Growth Mechanism Of Thermal Growth Oxide Layer And Characterization Of Its Mechanical Properties

Thermal barrier coating,as a high temperature resistant and corrosion resistant ceramic protective material,is widely used in high temperature parts of aerospace engines to improve the efficiency and service life of the engine.Spallation is the key bottleneck to its safe application on the high-performance aero-engines.Interface oxidation is regarded as the first key factor that results in the spallation of TBCs In the high-temperature service environment,TGO growth due to the oxidation of TBCs are the main reasons for the failure of TBC.Therefore,it is very important to accurately predict the evolution of TGO growth in TBCs.The oxidative growth of TGO changes the stress-strain field of the coating system.At present,the relevant mechanical properties of TGO are not clear,and it cannot be effectively carried out when analyzing the change of the stress-strain field of the TBCs.Therefore,in order to solve this critical problem,it is urgent to conduct in-depth research on the growth law of TGO,the evolution of microscopic morphology and the mechanical properties of TGO.Based on this,the main research contents of this paper include:1.The coating oxidation experiments of different preparation processes and the oxidation experiments of alloy materials were compared,to study the growth rule as well as the microstructure evolution law of the TGO,By analyzing the results of oxidation of different materials,we found that the coatings prepared by electron beam physical vapor deposition technology have the best oxidation resistance and Fe-based alloy materials have the worst oxidation resistance,However,the oxide generated on the surface of Fe-based alloy is uniform and compact,which has good adhesion with the base.2.The hardness and Young’s modulus of TGO and alumina ceramics and the scale effect of these mechanical parameters were analyzed by nanoindentation technique.It is found through experiments that there are obvious indenter scale effects on the mechanical parameters of TGO and alumina ceramics.The intrinsic Young’s modulus of TGO is 326 GPa and the intrinsic hardness is about 13.82 GPa,respectively.The Young’s modulus of alumina ceramics is 360 GPa and the hardness is about 20 GPa,respectively.From the experimental results,it is found that the Young’s modulus and hardness of TGO are smaller than that of alumina ceramic materials.3.The tensile fracture strength of TGO was characterized by tensile method combined with data image correlation technology.It is found by tensile test that when TGO is 0.25% strain,obvious cracks appear on the surface.In addition,the X-ray diffractometer method is used to characterize the internal residual stress of TGO,and the simplified shear lag model is used to calculate the final tensile strength of TGO is about 0.682 GPa.