Preparation of nickel-coated graphite by electroless plating under mechanical or ultrasonic agitation

In this paper, nickel-coated graphite powders were prepared by electroless plating. After a novel and facile pretreatment of graphite, electroless plating was carried out in an alkaline bath having nickel chloride (NiCl2) as a source of nickel and sodium borohydride (NaBH4) as a reducing agent. During the electroless nickel plating, mechanical or ultrasonic agitation was adopted to improve the properties of coating. The coated graphite powders were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results show that two different morphologies of Ni-B coatings were achieved on the surface of graphite. Both coatings on graphite are continuous and uniform. For mechanical agitation process, the coating exhibits a sesame-seed slice-like structure which is composed of large spherical grains. The ultrasonic agitation process results in a faster deposition rate and a well-knit membrane-like structure coating free of voids. This is attributed to the easier nucleation and fine particle distribution of nickel nuclei under the ultrasonic agitation.