Modification of ceramic thermal spray deposit microstructures implementing in situ laser remelting

Yttria partially stabilized zirconia thermal barrier coatings (TBCs) are widely used to protect components of gas turbines against deterioration at high temperatures. Air plasma spray and laser irradiation processes are combined to improve properties of TBCs. An in situ laser remelting plasma-spraying technique, implementing in particular a diode laser, was performed. Results show that laser treatment may induce: ( I) no phase transition: the metastable tetragonal phase still remains the predominant phase after laser treatment; (2) a decrease of the pore network connectivity level for a laser energy density ranging from 1.7 to 1.9 J mm(-2). (3) the growth of fine dendritic structures (due to the rapid solidification), which could be interesting with regard to the improvement of the thermo-mechanical properties of the coating. (C) 2003 Elsevier Science B.V. All rights reserved.