| A classic two-layer thermal barrier coating consisting of a metal bond coat and a top ceramic coating has been used for decades to improve the service temperature of aerospace engine hot end components and promote the development of aero-engine technology.It has made important contributions and is one of the three key technologies for the manufacture of advanced aero-engines and high-pressure turbine blades,together with high-efficiency gas-cooled technology and high-temperature structural materials.Plasma Spray-Physical Vapor Deposition?PS-PVD?technology is considered as one of the most promising preparation methods for the future aero-engine thermal barrier coatings because of its advantages in both APS and EB-PVD technologies.At present,some progresses have been made on the preparation of 7YSZ ceramic coatings by PS-PVD technology.In order to further improve the performance of the PS-PVD thermal barrier coating,it is a feasible method to optimize the material and preparation process of the metal bonding coating with the 7YSZ ceramic layer.In this paper,MCrAlY alloy and nano-agglomerate 7YSZ are used as raw materials,and PS-PVD technology is used to prepare the bonding coating and top ceramic coating on the nickel-base superalloy substrate.The main researches are as follows:1)Using CoCrAlSiY alloy powder as material and K452G superalloy as matrix,explore the structural and performance characteristics of the bonding coating prepared by PS-PVD technology,and appropriate subsequent heat treatment process.The results show that the surface of the PS-PVD bonding coating is rough and has a typical lamellar structure with a cross-sectional microhardness of 530.92 HV0.1.Vacuum heat treatment causes interdiffusion of the elements between bonding coating and the matrix,making the composition of the elements and phases near the interface tend to be uniform,the bonding mode tends to metallurgical bonding,and the brittle phase will precipitate,affecting the oxidation resistance performance and mechanical properties of the bonding coating.1030°C+4h vacuum heat treatment is better.2).NiCoCrAlTaY and Ni CrAlY alloy powders were used as the bonding coating material,and 7YSZ was the ceramic coating material.The influence of different material bonding coating on the overall performance of the PS-PVD thermal barrier coating was investigated.The results show that the macroscopic morphology,porosity and hardness of the feather-columnar ceramic layers of NiCoCrAlTa Y-7YSZ and NiCrAlY-7YSZ thermal barrier coatings are not significantly different;the bond strengths are significantly different,which are 21.89 MPa and 29.74 MPa,respectively;high-temperature oxidation kinetic equation parabolic fitting formula is h=1.14+0.305·t1/2 and h=0.63+0.375?t1/2,respectively;water quenching and thermal shock tests at 1100°C are failed after 60 and 70cycles,respectively.It shows that the bonding coating material has no significant effect on the macroscopic structure and hardness of the ceramic layer,but has great influence on the overall bonding strength,high temperature oxidation resistance and thermal shock resistance of the thermal barrier coating.3).A certain thickness of thermal barrier coating was prepared by PS-PVD,and the effects of BC and TC on the film cooling holes were investigated.The results show that the BC is the key reason for the blockage of the film cooling holes.When the pore size is 0.85mm,the pore shrinkage of the film cooling hole decreases with the increase of the angle,in which the BC is greatly affected by the angle,and the TC is less affected by the angle.When the film cooling hole angle is 30°,the pore shrinkage decreases with increasing pore size,but the pore size change has no effect on the deposition state of the BC and TC in the film cooling hole,and the coating thickness is similar.Only the numerical calculation result of the aperture shrinkage rate will be affected.To produce coatings of the same thickness,the BC caused pore shrinkage three times that of the TC. |
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