Title

Effects Of Phase Constituents/Microstructure Of Thermally Grown Oxide On The Failure Of Eb-Pvd Thermal Barrier Coating With Nicocraly Bond Coat

Keywords

Photoluminescence; Surface modification; Thermal barrier coatings; Thermal cycling; Thermally grown oxide

Abstract

A correlation among thermal cycling lifetime, bond coat surface preparation, phase constituents and microstructure of thermally grown oxide (TGO) was examined for electron beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) consisting of ZrO2-7 wt.% Y2O3 (YSZ) ceramic topcoat, NiCoCrAlY bond coats and CMSX-4 superalloy. Variation in the bond coat surface is characterized based on surface roughness modification and pre-oxidation (1100 °C at PO2 of 10-8 atm up to 4 h) carried out prior to YSZ deposition by EB-PVD. TBC specimens with pre-oxidized bond coats exhibited longer lifetimes than those without pre-oxidation, especially for metallographically polished bond coats. Given a surface roughness of NiCoCrAlY bond coats, TBC lifetime was observed to increase with an increase in the amount of α-Al2O3 in the initial thermally grown oxide (TGO) scale, which was detected by photostimulated luminescence (PL). Using focused ion beam in-situ lift out technique (FIB-INLO), site-specific preparation of thermally cycled TBC specimens for transmission electron microscopy (TEM) was successfully carried out. In addition to the presence of α-Al2O3, a small particulate phase identified as cubic Y2O3 was observed within the TGO scale by electron diffraction analysis on TEM. © 2005 Elsevier B.V. All rights reserved.

Publication Date

5-22-2006

Publication Title

Surface and Coatings Technology

Volume

200

Issue

20-21

Number of Pages

5869-5876

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.surfcoat.2005.08.140

Socpus ID

33645832380 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/33645832380

This document is currently not available here.

Share

COinS