Details

Autor(en) / Beteiligte

• Bhat, N P
• Borgstedt, H U

Titel

Thermodynamic Stability of Na sub 4 FeO sub 3 and Threshold Oxygen Levels in Sodium for the Formation of This Compound on AISI 316 Steel Surfaces

Ist Teil von

• Journal of nuclear materials, 1988-08, Vol.158, p.7-11

Erscheinungsjahr

1988

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• The corrosion mechanism of ferritic and austenitic steels in liquid Na is believed to occur by means of the formation of the ternary oxide Na sub 4 FeO sub 3 rather than by a simple dissolution process. To determine the thermodynamic stability of this compound, the reaction of Fe sub 2 O sub 3 with liquid Na has been studied with the help of two separate solid electrolyte galvanic cells with indium, In sub 2 O sub 3 and Sn, SnO sub 2 reference electrodes, respectively, over the temperature range 623-873K. Fe sub 2 O sub 3 reacts with Na at 623K, forming Fe and oxygen saturated Na. The formation of the ternary oxide Na sub 4 FeO sub 3 is indicated at 723K. Standard Gibbs energy of formation of Na sub 4 FeO sub 3 has been calculated from the emf data of both cells over the temperature range 723-873K. Utilizing the value and other literature data, threshold O levels in Na for the formation of Na sub 4 FeO sub 3 on AISI 316 steel surfaces have been calculated. 20 ref.--AA