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Microstructure and TCE Control for Glass Ceramic Substrates By Controlled Glass in Glass Phase Separation

IP.com Disclosure Number: IPCOM000101957D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Bezama, RJ: AUTHOR [+3]

Abstract

In the past, the nucleation and crystallization of powder processed near stoichiometric cordierite was believed to happen by a surface nucleation followed by the crystal growth starting at the surface and working its way towards the center of each glass particle. It was believed that one way to change the resulting microstructure is by changing the glass particle size.

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Microstructure and TCE Control for Glass Ceramic Substrates By Controlled Glass in Glass Phase Separation

       In the past, the nucleation and crystallization of powder
processed near stoichiometric cordierite was believed to happen by a
surface nucleation followed by the crystal growth starting at the
surface and working its way towards the center of each glass
particle.  It was believed that one way to change the resulting
microstructure is by changing the glass particle size.

      Extended studies of nucleation and crystallization showed that
the crystallization happens to a large extent as a volume
crystallization.  Some contributions of surface nucleation cannot be
excluded.  That means nucleation and crystallization start in the
bulk of each glass particle.

      The volume crystallization happens in three stages:
      1)   glass in glass phase separation (immiscibility);
      2)   spherulitic crystallization of phase-separated glass
droplets to cordierite; formation of metastable cordierite phases in
the glass matrix; growth of cordierite spherulites;
      3)   recrystallization process driving the non-stochiometric
highly disordered alpha-cordierite towards the stoichiometric
orthorhombic cordierite.

      The discovery of the volume crystallization mechanism for
powder-processed glass ceramics opens new ways to improve the glass
ceramic strength and to tailor the TCE according to the requirements
by tailoring the gl...