The corrosion of some superalloys in contact with coal chars in coal gasifier atmospheres
Six alloys, 310 stainless steel, Hastelloy X, Inconel 671, Incoloy 800, Haynes 188, and FeCrAlY (GE1541 and MA956), were corroded in two chars at 160/sup 0/C and 1800/sup 0/C. The chars, FMC and Husky, contained 2.7% and 0.9% sulfur, respectively. Various parameters were investigated, including char size, cover gas, char quantity, char replenishment period, gas composition, and the use of coatings. The corrosion process was strictly sulfidation when the char was replenished every 24 hr or less. The kinetics of reaction were nearly linear with time. The reaction resulted in thick external sulfide scales with extensive internal sulfidation in the substrate. The kinetics and reaction-product morphologies suggested that diffusion through the sulfide scale played a minor role, and that an interfacial reaction was the rate-controlling step. A mathematical model was developed which supported this hypothesis. The reaction rates showed a relatively minor role on alloy composition, depending upon whether the alloys were tested singularly or in combination with others. Inconel 671, the best alloy in CGA environments, consistently corroded the most rapidly of the chromia-former types regardless of char sulfur content or of the temperature. Type 310 stainless was marginally better than Inconel 671. Incoloy 800 was intermediate, wheras, Haynes 188 and Hastelloy X exhibited the best corrosion resistance. The FeCrAlY alloys reacted very rapidly in the absence of preoxidation treatments. All alloys corroded in char at least 1000 times more rapidly than in the CGA (MPC-ITTRI) environment. None of the alloys will be acceptable for use in contact with char unless coatings are applied.
- Research Organization:
- Materials Department, School of Engineering and Applied Science, University of California, Los Angeles, California.
- OSTI ID:
- 7096636
- Journal Information:
- Oxid. Met.; (United States), Vol. 16:1/2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
CHARS
CORROSIVE EFFECTS
HASTELLOY X
CORROSION
HAYNES 188 ALLOY
INCOLOY 800H
INCONEL 671
QUATERNARY ALLOY SYSTEMS
STAINLESS STEEL-310
ALLOYS
ALUMINIUM ALLOYS
ATMOSPHERES
CHROMIUM ALLOYS
COAL GASIFICATION
IRON ALLOYS
MATHEMATICAL MODELS
REACTION KINETICS
SULFIDATION
VERY HIGH TEMPERATURE
YTTRIUM ALLOYS
ALLOY SYSTEMS
ALUMINIUM ADDITIONS
CHEMICAL REACTIONS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COBALT ALLOYS
CORROSION RESISTANT ALLOYS
GASIFICATION
HASTELLOYS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY ALLOYS
IRON BASE ALLOYS
KINETICS
MANGANESE ADDITIONS
MANGANESE ALLOYS
MATERIALS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
PYROLYSIS PRODUCTS
SILICON ADDITIONS
SILICON ALLOYS
STAINLESS STEELS
STEELS
THERMOCHEMICAL PROCESSES
TITANIUM ADDITIONS
TITANIUM ALLOYS
TUNGSTEN ALLOYS
360105* - Metals & Alloys- Corrosion & Erosion
010404 - Coal
Lignite
& Peat- Gasification