Foreign Object Damage (FOD) of Ceramic Thermal Barrier Coatings (TBCs) in Gas Turbine Airfoils

2013 ◽  
Author(s):  
Jennifer M. Wright ◽  
D. Calvin Faucett ◽  
Matthew Ayre ◽  
Sung R. Choi
Keyword(s):  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Foreign Object ◽  
Remaining Life ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Foreign Object Damage ◽  
Turbine Airfoils ◽  
Energy Balance Approach ◽  
Vapor Deposit

Ceramic thermal barrier coatings (TBCs), attributed to their inherent brittle nature, are highly susceptible to damage by impacting foreign particles when the impacting kinetic energy exceeds certain limits. The damage is termed foreign object damage (FOD) in related turbine components and results in various issues/problems to coatings as well as to substrates from delamination to spallation to cracking to catastrophic failure depending on the severity of impact. The FOD testing was performed using a ballistic impact gun for turbine airfoil components coated with 7% yittria stabilized zirconia (7YSZ) by electron beam physical vapor deposit (EB-PVD). A range of impact velocities up to Mach 1 was applied with three different projectile materials of steel, silicon nitride, and glass balls. The damage was assessed and characterized in terms of impact velocity, projectile material, and remaining life of turbine components. An energy-balance approach was made to develop a model to predict delamination of the TBCs upon impact.

Phenomena of Foreign Object Damage by Spherical Projectiles in EB-PVD Thermal Barrier Coatings of Turbine Airfoils

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Sung R. Choi ◽  
Jennifer M. Wright ◽  
D. Calvin Faucett ◽  
Matthew Ayre
Keyword(s):  
Thermal Barrier Coatings ◽  
Order Approximation ◽  
Crack Size ◽  
Thermal Barrier ◽  
Foreign Object ◽  
Barrier Coatings ◽  
Foreign Object Damage ◽  
First Order Approximation ◽  
Turbine Airfoils ◽  
Energy Balance Approach

Thermal barrier coatings (TBCs), attributed to their inherent brittleness, are vulnerable to damage by impacting foreign objects when kinetic energy of the objects surpasses certain limits. The damage is termed foreign object damage (FOD) and results in various issues to coatings as well as to substrates, from plastic impression to delamination to spallation to cracking, depending on the severity of impact. The FOD experiments were conducted utilizing a ballistic impact gun for vane airfoil components coated with 220 μm-thick, 7% yttria–stabilized zirconia (7YSZ) by electron beam physical vapor deposit (EB-PVD). The testing was performed with impact velocities ranging from 150 m/s to Mach 1 using 1.6-mm hardened chrome-steel ball projectiles. The resulting FOD was in the forms of impact impressions, cone cracking, and delamination of the coatings/substrates. Prediction of delamination crack size as a function of impact velocity was made based on an energy-balance approach through a quasistatic, first-order approximation. The prediction was in reasonable agreement with experimental data considering a presumable compaction of the TBCs upon impact.

Time-Dependent Behavior and Fracture of Functionally Graded Thermal Barrier Coatings under Thermal Shock

2005 ◽  
Vol 492-493 ◽  
pp. 379-384 ◽  
Author(s):  
Klod Kokini ◽  
Sudarshan V. Rangaraj
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Functionally Graded ◽  
Yttria Stabilized Zirconia ◽  
Time Dependent ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Dependent Behavior ◽  
Bond Coat Alloy

The thermal fracture and its dependence on time-dependent behavior in functionally graded yttria stabilized zirconia - NiCoCrAlY bond coat alloy thermal barrier coatings was studied. The response of three coating architectures of similar thermal resistance to laser thermal shock tests was considered, experimentally and computationally.

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