Investigation On Design And Properties Of New Type Of High Entropy Ceramic Structured Thermal Barrier Coating

To improve higher thermal efficiency and thrust of gas turbine,surface temperature of combustion chamber should be increased.Thermal barrier coating(TBC)is used to keep the mechanical properties of the alloy matrix at high temperature.Traditional TBC materials such as YSZ and La2Zr2O7 can not meet the increasing temperature requirements,which urgently needs to develop new TBC materials.For the past few years,high entropy materials have shown many remarkable thermophysical properties such as low thermal conductivity and good thermal stability,which have developed a number of material systems,and high entropy materials have gradually become research hot point.For TBCs with lower thermal conductivity and excellent thermal shock resistant performance.La2(Ce0.2Hf0.2Zr0.2Ti0.2Sn0.2)2O7 high entropy ceramics were synthesized by solid phase synthesis by choosing a suitable single component material,combining ion radius and defect formation factors for elemental selection.It shows the crystal structure of pyrochlore with porous morphology,and its porosity is 24.7%.Differential Scanning Calorimetry(DSC)curve indicates that there is no obvious heat inspiration or release peak,which indicates that the thermal stability of the material is better.Its specific heat capacity result shows parabolic form and the thermal conductivity at 1000? is only 0.54 W·m-1·K-1.In order to verify the performances of high entropy ceramic,static oxidation and calcium magnesium alumina silicate(CMAS)corrosion experiments were carried out.X-ray diffraction(XRD)for the static oxidation for 100h at 1100? shows that the main peak strength corresponds to the pyrochlore structure.It is pure pyrochlore structure.Due to high entropy effect,the transistor structure causes a rough Prague diffraction surface,and the different atomic radius affect the X-ray signal to form different diffraction peaks.Scanning Electron Microscope(SEM)result indicates that the material is a porous high entropy ceramic morphology.CMAS corrosion experiments indicates that CMAS and materials can not react,and CMAS can not infiltrate through the coating to damage the microstructure.TBCs with high entropy ceramic coating were prepared by plasma spray.The thickness of the coating is 100?m.XRD is used to analyze coating surface,which is characterized by single-phase pyrochlore structure and no miscellaneous phase.SEM result indicates a typical spray-shaped surface morphology,and coating hardness data indicate high mechanical properties.The XRD results before and after the thermal cycling experiment indicate that the phase transition does not happen.The bond coat XRD result after spallation indicates that thermally growth oxide(TGO)with Al2O3 does not form.It indicates that the coating is oxygen impermeable.Static oxidation experiment for 100h indicates that it does not have phase change and decomposition,but forming small crystal grains similar to the crystalline state,the organizational structure becomes loose,causing the coating stripping.In order to explore the feasibility of the high entropy ceramic coating,the Fluent software is used to simulate the temperature site of different scanning speed and power in the cladding process.The simulation results indicate that the laser power is 700W,the scanning speed is 1.8cm/s and the laser radius is 0.5mm process.Experimental verification indicates that high entropy ceramics is uniformly prepared on the substrate,and there is deficiency that the substrate is subjected to a degree of damage.