scholarly journals Proposal of Residual Stress Evaluation Method for Ceramic Thermal Barrier Coatings in Consideration of Plasma-Spray Condition

2011 ◽  
Vol 60 (2) ◽  
pp. 153-158
Author(s):  
Masayuki ARAI
Keyword(s):  
Residual Stress ◽  
Thermal Barrier Coatings ◽  
Plasma Spray ◽  
Evaluation Method ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Stress Evaluation

Engineered thermal barrier coatings deposited by suspension plasma spray

2017 ◽  
Vol 209 ◽  
pp. 517-521 ◽  
Author(s):  
Satyapal Mahade ◽  
Nicholas Curry ◽  
Stefan Björklund ◽  
Nicolaie Markocsan ◽  
Per Nylén
Keyword(s):  
Thermal Barrier Coatings ◽  
Plasma Spray ◽  
Suspension Plasma Spray ◽  
Thermal Barrier ◽  
Barrier Coatings

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.

scholarly journals Nondestructive Evaluation of Thermal Barrier Coatings Interface Delamination Using Terahertz Technique Combined with SWT-PCA-GA-BP Algorithm

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 859
Author(s):  
Dongdong Ye ◽  
Weize Wang ◽  
Changdong Yin ◽  
Zhou Xu ◽  
Huanjie Fang ◽  
...  
Keyword(s):  
Neural Network ◽  
Thermal Barrier Coatings ◽  
Time Domain ◽  
Evaluation Method ◽  
Structural Integrity ◽  
Early Stage ◽  
Percentage Error ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Interface Delamination

Thermal barrier coatings (TBCs) are usually subjected to the combined action of compressive stress, tensile stress, and bending shear stress, resulting in the interfacial delamination of TBCs, and finally causing the ceramic top coat to peel off. Hence, it is vital to detect the early-stage subcritical delamination cracks. In this study, a novel hybrid artificial neural network combined with the terahertz nondestructive technology was presented to predict the thickness of interface delamination in the early stage. The finite difference time domain (FDTD) algorithm was used to obtain the raw terahertz time-domain signals of 32 TBCs samples with various thicknesses of interface delamination, not only that, the influence of roughness and the thickness of the ceramic top layer were considered comprehensively when modeling. The stationary wavelet transform (SWT) and principal component analysis (PCA) methods were employed to extract the signal features and reduce the data dimensions before modeling, to make the cumulative contribution rate reach 100%, the first 31 components of the SWT detail data was used as the input data during modeling. Finally, a back propagation (BP) neural network method optimized by the genetic algorithm (GA-BP) was proposed to set up the interface delamination thickness prediction model. As a result, the root correlation coefficient R2 reached over 0.95, the various errors—including the mean square error, mean squared percentage error, and mean absolute percentage error—were less than or equal to 0.53. All these indicators proved that the trained hybrid SWT-PCA-GA-BP model had excellent prediction performance and high accuracy. Finally, this work proposed a novel and convenient interface delamination evaluation method that could also be potentially utilized to evaluate the structural integrity of TBCs.

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