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Abstract: The ablated surface morphology feature of plasma sprayed Cr2O3 coatings on heat-resistant steel irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 300–500A/cm2 with a shot number of 1–10 was investigated by using scanning electron microscopy, X-ray diffractometry, microhardness testers, respectively, in order to explore the modification mechanism of HIPIB onto coatings. HIPIB irradiation caused a melting and ablating of Cr2O3 coating surface and formed a thin remelted Cr2O3 layer with compact structure. At the low ion current density of 300A/cm2, the splat melting and cavity sealing caused a partially compact surface with several microcracks. And a discontinuous remelted Cr2O3 layer on the compact matrix coating was obtained. With increasing the ion current density to 500A/cm2, the reformed splats by serious splat melting and sufficient cavity sealing induced a more compact surface with a continuous and thicker remelted layer, companying with a slight increase of microcracks. The enlarged splats reformed by serious splats remelting and sufficient cavities sealing induced a gradually compact and smooth surface on the irradiated Cr2O3 coatings with increasing the shot number and a more uniform and smooth surface with compact structure was obtained by the agglomeration of the enlarged splats after 10 shots. It is found that the change in microhardness of the compact remelted layer was consistent with the sealing feature on the irradiated surface. [Copyright &y& Elsevier]

Abstract: ZrO2 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. [Copyright &y& Elsevier]