Study On Preparation And Thermal Properties Of ZrO₂Thermal Barrier Coatings Stabilized By Nano CeO₂/Y₂O₃Based On Coprecipitation Method

In order to improve the service life of the thermal barrier coating performance, reduce the thermal conductivity, improve the thermal shock resistance and meet the requirements of increasing working temperature of the engine hot components. ZrOo ceramic powders stabilized by nano CeO2/Y2O3(CYSZ) were prepared by coprecipitation method in this subject. The effects of processing parameters such as reaction temperature. pH value, calcination temperature on the nano ceramic powders were studied. Research showed that the optimum process parameters of preparing nano-CYSZ ceramic powders by coprecipitation method were the reaction temperature of75℃. the pH value of10. the calcination temperature of500℃and Y content of7.5mol%. CYSZ ceramic powders had small particle size and good dispersion on this condition.Five kinds of nano-CYSZ ceramic powders were prepared with the optimum process parameters, which the content of CeO2were0.1.5.10.15mol%. and used the spray drying on them. The phase structures of the ceramic powders before and after spray drying were the same, remained the tetragonal ZrO2structure. The Ce existed on ceramic powder surface was CeO2.The granulated powders had spherical shape and uniform distribution with size in20-60μm. The liquidity of the powders was good and the powders could be used for atmospheric plasma spraying.Nano-CYSZ thermal barrier coatings were prepared by atmospheric plasma spraying process. Research showed that the phase structures of five kinds of ceramic coatings were tetragonal phase ZrO2. The thickness of bond layer was about100μm and the thickness of ceramic layer was about200μm. The number of the porosities and micro cracks of the coatings decreased with the increase of CeO2content. The combination of the ceramic layer and the bond layer was tight. The hardness of the coatings decreased with CeO2content increasing. The bonding strength of the coatings increased first and then decreased with the content of CeO2increasing. The thermal conductivity of the coatings increased with the content of CeO2increasing, but was lower than that without CeO2containing coating. The coatings with CeO2had short crack initiation and the instability process of thermal shock was slow. TGO formed in the bond layer was thinner, so the thermal shock resistance of the coating was significantly better than that without CeO2.