Thermal fracture of zirconia–mullite composite thermal barrier coatings under thermal shock: A numerical study

2008 ◽  
Vol 203 (1-2) ◽  
pp. 91-98 ◽  
Author(s):  
Anna Gilbert ◽  
Klod Kokini ◽  
Santosh Sankarasubramanian
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Numerical Study ◽  
Thermal Barrier ◽  
Thermal Fracture ◽  
Barrier Coatings

Multiple Surface Cracking and Its Effect on Interface Cracks in Functionally Graded Thermal Barrier Coatings Under Thermal Shock

2003 ◽  
Vol 70 (2) ◽  
pp. 234-245 ◽  
Author(s):  
S. Rangaraj ◽  
K. Kokini
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Architectural Design ◽  
Effective Properties ◽  
Mean Field ◽  
Functionally Graded ◽  
Analytical Models ◽  
Thermal Barrier ◽  
Thermal Fracture ◽  
Barrier Coatings

The thermal fracture behavior in functionally graded yttria stabilized zirconia–NiCoCrAlY bond coat alloy thermal barrier coatings was studied using analytical models. The response of three coating architectures of similar thermal resistance to laser thermal shock tests was considered. Mean field micromechanics models were used to predict the effective thermoelastic and time-dependent (viscoplastic) properties of the individual layers of the graded thermal barrier coatings (TBCs). These effective properties were then utilized in fracture mechanics analyses to study the role of coating architecture on the initiation of surface cracks. The effect of the surface crack morphology and coating architecture on the propensity for propagation of horizontal delamination cracks was then assessed. The results of the analyses are correlated with previously reported experimental results. Potential implications of the findings on architectural design of these material systems for enhanced thermal fracture resistance are discussed.

A Study of Thermal Fracture in Functionally Graded Thermal Barrier Coatings Using a Cohesive Zone Model

2004 ◽  
Vol 126 (1) ◽  
pp. 103-115 ◽  
Author(s):  
Sudarshan Rangaraj ◽  
Klod Kokini
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Cohesive Zone ◽  
Functionally Graded ◽  
Systematic Evaluation ◽  
Thermal Barrier ◽  
Zone Model ◽  
Thermal Fracture ◽  
Barrier Coatings ◽  
Separation Relation

This work describes the application of two-dimensional finite element models with a cohesive zone to study quasi-static crack extension in functionally graded Yttria stabilized Zirconia (YSZ)-Bond Coat (BC) alloy (NiCoCrAlY) thermal barrier coatings (TBC). Crack growth under a single heating-cooling cycle simulating a laser thermal shock experiment is considered. The traction-separation relations for YSZ and BC alloy are coupled to yield a traction-separation relation for the individual layers of the graded TBC. Results from laser thermal shock experiments are then used for a systematic evaluation of the material properties in this traction-separation relation. The effective work of separation for YSZ-BC alloy composites, which is indicative of the material’s fracture toughness, is then computed. The model is then used to predict the surface thermal fracture response in a graded TBC having an architecture different from the coatings that were used to evaluate the cohesive properties. These model predictions are then compared with results from laser thermal shock experiments.

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.

Vacuum Plasma Sprayed ZrO2-Based Thermal Barrier Coatings for Aerospace Applications

1998 ◽  
Author(s):  
T. Brzezinski ◽  
A. Cavasin ◽  
S. Grenier ◽  
E. Kharlanova ◽  
G. Kim ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Temperature Drop ◽  
Single Step ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Vacuum Plasma Spray ◽  
Barrier Coatings ◽  
Vacuum Plasma ◽  
Plasma Sprayed

Abstract Zirconia-based thermal barrier coatings (TBCs), produced using Vacuum Plasma Spray (VPS) technology, were recently subjected to burner rig testing. The VPS TBC performance was compared to TBCs deposited using conventional Atmospheric Plasma Sprayed (APS) and Electron Beam Physical Vapor Deposition (EB-PVD) techniques. All of the coatings consisted of an MCrAlY bond coat and a partially stabilized ZrO2-8%Y2O3 (PSZ) top coat. The TBC coated pins (6.35 mm in diameter) were tested using gas temperatures ranging from 110CC to 1500°C. The pins were tested to failure under severe conditions (1500°C gas temperature, with no internal cooling). The initial testing indicated that under typical operating gas temperatures (1400°C), the VPS TBC performance was comparable, if not superior, to conventional TBCs. Following the encouraging results, thick composite TBCs, produced in a single-step operation, were investigated. Preliminary work on ZrO2-8% Y2O3/Ca2SiO4 composite TBCs with interlayer grading included thermal shock testing and temperature drop measurements across the TBC. The composite TBC thicknesses ranged from 850µm to 1.8 mm. Initial results indicate that thick adherent composite TBCs, with high resistance to severe thermal shock, can be produced in a single step using the VPS process.

Thermal Shock Resistance of APS 8YSZ Thermal Barrier Coatings on Titanium Alloy

2011 ◽  
Vol 21 (2) ◽  
pp. 335-343 ◽  
Author(s):  
Shuibing Zeng ◽  
Yangjia Liu ◽  
Xizhi Fan ◽  
Wenzhi Huang ◽  
Lijian Gu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Thermal Shock Resistance ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Shock Resistance
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