ISSN: 0970-938X (Print) | 0976-1683 (Electronic)
An International Journal of Medical Sciences
A D Chandio
NED University of Engineering and Technology, Pakistan
Posters & Accepted Abstracts : Biomed Res
DOI: 10.4066/biomedicalresearch-C4-011
Bond coats (BCs) based on �²NiAl matrix are commonly employed in thermal barrier coating systems (TBC) for aero-engine applications. The addition of reactive elements (REs) such as; Zr, Hf and Y in �²NiAl are being researched extensively since they offer improved oxidation performance at high temperatures. In this study, experimental findings will be presented on the �²NiAl matrix-based BCs that were prepared onto CMSX-4 superalloy with and without additions of Zr and Hf using an in-situ chemical vapor deposition (CVD) method. The BCs were isothermally oxidized at 1150oC for 100 hours in laboratory air. The processing of REs-�²NiAl and their effects on oxidation were studied in comparison to undoped �²NiAl. This was followed by characterization techniques including TEM, FIB, ASTAR analysis; SEM, XRD, Proto iXRD and Raman spectroscopy/PLPS. The REs doped �²NiAl were successfully prepared using in-situ CVD technique. BC performance is discussed in detail such as thermally grown oxide (TGO) phases, stresses, morphologies etc. In general, TGO formed due to oxidation of REs doped samples consisted of alpha alumina alone; on contrary mixture of TiO2, NiAl2O4, �¸-Al2O3 and �±-Al2O3 was seen in their undoped counterparts. In addition, the TGO growth rate and residual stresses on REs- �²NiAl were found to be lower than that of the undoped �²NiAl. In addition, oxide pegging (OP) due to REs were also analyzed using TEM with the aid of FIB this was followed by ASTAR indexing. The OP was emerged to be one of key features of REs doped BCs which is crtical factor for lifespan of the TBC.
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