Preparation And Mechanical Properties Characterization Of Environmental/Thermal Barrier Coatings Materials

In order to further improve the service life of hot-end components such as gas turbine engines and aero-engines,environmental/thermal barrier coatings?TBCs/EBCs?materials are used to improve component performance in terms of anti-oxidation corrosion and increasing tolerance temperature.As a new generation of environmental barrier coatings material,rare earth ytteribum silicate material due to low thermal expansion coefficient,good oxidation corrosion resistance,low silicon activity,low volatility and stability of high-temperature phase,has promising development prospect in the application of EBCs material.At the same time,6-8wt.%yttria-stabilized zirconia?YSZ?has become a mainstay of thermal barrier coatings materials with advantages of low thermal conductivity,high thermal expansion coefficient and good mechanical properties.In this paper,the preparation,structural analysis and mechanical properties of ytteribum silicate environmental barrier coatings and 8YSZ block were studied.Ytterbium silicate precursor sol was prepared by sol-gel method.Ytterbium silicate coating was prepared by adding ytterbium nitrate?1mol,2mol,3mol and 4mol?with different mole contents in 10ml solvent.The coating was prepared on Si C substrate combining with spin coating process and calcined at different temperatures to obtain dense ytterbium silicate coating.In addition,pure metastable tetragonal phase?T'?YSZ powder was prepared by atmospheric plasma spraying?APS?,and pure T'phase 8YSZ block was prepared by spark plasma sintering?SPS?after powder ball grinding.Samples with different contents of tetragonal phase?T?and cubic phase?C?were obtained by heating treatment at different hours.The phase structure of ytterbium silicate environmental barrier coatings material at different temperatures was studied,and the effects of different solid phase contents on the densification of the coating were analyzed.The results show that?-Yb₂Si₂O₇,?-Yb₂Si₂O₇and Yb₂Si O₅ high temperature phase of ytterbium silicate coating can be obtained at 1000?calcination,and?-Yb₂Si₂O₇ shifts into?-Yb₂Si₂O₇ at 1100?calcination.High solid content coatings easily causes crack,while low content coating obtains coating island structure.In this paper,the optimal concentration range is 0.2M.Also,its mechanical properties are optimal,in which the hardness is 1.67GPa,and the young's modulus is19.8GPa.The spin coating process has great potential in producing dense environmental barrier coating materials.The phase structure of 8YSZ block at different annealing time was studied,the phase transition process was analyzed,and the mechanical properties of single phase were tested by nano indentation.The results show that the metastable tetragonal phase T'is decomposed into cubic phase C and tetragonal phase T after the aging treatment.The phase structure of grains can be distinguished on account of the growth of grains and the content of Y element.The nano-indentation mapping can roughly reflect the phase distribution of YSZ surface,and the mechanical properties of a single phase vary with the aging time.The method of measuring mechanical property to reflect phase structure can be applied to more ceramic materials.