Effect Of Multi-Rare Earth Element Doping On Thermal Insulation Properties Of Thermal Barrier Coatings

The turbine inlet temperature has increased significantly,making the use of traditional 6wt.%～8 wt.%Y₂O₃-Zr O₂ thermal barrier coatings encounter challenges.It is of strategic significance to study new thermal barrier coatings with low thermal conductivity and good thermal stability.The research purpose is to use air plasma spraying to prepare europium oxide doped YSZ coating（Eu YSZ）,samarium oxide doped YSZ coating（Sm YSZ）and YSZ coating（YSZ）,studying the basic performance,heat insulation performance and thermal stability of the three coatings to analyze the influence of the doping of multi-element rare earth elements on the performance of the thermal barrier coating.The main research contents include:At first,the basic performance of the three coatings is characterized.The micro morphology of the three coatings is similar.All coatings are composed of t’-Zr O₂phase.The hardness of the three coatings is nearly the same;the elastic modulus of Eu YSZ and Sm YSZ coatings is lower than that of YSZ coatings;the fracture toughness of Eu YSZ and Sm YSZ coatings is slightly higher than that of YSZ coatings.Then,the three coatings were tested for thermal conductivity and heat insulation.In the thermal conductivity measurement,Eu³⁺or Sm³⁺doping does not affect the coating density,but reduces the specific heat capacity and the thermal diffusion coefficients of coatings,the thermal conductivity of Sm YSZ and Eu YSZ coatings is significantly lower than that of the YSZ coating.Eu YSZ and Sm YSZ also have better thermal insulation performance than YSZ coatings.Finally,the thermal stability of three coatings is analyzed.At 1200℃,the order of phase stability of the three coatings from high to low is YSZ,Sm YSZ,Eu YSZ;at 1400℃,the phase stability of Eu YSZ is slightly worse than that of Sm YSZ and YSZ,while the phase stability of Sm YSZ and YSZ is similar.Sm YSZ shows better sintering resistance than Eu YSZ and YSZ coatings;while Eu YSZ and YSZ coatings have similar sintering resistance.The order of thermal cycle life of the three coatings from high to low is Sm YSZ,Eu YSZ,and YSZ.