Phase Transformation and Microstructure of Nanostructured Ni/Al2O3 Coating Deposited by Plasma Spraying

Nanostructured Ni/Al2O3 feedstock was prepared by chemical wrapping, spraying dry and gas protected sintering, and nanostructured coatings were deposited subsequently by plasma spraying. XRD, SEM and TEM were used to detect the phase and microstructure of the coatings. The great mass of α-Al2O3 was transferred into γ- Al2O3 during plasma spraying process. The Ni/Al2O3 coatings are composed of irregular fully deformed layers. The grain size of the coatings is about 100 nm. There are two states of Ni in the coatings, some of them form uniform thin layer which separate the adjacent Al2O3 phase, and the others form sphericity particle enveloped in Al2O3.