Influence Of The Equimolar Substitution Of Gd₂O₃for Y₂O₃on The Structure And Properties Of Y₂O₃-Ta₂O₅-ZrO₂Ceramics

The ceramic coating of thermal barrier coatings was used to protect the metal base,which have a broad and significant pplication in the aviation, aerospace, automotive,large-scale thermal power generation and other aspects.This not only can improve corrosionresistance, but also improve gas turbine efficiency and the working temperature of engine hotcomponents.The widely used6⁸wt%Y₂O₃partially stabilized ZrO₂（6⁸YSZ） thermalbarrier coatings have many good characteristics, but it is more likely to occur t-m phasetransformation in the1443K. So （6⁸）YSZ have to work below the temperature of1443K. Ithas been not meeting the needs of future development. Therefore, it is important for thermalbarrier coating to develop novel ceramics material to alternative YSZ. In recent years,theTa₂O₅-Y₂O₃-ZrO₂ceramic materials of thermal barrier coatings is relatively superior to othernew type materials. The Ta₂O₅-Y₂O₃-ZrO₂material solely composed with tetragonal phase.The microstructure is homogeneous than that of YSZ. The thermal expansion coefficient ishigher than YSZ.The thermal conductivity is lower than YSZ. When the temperature isabove1500℃, the Ta₂O₅-Y₂O₃-ZrO₂material is also stable in the tetragonal phase. TheTa₂O₅-Y₂O₃-ZrO₂coating has light cirrosion when thermal cycled500h at1100℃.But theYSZ coating is shed when thermal cycled50-100h at1100℃.This text take Ta₂O₅、Gd₂O₃、Y₂O₃、ZrO₂for rawmaterial,on the basis of Ta₂O₅-Y₂O₃-ZrO₂use Gd³⁺substitute for Y³⁺until Y³⁺was fully displaced by Gd³⁺.Gd₂O₃dopedTa₂O₅-Y₂O₃-ZrO₂ceramics and Ta₂O₅-Y₂O₃-ZrO₂ceramics were prepared using the solidstate reaction method. The phase structure, microstructure,thermal expansion and thermalconductivity behavior of the ceramics were characterized by X-ray diffraction, scanningelectron microscopy, dilatometer and laset thermal diffusivity respectively. The resultsshowed that the Gd₂O₃-Y₂O₃-Ta₂O₅-ZrO₂ceramics material and Ta₂O₅-Y₂O₃-ZrO₂ceramicsmaterial are composed mainly of the tetragonal phase. When the content of Gd³⁺substitutefor Y³⁺is increased, the content of the monoclinic phase and bulk density basically increase,whereas the grain size relatively homogeneous and the thermal expansion coefficientdecrease. When the content of Gd³⁺substitute for Y³⁺is2mol%、3mol%、4mol%、6mol%、7mol%, The thermal conductivity of the Gd₂O₃-Y₂O₃-Ta₂O₅-ZrO₂ceramicsmaterial is lower than that of Ta₂O₅-Y₂O₃-ZrO₂ceramics material. It has the smallest thermalconductivity when the content of Gd³⁺substitute for Y³⁺is2mol%. This is propitious toimprove the service life of thermal barrier coatings.