Synthesis and characterization of electroless Ni-P coated graphite particles

Electroless alkaline bath is used to coat Ni-P graphite particles of average size, 150 μm. Amorphous nickel and graphite phases are observed in X-ray diffraction of the coated particles. The crystallite size from diffraction peaks is found to be 9·56 nm. The microstructural studies are carried out with field emission scanning electron microscope (SEM) on the uncoated and coated graphite particles. Uncoated particles showed irregular and fractured surfaces while the surface of coated particles revealed the presence of Ni-P globules. Sizes of Ni-P globules are observed to be in the range 175–250 nm. The presence of Ni and P are confirmed by the energy dispersive spectrometer results. The effect of coating bath composition is studied and an increasing trend in deposition is observed up to 50 gl−1 of stabilizer as well as up to 20 gl−1 of the reducing agent, however, the trend reverses afterwards. The phenomena of nucleation and growth of the Ni-P layer over the graphite surface have been demonstrated through SEM studies and a model has been proposed to demonstrate the growth mechanism of Ni-P globules.