PS-PVD 7YSZ Thermal Barrier Coatings "Primitive + Sequence" Deposition Mechanism

Thermal Barrier Coatings(TBCs)are one of the key technologies for aero-engine turbine blades.The development of aero engines cannot be achieved without high thrust,which inevitably leads to high temperatures.TBCs reduce the amount of heat transferred to the turbine blades,increasing the resistance to high temperatures and extending their service life.Plasma Spray-Physical Vapor Deposition(PS-PVD)is one of the main technologies for the preparation of TBCs for future aero engines.At present,the deposition mechanism of PS-PVD is not well studied,and some traditional theoretical models of PVD deposition cannot explain the deposition process of PS-PVD coatings,especially when compared with the mainstream technology of Electron Beam-Physical Vapor Deposition(EB-PVD).There are many similarities and differences that need to be explored.In this paper,a theoretical model of “primitive + sequence” structure is proposed to explain the deposition process of PS-PVD 7YSZ TBCs.The study of the PS-PVD deposition mechanism has been advanced to the nanoscale.Energy influences the deposition of vapor phase particles on the substrate,which are first randomly bound to the surface of the substrate in a disordered state,and then diffuse to the lattice location through surface migration.Plasma gun oscillation causes the PS-PVD substrate to have a disordered surface particle arrangement and an ordered central particle arrangement,with the substrate stacking sequence forming a feathery columnar structured coating.Based on the properties of PS-PVD,a practically engineered duplex blade TBCs was investigated.PS-PVD technology can achieve full coverage of the thermal barrier coating with less thickness loss in the shadow area between the blades,reaching 60% of the average thickness at the thinnest point.The performance of PS-PVD non-line of sight deposition has been investigated and the velocity and temperature fields of the plasma jet have been simulated to explain the nucleation pattern of the frontal and shaded surfaces in relation to the formation energy.The tuning of the substrate size was successfully achieved by adjusting the PS-PVD process.The effect of large-sized primitives on the growth of the coating was investigated,which can interrupt the growth of its columnar structure or create branching.