Investigation of the effects of microalloy constituents surface treatments and oxidation conditions on the development and breakdown of protective oxide scales

Technical Report · Mon Oct 01 04:00:00 EDT 1990

DOI:https://doi.org/10.2172/6474838· OSTI ID:6474838

Srinivasan, V ^[1]

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1. Universal Energy Systems, Inc., Dayton, OH (USA)

This research explores the scientific principles behind improving the corrosion resistance of traditional ferritic and austenitic steels that are used extensively in fossil energy sysyems. The objective of this program is to understand and gain control over factors that improve and extend significantly the protectiveness of chromia and alumina scales. Investigations were carried out to understand the effects of minor alloying additions, the methods of their incorporation, surface treatments and oxidizing conditions on the formation and breakdown of protective oxide scales. High purity Fe-25Cr, Fe-25Cr-20Ni and Fe-25Cr-6Al were chosen as base alloys. The additives were Ce, Hf, La, O, Pt, Si, Y and {alpha}-Al{sub 2}O{sub 3} dispersoids. In-got metallurgy (I/M) and powder metallurgy (P/M) routes and ion implantation procedures were used to incorporate them. Cold rolling (50%) was included as a surface pretreatment. Coupons of these alloys were exposed isothermally and cyclically to gas mixtures of H{sub 2}/H{sub 2}O/H{sub 2}S/Ar with oxygen and sulfur activities simulating coal derived atmospheres. The test temperatures were between 700{degree} and 500{degree}C, and exposure times were up to 500 h. In addition, isothermal and cyclic oxidation runs in O{sub 2} at 1 atm or low pO{sub 2}, and preoxidation followed by multioxidant exposures were made. For kinetics studies, TGA apparatus was used. Scales at different stages of formation and breakdown, and the substrates were examined using a variety of conventional and advanced surface analytical tools to find the initial and final location and chemical status of additives and scale-forming species. 80 refs., 106 figs., 13 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA); Universal Energy Systems, Inc., Dayton, OH (USA)
• Sponsoring Organization: DOE/FE
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6474838
• Report Number(s): ORNL/Sub-86-95901/02; ON: DE91004521
• Country of Publication: United States
• Language: English

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ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBONACEOUS MATERIALS
CERIUM
CHALCOGENIDES
CHEMICAL REACTIONS
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CHROMIUM COMPOUNDS
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CRYSTAL STRUCTURE
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
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HAFNIUM
ION IMPLANTATION
IRON ALLOYS
IRON BASE ALLOYS
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NICKEL ALLOYS
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OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
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THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YTTRIUM