Study On The Relationship Between Microstructure And Elastic Modulus Of ZrO₂-YO_1.5-TaO_2.5 Composite Ceramics

Composite ceramic materials have a wide range of applications in aerospace,engine hot zone components,refractory materials,and even more important in thermal barrier coatings.The Zr O₂-YO_1.5-Ta O_2.5 system is reported to have low thermal conductivity and good phase stability,which makes it a promising candidate for next-generation thermal barrier coating materials.The purpose of this paper is to study the relationship between the microstructure and elastic constant of the two-phase Zr O₂-YO_1.5-Ta O_2.5 system.Specifically,to explore the specific proportion of the two phases in Zr O₂-YO_1.5-Ta O_2.5 ceramics Quantitative relationship with macroscopic elastic modulus.The main research results are as follows:（1）The elastic moduli of the five groups of samples were measured by DIC-three-point bending experiment,and they were 78.3,89.3,112.8,92.7,and 45.1GPa.The results of the five groups of samples obtained by the numerical homogenization algorithm based on Fast Fourier Transform（FFT）were 80.5,94.7,92.7,71.1,95GPa,the change trend is basically consistent with the experiment,with the increase of Zr O₂content,it first increases and then decreases.The experimental results of samples 1-4are basically consistent with the calculated results,and the deviation of sample 5 is the largest,which may be because its phase structure is significantly different from other samples.The degree of dispersion of the experimental elastic modulus data is larger than that of the calculation.The standard deviation of the elastic modulus of the experimental result is 22.26,and the standard deviation of the elastic modulus of the calculated result is 9.49.（2）According to the theory of solid mechanics,a three-point bending finite element model was established,and the load-displacement curves of five groups of samples were calculated and compared.The slopes of the curves measured by the experiment are 2737,1852,2563,2349,and 1391 N/mm,respectively,and the slopes of the finite element calculation are 2609,1823,1944,1644,and 2641 N/mm,respectively.The change of the slope of the load-displacement curve is basically the same.The Zr O₂ content increases first and then decreases,which is consistent with the comparison results of the experimental and calculated elastic modulus,which confirms the reliability of the material’s elastic modulus and its relationship with the phase composition.Comparing the maximum load of experiment and simulation,the difference between the results of No.1 sample is the smallest,and the difference of No.3 sample is the largest,which is 41N.（3）Comparing the experimental and COMSOL simulated strain distributions in the x-and y-directions,the x-direction strain has a stress peak below the loading point.The strain peak area in the strain cloud image simulated by the finite element model is wide and flat,and it is located just below the loading point,while the strain peak area in the cloud image measured by DIC is narrow and sharp,with obvious fracture tendency.The y-direction strain appears negative strain at the loading point,indicating compression.In the finite element simulation results,the y-direction strain area is small and the distribution rules are obvious.The y-direction strain distribution in the experiment is basically consistent with the finite element simulation,Indicates the reliability of the measured elastic modulus of the material.