Yttria partially stabilized Zirconia (Y-PSZ) thermal barrier coatings (TBCs) have numerous applications as insulation layers onto gas turbine components. The main function of TBC is to enhance efficiency by increasing working temperature. These coatings are commonly manufactured using air plasma spraying. The characteristics of TBCs strongly depends on their pore and crack network architecture. Engineering the coating architecture by an adapted process is a prerequisite to modify TBC characteristics. Therefore, air plasma spray and in situ laser irradiation by diode laser processes were combined in this study to modify structural characteristics of TBCs. The coatings were remelted layer by layer during their deposition or alternately (i.e., an as-sprayed layer followed by an in situ remelted layer). This process was named MELTPRO. TBC apparent thermal conductivity was quantified implementing numerical computations based on 2-D real discrete structures. Coating thermal properties were correlated to their pore network architecture characteristics quantified by image analysis (i.e., nature, orientation, percentage, etc.). Moreover, thermal annealing at 1100°C were performed to compare sintering phenomenon of manufactured TBCs. Results show that the MELTPRO process permits: (i) to modify of the pore network architecture of as-sprayed TBCs. The porosity level increases by the in situ remelting process due to the formation of large horizontal cracks (as shown by image analysis). These horizontal cracks behave as thermal resistances and are responsible for the decrease of the coating thermal conductivity of about 30 % compared to the as-sprayed ones; (ii) to architecture differently the pore network for a constant thermal conductivity, because thermal conductivity and porosity level are not explicitly correlated; (iii) to improve the thermal insulation which remains unchanged after thermal annealing treatments: this seems to be due to the fact that the large cracks of remelted TBCs are less sensitive to sintering than inter and intra lamellar cracks of as-sprayed TBCs.

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