Title

Effects Of Bond Coat Surface Roughness And Pre-Oxidation On The Thermal Cycling Lifetime Of Thermal Barrier Coatings

Abstract

Effects of surface roughness and pre-oxidation heat treatment for the NiCoCrAlY bond coat (PWA276), carried out prior to the electron beam physical vapor deposition (EB-PVD) of ZrO 2-7 wt.% Y 2O 3 (7YSZ) ceramic topcoat, on the thermal cycling lifetime of thermal barrier coatings (TBCs) were examined. As a junction of bond coat processing and thermal cycling, TBCs were characterized by using optical profilometry, photo-stimulated luminescence spectroscopy (PSLS), optical microscopy, and scanning electron microscopy. TBC specimens with preoxidized bond coats, in general, exhibited longer lifetime than those without pre-oxidation. The longest TBC lifetime was observed when hand-polished (i.e., smoothest) bond coats were preoxidized prior to EB-PVD of 7YSZ. However, without pre-oxidation, TBC specimen with handpolished and barrel-finished bond coats failed prematurely due to underdeveloped thermally grown oxide (TGO) and/or failure at the YSZ/TGO interfaces. For TBCs specimens with preoxidized bond coats, a greater lifetime was observed with a higher initial compressive residual stress within the TGO.

Publication Date

12-1-2004

Publication Title

Ceramic Engineering and Science Proceedings

Volume

25

Issue

4

Number of Pages

399-404

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

31844452804 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/31844452804

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