Effect of Zr/Dy on thermal corrosion resistant properties of NiCrAlY coatings

Dy or Zr doped NiCrAlY coatings were fabricated via arc ion plating technology on nickel-based single crystal superalloy. Thermal corrosion tests of NiCrAlY, NiCrAlYZr, and NiCrAlYDy coatings with 75 wt% Na2SO4 + 25 wt% NaCl mixed salt were conducted at 900 °C. The weight gain of the NiCrAlY, NiCrAlYZr, and NiCrAlYDy coating samples after 100 h of thermal corrosion was as follows: −11.32, 1.06 and −6.56 mg∙cm−2. The results indicated that the NiCrAlYZr coating exhibits superior thermal corrosion resistance compared to both NiCrAlY and Dy-doped NiCrAlY coatings due to the beneficial effects of Zr interacting with S and Cl, making it more effectively protect the hot components of aircraft engine from thermal corrosion. •Mass gain and corrosion behaviour results show that the NiCrAlYZr coating offers superior thermal corrosion resistance compared to both NiCrAlY and Dy-doped coatings.•Zr doping enhances S trapping and prevents chloride infiltration into deeper layers. It also inhibits Al2O3 alkaline dissolution and the formation of a porous oxide structure.•Dy doping enhances S immobilization by promoting α-Cr phase precipitation and forms AlDyO3 during initial thermal corrosion stages, which inhibits Al3+ ion diffusion, thus improving the coating's thermal corrosion resistance.