Corrosion behavior of air plasma spraying zirconia-based thermal barrier coatings subject to Calcium–Magnesium–Aluminum-Silicate (CMAS) via burner rig test.

Three different kinds of thermal barrier coatings (TBCs) — 8YSZ, 38YSZ and a dual-layered (DL) TBCs with pure Y 2 O 3 on the top of 8YSZ were produced on nickel-based superalloy substrate by air plasma spraying (APS). The Calcium–Magnesium–Aluminum-Silicate (CMAS) corrosion resistance of these three kinds of coatings were researched via burner rig test at 1350 °C for different durations. The microstructures and phase compositions of the coatings were characterized by SEM, EDS and XRD. With the increase of Y content, TBCs exhibit better performance against CMAS corrosion. The corrosion resistance against CMAS of different TBCs in descending was 8YSZ + Y 2 O 3 , 38YSZ and 8YSZ, respectively. YSZ diffused from TBCs into the CMAS, and formed Y-lean ZrO 2 in TBCs because of the higher diffusion rate and solubility of Y3+ in CMAS than Zr4+. At the same time, 38YSZ/8YSZ + Y 2 O 3 reacts with CAMS to form Ca 4 Y 6 (SiO 4) 6 O/Y 4·67 (SiO 4) 3 O with dense structure, which can prevent further infiltration of CMAS. The failure of 8YSZ coatings occurred at the interface between the ceramic coating and the thermally grown oxide scale (TGO)/bond coating. During the burner rig test, the Y 2 O 3 layer of the DL TBCs peeled off progressively and the 8YSZ layer exposed gradually. DL coatings keep roughly intact and did not meet the failure criteria after 3 h test. 38YSZ coating was partially ablated, the overall thickness of the coating is thinned simultaneously after 2 h. Therefore, 8YSZ + Y 2 O 3 dual-layered coating is expected to be a CMAS corrosion-resistant TBC with practical properties. [ABSTRACT FROM AUTHOR]