The nucleation and crystallization of fine grained leucite glass-ceramics for dental applications

Cattell, Michael J.; Chadwick, Thomas C.; Knowles, Jonathan C.; Clarke, Richard L.; Samarawickrama, Dayananda Y.D.

doi:10.1016/j.dental.2005.10.003

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Volume 22, Issue 10 , Pages 925-933, October 2006

The nucleation and crystallization of fine grained leucite glass-ceramics for dental applications

Michael J. Cattell
- Centre for Adult Oral Health, Barts and the London, Queen Mary's School of Medicine and Dentistry, University of London, Turner Street, Whitechapel, London E1 2AD, UK
- Corresponding author. Tel.: +44 2073777000x2160; fax: +44 2073777375.
Thomas C. Chadwick
- 496 Alegre Avenue, Nipomo, CA 93444, USA
Jonathan C. Knowles
- Division of Biomaterials and Tissue Engineering, Eastman Dental Institute, University College London, 256 Gray's Inn Road, London WC1X 8LD, UK
Richard L. Clarke
- Department of Biomaterials in Relation to Dentistry, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
Dayananda Y.D. Samarawickrama
- Centre for Adult Oral Health, Barts and the London, Queen Mary's School of Medicine and Dentistry, University of London, Turner Street, Whitechapel, London E1 2AD, UK

Received 22 July 2005; accepted 27 October 2005.

Abstract

Objectives

The aims of the study were to control the nucleation and crystal growth of selected aluminosilicate glass powders, to produce uniform leucite glass-ceramic microstructures consisting of fine (<1000nm) grained leucite crystals.

Methods

A starting glass composition of wt%; 64.2% SiO₂, 16.1% Al₂O₃, 10.9% K₂O, 4.3% Na₂O, 1.7% CaO, 0.5% LiO₂ and 0.4% TiO₂ was heated in an electric furnace and later quenched to produce glasses. The glass powders were ball milled to two different particle sizes and heat-treated using one and two-step crystallization heat treatments. Dta, Xrd, and Sem analyses was used to characterise and explore the crystallization kinetics of the glasses.

Results

Selected heat treatments of the glass powders produced a uniform distribution of fine tetragonal leucite crystals (mean±S.D.) 0.1±0.2μm² in the glassy matrix, with minimal matrix microcraking in the glass-ceramics produced. The addition of a two-step heat treatment increased the leucite volume fraction in all instances.

Significance

Selected crystallization heat treatments and powder particle sizes were used to control the leucite crystal size, distribution and volume fraction, in order to produce uniformly distributed ultra fine grained tetragonal leucite glass-ceramics for dental applications.

Keywords: Ceramics, Leucite, Microscopy, X-ray diffraction