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From Molten Calcium Aluminates through Phase Transitions to Cement Phases.
Hao Liu1,2, Wenlin Chen3, Ruikun Pan1,4
1State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology Wuhan 430070 China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|January 30, 2020
Summary
This study reveals the nanoscale mechanisms behind calcium aluminate transitions in cement production, detailing viscosity and density changes from liquid to solid states. These findings explain crucial temperature zones and phase transitions in cement manufacturing.
Area of Science:
- Materials Science
- Chemical Engineering
- Geochemistry
Background:
- Crystalline calcium aluminates are vital for cement setting.
- Microscopic mechanisms of transitions in molten aluminate liquids are poorly understood.
- Understanding these transitions is key to optimizing cement clinker production.
Purpose of the Study:
- To investigate the in situ thermophysical properties (viscosity, density) of molten calcium aluminates.
- To elucidate the nanoscale structural evolution during transitions from liquid to glassy and crystalline phases.
- To correlate these properties with cement production processes and phase behavior.
Main Methods:
- In situ measurements of viscosity and density across principal molten phases.
- Bulk atomistic computer simulations to analyze network substructures.
- Analysis of glass transition temperature (Tg) and liquidus temperature (Tm).
Main Results:
- Thermophysical properties correlate with nanoscale network substructure evolution.
- Glass transition temperature (Tg) follows the eutectic profile of liquidus temperature (Tm).
- Viscosity charted over 14 decades, justifying industrial temperature zones.
- Fragile-strong phase transitions observed near 1.2Tg, linked to heterogeneous nucleation.
Conclusions:
- The study provides the first in situ data on viscosity and density for calcium aluminate melts.
- Nanoscale structural changes dictate macroscopic thermophysical properties.
- Findings clarify phase transitions and temperature zones critical for cement manufacturing and processing.
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