Effect of thermally growth oxides (TGO) on adhesion strength for high purity yitria stabilised zirconia (YSZ) and rare – Earth lanthanum zirconates (LZ) multilayer thermal barrier coating before and after isothermal heat treatment

2017 ◽  
Author(s):  
Salmi Mohd Yunus ◽  
Azril Dahari Johari ◽  
Shuib Husin
Keyword(s):  
Heat Treatment ◽  
Rare Earth ◽  
Thermal Barrier Coating ◽  
Adhesion Strength ◽  
High Purity ◽  
Thermal Barrier ◽  
Isothermal Heat Treatment ◽  
Barrier Coating ◽  
Before And After

On the Change in Stress State Associated with Bond Coat Oxidation during Heat Treatment of a Thermal Barrier Coating System

1997 ◽  
Author(s):  
Y.C. Tsui ◽  
T.W. Clyne ◽  
R.C. Reed
Keyword(s):  
Heat Treatment ◽  
Stress State ◽  
Oxide Layer ◽  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Driving Forces ◽  
Lateral Strain ◽  
Thermal Barrier ◽  
Residual Stress State ◽  
Barrier Coating

Abstract Thermal barrier coating systems have been heat treated in order to study the oxidation kinetics of the bond coat. All the surfaces of Ni superalloy substrates were sprayed with ~100 μm of a NiCrAlY bond coat, with or without ~250 μm of a ZrO2 top coat. Thermogravimetric analysis (TGA) was used to monitor continuously the mass change as a result of oxidation of the bond coat during heating at 1000°C for 100 hours in flowing air. In addition, some specimens were heated to 1000°C in static air, cooled to room temperature, weighed and re-heated cyclically. The total exposure time was 1000 hours. Rates of weight gain were found to be higher for the cycled specimens, despite the absence of air flow. This is attributed to damage to the oxide film, which was predominantly α-Al2O3, as a consequence of differential thermal contraction stresses. The changing residual stress state during heat treatment was predicted using a previously-developed numerical model. A thin (1 mm) substrate with ~100 μm bond coat and ~250 μm ZrO2 top coat was used in these simulations, which incorporated creep of the bond coat and the lateral strain associated with oxidation. It is concluded from these computations that, while high stresses develop in the oxide layer, the associated driving forces for interfacial debonding remain relatively low, as do specimen curvature changes. It seems likely that coating spallation after extensive oxide layer formation arises because the interface is strongly embrittled as the layer thickens.

Towards thermal barrier coating application for rare earth silicates RE2SiO5 (RE= La, Nd, Sm, Eu, and Gd)

2019 ◽  
Vol 39 (4) ◽  
pp. 1463-1476 ◽  
Author(s):  
Zhilin Tian ◽  
Jie Zhang ◽  
Tianyin Zhang ◽  
Xiaomin Ren ◽  
Wanpeng Hu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coating ◽  
Thermal Barrier ◽  
Coating Application ◽  
Barrier Coating

“Multilayer thermal barrier coating (TBC) architectures utilizing rare earth doped YSZ and rare earth pyrochlores”

2014 ◽  
Vol 251 ◽  
pp. 56-63 ◽  
Author(s):  
Michael P. Schmitt ◽  
Amarendra K. Rai ◽  
Rabi Bhattacharya ◽  
Dongming Zhu ◽  
Douglas E. Wolfe
Keyword(s):  
Rare Earth ◽  
Thermal Barrier Coating ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Rare Earth Doped
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