The nucleation and crystallization of fine grained leucite glass-ceramics for dental applications.
OBJECTIVE
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 (<1000 nm) grained leucite crystals.


METHODS
A starting glass composition of wt%; 64.2% SiO(2), 16.1% Al(2)O(3), 10.9% K(2)O, 4.3% Na(2)O, 1.7% CaO, 0.5% LiO(2) and 0.4% TiO(2) 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+/-0.2 microm(2) 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.


CONCLUSIONS
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.
Cattell
Michael J
MJ
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. m.cattell@qmul.ac.uk <m.cattell@qmul.ac.uk>
Chadwick
Thomas C
TC
Knowles
Jonathan C
JC
Clarke
Richard L
RL
Samarawickrama
Dayananda Y D
DY
D000538:Aluminum Silicates; D002516:Ceramics; D003460:Crystallization; D018360:Crystallography, X-Ray; D003776:Dental Porcelain / Q000138:chemical synthesis*; D004055:Differential Thermal Analysis; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011208:Powders
D000538:Aluminum Silicates; D011208:Powders; D003776:Dental Porcelain; C078519:leucite; C023506:Glass ceramics