Numerical study on modification of ceramic coatings by high-intensity pulsed ion beam

Abstract

ZrO 2 ceramic coatings, which often call thermal barrier coatings (TBCs), fabricated by electron beam physical vapor deposition (EB-PVD), are widely used in high-temperature environment of aircraft and industry gas-turbine engines, because of the excellent strain tolerance imparted by the columnar structure. However, channels separating the columnar grains in EB-PVD TBCs provide paths for oxygen or other aggressive species from ambient atmosphere into the bond coat, resulting in the premature spallation-failure during high-temperature service. In our previous study, high-intensity pulsed ion beam (HIPIB) technique has been proposed to modify the EB-PVD TBCs, where a melted, densified top layer can be produced as a result of extremely thermal effect induced by the HIPIB irradiation. In this paper, HIPIB melting process is investigated numerically using a physical model based on experimental data, taking into account the surface morphology of HIPIB-melted TBCs to explore the mechanism of interaction between HIPIB and the coatings. Deposition process of the beam energy in TBCs was simulated by Monte Carlo method, and the non-linear equations describing the thermal conducting process were solved numerically based on the deposited energy to obtain the evolution of the temperature field of TBCs. The calculated melting depth of irradiated EB-PVD TBCs is consistent with results obtained in the HIPIB irradiation experiments.