Insight into Metastable Lifetime of α‐Calcium Sulfate Hemihydrate in CaCl2 Solution. Issue 10 (14th June 2013)

• Record Type: Journal Article
• Authors: Jiang, Guangming; Mao, Jingwei; Fu, Hailu; Zhou, Xu; Guan, Baohong; Struble, L.
• Is Part Of: Journal of the American Ceramic Society. Volume 96:Issue 10(2013)
• Page Start: 3265
• Page End: 3271
• Publication Date: 2013-06-14
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.12451
• Languages: English
• ISSNs: 0002-7820

Abstract

<abstract abstract-type="main" id="jace12451-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Alpha calcium sulfate hemihydrate (α‐HH), an important kind of cementitious material, is a metastable phase in CaSO₄–H₂O system. In CaCl₂ solution, thermodynamic metastable window for α‐HH preparation from calcium sulfate dihydrate is constructed as a function of CaCl₂ concentration (0–4.0<italic>m</italic>) and temperature (60°C–130°C), and then the metastability of α‐HH is characterized by the metastable lifetime (MLT). As the concentration of CaCl₂ is raised from 1.5 to 4.0<italic>m</italic> and temperature from 80°C to 110°C, MLT of α‐HH decreases gradually from 2920 to 60 min. The reducing effect of CaCl₂ on MLT arises from its contribution to lowering the total interfacial Gibbs free energy required for the subsequent phase transition of α‐HH to anhydrite, the thermodynamic stable phase. This work establishes a method to evaluate the phase metastability and provides a potential approach to optimize the reaction time in metastable material synthesis according to the MLT value for purity control.</p> </abstract>