Microstructural stability of nanostructured YSZ–alumina composite TBC compared to conventional YSZ coatings by means of oxidation and hot corrosion tests

•This work aims to investigate oxidation and hot corrosion of nano YSZ+Al2O3 coating to normal YSZ.•Nano composite coating showed a better oxidation and hot corrosion resistance than normal one.•Bond strength test during which nano YSZ+Al2O3 composite coating showed a better performance.•This research is novel and has not been reported before. The spallation of ceramic coating from the bond coat is important problem for TBC systems. And the spallation is caused the oxidation and corrosion at the interface of ceramic layer and bond coat. In this research the stability of conventional YSZ coating was compared to the particulate nanostructured YSZ+alumina composite coating by means of oxidation and hot corrosion tests. The coatings have been deposited by plasma spray method. High temperature oxidation test at 1100°C and hot corrosion test at 1050°C using Na2SO4 and V2O5 molten salts were performed on the coatings. The experimental results showed nanostructured YSZ+Al2O3 composite coating had higher oxidation and hot corrosion resistance than those of the conventional YSZ coating. The microstructural analysis indicated that the growth of TGO was much less for this nanostructured composite coating while it reduced infiltration of both oxygen and aggressive molten salt.