Thermal cycling behavior and interfacial stability in thick thermal barrier coatings

• Published in: Surface & coatings technology 2010-11, Vol.205 (5), p.1250-1255
• Main Authors: Lee, Pyung-Ho, Lee, Sang-Yup, Kwon, Jae-Young, Myoung, Sang-Won, Lee, Je-Hyun, Jung, Yeon-Gil, Cho, Hyun, Paik, Ungyu
• Format: Article
• Language: English
• Subjects: Adhesive strength; Applied sciences; Coatings; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fracture mechanics; Fracture toughness; Hardness; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical property; Metals. Metallurgy; Microstructure; Nonmetallic coatings; Physics; Porosity; Production techniques; Spray gun; Surface treatment; Surface treatments; Thermal barrier coating; Thermal barrier coatings; Thermal cycling; Thermal cycling behavior; Thick coating
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2010.08.062

The thermal cycling behavior of thermal barrier coatings (TBCs), which were prepared by two different air-plasma spray (APS) guns of 9 MB and TriplexPro™-200, was investigated to understand the effects of the microstructure on the interfacial stability and fracture behavior of TBCs. The porosities of the top coats could be controlled by changing the gun, showing porosity of about 15% using the 9 MB and 19% using the TriplexPro™-200, which decreased slightly with thermal exposure. Defects, such as interlamellar cracks, vertical cracks, and intrasplat cracks, were freshly produced in both TBCs after thermal exposure, showing delamination in the case of 2000 μm TBCs prepared using the TriplexPro™-200. The adhesive strength values of TBCs with 600 and 2000 μm thicknesses were about 8 and 6 MPa, respectively, indicating that the adhesive strength values of TBCs were affected by the coating thickness, independent of the gun. The hardness values increased after thermal exposure, and the TBCs prepared using the TriplexPro™-200 showed higher values than those prepared using the 9 MB for both thicknesses. The toughness values were not dependent on the gun, only showing an effect from coating thickness. The increase in coating thickness enhanced the densification, resulting in higher hardness and toughness values, and the microstructure could be controlled by changing the gun.