| With the development of China's aviation industry,the thrust-to-weight ratio of the engine is constantly increasing,and the temperature of the engine blades is also getting higher.It is necessary to combine the thermal barrier coating technology to reduce the temperature of the blade.Plasma Spray-Physical Vapor Deposition(PS-PVD)technology is a new type of multifunctional film and coating deposition technology developed based on low pressure plasma spraying.Due to its unique plasma jet characteristics,gas liquid solid multiphase coating deposition can be realized.At the same time,non-line-of-sight deposition is also possible,and this technology is expected to replace the traditional technology as the next generation of new thermal barrier coatings deposition technology.As an integral part of the thermal barrier coating system,the bond coating provides anti-oxidation,anti-corrosion and adjustment of thermal expansion coefficient,and affects the anti-flaking properties of thermal barrier coatings,which has important research significance.In this dissertation,DZ40 M alloy was selected as the substrate,and two kinds of bond coating,NiCrAlY and CoCrAlSiY,were deposited to investigate the diffusion of Al in the bond coating/substrate.YSZ coating was deposited on different bond coatings by PS-PVD.The bonding strength,thermal shock resistance and oxidation resistance of the thermal barrier coatings of two different bond coatings systems were studied.The conclusions were as follows.(a)Two kinds of bond coatings of NiCrAlY and CoCrAlSiY were prepared on the DZ40 M superalloy substrate.The vacuum diffusion treatment was carried out on the two samples for 25 h,50h and 100 h,and measure the content of Al at the interface of the bond coating/substrate after diffusion.After the experiment,it was found that the Al element was diffused into the body in the bond coating.The content of Al element decreased with the increase of the diffusion distance,and the longer the diffusion time at the same position,the higher the content of Al element.At the same time,the diffusion coefficients of Al elements at different positions of the two samples were calculated,and it was found that the diffusion coefficient decreased with increasing diffusion distance.(b)The bonding strengths of the two thermal barrier coatings of NiCrAlY/YSZ and CoCrAlSiY/YSZ were 66.7MPa and 59.0MPa,respectively,and the difference in bondingstrength was caused by the difference in the fracture positions of the two coatings.After 150 water quenching experiments on the two coatings,the NiCrAlY/YSZ coating showed continuous cracks at the interface between the TGO coating and the ceramic coating,while the crack of the CoCrAlSiY/YSZ coating was mainly located in the middle of the ceramic coating.The residual stress in the bond coatings after water quenching of the two coatings was analyzed by nanoindentation test.The results show that the residual tensile stress is generated in the bond coatings after water-quenching of the two coatings,and the residual pulling in the CoCrAlSiY bond coating.The greater the stress,the larger the size and number of cracks in the CoCrAlSiY/YSZ coating.(c)Both NiCrAlY/YSZ and CoCrAlSiY/YSZ coatings grow TGO coatings between the bond coatings and the ceramic coatings after oxidation test at 1100°C.The growth rate of the TGO coating of NiCrAlY bond coating is smaller than that of CoCrAlSiY with oxidation.The growth rate of the TGO coating of the bond coatings,but there is a large crack between the NiCrAlY bond coating and its TGO coating after 150 h of oxidation.Cracks also occur between the CoCrAlSiY bond coating and the TGO coating after 200 h of oxidation,but the crack width is smaller.The growth of TGO coating on both bond coatings is parabolic,and the growth rate of TGO coating decreases with the increase of oxidation time. |
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