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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]

Deep oscillation magnetron sputtering (DOMS) is an alternative high-power pulsed magnetron sputtering technique, which offers virtually arc-free depositions especially for reactive depositions of some insulating coatings under optimized pulsing conditions. CrN/TiN superlattice coatings with a modulated period (Λ) ranging from 5.7 to 10.2 nm were deposited using a combination of DOMS and pulsed dc magnetron sputtering in a closed field unbalanced magnetron sputtering system. As a Λ was increased from 5.7 to 10.2 nm, CrN/TiN superlattice coatings with the increased Cr/(Cr + Ti) ratio from 0.177 to 0.496 exhibited a single phase face-centered cubic structure with a strong {111} texture. Correspondingly, the hardness, the H/E* and H 3 /E* 2 ratios showed an initial increase, followed by a decrease. The coatings at Λ = 6.3 nm with the Cr/(Cr + Ti) ratio of 0.294 and fine grain size of about 30 nm showed the highest hardness of 36 GPa, H/E* ratio of 0.093 and H 3 /E* 2 ratio of 0.313. It also showed a mild abrasive wear with the lowest friction coefficient and specific wear rate of 0.27 and 0.5 × 10 − 6 mm 3 N − 1 m − 1 , respectively. With increasing Λ, the friction coefficient and specific wear rate decreased and then increased. The dominant wear mechanism changed from oxidative wear to mild abrasive wear, and then to severe oxidative wear. The changes of H, H/E* and H 3 /E* 2 ratios and adhesion of CrN/TiN superlattice coatings resulted in variation of tribological properties and wear mechanism. [ABSTRACT FROM AUTHOR]