327 Effects of additional Ce and Si elements to CoNiCrAlY on bond strength at the interface between thermal barrier coating and bond 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.

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Thermal failure of thermal barrier coating with thermal sprayed bond coating on titanium alloy

Journal of Coatings Technology and Research ◽

10.1007/s11998-007-9070-8 ◽

2008 ◽

Vol 5 (1) ◽

pp. 99-106 ◽

Cited By ~ 3

Author(s):

Bo He ◽

Fei Li ◽

Hong Zhou ◽

Yongbing Dai ◽

Baode Sun

Keyword(s):

Titanium Alloy ◽

Thermal Barrier Coating ◽

Thermal Barrier ◽

Thermal Failure ◽

Bond Coating ◽

Barrier Coating

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Failure Mechanism of 7YSZ Splat as Thermal Barrier Coating

Materials Science Forum ◽

10.4028/www.scientific.net/msf.816.219 ◽

2015 ◽

Vol 816 ◽

pp. 219-225

Author(s):

Xiao Feng Zhang ◽

Ke Song Zhou ◽

Xiao Ling Xiao ◽

Min Liu

Keyword(s):

High Temperature ◽

Failure Mechanism ◽

Thermal Barrier Coating ◽

Ion Beam ◽

Atmospheric Plasma ◽

Nickel Base Superalloy ◽

Thermal Barrier ◽

Bond Coating ◽

Oxidation Test ◽

Barrier Coating

An investigation of spallation behaviors of plasma-sprayed ZrO2-7wt.%Y2O3(7YSZ) splat at high temperature was carried out to understand the failure mechanism of thermal barrier coating (TBC). In present work, 7YSZ splats prepared by atmospheric plasma spray (APS) were collected on mirror polished NiCoCrAlYTa bond coating holding at 250 °C, where the nickel base superalloy K4169 was used as substrate. Then the samples with splats were taken into air furnace for isothermal oxidation test at 900 °C for different time. The surface of splat and cross section of splat-bond coating interface during isothermal test were characterized using a focused ion beam (FIB) assisted field emission scanning electron microscope (FE-SEM). Besides, the compositions of thermally grown oxide (TGO) layer at splat-bond coating interface were analyzed after oxidation test. In addition, the schematic diagram of spallation process and oxidation model of splat has been presented at relatively high temperature.

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