Microstructural evolution and degradation modes in cyclic and isothermal oxidation of an EB-PVD thermal barrier coating

2000 ◽  
Vol 17 (2) ◽  
pp. 205-217 ◽  
Author(s):  
F. Ibegazene-Ouali ◽  
R. Mevrel ◽  
C. Rio ◽  
Y. Renollet
Keyword(s):  
Thermal Barrier Coating ◽  
Microstructural Evolution ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Degradation Modes

scholarly journals An Investigation of the Effects of Isothermal Exposure on Microstructural Evolution and Oxidation in a Thermal Barrier Coating

2000 ◽  
Author(s):  
T. Chang ◽  
C. Mercer ◽  
M. E. Walter ◽  
W. O. Soboyejo
Keyword(s):  
Thermal Barrier Coating ◽  
Microstructural Evolution ◽  
Isothermal Oxidation ◽  
Systematic Investigation ◽  
Thermal Barrier ◽  
Isothermal Exposure ◽  
Analysis And Design ◽  
Pull Out ◽  
Platinum Aluminide ◽  
Barrier Coating

Abstract This paper presents the results of a systematic investigation of the effects of isothermal exposure on the microstructural evolution and the isothermal oxidation behavior of a thermal barrier coating with a platinum aluminide bond coat. Sintering of the columnar partially stabilized zirconia is shown to occur during isothermal exposure at 1150°C for durations up to 200 hours. This is accompanied by roughening of the TGO layers, the formation of hemi-spheroidal defects, parabolic coarsening of the TGO and final pull-out of the zirconia layers. The implications of the results are discussed for the analysis and design of TBCs for aeroengine applications.

Analysis of YSZ-Al2O3/YSZ Flame Sprayed Thermal Barrier Coating to Thermal Resistance

2015 ◽  
Vol 1112 ◽  
pp. 338-344
Author(s):  
Widyastuti ◽  
Kusriantoko Parindra ◽  
Lilis Mariani ◽  
Hosta Ardhyananta ◽  
Sulistijono
Keyword(s):  
Surface Morphology ◽  
Thermal Barrier Coating ◽  
Feed Rate ◽  
Composite Layer ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
Rocket Nozzle ◽  
Oxidation Test ◽  
Thermal Test ◽  
Barrier Coating

TBC (Thermal Barrier Coating) with YSZ-Al2O3/YSZ as top coat (TC) and MCrAlY alloy as bond coat (BC) marked as YSZ-Al2O3/YSZ double layer TBC was used for thermal barrier material on rocket nozzle wall. Several test have been conducted (thermal test and SEM-EDX). Thermal test was divided into two part, Thermal Torch and Non-isothermal Oxidation Test which is used for measure the resistance of TBC structure against oxyacethylene flame penetration as a miniature of thermal static test for rocket nozzle until the specimen was failure and used to measure the resistance against non-isothermal oxidation as well as investigate the growth of TGO (Thermally Grown Oxide) layer on interface between TC/BC for thermal torch and non-isothermal oxidation test respectively. This test was performed at 1100o C with 10°C/min heating rate. The results showed that the improvement of feed rate on topcoat powder gave the effect on the surface morphology of topcoat. Lower feed rate bring in a coarse surface morphology and tend to be porous. Al2O3/YSZ composite layer affect on the growth of TGO layer after thermal test, which indicates the lower growth of TGO especially for 15%Al2O3/8YSZ. TGA test showed that the sample began to oxidize at temperature range c.a 1000 – 1030°C, however 1st derivative analysis indicated that 15% Al2O3/8YSZ, 14 g/min was the most stable sampel. Moreover this material has a good resistance from torch destruction.

Interfacial Fracture Toughness of APS Thermal Barrier Coating under High Temperature

2007 ◽  
Vol 348-349 ◽  
pp. 181-184 ◽  
Author(s):  
Hong Yu Qi ◽  
Xiao Guang Yang ◽  
Rui Li
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Thermal Barrier Coating ◽  
Interfacial Fracture ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
Interfacial Fracture Toughness ◽  
Air Plasma ◽  
Bond Coating ◽  
Barrier Coating

Thermal barrier coating (TBC) is an essential requirement of a modern gas turbine engine. The TBC failure is the delamination and spallation. The oxidation damage under high temperature results in the reduction of interfacial adhesion. The interfacial fracture toughness is an important property to analyze the TBC failure. The interfacial fracture toughness of ceramic coating - bond coating has been researched in the past. However, the facture toughness of the bond coating - substrate due to the Al depletion was very few studied. In this study, a NiCrAlY bond coating by air plasma spray (APS) was deposited. The substrate was directionally solidified superalloy (DZ40M). Isothermal oxidation was performed at 10500 for 100h. Using the HXZ-1000 micro-hardness equipment, the five different times was chosen to test the hardness and the crack length, and then the fracture toughness was obtained. While the oxidation exposure time increased at 10500, the hardness of the substrate close to the bond coating decreased with the increase of the bond coating’ hardness. Meanwhile, the interfacial fracture toughness of the bond coating - substrate decreased because of the Al depletion.

Transmission Electron Microscopy of Isothermally Oxidized EB-PVD Thermal Barrier Coating on (Ni,Pt)Al Bondcoat

2005 ◽  
Vol 486-487 ◽  
pp. 149-152 ◽  
Author(s):  
Jai Won Byeon ◽  
S. Laxman ◽  
Yong Ho Sohn
Keyword(s):  
Thermal Barrier Coating ◽  
Microstructural Analysis ◽  
Isothermal Oxidation ◽  
Dark Field ◽  
Thermal Barrier ◽  
Dark Field Imaging ◽  
Barrier Coating ◽  
Transmission Electron ◽  
Oxide Zone ◽  
Field Imaging

The growth and microstructure of the thermally grown oxide (TGO) underneath the electron beam physical vapor deposited (EB-PVD) yttria stabilized zirconia (YSZ) topcoat were examined after short-term isothermal oxidation (1100 °C, up to 50 hours) for the as-coated and gritblasted (Ni,Pt)Al bondcoats. Microstructural analysis was carried out by a high resolution scanning transmission electron microscope equipped with bright/dark field imaging, high angle annular dark field imaging, and nano-spot energy dispersive spectroscopy. Presence of mixed oxide zone (MOZ) and a continuous Al2O3 oxide zone (COZ) was observed on the thermal barrier coating (TBC) with the as-coated (Ni,Pt)Al bondcoat. However, on the TBC with grit-blasted bondcoat, only the continuous-columnar Al2O3 scale was observed. For the as-coated type bondcoat, numerous voids were observed near the interface between MOZ and COZ after isothermal oxidation. On the other hand, COZ showed parabolic growth without any formation of voids for the grit-blasted specimens.

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