Effect of Supersonic Fine Particles Bombarding on the Service Life of Thermal Barrier Coating

Abstract

Thermally Grown Oxide(TGO) is a dominating component in controlling the effectiveness of thermal barrier coating.During the growth of TGO,whether we could homogeneously distribute Al atom on the TGO and the intermediate metal layer will be the key factor in forming TGO with continuous,uniform and single-ingredient(Al2O3).In this experiment,we bombarded particles on to the metallic bound layer.We studied the influence of supersonic particle bombardment on the diffusion of Al.We hope to control the growth of TGO by monitoring the diffusion of Al.Thermal barrier coating(TBC),which consists of a NiCoCrAlY bond coat and a ZrO2-8Y2O3(wt.%) topcoat(TC),is fabricated on the nickel-base superalloy by air plasma spray(APS).NiCoCrAlY bond coat is treated by supersonic fine particles bombarding(SFPB).The morphology,oxidation behavior of TBC and phase are characterized by scanning electron microscope(SEM) equipped with an energy dispersive spectromrter(EDS) and X-ray diffractometer(XRD).The influence of supersonic fine particles bombarding technique on the service life of thermal barrier coating is studied.The results show that SFPB technique improves the flaw of excessive surface undulation in the as-sprayed bond coat.A continuous,uniform and single-ingredient(Al2O3) TGO can quickly form in the SFPB TBC during high temperature oxidation process.The thickening of TGO is relatively slow.These will effectively suppress the formation of other non-protective oxides.Therefore,SFPB technique reduces the growth stress level generated by the continuous growth of TGO,and also avoids the stress concentration induced by formation of the large particle spinal oxide.Thermal barrier coating still remains well after 350 thermal cycles.The service life of TBC is improved.The proposed research provides theoretical basis and technical references to further improve and enhance the SFPB technique.