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Open AccessArticle

Damage Assessment and Fracture Resistance of Functionally Graded Advanced Thermal Barrier Coating Systems: Experimental and Analytical Modeling Approach

1
TECSIS Corporation, Ottawa, ON K2E 7L5, Canada
2
Structures, Materials Performance Laboratory, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
*
Author to whom correspondence should be addressed.
Coatings 2020, 10(5), 474; https://doi.org/10.3390/coatings10050474
Received: 20 March 2020 / Revised: 1 May 2020 / Accepted: 6 May 2020 / Published: 14 May 2020
(This article belongs to the Special Issue Erosion of Nanostructured Coatings)
Enhancement of stability, durability, and performance of thermal barrier coating (TBC) systems providing thermal insulation to aero-propulsion hot-section components is a pressing industrial need. An experimental program was undertaken with thermally cycled eight wt.% yttria stabilized zirconia (YSZ) TBC to examine the progressive and sequential physical damage and coating failure. A linear relation for parameterized thermally grown oxide (TGO) growth rate and crack length was evident when plotted against parameterized thermal cycling up to 430 cycles. An exponential function thereafter with the thermal cycling observed irrespective of coating processing. A phenomenological model for the TBC delamination is proposed based on TGO initiation, growth, and profile changes. An isostrain-based simplistic fracture mechanical model is presented and simulations carried out for functionally graded (FG) TBC systems to analyze the cracking instability and fracture resistance. A few realistic FG TBCs architectures were considered, exploiting the compositional, dimensional, and other parameters for simulations using the model. Normalized stress intensity factor, K1/K0 as an effective design parameter in evaluating the fracture resistance of the interfaces is proposed. The elastic modulus difference between adjacent FG layers showed stronger influence on K1/K0 than the layer thickness. Two advanced and promising TBC materials were also taken into consideration, namely gadolinium zirconate and lanthanum zirconate. Fracture resistance of both double layer and trilayer hybrid architectures were also simulated and analyzed. View Full-Text
Keywords: YSZ thermal barrier coating; damage modeling; crack; oxide growth; interface; stress intensity; gadolinium zirconate; lanthanum zirconate YSZ thermal barrier coating; damage modeling; crack; oxide growth; interface; stress intensity; gadolinium zirconate; lanthanum zirconate
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MDPI and ACS Style

Kumar, A.; Patnaik, P.C.; Chen, K. Damage Assessment and Fracture Resistance of Functionally Graded Advanced Thermal Barrier Coating Systems: Experimental and Analytical Modeling Approach. Coatings 2020, 10, 474. https://doi.org/10.3390/coatings10050474

AMA Style

Kumar A, Patnaik PC, Chen K. Damage Assessment and Fracture Resistance of Functionally Graded Advanced Thermal Barrier Coating Systems: Experimental and Analytical Modeling Approach. Coatings. 2020; 10(5):474. https://doi.org/10.3390/coatings10050474

Chicago/Turabian Style

Kumar, Amarnath; Patnaik, Prakash C.; Chen, Kuiying. 2020. "Damage Assessment and Fracture Resistance of Functionally Graded Advanced Thermal Barrier Coating Systems: Experimental and Analytical Modeling Approach" Coatings 10, no. 5: 474. https://doi.org/10.3390/coatings10050474

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