Pure Cr coating was deposited by multi-arc ion plating under different duty cycles on surface of zirconium alloy. Changes of surface micro morphology and preferential growth orientation of pure Cr coatings were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD), and porosity of the pure Cr coating was analyzed by using Image J software. The results show that the microstructure, preferential growth orientation and porosity of the pure Cr coating are significantly influenced by duty cycle. As the duty cycle increa...