Microstructure and Mechanical Properties of Yttria Partially Stabilized Zirconia Coatings Deposited by Laser-Assisted Air Plasma Spraying

In laser-assisted air plasma spraying (LAAPS), a laser beam interacts simultaneously with the coating surface during plasma spraying in order to increase the coating surface temperature and possibly remelt the coating surface. As a result, the microstructure is partially densified and macrocracks can be inhibited. In this paper, LAAPS was performed to improve the mechanical properties of ZrO₂ – 8 wt.% Y₂O₃ coatings. The coating microstructure was characterized by optical microscopy, SEM and X-ray diffraction. The mechanical characterization was done by hardness measurements, thermal shock resistance and erosive wear tests. Results showed that laser assistance may induce: (1) a decrease of the amount of microcracks and interlamellar pores, (2) a columnar dendritic structure in the coating splats and (3) an improvement of the thermal shock resistance. LAAPS did not affect the hardness or the erosive wear resistance of yttria partially stabilized zirconia coatings.