Heterogeneous surface nucleation of lithium disilicate glass: An isothermal DSC study

The paper aims in correlating isothermal DSC signals to the actual nucleation and crystallization processes in a lithium disilicate glass as determined by optical microscopy. The results show that the DSC signal reflects the change from an initial surface nucleation to a site saturation regime (cons...

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Bibliographic Details
Published in:Journal of non-crystalline solids 2015-06, Vol.417-418, p.45-51
Main Authors: Krüger, S., Deubener, J.
Format: Article
Language:English
Subjects:
Approximation
Constants
Correlation
Glass
Impingement
Instantaneous Avrami coefficient
Isothermal DSC
JMAK analysis
Lithium
Lithium disilicate
Nucleation
Saturation
Surface nucleation
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Summary:The paper aims in correlating isothermal DSC signals to the actual nucleation and crystallization processes in a lithium disilicate glass as determined by optical microscopy. The results show that the DSC signal reflects the change from an initial surface nucleation to a site saturation regime (constant number of crystals) leading to a coast-island microstructure in monolithic samples. An isothermal JMAK analysis revealed a maximum of the instantaneous Avrami coefficient at the onset time of saturation (impingement time). Impingement times were used to approximate heterogeneous surface nucleation rates, which were found to be up to 14 orders of magnitude higher than those of homogeneous volume nucleation and correlate positively with temperature in the range 0.64–0.68 Tm. •Isothermal DSC measurements of the crystallization of lithium disilicate glass•Polymodal distribution of heat flow due to surface and volume crystallization•Impingement time of crystal growth at the surface from instantaneous Avrami analysis•Surface nucleation rates are up to 1014 times larger than those in the volume.•Maximum of the surface nucleation rate curve is located close to the melting point.
ISSN:0022-3093
1873-4812
DOI:10.1016/j.jnoncrysol.2015.03.013