Creep and the corrosion characteristics of Incoloy Alloy 800 in molten nitrate salts
Incoloy Alloy 800 (I800) has been proposed for use in the receiver tube panel arrays in a number of advanced solar central receiver (SCR) concepts. Because of their high heat capacity and high thermal energy density, several designs require the use of molten sodium and potassium nitrate salt mixture to act as the cooling or heat transfer fluid. The effects of deformation on the corrosion resistance of Incoloy Alloy 800 in sodium nitrate and potassium nitrate salt mixtures have been studied. Hollow tube specimens filled with the salt mixture (60%-NaNO/sub 3/-40% KNO/sub 3/) were tested in constant load tension creep at elevated temperatures (550/sup 0/ less than or equal to T less than or equal to 670/sup 0/C). Depending on the temperature and initial stress, fracture times (and therefore salt exposure times) ranged between 300 and 1000 hours. While the fracture strain of specimens tested to failure was only slightly reduced when exposed to the salt environment, metallographic observations of polished cross-sections revealed severe surface oxidation. In order to characterize the effect of total imposed strain on oxide morphology a number of creep tests were terminated prior to fracture. Increasing deformation resulted in a more extensively damaged surface oxide as well as a more rapid rate of corrosion. EDX analysis revealed that the oxide was multiphase, with a near surface iron rich oxide above a chromium-rich oxide layer. Below 630/sup 0/C the oxide-metal interface was well defined (although irregular). Above 630/sup 0/C the interface was more diffuse with fine oxide intrusions growing into the base metal and small particles of the alloy visible in the oxide near the base metal interface.
- Research Organization:
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6579692
- Report Number(s):
- SAND81-8665
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
INCOLOY 800
CORROSION
CREEP
MOLTEN SALTS
CORROSIVE EFFECTS
POTASSIUM NITRATES
SODIUM NITRATES
TOWER FOCUS COLLECTORS
MATERIALS TESTING
CENTRAL RECEIVERS
CORROSION RESISTANCE
DEFORMATION
EXPERIMENTAL DATA
FAILURES
GRAPHS
HEAT TRANSFER FLUIDS
HIGH TEMPERATURE
MIXTURES
STRAINS
ALKALI METAL COMPOUNDS
ALLOYS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CONCENTRATING COLLECTORS
DATA
DISPERSIONS
EQUIPMENT
FLUIDS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY ALLOYS
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
NICKEL ALLOYS
NITRATES
NITROGEN COMPOUNDS
NUMERICAL DATA
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
SALTS
SODIUM COMPOUNDS
SOLAR COLLECTORS
SOLAR EQUIPMENT
SOLAR RECEIVERS
TESTING
CSP
Concentrating Solar Power
141000* - Solar Collectors & Concentrators
360105 - Metals & Alloys- Corrosion & Erosion