The effects of coating thickness on the delamination and fracture behavior of thermal barrier coating (TBC) systems were investigated with cyclic flame thermal fatigue (FTF) and thermal shock (TS) tests. The top and bond coats of the TBCs were prepared by electron beam-physical vapor deposition and low pressure plasma spray methods, respectively, with a thickness ratio of 2:1 in the top and bond coats. The thicknesses of the top coat were 200 and 500 μm, and those of the bond coat were 100 and 250 μm. FTF tests were performed until 1140 cycles at a surface temperature of 1100 oC for a dwell time of 5 min. TS tests were also done until more than 50 % delamination or 1140 cycles with a dwell time of 60 min. After the FTF for 1140 cycles, the interface microstructures of each TBC exhibited a sound condition without cracking or delamination. In the TS, the TBCs of 200 and 500 μm were fully delaminated (> 50 %) within 171 and 440 cycles, respectively. These results enabled us to control the thickness of TBC systems and to propose an efficient coating in protecting the substrate in cyclic thermal exposure environments.

1. Introduction
 2. Experimental Procedure
  2.1 Preparation of TBC specimens
  2.2 Characterization
  2.3 Thermal fatigue and thermal-shock tests
 3. Results and Discussion
  3.1 Microstructure of as-prepared TBCs
  3.2 Lifetime of TBC systems
  3.3 Mechanical properties
 4. Conclusions
 Acknowledgement
 Reference

• Zhe Lu(School of Nano & Advanced Materials Engineering, Changwon National University, Changwon, Gyeongnam 641-773, Korea)
• Seoung Soo(School of Nano & Advanced Materials Engineering, Changwon National University, Changwon, Gyeongnam 641-773, Korea)
• Je-Hyun Lee(School of Nano & Advanced Materials Engineering, Changwon National University, Changwon, Gyeongnam 641-773, Korea)
• Yeon-Gil Jung(School of Nano & Advanced Materials Engineering, Changwon National University, Changwon, Gyeongnam 641-773, Korea) Corresponding author