Bonding Property of High-thickness Gradient NiCoCrAlYAfSZ Thermal Barrier Coatings
Author of the article:CHONG Nanjing;LIU Qi;LI Tianqing;WANG Yu;BAI Yu
Author's Workplace：State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an 710049,China
Key Words：high-thickness gradient coating synchronous feeding plasma spraying bonding strength finite element simulation
Abstract：The thermal insulation property of thermal barrier coatings(TBCs)can be significantly improved with increasing the coating thickness.However,the increase in thickness leads to a lower interfacial bond inside,which severely restricts the reliability and service life of TBCs.A series of NiCoCrAlYA'SZ gradient thermal barrier coatings with millimeter thickness were deposited on the substrate by a novel and efficient supersonic plasma synchronous dual powder feeding method.The bond strength of the coating was tested by tensile method,and the influence of coating thickness and microstructure on the bond strength was discussed.At the same time,the finite element simulation method was used to verily the relationship between the internal residual stress and the bonding strength of TBCs.The results show that when the thickness of the coating increases from 1000μm to 2500μm the bonding strength of the coating gradually decreases from 44.5 MPa to 29.4 MPa.The decrease of the bonding strength is due to the accumulation of residual stress in the deposition process of the coating.The fracture site is gradually transferred from the adhesive layer to the gradient transition zone due to the different accumulation positions of the residual stress.Finally,fracture occurs inside the ceramic layer.
