The oxidation performance of plasma-sprayed NiAl bond coat: Effect of Hf addition in bond coat and substrate

Abstract

NiAl bond coats with and without Hf addition (0.1 at%) were deposited on two types of superalloy substrates (i.e., DZ125L, no Hf, and DZ125, 0.51 at% Hf) using plasma spraying technique, and isothermally oxidized at 1150 ºC. It demonstrates that Hf addition in the bond coat is more effective than in the superalloy substrate for improving the bond coat oxidation resistance. In addition, though the substrate chemistry could affect the bond coat oxidation performance, this effect was very sensitive to the chemistry of the bond coat -obvious for the RE (reactive element)-free NiAl bond coat, but less obvious for the RE-containing bond coats (NiAlHf and NiCoCrAlY). Moreover, compared with the NiCoCrAlY bond coat, the NiAlHf bond coat showed significantly improved oxidation resistance, regardless of the substrate chemistry, suggesting that NiAlHf bond coat prepared by plasma spraying is a promising candidate for the thermal barrier coating application.

The mechanisms of controlling FCT life and failure mode of Ni-based EBPVD YSZ thermal barrier coatings via the effects of both substrate elements and reactive element doping

“…With these arguments in mind a corrected phase relationship would result from this estimate giving Equation (6) perfectly matches the fine-grained, multiphase oxide phase assemblage typically retrieved from those microsturtcures [56]. This hypothetical phase relationship from Eq.…”

“…Thus the dominant effect of Hf may possibly be undermined by the high Ti content in IN100 and not by the vanadium content of 1 wt%. Related oxidation experiments on a comparison system of Hf doped NiAl bond coats on vanadium-free substrate alloys containing 4.3 at% Ti are reported to show the formation of spinel phase insets either [56]. The results suggest that a high concentration of Ti is a crucial factor to limit the dominant role of Hf and to promote a cationruled transport mechanism in alumina.…”

Progress update on extending the durability of air plasma sprayed thermal barrier coatings

“…Minor reactive elements (REs) such as Y, La, Zr, and Hf (typically 0.2~0.6 wt. %) have been added to MCrAlY coatings to improve interfacial adhesion [173][174][175][176]. First, minor addition of REs can prevent the lateral growth of the scale in the alumina scale, which decreases the deformation of the oxide.…”

Research Progresses on Ceramic Materials of Thermal Barrier Coatings on Gas Turbine

“…Adding some noble metals into MCrAlY to modify its performances is the main current. The addition of Hf, Pt revealed significant improvement of oxidation resistance and thermal cycling resistance [6,19,20]. Cr 2 AlC with good oxidation resistance [21,22], CoCrAlY-TiB 2 with significantly enhanced anti-oxidation performance [23], CuAlNiCrFe with excellent oxidation and diffusion resistance [24], are regarded as promising new bond coat materials.…”