Chemical mechanisms and reaction rates for the initiation of hot corrosion of IN-738

Technical Report · Sun Jul 01 04:00:00 EDT 1984

OSTI ID:6122018

Fryburg, G C; Kohl, F J; Stearns, C A

Sodium-sulfate-induced hot corrosion of preoxidized IN-738 was studied at 975 C with special emphasis placed on the processes occurring during the long induction period. Thermogravimetric tests were run for predetermined periods of time, and then one set of specimens was washed with water. Chemical analysis of the wash solutions yielded information about water soluble metal salts and residual sulfate. A second set of samples was cross sectioned dry and polished in a nonaqueous medium. Element distributions within the oxide scale were obtained from electron microprobe X-ray micrographs. Evolution of SO was monitored throughout the thermogravimetric tests. Kinetic rate studies were performed for several pertinent processes appropriate rate constants were obtained from the following chemical reactions: Cr2O3 + 2 Na2SO4(1) + 3/2 O2 yields 2 Na2CrO4(1) + 2 SO3(g)n TiO2 + Na2SO4(1) yields Na2O(TiO2)n + SO3(g)n TiO2 + Na2CrO4(1) yields Na2O(TiO2)n + CrO3(g).

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
• OSTI ID: 6122018
• Report Number(s): N-84-28958; NASA-TP-2319; E-1847
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOY-IN-738
ALLOYS
ALUMINIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
CARBON ADDITIONS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COBALT ALLOYS
CORROSION
GAS TURBINES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
KINETICS
MACHINERY
MATERIALS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ADDITIONS
NIOBIUM ALLOYS
PHOTOGRAPHY
PHOTOMICROGRAPHY
REACTION KINETICS
TANTALUM ALLOYS
TITANIUM ALLOYS
TUNGSTEN ALLOYS
TURBINES
TURBOMACHINERY
ZIRCONIUM ADDITIONS
ZIRCONIUM ALLOYS