Microstructural design and properties of supersonic suspension plasma sprayed thermal barrier coatings

In the present work, one new technique named as supersonic suspension plasma spraying (SSPS) is employed to fabricate high-performance yttria-stabilized zirconia (YSZ) based thermal barrier coatings (TBCs). The typical microstructures, such as vertical-cracked and columnar-structured coatings, were tailored by controlling the key spray parameters. The process-microstructure-property relationship of SPPS-coating was investigated. It was found that the deposition rate was significantly improved by reducing the stand-off distance or increasing the solid content and spray power. The columnar structured coating exhibited the longest thermal cycling life at 1300 degrees C, which was approximately 7 times longer than that of coating with wide vertical cracks. Both the simulation and experimental results showed that the failure of SPPS-coating occurred near the top coat/bond coat interface. However, the failure modes were largely dependent on its microstructure. For the coating with wide vertical cracks, the oxidation of bond coat was the main reason that caused its spallation, while the failure of columnar structured coating was attributed to the accumulation of sintering stress. (C) 2016 Elsevier B.V. All rights reserved.