Electrode-polarization studies in hot corrosion systems. Progress report, June 1, 1982-May 31, 1983

Technical Report · Sat Jan 01 00:00:00 EST 1983

OSTI ID:6538972

Devereux, O F

Electrode polarization studies in molten sodium sulfide: polarization of nickel electrodes in molten 25% FeS - 75% Na/sub 2/S was found to be linear in current, with the major part due to ohmic electrolyte resistance. Nickel was observed to undergo nonelectrodic dissolution in this electrolyte at the rate of 1.6 x 10/sup -6/g cm/sup -2/sec/sup -1/, with anomalous initial behavior attributed to the presence of polysulfide in the melt. Electrode polarization studies in molten sodium carbonate: this task is proceeding in the direction of a complete mechanistic and kinetic understanding of electrode reactions at the H/sub 2//H/sub 2/S/CO/CO/sub 2/, Ni electrode in molten sodium carbonate. Progress is hampered in working with H/sub 2/S. Gas/metal reactions in mixed oxidants: the kinetics of scale formation on iron in H/sub 2//H/sub 2/S/CO/CO/sub 2/ mixtures at 900/sup 0/C was studied over a range of P/sub O/sub 2// values encompassing thermodynamic stability of FeS and Fe/sub 3/O/sub 4/. All scales, however, were FeS, and all behavior seen could be treated as a perturbation of sulfidation kinetics in H/sub 2//H/sub 2/S alone. During this period a highly successful model was developed which invokes an initial period in which islands of scale form and grow laterally and in thickness. After the surface is entirely covered, i.e., the islands impinge, the scale undergoes a period of diffusion-controlled, parabolic growth, following which the outer portion of the scale ceases to be a diffusion barrier by some process, such as recrystallization, which progresses linearly with time. The inner, barrier portion of the scale thus diminishes in thickness until a steady state condition, with linear scale growth, is attained.

• Research Organization: Connecticut Univ., Storrs (USA). Inst. of Materials Science
• DOE Contract Number: AC02-76ER02960
• OSTI ID: 6538972
• Report Number(s): DOE/ER/02960-7; ON: DE83002732
• Resource Relation: Other Information: Portions are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON
SCALING
SULFIDATION
IRON SULFIDES
ELECTROCHEMISTRY
NICKEL
DISSOLUTION
SODIUM SULFIDES
CARBON DIOXIDE
CARBON MONOXIDE
ELECTRODES
HYDROGEN SULFIDES
MOLTEN SALTS
RESEARCH PROGRAMS
SODIUM CARBONATES
VERY HIGH TEMPERATURE
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
ELEMENTS
HYDROGEN COMPOUNDS
IRON COMPOUNDS
METALS
OXIDES
OXYGEN COMPOUNDS
SALTS
SODIUM COMPOUNDS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400400* - Electrochemistry