Effect of laser glazing on the thermo-mechanical properties of plasma-sprayed LaTi2Al9O19 thermal barrier coatings

Conventional duplex (DL) and functionally graded (FG) LaTi2Al9O19 (LTA) coatings were deposited over C263 nickel alloy by air plasma spray (APS) and compared with subsequent laser glazing processes. The effect of laser glazing on adhesion strength and thermal barrier performance was investigated. The thermal barrier effect was measured using the temperature difference technique involving infrared (IR) rapid heater and the adhesion strength was measured using the scratch tester. The surface morphology and microstructure were analyzed by optical microscopy (OM), Scanning Electron Microscope (SEM) and 3D profilometer. Based on the experimental results, the laser glazing showed a remarkable temperature drop after IR rapid heating. The changes in porosity and grain refinement make more contributions to the temperature drop of the laser-glazed coatings than that of as-sprayed coatings. The temperature drop is about 110 degrees C for laser-glazed LTA FG coating after 100s of IR flash, while the drop in DL as-sprayed coating is 60 degrees C compared to the base material.