Abstract
Thermal barrier coatings (TBCs) prolong the durability of gas turbine engine components and enable them to operate at high temperature. Several degradation mechanisms limit the durability of TBCs during their service. Since the atmospheric plasma spray (APS) processed 7–8 wt.% yttria stabilized zirconia (YSZ) TBCs widely utilized for gas turbine applications are susceptible to erosion damage, this work aims to evaluate the influence of their porosity levels on erosion behavior. Eight different APS TBCs were produced from 3 different spray powders with porosity ranging from 14% to 24%. The as-deposited TBCs were examined by SEM analysis. A licensed software was used to quantify the different microstructural features. Mechanical properties of the as-deposited TBCs were evaluated using micro-indentation technique. The as-deposited TBCs were subjected to erosion tests at different angles of erodent impact and their erosion performance was evaluated. Based on the results, microstructure-mechanical property-erosion performance was correlated. Findings from this work provide new insights into the microstructural features desired for improved erosion performance of APS deposited YSZ TBCs.
Highlights
Thermal barrier coatings (TBCs) are vital in improving the efficiency and durability of gas turbine engine components used in the hot sections [1]
The erosion performance of electron beam physical vapor deposition (EB-PVD) coatings has been reported to be superior to lamellar structured atmospheric plasma spray (APS) TBCs due to their columnar microstructure and column gaps, which localize the erosion damage within the column [14,15]
The relatively more aggressive erosion test parameters were chosen in the present study to achieve test conditions closer to those experienced in a gas turbine engine, i.e., high erodent velocity
Summary
Thermal barrier coatings (TBCs) are vital in improving the efficiency and durability of gas turbine engine components used in the hot sections [1]. During the TBC service lifetime, degradation mechanisms such as molten salt infiltration (hot corrosion) [2], CMAS infiltration [3], thermal cyclic fatigue [4], sintering induced stiffening [5], erosion [6,7], phase instability [8], etc., limit their longevity [9]. Apart from the above damage mechanisms, erosion can lead to significant loss of TBC material and result in premature failure in both land-based and certain aero-engine gas turbines. The erosion performance of EB-PVD coatings has been reported to be superior to lamellar structured APS TBCs due to their columnar microstructure and column gaps, which localize the erosion damage within the column [14,15].
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