Bond coatings with high rumpling resistance: Design and characterization

• γ' Ni3Al bond coats resist rumpling during cyclic oxidation tests to 1204 °C.
• Fourier transform of surface profile scan quantifies rumpling.
• γ' coating resist TGO spallation more than (Pt,Ni)Al despite faster oxidation.
• High strength and creep resistance of Ni3Al provides rumpling resistance.

The behavior of two new high-strength γ'-Ni3Al-base bond coats have been compared to a baseline β-(Pt,Ni)Al bond coat via thermal cycling to a maximum temperature of 1204 °C. The rumpling amplitude of the γ' coating is significantly lower than the (Pt,Ni)Al as characterized by a nondestructive optical profilometry technique. The γ' coatings resist rumpling and spallation of the thermally grown oxide in spite of faster oxidation compared to Pt-modified NiAl. This behavior is analyzed using an analytical rumpling model to explain that the improved bond coat strength is the major contributing factor to rumpling inhibition.