Surface morphology of Cr 2O 3 coatings on steel irradiated by high-intensity pulsed ion beam

Abstract

The ablated surface morphology feature of plasma sprayed Cr 2O 3 coatings on heat-resistant steel irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 300–500 A/cm 2 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 Cr 2O 3 coating surface and formed a thin remelted Cr 2O 3 layer with compact structure. At the low ion current density of 300 A/cm 2, the splat melting and cavity sealing caused a partially compact surface with several microcracks. And a discontinuous remelted Cr 2O 3 layer on the compact matrix coating was obtained. With increasing the ion current density to 500 A/cm 2, 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 Cr 2O 3 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.