Microstructural analysis of YSZ and YSZ/Al2O3 plasma sprayed thermal barrier coatings after high temperature oxidation

2008 ◽  
Vol 202 (14) ◽  
pp. 3233-3238 ◽  
Author(s):  
Mohsen Saremi ◽  
Abbas Afrasiabi ◽  
Akira Kobayashi
Author(s):  
Winston Soboyejo ◽  
Patrick Mensah ◽  
Ravinder Diwan

This paper presents the results of an experimental study of the high-temperature isothermal oxidation behavior and micro-structural evolution in plasma sprayed thermal barrier coatings (TBCs) at temperatures between 900 and 1200 °C. Two types of specimens were produced for testing. These include a standard and vertically cracked (VC) APS. High temperature oxidation has been carried out at 900, 1000, 1100 and 1200 °C. The experiments have been performed in air under isothermal conditions. At each temperature, the specimens are exposed for 25, 50, 75 and 100 hours. The corresponding microstructures and microchemistries of the TBC layers are then examined using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy EDS. Changes in the dimensions of the thermally grown oxide (TGO) layer are determined as functions of time and temperature. The evolution of bond coat microstructures/interdiffusion zones and thermally grown oxide (TGO) layers are compared in TBCs with standard (STD) and vertically cracked (VC) microstructures.


2012 ◽  
Vol 433-440 ◽  
pp. 315-318
Author(s):  
Seyid Fehmi Diltemiz ◽  
Melih Cemal Kushan

Thermal barrier coatings (TBCs) have been widely used by aero and land based gas turbines to protect hot section parts from oxidation and thermal loads. These coatings are generally consisting of multiple layers of coating (usually two) with each layer having a specific function. TBCs are generally deposited with air plasma spray (APS) or electron beam physical vapor deposition (EB-PVD) techniques. In this paper plasma sprayed TBCs were deposited on to 304 stainless steel substrates then ceramic surfaces were glazing with Nd-YAG laser. Metallographic examinations were applied to the samples to investigate microstructural changes in glazed ceramic layer. Both glazed and as-coated samples were subjected to oxidation tests to measure the high temperature oxidation resistance. The tests showed that, laser glazing is beneficial to oxidation resistance of TBCs. This improvement is attributed to sintering of zirconia layer which act as oxygen barrier and formed during glazing process.


2007 ◽  
Vol 46 (9-10) ◽  
pp. 483-491 ◽  
Author(s):  
V. E. Oliker ◽  
A. A. Pritulyak ◽  
V. L. Syrovatka ◽  
E. F. Grechishkin ◽  
T. Ya. Gridasova

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