COMPOSITIONAL DISTRIBUTION AND MECHANICAL PROPERTIES OF PLASMA SPRAYED ZrO_2- NiCoCrAlY GRADED COATING

In plasma sprayed ZrO₂ NiCoCrAlY graded coating, the amount of ZrO₂ increases gradually along the coating thickness from TC4 substrate to coating surface, while that of NiCoCrAlY changes oppositely, and the macro interface between ZrO₂ and NiCoCrAlY which exists in duplex coating is eliminated. With the increasing of the amount of ZrO₂, the density of ZrO₂ NiCoCrAlY composite coating decreases gradually, and the hardness decreases firstly and then improves ; the 60 vol% ZrO₂ Ni CoCrAlY coating has the lowest hardness, and the porosity in the rich NiCoCrAlY coatings is slightly lower than thaTin the rich ZrO₂ coating. The gradual distribution of composition improves the adherent strength of coating and the coherent strength between coating and substrate. The interface between coating and TC4 substrate is the weakest zone in the graded coating.