Residual stress measurement of thermal barrier coatings using laser fluorescence technique and their life prediction

2002 ◽  
Author(s):  
E.H. Jordan ◽  
Y.H. Sohn ◽  
W. Xie ◽  
M. Gell ◽  
L. Xie ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Barrier Coatings ◽  
Life Prediction ◽  
Stress Measurement ◽  
Laser Fluorescence ◽  
Residual Stress Measurement ◽  
Thermal Barrier ◽  
Fluorescence Technique ◽  
Barrier Coatings

scholarly journals Bond Strength and Stress Measurements in Thermal Barrier Coatings

1997 ◽  
Author(s):  
Eric H. Jordan ◽  
Maurice Gell ◽  
Doug M. Pease ◽  
Leon Shaw ◽  
David R. Clarke ◽  
...  
Keyword(s):  
Bond Strength ◽  
Thermal Barrier Coatings ◽  
Stress Measurement ◽  
Laser Fluorescence ◽  
Thermal Barrier ◽  
Thermal Cycles ◽  
Strength Measurement ◽  
Barrier Coatings ◽  
Chevron Notch ◽  
Pull Testing

The failure mode for thermal barrier coatings in gas turbine engines is spallation at or near the ceramic to metal interface. We propose that the two most important factors leading to this failure are the change in the bond strength and bond stress with cycling. Five methods of measuring stress near the ceramic bond coat interface and four methods of bond strength measurement were investigated. Laser fluorescence and enhanced laboratory x-ray methods have the most potential for stress measurement, while the promising bond strength measurement methods are direct pull testing, chevron notch fracture toughness, and laser induced ultrasonic spallation. The stress and strength as a function of thermal cycles was determined for one set of yttria stabilized zirconia coated single crystal samples. Both a decreasing residual compression stress in the oxide layer that joins the ceramic to the metal and a decreasing bond strength were measured as a function of thermal cycles.

scholarly journals Analytical and Experimental Study of Residual Stresses in Thermal Barrier Coatings Deposited on Gas Turbine Blades in Laboratory Dimensions by APS and HVOF Methods to Calculate the Optimal Thickness

2021 ◽  
Vol 3 (1) ◽  
pp. 63-67
Author(s):  
Esmaeil Poursaeidi ◽  
◽  
Farzam Montakhabi ◽  
Javad Rahimi ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Analytical Model ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Optimal Thickness ◽  
Barrier Coatings

The constant need to use gas turbines has led to the need to increase turbines' inlet temperature. When the temperature reaches a level higher than the material's tolerance, phenomena such as creep, changes in mechanical properties, oxidation, and corrosion occur at high speeds, which affects the life of the metal material. Nowadays, operation at high temperatures is made possible by proceedings such as cooling and thermal insulation by thermal barrier coatings (TBCs). The method of applying thermal barrier coatings on the turbine blade creates residual stresses. In this study, residual stresses in thermal barrier coatings applied by APS and HVOF methods are compared by Tsui–Clyne analytical model and XRD test. The analytical model results are in good agreement with the experimental results (between 2 and 8% error), and the HVOF spray method creates less residual stress than APS. In the end, an optimal thickness for the coating is calculated to minimize residual stress at the interface between the bond coat and top coat layers.

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