The Role of Nanostructured Al2O3 Layer in Reduction of Hot Corrosion Products in Normal YSZ Layer

YVO 4 crystals and monoclinic ZrO 2 are known as hot corrosion products that can considerably reduce the lifetime of thermal barrier coatings during service. The hot corrosion resistance of two types of air plasma sprayed thermal barrier coating systems was investigated: an Inconel 738/NiCrAlY/YSZ (yttria‐stabilized zirconia) and an Inconel 738/NiCrAlY/YSZ/nano‐Al 2 O 3 as an outer layer. Hot corrosion test was accomplished on the outer surface of coatings in molten salts (45% Na 2 SO 4 + 55% V 2 O 5 ) at 1000°C for 52 hour. It was found that nanostructured alumina as outer layer of YSZ/nano‐Al 2 O 3 coating had significantly reduced the infiltration of molten salts into the YSZ layer and resulted in lower reaction of fused corrosive salts with YSZ, as the hot corrosion products had been substantially decreased in YSZ/nano‐Al 2 O 3 coating in comparison with normal YSZ coating after hot corrosion process.