In order to investigate the hot corrosion behavior of the commonly-used bond coats for thermal barrier coating system

four typical bond coats (i.e.

plain NiAl coating

NiCoCrAlY coating

Pt modified NiAl coating and Pt+Hf co-modified NiAl coating) were comparably evaluated in the mixed salts of Na2SO4/NaCl (mass fraction 75%∶25%) at 900℃. The phase constitution evolution and microstructure change during hot corrosion were analyzed by scanning electron microscope (SEM)

electron probe micro-analyzer (EPMA) and X–ray diffractometer (XRD). The results showed that plain NiAl coating degrades fastest during hot corrosion test. In contrast

the degradation rate of NiCoCrAlY coating is slower. The hot corrosion resistance of the two modified NiAl coatings is satisfactory

Pt modified NiAl is the best among the four coatings. It seems that the addition of Hf does not benefit the hot corrosion resistance of Pt–Al coating.