High temperature characteristics of Ir–Ta coated and aluminized Ni-base single crystal superalloys

Abstract

High temperature oxidation and hot corrosion properties of Ir-Ta coated and aluminized Ni-base superalloys are presented. An Ir-Ta binary alloy, proposed as a novel metallic bond coat material, was coated on a Ni-base single crystal superalloy TMS-75 using electron beam physical vapor deposition, followed by a conventional low activity Al pack cementation process. Cyclic oxidation tests and hot corrosion tests revealed that these Ir-Ta coated and aluminized specimens showed reasonably good oxidation and hot corrosion resistance. In addition, it was found that the formation of TCP phases is suppressed by the presence of the Ir -Ta enriched layer. These results indicated that the Ir-Ta alloy system is promising as a new metallic bond coat material for high temperature structural materials. q

Improvement of the Oxidation Resistance of the Single-Crystal Ni-Based TMS-82+ Superalloy by Ni–Al Coatings with/without the Diffusion Barrier

“…The coated specimens showed lower mass gains than those of the base superalloy. For example, after 200 h exposure in air, the mass gains for the specimens with/without the diffusion barrier were 6.0 and 5.0 g/m 2 , respectively, which was lower than those of the base superalloy (*6.9 g/m 2 ). An identical increase trend of mass gain was observed for the both coated specimens at the initial exposure period, however, the mass gain of the base superalloy was much higher.…”

“…Development of novel bond-coat materials is a key to improve the service life of TBCs of next-generation gas turbines and jet engines. Generally, simple Al-pack cementation, PtAl or MCrAlY is used as a bond-coat material for preventing the internal oxidation of substrates [2][3][4]. However, the increase in operating temperature for current turbine systems has brought about serious problems, such as the acceleration of interdiffusion between the substrate and the bond-coat, which may promote the precipitation of detrimental phases in the substrate, and the rapid growth of a thermally grown oxide on the bond-coat surface.…”

“…In order to satisfy the application for 1300, 1500 and 1700°C-class gas turbines, continuous efforts have been made for improving the oxidation resistance of thermal barrier coatings (TBCs) of Ni-based superalloys. In the case of the TBCs, typical metallic bond-coat layers consists of Al-pack cementation, PtAl and MCrAlY (M=Co, Ni or NiCo) for preventing the internal oxidation of substrates, and Y 2 O 3 stabilized ZrO 2 is used as a top-coat material for insulating heat conduction [2]. In commercial engines, the high-pressure turbine blades and vanes exposed to hot gases experience metal surface temperatures of about 1000°C which leads to some serious problems for both the bond-coat and top-coat layers and the service life of TBCs is shortened.…”

Hot Corrosion Behavior of Co–Al–W Superalloys with Si Additions

“…Numerous efforts were made to improve mechanical strength at high temperatures and to achieve better oxidation and hot corrosion resistance [21][22][23][24][25]. Gao found that the hot corrosion resistance of Co-Ni-Al-W-Cr alloys varied with variations in Ni content.…”

The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy

“…The TBCs are typically two-layered, metallic bond-coat layer consists of Al-pack cementation, b-Ni(Pt)Al and MCrAlY (M = Co, Ni or NiCo) for preventing the internal oxidation of substrate, and Y 2 O 3 stabilized ZrO 2 is used as a ceramic topcoat material for insulating heat conduction [2]. The TBCs and its degradation modes are usually divided into two groups.…”