Microstructure and kinetics of hot corrosion for a nickel alloy in molten salt

Conference · Sun Dec 01 04:00:00 EST 1996

OSTI ID:462876

Stevens, D W; Brummond, W A ^[1]; Grimmett, D L; Newcomb, J C; Chiang, K T; Gay, R L ^[2]

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1. Lawrence Livermore National Lab., CA (United States)
2. Boeing North American, Inc., Canoga Park, CA (United States). Rocketdyne Div.

Metallography, analytical SEM, and XRD were used to measure kinetics and characterize the microstructure of hot corrosion of the Ni-Cr-Fe alloy INCONEL 600 after 500 h immersion in molten Na{sub 2}CO{sub 3}- NaCl salt at 900-950 C in an oxidizing atmosphere. This was done to assess the alloy as a reaction vessel material for a waste treatment process known as Molten Salt Oxidation. The alloy was found to hot corrode by surface oxidation and intergranular attack. Combined rate for loss of load-bearing cross-section metal was comparable to corrosion rates for analogous salts. About 5% of the oxide scale was a continuous, dense, protective layer of Cr{sub 2}O{sub 3} at the metal/oxide interface. A middle portion comprised about 55% of the scale and was a porous, mixed oxide of NiO>Cr{sub 2}O{sub 3}>Fe{sub 2}O{sub 3}. The outer 40% was nearly all NiO with dense grains and cavitated grain boundaries. Overall, the NiO was dominant and the lesser amounts of Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} were roughly equivalent. No direct invasion of salt through the oxide to the metal was observed.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 462876
• Report Number(s): UCRL-JC--126053; CONF-9607183--2; ON: DE97051679
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORROSION
CORROSIVE EFFECTS
INCONEL 600
MICROSTRUCTURE
MOLTEN SALTS
SCALING
SODIUM CARBONATES
SODIUM CHLORIDES
TEMPERATURE RANGE 1000-4000 K