Abstract
The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs) was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF) for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS) method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF) for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF) and low-pressure plasma spray (LPPS) methods showed a partial cracking (and/or delamination) and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50%) after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.
Highlights
Thermal barrier coatings (TBCs) have been applied to the hot components of engines because of the increasing demands for higher gas turbine engine performance
The cross-sectional microstructures of as-prepared thermal barrier coatings (TBCs) specimens are shown in Figure 2, indicating that Figure 2(A-1)–(C-1) are the microstructures of the TBCs with different bond coats prepared by the air-plasma spray (APS), high-velocity oxygen fuel (HVOF) and low-pressure plasma spray (LPPS) processes, respectively
The influences of bond coat species on the thermal fatigue behavior, especially on the thermal durability, of the top coat prepared by the APS were investigated through cyclic thermal exposure
Summary
Thermal barrier coatings (TBCs) have been applied to the hot components of engines because of the increasing demands for higher gas turbine engine performance. The TBCs can be considered as a three-layered material system, consisting of (1) a substrate (nickel- or cobalt-based superalloy); (2) an oxidation-resistant metallic bond coat (MCrAlY or a platinum aluminide coating); and (3) a ceramic top coating (6–8 wt % yttria-stabilized zirconia) deposited either by the air-plasma spray (APS) or electron beam–physical vapor deposition (EB–PVD) process. A thermal-spraying process, such as APS, twin wire-arc spraying, and high-velocity oxygen fuel (HVOF) spraying, is the most popular deposition technology from an economic point of view and involves many small particles being accelerated by the high-power plasma or combustion flow to form a coating layer. It is well known that many new techniques, such as solution-precursor plasma spraying and electron beam–directed vapor deposition, have exhibited increasing potential in improving the thermal durability of thermal barrier coating (TBC) systems [1,2,3,4]. The bond coat plays an important role in ensuring structural effectiveness and affording extra adhesion of the top coat to the substrate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
