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6433 |
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Wednesday, June 10, 2020, Hall D 3:00 PM Aviation Industry II |
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The influence of plasma composition in the deposition efficiency, thermal conductivity, bond strength and thermal cyclic performance of yttria stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) |
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Bruno Guerreiro / NRC Boucherville, Canada Rogerio Lima* / National Research Council Canada, Canada Nicholas Curry/ Treibacher Industrie AG, Austria Matthias Leitner/ Treibacher Industrie AG, Austria Karl Körner / Treibacher Industrie AG, Austria |
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In the combustion chambers of gas turbine engines, 8YSZ TBCs are commonly applied by air plasma spray (APS) using Ar/H2 based plasmas via legacy torches. Alternatively, N2/H2 plasmas could be used with the potential of increasing overall deposition efficiency (DE), and hence reduce the consumption of high value feedstock powder. Also, by increasing DE, machine costs and spray time would be reduced. In this work, TBCs were prepared with Ar and N2 based plasmas with different 8YSZ powders using a legacy APS torch (Metco 9MB). The use of nitrogen based plasma resulted in higher particle temperature and lower particle velocity values than those provided by the Ar based plasma. The measured DEs for the powders were between 41-43 and 53-60% for the Ar and N2 based plasmas, respectively. This represents a ~40% increase in the DE. The coatings produced with the two different plasmas exhibited equivalent porosity levels ~11-13%. In general and for each powder, the YSZ TBCs prepared with the nitrogen based plasma exhibited lower thermal conductivity values than those of the Ar-based ones; at room and high temperatures (1200oC). Bond strength results of the as-sprayed coatings did not show a strong difference between plasma types used or powders tested. In the furnace cycle test (FCT), the performance of the TBCs prepared with the N2-based plasma was superior to that of the TBCs prepared with the Ar plasma, and always higher than an industrial APS TBC reference. |