Hostname: page-component-848d4c4894-8bljj Total loading time: 0 Render date: 2024-07-03T15:17:23.609Z Has data issue: false hasContentIssue false
  • English
  • Français

Oxide reduction and sintering of Fe–Cr alloy honeycombs

Published online by Cambridge University Press:  31 January 2011

Jason H. Nadler ,
Thomas H. Sanders Jr.  and
Robert F. Speyer
Jason H. Nadler
Affiliation:
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
Thomas H. Sanders Jr.
Affiliation:
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
Robert F. Speyer
Affiliation:
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
Get access

Abstract

H2 reduction and densification of extruded Fe2O3–Cr2O3 mixtures with honeycomb geometry (0.3-mm wall thickness) were studied using dilatometry, x-ray diffraction, and scanning electron microscopy. Reduction of pure Fe2O3 heated at 5 °C/min was completed by approximately 525 °C. Two separate sintering steps ensued, well separated in temperature from reduction, one associated with elimination of pores between Fe agglomerates (750–900 °C), and the other associated with sintering of these agglomerates (995–1275 °C). With increasing Cr2O3 content, sintering was increasingly delayed until initiation of Cr2O3 reduction above 1000 °C. The α → γ iron phase transformations were consistent with the Fe–Cr phase diagram, but the γ → α transformations at higher temperatures deviated from the phase diagram because of the influence of impurities (Si, Ca) in the solid solution. Pure Cr2O3 honeycomb formed an approximately 35-μm-thick porous Cr coating that imposed a diffusion barrier to further reduction. The high vapor pressure of chromium prohibited compositions in excess of 25 wt.% Cr2O3 from full reduction and densification.

Type
Articles
Information
Journal of Materials Research , Volume 18 , Issue 8 , August 2003 , pp. 1787 - 1794
Copyright
Copyright © Materials Research Society 2003

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Hurysz, K.M., Oh, R., Cochran, J.K., Sanders, T.H. Jr, and Lee, K.J., in Processing and Properties of Lightweight Cellular Metals and Structures edited by Ghosh, A.K., Sanders, T.H., and Claar, T.D. (TMS, Warrendale, PA, 2002), pp. 167–176.Google Scholar
Gurevich, Y.G., Radomysel’skii, I.D., Barschevskaya, L.F., Frage, N.R., and Pozhidaev, Y.I., Sov. Powder Metall. Met. Ceram. 14(1), 13 (1975).CrossRefGoogle Scholar
Chinje, U.F. and Jeffes, J.H.E., Ironmaking Steelmaking 13(2), 90 (1989).Google Scholar
Chinje, U.F. and Jeffes, J.H.E., Ironmaking Steelmaking 17(5), 317 (1990).Google Scholar
Kedr, M.H., ISIJ Int. 40(4), 309 (2000).CrossRefGoogle Scholar
Strangway, P.K., Ph.D. Thesis, University of Toronto, Toronto, Canada (1966).Google Scholar
Szekely, J. and Evans, J.W., Met. Trans. 2, 1691 (1971).CrossRefGoogle Scholar
Maier, C.G., US Bur. Mines Bull. 436 (1989).Google Scholar
Rohn, W., U.S. Patent No. 1 915 243 (1933).Google Scholar
Nadler, J.H., Sanders, T.H., and Cochran, J.K., in Processing and Properties of Lightweight Cellular Metals and Structures edited by Ghosh, A.K., Sanders, T.H., and Claar, T.D. (TMS, Warrendale, PA, 2002), pp. 147–155.Google Scholar
Nelson, J.B. and Riley, D.P., Proc Phys. Soc. (London) 57, 160 (1945).CrossRefGoogle Scholar
Pearson, W.B., A Handbook of Lattice Spacings and Structures of Metals and Alloys (Pergamon Press, New York, 1958).Google Scholar
ASM Handbook Volume 3, Alloy Phase Diagrams, edited by Baker, H. (ASM International, Materials Park, OH, 1997).Google Scholar
German, R.M., Sintering Theory and Practice (John Wiley and Sons, New York, 1996).Google Scholar