TITLE:
Volume and Surface Nucleation of Crystals in Glass Based on Blast-Furnace Slag
AUTHORS:
Galina A. Sycheva
KEYWORDS:
Glass Based on Blast-Furnace Slag, Volume Nucleation, Catalyzed Volume Nucleation, Surface Crystal Growth and Nucleation
JOURNAL NAME:
Journal of Crystallization Process and Technology,
Vol.7 No.2,
April
30,
2017
ABSTRACT: Using differential thermal
analysis, X-ray phase analysis, electron microscopy, and optical microscopy, the
nucleation of crystals in glass obtained by blending metallurgical slag with silicon
dioxide has been studied. The type of crystallization (homogeneous or heterogeneous,
volume or surface) is revealed for each of nine compositions of synthesized glass.
It is shown that the first crystalline phase in a volume crystallizing glass is
perovskite (CaO·TiO2); in this phase a nucleation of the main phase occurs: melilite
(solid solution of gehlenite 2CaO·Al2O3·SiO2 in akermanite
2CaO·MgO·2SiO2). The fundamental characteristics of homogeneous (for a catalizing
phase, perovskite) and heterogeneous (for a catalyzed phase, melilite) of crystallization
are determined: the steady state nucleation rate Ist, time of
unsteady state nucleation τ, crystal growth rate U, and activation energy of frictional flow.
The temperature dependences of Ist, τ, and U are obtained.
The kinetics of the crystallization of glass is studied and the rates of the surface
crystal growth are determined in the glass of nine compositions. The influence of
grinding the particles of the original glass on the sequence of deposition of the
crystalline phases was studied. Practical recommendations are presented for the
use of blast-furnace slag as a raw material for the synthesis of glass and their further
utilization.