Characterization of Electroplated Platinum-Iridium Alloys on the Nickel-Base Single Crystal Superalloy

As a high temperature protective layer, platinum-iridium alloys were electroplated on the nickel-base single crystal superalloy TMS-82+ from amidosulfuric acid solutions by the direct current method. It was found that Ir content in the films was always lower than the ratio of concentration ([Ir 3 + ]/([PtCl 6 2 - ] + [Ir 3 + ])) in the electrolytes, indicating that preferential deposition of Pt occurred in this study. The as-deposited Pt-Ir films formed an fee single phase structure with a granular surface. When Ir content exceeded 3 at%, Pt-Ir films exhibited the (111) preferred growth orientation. It was also found that pre-deposition of Ni and Pt promoted the deposition rate and changed composition of overlaying Pt-lr films.