NiCrAlY bond coat was prepared by HVOF (high-velocity oxygen fuel) spray on nickelbased superalloy.Surface treatments like grit-blasting,shot-peening and vacuum treatment methods were carried out in order to study the effects of surface modification on thermal cycling lifetime of TBCs.The surface-modified TBCs exhibited better thermal shock resistance.Failure of TBCs with the as-sprayed bond coat occurred within the top coat and at the interface between spinels and the top coat,while that of after shot-peening,grit-blasting and vacuum treatment occurred mainly within the top coat.TGO (thermally grown oxide) formed on as-sprayed bond coat was composed of a Ni(Al,Cr)2O4 spinels outer layer and a Al2O3 inner layer.But,a continuous and uniform Al2O3 formed after surface modification.Formation of the mixed oxides (spinels) on the as-sprayed bond coat accelerated the failure of TBCs.