Solubility Behavior and Phase Stability of Transition Metal Oxides in Alkaline Hydrothermal Environments

Ziemniak, S.E.

Lockheed Martin

关键词: Thermodynamics;    Alloys;    Oxides;    Phase Stability;    Stabilization;   

DOI  :  10.2172/821298
RP-ID  :  LM-00K035
RP-ID  :  AC 12-00-SN39357
RP-ID  :  821298

美国|英语

来源: UNT Digital Library

【 摘 要 】

The solubility behavior of transition metal oxides in high temperature water is interpreted by recognizing three types of chemical reaction equilibria: metal oxide hydration/dehydration, metal oxide dissolution and metal ion hydroxocomplex formation. The equilibria are quantified using thermodynamic concepts and the thermochemical properties of the metal oxides/ions representative of the most common constituents of construction metal alloys, i.e., element shaving atomic numbers between Z = 22 (Ti) and Z = 30 (Zn), are summarized on the basis of metal oxide solubility studies conducted in the laboratory. Particular attention is devoted to the uncharged metal ion hydrocomplex, M{sup Z}(OH){sub Z}(aq), since its thermochemical properties define minimum solubilities of the metal oxide at a given temperature. Experimentally-extracted values of standard partial molal entropy (S{sup 0}) for the transition metal ion neutral hydroxocomplex are shown to be influenced by ligand field stabilization energies and complex symmetry.