LAUSR

Abstract Corrosive attack of the molten 50 wt. % V2O5 + 50 wt.% Na2SO4 salt mixture has been comparably studied for the APS YSZ and LnMgAl11O19 (LnMA, Ln = Nd, Sm, Gd) thermal barrier coatings upon a 10 h anneal at 1100 °C in air. The YSZ coating suffered from a deepest infiltration of the molten salt along its thickness direction through the open and connected pores as well as inter-lamellae microcracks. A large number of newly formed voids were widely distributed in the YSZ coating due to the corrosion degradation followed by the t, t’ to m-ZrO2 phase transformation. While, a relative thin corrosion layer mainly consisting of α-Al2O3 and LnVO4 were present for the corroded LnMA coatings. The much reduced number of open pores and connected microcracks together with the rapid chemical reaction between the molten salt and LnMA coatings, especially for the NdMA coating, preventing further infiltration of the molten salt, was beneficial to mitigate further attacks to the inner coating at the expense of sacrificing a thinner top layer. The presences of amorphous phases were thought to further accelerate the corrosion reaction and strengthen such a corrosion protection mode for all the APS LnMA coatings.