Design of High Thermal Expansion Glass-Ceramics Through Microstructural Control

  • R. E. Loehman
  • T. J. Headley
Part of the Materials Science Research book series (MSR, volume 21)


High thermal expansion glass-ceramics can be made from lithium silicate glasses that contain small amounts of P2O5. The essential step involves heating the glass to a temperature near 1000°C to grow well-faceted 0.1–0.5 μm Li3PO4 crystallites in the molten glass matrix. When the temperature is lowered to the 750°–850°C range, a mixture of high expansion SiO2 polymorphs and lithium silicate phases crystallize. TEM observations on one composition reveal the crystallization is by epitaxial growth on specific faces of the Li3PO4 crystallites. Heat treatments that do not form faceted Li3PO4 crystallites give glass-ceramics with much lower expansion coefficients. Our understanding and control of this epitaxial crystallization and growth mechanism has led to the development of a family of high thermal expansion glass ceramics useful for making hermetic seals with a number of stainless steels and superalloys.


Epitaxial Growth Glass Composition High Expansion Lithium Disilicate Lithium Silicate 
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Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • R. E. Loehman
    • 1
  • T. J. Headley
    • 1
  1. 1.Sandia National LaboratoriesAlbuquerqueUSA

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