等离子物理气相沉积制备叶片热障涂层及新工艺开发OA

To mitigate the problem of overheating-induced deformation during the deposition of thermal barrier coatings(TBCs)on the first-stage guide vanes of a turboshaft engine using high-power plasma spray-physical vapor deposition(PS-PVD),and in response to the technological demand for advanced national aero-engine manufacturing,a low-power PS-PVD process is developed and investigated.The adjustment of plasma parameters plays a crucial role in balancing coating quality and substrate protection.By reducing the discharge current,the energy input per unit time is effectively decreased,which in turn lowers the substrate temperature of the blade during coating deposition.This reduction in thermal load helps to minimize thermal distortion and prevent microstructural degradation of the superalloy substrate.However,the low-pressure environment inherent to the PS-PVD process significantly limits heat transfer from the plasma jet to the feedstock powder.Under such conditions,the particle-plasma interaction time and collision frequency are reduced,leading to insufficient powder heating and incomplete vaporization.Consequently,achieving full powder vaporization becomes the primary technical challenge in low-power operation.The results of this study demonstrate that when the spraying is conducted under low-power conditions,the ambient air pressure must be increased from 200 Pa to 300 Pa.The elevated pressure enhances the convective and radiative heat transfer from the plasma jet to the feedstock powder,thereby compensating for the reduced plasma energy.This adjustment ensures sufficient powder melting and vaporization,which is essential for forming coatings with a quasi-columnar microstructure characteristic of vapor-deposition-dominated growth.Using the optimized parameters,a YSZ/GYbZ double-layer thermal barrier coating with an approximate thickness of 60 μm is successfully deposited on the blade surface.The coating cross section exhibits a well-defined quasi-columnar morphology,while the surface displays a characteristic cauliflower-like texture.This microstructural feature is indicative of high adatom mobility and directional growth under the influence of plasma vapor deposition,reflecting the transition from liquid splat-based to vapor-phase deposition mechanisms.Such structures are known to improve strain tolerance and thermal insulation performance in service.However,after slow cooling to room temperature,coating delamination occurred at the large edge plate.Microstructural analysis indicates that this failure originates from the insufficient substrate temperature,approximately 600℃during deposition,which hinders the rapid formation of a dense and continuous oxide film on the bond coat.Without this protective Al2O3 layer,interdiffusion between the YSZ ceramic layer and the bond coat is promoted,resulting in the nucleation of numerous interfacial voids.These voids gradually coalesce to form cracks,ultimately causing coating separation.To address this issue,the fixture design is optimized from a 5 mm-thick stainless-steel structure to a 2 mm-thick high-temperature alloy configuration,which improves thermal conductivity and temperature uniformity across the blade surface.Simultaneously,by increasing the edge plate temperature from 600℃to 800℃,rapid oxidation of the bonding layer is achieved,leading to the formation of a dense and adherent oxide film.This improvement effectively suppresses interdiffusion and prevented coating delamination,ensuring a stable interface and enhanced coating integrity.The optimization of both processing parameters and fixture design therefore provides a feasible route to achieving reliable PS-PVD coatings for advanced turbine components.