High temperature corrosion by deposits of alkali salts
- Krupp VDM GmbH, Werdohl (Germany)
In order to understand and predict how corrosion behavior of metallic high temperature materials is affected by deposits of alkali salts, eight commercial high temperature alloys (AISI 314, alloy 800H, alloy 31, AC66, alloy 45-TM, alloy 625, alloy 59 and alloy C-4) coated with alkali sulfates and chlorides (Na{sub 2}SO{sub 4}/KCl) were investigated in both air and in HCl/SO{sub 2}-containing waste incineration environments. The corrosion rates were found to depend sensitively on the alloy composition, especially on the concentration of molybdenum and silicon. Both stainless steels and nickel base alloys without molybdenum were resistant to dissolution by sulfates in air. Molybdenum-containing steels and nickel base alloys, on the other hand, were extremely susceptible to acidic dissolution in sodium sulfate. These high corrosion rates can be attributed to an increase in salt acidity caused by dissolution of MoO{sub 3}. The effect of HCI in the gas atmosphere was contradictory. All alloys without molybdenum suffered severe internal oxidation, when chlorine was present in the gas atmosphere. The corrosion rates of the nickel-molybdenum alloys, however, were decreased when chlorine was added to the gas phase. The highest corrosion resistance to synthetic waste incineration gas in combination with deposits of alkali sulfates and chlorides was found in the nickel base alloys 45 TM and alloy 625.
- OSTI ID:
- 397811
- Report Number(s):
- CONF-960389-; TRN: IM9649%%19
- Resource Relation:
- Conference: National Association of Corrosion Engineers (NACE) annual corrosion conference and exposition: water and waste water industries, Denver, CO (United States), 24-29 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of Corrosion/96 conference papers; PB: [6615] p.
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES
01 COAL, LIGNITE, AND PEAT
HEAT RESISTING ALLOYS
CORROSION
INCINERATORS
MATERIALS
BOILERS
COAL GASIFICATION PLANTS
FLUIDIZED-BED COMBUSTORS
CHEMICAL COMPOSITION
SULFATES
CHLORIDES
AIR
HYDROCHLORIC ACID
SULFUR DIOXIDE
DISSOLUTION
SCALING
WEIGHT MEASUREMENT
OPTICAL MICROSCOPY
SCANNING ELECTRON MICROSCOPY
X-RAY SPECTRA
EXPERIMENTAL DATA