ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The University of North Dakota Energy & Environmental Research Center is workingwith Oak Ridge National Laboratory to test two oxide dispersion-strengthened alloys that could beused to construct very high-temperature heat recuperators for the aluminum-melting industry. Forthe initial tests, uncooled rings of MA754 and MA956 piping were exposed for 5½ months to gasesleaving an aluminum melter furnace at 1200°–1290°C. The MA956 suffered spotty areas of severecorrosion and lost 25% of its weight. Scanning electron microscopy showed that there were smallspots of alkali-rich corrosion products on the alloy surfaces, indicating the impact of droplets offluxing agents. The corrosion products in these areas were mixed Fe, Cr, and Al oxides, which weredepleted in Cr near the gas surface. However, Al concentrations in the remaining metal weretypically between 3.5% and 4.0%, so there was a sufficient reservoir of Al remaining in the alloy toprevent simple breakaway corrosion which could have occurred if the Al were significantlydepleted.The MA754 lost approximately 15% of its weight and showed void formation within 2 mm of thegas–metal surfaces. Within the porous area, the Cr had largely segregated into oxide precipitates upto 50 9m in diameter, leaving the remaining metal Ni-rich. Below the porous layer, the alloycomposition was relatively unchanged. Remains of Na- and Al-rich particles that had impacted thesurface sporadically were visible but had not obviously affected the surface scale as they had withthe MA956
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.595-598.611.pdf
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