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Redox‐Control Solubility of Chromium Oxide in Soda‐Silicate Melts
Author(s) -
Khedim Hichem,
Podor Renaud,
Rapin Christophe,
Vilasi Michel
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02692.x
Subject(s) - chromium , dissolution , solubility , mineral redox buffer , silicate , redox , chemistry , oxide , inorganic chemistry , chromium oxide , equilibrium constant , analytical chemistry (journal) , mineralogy , oxygen , chromatography , organic chemistry
The total chromium oxide (Cr 2 O 3 ) solubility is measured in Na 2 O– x SiO 2 melts as a function of temperature (1125°< T <1250°C), glass composition (1.5< x <3.5), and oxygen fugacity (−15< f O 2 <−0.61) using a closed and single‐use reactor. The presence of Cr(II), Cr(III), and Cr(VI) species is evidenced and their respective contributions in the total Cr content dissolved in the melt are determined. The experimental results are described using a model of chromium chemistry in silicate melts involving dissolution, redox, and oxo‐complex reactions, whose equilibrium constants areA mathematical treatment, using the results obtained, allows the correlation between the proposed model and thermodynamic properties of the system. The standard enthalpies and entropies associated with the oxidation and reduction reactions are: Δ H ox =−36 kJ/mol; Δ H red =208 kJ/mol; Δ S ox =68 J·(mol·K) −1 ; and Δ S red =87 J·(mol·K) −1 .