The structure and high temperature corrosion performance of medium-thickness aluminide coatings on nickel-based superalloy GTD-111

摘要

Simple and Si-modified aluminide coatings having medium-thickness (40-60 μm) have been applied on the superalloy GTD-111 by a slurry technique. Hot corrosion and cyclic oxidation performance of the uncoated and the coated superalloy were investigated by exposing samples to a molten film of Na_2SO_4-40 %wt NaVO_3-10%wt NaCl at 780 ℃ and 1 h cyclic oxidation at 1100℃ in air, respectively. The presence of silicon in the aluminide structure increased the oxidation resistance by a factor of 1.7 times. In addition, a SiO_2-containing scale, which formed on the Si-containing coating surface, was stable during of the hot corrosion testing.