CMAS infiltration behavior of atmospheric plasma-sprayed thermal barrier coating with tailored pore structures

Abstract

The degradation of atmospheric plasma spraying (APS) thermal barrier coatings (TBCs) due to calcium-magnesium-alumina-silicate (CMAS) corrosion is considered as a critical issue. In present work, mitigation of CMAS infiltration of APS TBCs has been achieved by tailoring pore characteristics based on a novel APS structure regulation method, and its thermal conductivity, thermal shock lifetime and infiltration behavior were evaluated. The results revealed that the laminar pore distributed TBC formed by horizontally aligned porous embedded particle clusters (PEPC) showed longest thermal shock lifetime and lowest thermal conductivity. Characterization of CMAS corrosion suggested that whilst all the TBCs samples with different pore structures suffered corrosion by CMAS melt, the severity fluctuated greatly. Compared with randomly distributed PEPC areas, these horizontally aligned PEPC areas have a noticeable potential for restricting CMAS infiltration. This unique structure consumes a large amount of CMAS melt and creates anti-CMAS filling pores, thus improving the overall CMAS infiltration resistance of the coating. The alternating dense layers outside the porous layers also provide a layer-by-layer barrier to CMAS infiltration. This study emphasizes that the modulation of the pore structure of APS TBCs is a promising strategy to mitigate CMAS infiltration.