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Hot corrosion behaviour of plasma sprayed YSZ/Al(2)O(3) dispersed NiCrAlY coatings on Inconel-718 superalloy

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Title Hot corrosion behaviour of plasma sprayed YSZ/Al(2)O(3) dispersed NiCrAlY coatings on Inconel-718 superalloy
 
Creator SREEDHAR, G
ALAM, MDM
RAJA, VS
 
Subject thermal barrier coatings
ni3al coatings
nondestructive evaluation
oxidation behavior
cyclic conditions
residual-stress
ni-cr
stellite-6
resistance
piezospectroscopy
tbc
ysz dispersed nicraly coatings
hot corrosion
na(2)so(4)-v(2)o(5) melts
 
Description Oxide dispersed NiCrAlY bond coatings have been developed for enhancing thermal life cycles of thermal barrier coatings (TBCs). However, the role of dispersed oxides on high temperature corrosion, in particular hot corrosion, has not been sufficiently studied. Therefore, the present study aims to improve the understanding of the effect of YSZ dispersion on the hot corrosion behaviour of NiCrAlY bond coat. For this, NiCrAlY, NiCrAlY + 25 wt.% YSZ, NiCrAlY + 50 wt.% YSZ and NiCrAlY + 75 wt.% YSZ were deposited onto Inconel-718 using the air plasma spraying (APS) process. Hot corrosion studies were conducted at 800 degrees C on these coatings after covering them with a 1:1 weight ratio of Na(2)SO(4) and V(2)O(5) salt film. Hot corrosion kinetics were determined by measuring the weight gain of the specimens at regular intervals for a duration of 51 h. X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques were used to determine the nature of phases formed, examine the surface attack and to carry out microanalysis of the hot corroded coatings respectively. The results show that YSZ dispersion causes enhanced hot corrosion of the NiCrAlY coating. Leaching of yttria leads not only to the formation of the YVO(4) phase but also the destabilization of the YSZ by hot corrosion. For the sake of comparison, the hot corrosion behaviour of a NiCrAlY + 25 wt.% Al(2)O(3) coating was also examined. The study shows that the alumina dispersed NiCrAlY bond coat offers better hot corrosion resistance than the YSZ dispersed NiCrAlY bond coat, although it is also inferior compared to the plain NiCrAlY bond coat. (C) 2009
 
Publisher ELSEVIER SCIENCE SA
 
Date 2011-07-28T09:12:24Z
2011-12-26T12:58:48Z
2011-12-27T05:49:22Z
2011-07-28T09:12:24Z
2011-12-26T12:58:48Z
2011-12-27T05:49:22Z
2009
 
Type Article
 
Identifier SURFACE & COATINGS TECHNOLOGY, 204(3), 291-299
0257-8972
http://dx.doi.org/10.1016/j.surfcoat.2009.07.026
http://dspace.library.iitb.ac.in/xmlui/handle/10054/7360
http://hdl.handle.net/10054/7360
 
Language en