A microstructural observation of near-failure thermal barrier coating: a study by photostimulated luminescence spectroscopy and transmission electron microscopy

2004 ◽  
Vol 466 (1-2) ◽  
pp. 128-136 ◽  
Author(s):  
B.W. Kempshall ◽  
Y.H. Sohn ◽  
S.K. Jha ◽  
S. Laxman ◽  
R.R. Vanfleet ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Barrier Coating ◽  
Luminescence Spectroscopy ◽  
Thermal Barrier ◽  
Photostimulated Luminescence ◽  
Microstructural Observation ◽  
Barrier Coating ◽  
Transmission Electron

New Technique for Successful Thermal Barrier Coating Specimen Preparation for Transmission Electron Microscopy

2000 ◽  
Vol 6 (3) ◽  
pp. 231-236
Author(s):  
M.R. Brickey ◽  
J.L. Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Specimen Preparation ◽  
Ion Milling ◽  
New Approach ◽  
Barrier Coating ◽  
Transmission Electron ◽  
Thermal Histories

Abstract Reliability of thermal barrier coatings (TBC) hinges on the adhesion of a thermally grown oxide scale to an insulative ceramic topcoat and an underlying metallic bondcoat. The width of the scale and its interfaces makes transmission electron microscopy (TEM) an appropriate tool for its analysis. However, specimen preparation has proven to be a challenging obstacle leading to a dearth of TEM research on TBCs. A new approach to cross-section TBC TEM specimen preparation is described. The principal advantages of this technique are reproducibility, reduced specimen damage, and time savings resulting from decreased ion milling. This technique has been successfully applied to numerous TBC specimens with various thermal histories.

New Technique for Successful Thermal Barrier Coating Specimen Preparation for Transmission Electron Microscopy

2000 ◽  
Vol 6 (3) ◽  
pp. 231-236 ◽  
Author(s):  
M.R. Brickey ◽  
J.L. Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Specimen Preparation ◽  
Ion Milling ◽  
New Approach ◽  
Barrier Coating ◽  
Transmission Electron ◽  
Thermal Histories

AbstractReliability of thermal barrier coatings (TBC) hinges on the adhesion of a thermally grown oxide scale to an insulative ceramic topcoat and an underlying metallic bondcoat. The width of the scale and its interfaces makes transmission electron microscopy (TEM) an appropriate tool for its analysis. However, specimen preparation has proven to be a challenging obstacle leading to a dearth of TEM research on TBCs. A new approach to cross-section TBC TEM specimen preparation is described. The principal advantages of this technique are reproducibility, reduced specimen damage, and time savings resulting from decreased ion milling. This technique has been successfully applied to numerous TBC specimens with various thermal histories.

scholarly journals Thermal Stability of Rare Earth-PYSZ Thermal Barrier Coating with High-Resolution Transmission Electron Microscopy

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1206
Author(s):  
Savisha Mahalingam ◽  
Abreeza Manap ◽  
Salmi Mohd Yunus ◽  
Nurfanizan Afandi
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Transmission Electron ◽  
Α Al2o3

Durability of a thermal barrier coating (TBC) depends strongly on the type of mixed oxide in the thermally grown oxide (TGO) of a TBC. This study aims on discovering the effect of thermal stability in the TGO area containing mixed oxides. Two different bondcoats were studied using high-resolution transmission electron microscopy: high-velocity oxygen fuel (HVOF) and air-plasma spray (APS), under isothermal and thermal cyclic tests at 1400 °C. The HVOF bondcoats were intact until 1079 cycles. In comparison, APS failed at the early stage of thermal cycling at 10 cycles. The phase transformation of topcoat from tetragonal to the undesired monoclinic was observed, leading to TBC failure. The results showed that the presence of transient aluminas found in HVOF bondcoat helps in the slow growth of α-Al2O3. In contrast, the APS bondcoat does not contain transient aluminas and transforms quickly to α-Al2O3 along with spinel and other oxides. This fast growth of mixed oxides causes stress at the interface (topcoat and TGO) and severely affects the TBC durability leading to early failure. Therefore, the mixed oxide with transient aluminas slows down the quick transformation into alpha-aluminas, which provides high thermal stability for a high TBC durability.

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