Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


2015-Maryam Zahiri.pdf (78.52 MB)

ETD Abstract Container

Abstract Header

Early Stage Hot Corrosion Behavior of Pt/Cr-Modified ß-NiAl Alloys at 700°C

Zahiri Azar, Maryam
http://rave.ohiolink.edu/etdc/view?acc_num=case1434558093

Abstract Details

2015, Doctor of Philosophy, Case Western Reserve University, Materials Science and Engineering.
Early-stage (up to 20 hours) scaling behavior of Ni-36Al alloys containing 5 at% additions of Cr and/or Pt undergoing oxidation or sulfate-deposit induced Type II hot corrosion at 700°C was systematically studied using advanced micro-characterization techniques. The model compositions studied in this study are relevant to ß-NiAl coatings used in current technology to protect Ni-based superalloys. In Type II hot corrosion, there are two factors affecting the corrosion resistance of the alloy: the ability of the alloy to form a protective oxide, which reduce the degradation rate; and formation of eutectic liquid in the salt at temperatures below the melting point of Na2SO4, which accelerates the degradation rate. Eutectic liquid can form in the salt due to dissolution of various corrosion products. Changing the composition of the alloy can change the characteristics of the scale that develops, as well as the amount of eutectic liquid that forms, thus changing the degradation rate and possibly the corrosion mechanism. The addition of the minor elements significantly changed the hot-corrosion behavior compared to that of the base alloy. At early-stages of Na2SO4-induced hot corrosion, the base alloy formed a dense Al2O3 scale, which underwent local failure. The Cr-containing alloy formed the most uniform corrosion product, but it also sustained severe sulfur attack and developed a very porous scale. The alloy containing 5 at% Pt formed a dense, comparatively thin, Al2O3 oxide layer, and exhibited the best early-stage hot corrosion resistance.
ARTHUR HEUER (Advisor)
GLEESON BRIAN (Committee Member)
MCGUFFIN-CAWLEY JAMES (Committee Member)
WILLARD MATTHEW (Committee Member)
169 p.
Engineering; Materials Science
Characterization, TEM, hot corrosion, oxidation, NiAl

Recommended Citations

Citations

  • Zahiri Azar, M. (2015). Early Stage Hot Corrosion Behavior of Pt/Cr-Modified ß-NiAl Alloys at 700°C [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1434558093

    APA Style (7th edition)

  • Zahiri Azar, Maryam. Early Stage Hot Corrosion Behavior of Pt/Cr-Modified ß-NiAl Alloys at 700°C. 2015. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1434558093.

    MLA Style (8th edition)

  • Zahiri Azar, Maryam. "Early Stage Hot Corrosion Behavior of Pt/Cr-Modified ß-NiAl Alloys at 700°C." Doctoral dissertation, Case Western Reserve University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1434558093

    Chicago Manual of Style (17th edition)

case1434558093
370
© 2015, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.