Structure And Properties Of CeO₂and TiO₂ Co-doped Gd₂Zr₂o₇ Thermal Barrier Coating Materials

With the rapid development of the aviation industry,the operating temperature of a high thrust-to-weight ratio aeroengine is increasing,and thermal barrier coating materials can effectively protect the engine hot end components and improve their service life.Currently,6-8wt.%Y₂O₃partially stabilized Zr O₂（6-8YSZ）thermal barrier coating ceramic materials are widely used with the advantages of low thermal conductivity,but they can only work stably at temperatures below 1200°C.When the temperature rises further,6-8YSZ is prone to phase change and volume expansion,which makes the thermal barrier coating materials prone to cracking and peeling off.Therefore,the development of new thermal barrier coating ceramic materials with good high-temperature phase stability and long-term stable operation above1200℃has become the focus of research in this field.Among many materials,rare-earth zirconates have become the main research object.In this paper,Gd₂Zr₂O₇ceramic material is chosen to further improve the performance of this system by modifying the B-site with Ce O₂and Ti O₂doping.The main research contents are summarized as follows:Gd₂(Zr_0.7Ce_0.3-xTi_x)₂O₇（x=0,0.1,0.2,0.3）system ceramic materials were prepared by solid-phase synthesis method,when x was 0,0.1 mol,the physical phase structure of ceramic materials was defective fluorite structure;when x was 0.2,0.3 mol,the physical phase structure of ceramic materials was cubic pyrochlore structure,and the increase of Ti O₂doping made the The increase of Ti O₂doping makes the structure of ceramic material become more orderly.In the range of room temperature～1300℃,the increase of Ti O₂doping increases the average thermal expansion coefficient of the system material,and the thermal expansion coefficient reaches the maximum of 11.84×10^-6K^-1when x=0.3 mol.The thermal diffusion test results show that the thermal diffusion coefficient of the system ceramic material gradually decreases with the increase of temperature when the temperature is lower than 800℃,and when the Ti O₂doping amount is less than equals to 0.2 mol,the doping of Ti O₂effectively reduces the thermal diffusion coefficient of ceramic materials.The thermal conductivity of ceramic materials was calculated by thermal diffusion coefficient,and the results showed that the trend of thermal conductivity change was consistent with the thermal diffusion coefficient,and the thermal conductivity of Gd₂(Zr_0.7Ce_0.1Ti_0.2)₂O₇ceramic material was the lowest at 800℃,which was 1.15 Wm^-1·K^-1,and the co-doping of Ce O₂and Ti O₂enhanced phonon scattering,which reduced the thermal conductivity of ceramic materials.of thermal conductivity.For infrared emissivity,the introduction of Ti⁴⁺changes the lattice vibration and thus increases the emissivity of ceramic materials and decreases the photonic thermal conductivity.In terms of mechanical properties,the elastic modulus and fracture toughness of the ceramic materials of this system gradually increased with the increase of Ti O₂doping,reaching the maximum at x=0.3 mol,which were 217.2 GPa and 2.8 MPa·m^1/2,respectively.Gd₂(Zr_0.7Ce_0.1Ti_0.2)₂O₇ceramic materials were subjected to V₂O₅+Na₂SO₄molten salt corrosion tests for 5 h,10 h,and 20 h.The test results showed that the corrosion products were not altered by the corrosion time and doping ions,all of which were Gd VO₄with m-Zr O₂.