Preparation of thermal barrier coatings for gas turbine blades by EB-PVD

Thermal barrier coatings for gas turbine blades have been coated by the EB-PVD method. This paper will mainly focus on two aspects of thermal barrier coatings: (i) the formation mechanism of the initial cracks during thermal cycle process; and (ii) the thermal barrier effect. The microcracks were only discovered inside the ceramic top coat of the thermalcycled TBCs. SEM/EDS observations indicated that some different oxides exist at the point just below the cracks. It seems that the formation of initial cracks resulted from oxidation stress as well as thermal stress. A simulated test facility has been designed to investigate the thermal barrier effect. Based on the heat transfer theory of one-dimensional steady-state heat conduction, the thermal barrier effect (Delta T) of two-layer structure TBCs was theoretically and experimentally studied as a function of the thickness of the coatings, the thermal conductivity, lambda, and the temperatures of the operating conditions. (C) 1998 Elsevier Science S.A. All rights reserved.