the SiO2 phase diagram to crystallize both Quartz and Cristobalite as high expansion crystalline phases in the glass-ceramics. A key step in the thermal profile is the rapid cooling of glass-ceramic from the peak sealing temperature to suppress crystallization of Cristobalite. The rapid cooling of the glass-ceramic to an initial lower hold temperature is conducive to Quartz crystallization. After Quartz formation, a subsequent crystallization of Cristobalite is performed at a higher hold temperature. Quantitative X-ray diffraction analysis of a series of quenched glass-ceramic samples clearly revealed the sequence of crystallization in the new thermal profile. In conclusion, the coexistence of two significantly reduced volume changes, one at ~220°C from Cristobalite inversion and the other at ~470°C from Quartz inversion, greatly improves the linearity of the thermal strains of the glass-ceramics, and is expected to improve the thermal strain match between glass-ceramics and stainless steel over the sealing cycle.« less
  • Cited by 1