Preparation And Performance Studies Of SZO New Thermal Insulation Coatings

With the aviation turbine developing to high-flow ratio, high thrust to weight ratio, high inlet temperature, the gas temperature and pressure of combustion chamber constantly improve. However, for hot components of aircraft engine and gas turbine, conventional ZrO2 partially stabilized with Y2O3（YSZ） coatings cannot meet the demand and new types of ceramic thermal barrier coating materials should be found. With this objective, recent development efforts have focused on selecting novel TBCs ceramics, which have stable phase structure, low thermal conductivity, high melting point, etc. With a single pyrochlore struct ure, A₂B₂O₇ rare earth zirconate ceramics is considered the candidate materials of new thermal barrier coating. In this dissertation, taking Sm₂Zr₂O₇（SZO） ceramic materials as the research object, prepare two kinds materials, which are SZO+Al₂O₃ and（Sm0.5La0.4Gd0.1）2Zr2O7（SLGZO）.In this thesis, SZO and SLGZO were successfully synthesized by the chemical coprecipitation method and the suitable calcined mechanism. The spherical agglomerated powder of SZO+Al₂O₃ and SLGZO could be achieved by the spray drying technology and sintering at high temperature. With the process optimization, the induction plasma sphroidization method could prepare the spherical powder of SLGZO. The results of process were powder recovery rate reached 94.1%, the apparent density reached 3.25g/cm3 and the mobility 22s/50 g. Compared with the previous treatment, the apparent density and the mobility was increased by 121.1% and 60.7%.The ceramic block of SZO、SZO+Al₂O₃ and SLGZO were prepared by atmosphere plasma spraying method. When the Measuring temperature was 800 ℃, the thermal conductivity of the three kinds rare earth zirconate ceramics coatings were 0.69W/（m·k）、0.56W/（m·k）、0.74W/（m·k）. Compared with SZO, the thermal conductivity of SZO+Al₂O₃ was descended by 18.8%.SZO/YSZ、SZO+Al₂O₃/YSZ and SLGZO/YSZ thermal barrier coatings were prepared by atmosphere plasma spraying method. The cohesion strength of the coatings were 37.9 MPa、24.5MPa、36.9MPa. The porosity of the coatings were 13.2%、16.8%、14.5%.The thermal isulation effect of coatings was evaluated utilizing circular tube method under the same boundary conditions. The thermal isulation effect of coatings are ordered in descending sequence as fllows: SZO+Al₂O₃/YSZ>SZO/YSZ>SLGZO/YSZ. Compared to the SZO/YSZ coating, SZO+Al₂O₃/YSZ coating was increased by 31.1% and SLGZO/YSZ coating was decreased by 9.7% in the condition of coating thickness 0.1mm and cooling flow 3m3/h.The thermal shock performance of single-ceramic-layer under 1300℃ was measured with a burner rig for SZO+Al₂O₃/YSZ、SLGZO/YSZ. The thermal shock life of the coatings was 103 times and 13 times respectively. Two kinds of coating properties should be improved in the future.