Thermal Fracture Mechanisms in Plasma Sprayed Thermal Barrier Coatings under Cyclic Laser Irradiation

2009 ◽  
pp. 193-193-15
Author(s):  
X. Q. Ma ◽  
M. Takemoto
Keyword(s):  
Laser Irradiation ◽  
Thermal Barrier Coatings ◽  
Fracture Mechanisms ◽  
Thermal Barrier ◽  
Thermal Fracture ◽  
Barrier Coatings ◽  
Plasma Sprayed

scholarly journals Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

2019 ◽  
Vol 28 (8) ◽  
pp. 1881-1892 ◽  
Author(s):  
Jayaprakash Krishnasamy ◽  
Sathiskumar A. Ponnusami ◽  
Sergio Turteltaub ◽  
Sybrand van der Zwaag
Keyword(s):  
Thermal Barrier Coatings ◽  
Volume Fraction ◽  
Crack Nucleation ◽  
Thermal Barrier ◽  
Multiscale Approach ◽  
Thermal Fracture ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Fracture Properties ◽  
Plasma Sprayed

Abstract The effect of splat interfaces on the fracture behavior of air plasma-sprayed thermal barrier coatings (APS-TBC) is analyzed using finite element modeling involving cohesive elements. A multiscale approach is adopted in which the explicitly resolved top coat microstructural features are embedded in a larger domain. Within the computational cell, splat interfaces are modeled as being located on a sinusoidal interface in combination with a random distribution of pores. Parametric studies are conducted for different splat interface waviness, spacing, pore volume fraction and fracture properties of the splat interface. The results are quantified in terms of crack nucleation temperature and total microcrack length. It is found that the amount of cracking in TBCs actually decreases with increased porosity up to a critical volume fraction. In contrast, the presence of splats is always detrimental to the TBC performance. This detrimental effect is reduced for the splat interfaces with high waviness and spacing compared to those with low waviness and spacing. The crack initiation temperature was found to be linearly dependent on the normal fracture properties of the splat interface. Insights derived from the numerical results aid in engineering the microstructure of practical TBC systems for improved resistance against thermal fracture.

scholarly journals An image-based model for the sintering of air plasma sprayed thermal barrier coatings

2021 ◽  
Vol 206 ◽  
pp. 116649
Author(s):  
Xun Zhang ◽  
Alan C.F. Cocks ◽  
Yoshifumi Okajima ◽  
Kazuma Takeno ◽  
Taiji Torigoe
Keyword(s):  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Plasma Sprayed

NONDESTRUCTIVE IMPEDANCE SPECTROSCOPY EVALUATION OF THE BOND COAT OXIDATION IN THERMAL BARRIER COATINGS

2007 ◽  
Vol 14 (05) ◽  
pp. 935-943 ◽  
Author(s):  
L. YANG ◽  
Y. C. ZHOU ◽  
W. G. MAO ◽  
Q. X. LIU
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Equivalent Circuit Model ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Plasma Sprayed

In this paper, the impedance spectroscopy technique was employed to examine nondestructively the isothermal oxidation of air plasma sprayed (APS) thermal barrier coatings (TBCs) in air at 800°C. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were also used to characterize the microstructure evolution of TBCs. After oxidation, the thermally grown oxide (TGO), which was mainly composed of alumina as confirmed by EDX, formed at the upper ceramic coat/bond coat interface, the lower bond coat/substrate interface, and the bond coat. Impedance diagrams obtained from impedance measurements at room temperature were analyzed according to the equivalent circuit model proposed for the TBCs. Various observed electrical responses relating to the growth of oxides and the sintering of YSZ were explained by simulating the impedance spectra of the TBCs.

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