Characterization of oxide scales formed in very low oxygen potentials

Conference · Thu Aug 01 04:00:00 EDT 1996

OSTI ID:271995

Maldonado, L; Diaz, L ^[1]; Gruebmaier, H; Naoumidis, A; Nickel, H ^[2]

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1. Unidad Merida, Cordemex (Mexico). Centro de Investigacion y de Estudios Avanzados
2. Research Centre Juelich GmbH, Juelich (Germany). Inst. for Materials in Energy Systems

Samples of alloy 800 H (UNS N08810) and alloy 617 (LTNS N06617) were oxidized in a simulated process gas atmosphere. The principal elements of the gaseous environment were 50% H{sub 2}O, 35% H{sub 2} and 5% of CO{sub 2}, CO, and CH{sub 4}, respectively and a total pressure of 140 kPa. This gas in a state of thermodynamic equilibrium establishes oxygen partial pressures ranging from 3.0 {times} 10{sup {minus}17} kPa, at 800 C to 3.2 {times} 10{sup {minus}14} kPa at 950 C. The exposure time was from 600 to 5,000 hours. After the exposure the alloy surfaces showed compact oxide layers. On alloy N08810 a double oxide layer was built. A first layer was identified as the spinel phase, Mn{sub (1+x)}Cr{sub 2(1{minus}x)}Ti{sub x}O{sub 4}. The second one is the corundum type phase, Cr{sub 2{minus}y}Ti{sub y}O{sub 3}. On alloy N06617, lack of manganese produces the growth of a single layer, which was also identified as the phase Cr{sub 2{minus}y}Ti{sub y}O{sub 3}.

• OSTI ID: 271995
• Report Number(s): CONF-960389--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
36 MATERIALS SCIENCE
CARBON DIOXIDE
CARBON MONOXIDE
CHROMIUM OXIDES
COAL GASIFICATION PLANTS
CORROSION RESISTANT ALLOYS
HYDROGEN
INCOLOY 800H
INCONEL 617
MANGANESE OXIDES
METHANE
MICROSTRUCTURE
OXIDATION
PHASE STUDIES
PROTECTIVE COATINGS
TITANIUM OXIDES
WATER VAPOR