Study On Preparation And Properties Of Plasma Sprayed Ternary Nanometer Thermal Barrier Coatings Of YSZ

In order to adapt the even worse working environment, a new type of thermal barrier coatings doped additive become one of hot researches due to their large potential about lower thermal conductivity of coating and high thermal shock performance. In this paper, different content of nano-La2O3 and nano-NbO5 powder were doped in the nano-ZrO2-8wt%Y2O3, then be agglomerated by spray drying process and subjected thermal pretratment to use for insulation top material, NiCrAlY alloy was used to bond coating material. Nano-ZrO2-Y2O3-MxOy thermal barrier coating and nano-YSZ coating were prepared by air plasma spray. Studied the properties of particals adding oxide and the influence of the microstructure after subjecting thermal pretratment; microstructured characteristics of different coatings were compared and tested some capabilities; the insulation capability of coatings were tested under the same edge conditions, and analyzed the insulation mechanics; the coating capability at high temperature condition was studied by thermal shock-resistance test.The results showed that the nano structured thermal barrier coatings could be prepared by air plasma spray by nanometer agglomerated powder. The reunion particas with nanostructured adapt to air plasma spray; adoping oxide did not affect the microstructures and phase morphology of the reunion particles; there were two types of microstructure in thermal barrier coating, which is nanostructure and microsructure; phases composition of as-sprayed coatings was tetragonal phase, without moclinic phase, which was attributed to the rapid cooling velocity that prevent from the transition of tetragonal phase to moclinic phase; the morphologies and distribution of the microcracks were favorable in the coating, and both composed by nonsplat-structure and splat-structure which were the typical structures of coating preparing by air plasma spray.At the performance of the heat property, the thermal conductivity of coating reduce with the temperature up, the thermal conductivity of doping coating was lower than nano-YSZ coating, it could conclude that coating doped equal La2O3,Nb2O5 could reduce the thermal conductivity; under the same edge conditions, the doping nano-coating had better heat-shielding capacity than nano-YSZ coating; the result of the thermal shock-resistance test revealed that the perfomance of thermal shock was depressed by the coating doped La2O3 and Nb2O5, but the thermal barrier coatings were prepared by air plasma spray also had well thermal shock-resistance capacity; the adhesive strength of coating which doped equal La2O3 was higher than non-doped coating, and improved with the increase of La2O3; but the adhesive strength of coating which doped Nb2O5 was lower than nano-YSZ coating.