Preparation and Solid Particle Erosion Behaviors of Plasma-Sprayed and Laser-Remelted ZrO2-7wt.%Y2O3 Thermal Barrier Coatings

In this study, ZrO2-7wt.%Y2O3 thermal barrier coatings (TBCs) were prepared on TiAl base intermetallic alloy substrates by plasma spraying process. After that, the plasma-sprayed TBCs were laser remelted using a CO2 laser. Influences of laser remelting on the microstructure and solid particle erosion characterization of the coatings were researched. Meanwhile, the erosion damage modes of the two types of TBCs were discussed. The results show that the as-sprayed TBC has a typical lamellar stacking characteristic. The lamellar defect of the plasma-sprayed coating is erased, and the compactness of the coating is improved significantly after laser remelting. The laser-remelted coating consists of column-like crystals along the direction of the heat current. The laser-remelted coating had better erosion resistance than the as-sprayed coating. Owing to the limited bonding at the interfaces between lamellar, the spalling of the sprayed splats from the lamellar interface is mainly attributed to the erosion failure of the as-sprayed coating. In addition, crushing of brittle ceramic coating is also responsible for the erosion damage of the plasma-sprayed TBC. In contrast, cracking occurs within region near the surface of the laser-remelted layer and that erosion occurs mainly by removal of these small blocks. Moreover, the laser-remelted has evident mciro-cutting marks and shows some ductile erosion characteristic.