Effect of laser-glazed treatment on thermal cyclic behavior of plasma-sprayed Lanthanum Zirconate/Yttria-stabilized Zirconia double ceramic layered on NiCoCrAlYTa-coated Inconel

Abstract

This paper investigates the thermal barrier coating (TBC) performance of La2Zr2O7/ZrO (2-8 wt.%) Y2O3 coatings (LZ/YSZ TBCs) deposited using atmospheric plasma spray (APS) over high velocity oxy-fuel (HVOF) NiCoCrAlYTa coated on Inconel 625. On the outermost surface of the double-layered coating, a laser glazing method was used to treat the TBC systems. Specifically, a Nd:YAG pulsed laser was used to change the surface layer of plasma-sprayed La2Zr2O7 top coatings. The study found that the laser glazing treatment resulted in a higher number of temperature cycles needed to generate 5-20% spallation of the top surface of coatings, with 100 cycles compared to 30 cycles in the as-sprayed coatings. This improvement in performance was attributed to the dense surface of the laser-glazed LZ topcoat, which led to a lower thermally grown oxide (TGO) layer growth rate and improved TBC lifetime. Furthermore, the strain adaptation through segmented cracks that were created by laser glazing may have contributed to the enhanced TBC performance.