Improved hot corrosion resistance of Dy-Co-modified aluminide coating by pack cementation process on nickel base superalloys

摘要

Dy-Co-modified aluminide coating was deposited onto Ni-based superalloy DZ125 using pack cementation method. The microstructure and hot corrosion behavior of the coating were investigated. The results show that as-deposited coating has a two-layer structure. The outer layer of the coating is composed mainly of Al0.9Ni1.1 with dispersed Dy2Hf2O7. The mass gain of the coating is 0.23 mg/cm(2) after exposure to 75 wt.% Na2SO4 + 25 wt.% NaCl at 900 degrees C for 100 h. The corrosion product formed on the coating is characterized as Al2O3. Role of Dy in the improvement of the hot corrosion resistance has been discussed. (C) 2016 Elsevier Ltd. All rights reserved.