ISSN:
1573-4889
Keywords:
nickel-base alloys
;
sulfidation
;
preoxidation
;
Al2O3 scales
;
Cr2O3 scales
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Ni-20Cr alloys with 2, 3.5, and 5 wt.% Al have been preoxidized up to 100 hr at 1000°C in dry H2, in H2/23% H2O and in air and subsequently exposed to an H2/5% H2S atmosphere at 750° C. During the preoxidation treatment different types of oxide scales were formed which affect the sulfidation protection in different ways. Optimum results were obtained for alloys with 3.5 and 5 wt.% Al after 20 hr exposure to dry H2 at 1000°C. A thin Al2O3 scale is formed which decreases the sulfur attack by more than one order of magnitude. Preoxidation conditions for Ni-20Cr-2Al alloys in H2 and for Ni-20Cr-2Al and Ni-20Cr-3.5Al in H2/H2O were observed to be less effective. No improvement was found for preoxidation in air or for Ni-20Cr-5Al alloys preoxidized in H2/H2O.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01151587
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