Applyingof Electroless Ni- P/SiO2 Nano-composite Coatings Providing SiO2 via Nano Sol Particles and Investigation of its Corrosion Behavior

In present work, highly homogeneous Ni–P/SiO2 nanocomposite coatings were prepared by a new process on steel substrate. This method was developed by inserting of a sol containing SiO2 to Ni-P electroless bath in the presence of surfactant to produce a composite coating containing well dispersed SiO nanoparticles. The morphology and elemental composition were analyzed using a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDS) that confirmed the presence of silica in the coating matrix.The Results showed co-deposited SiO2 particles approximately 1.58wt% with no agglomeration. X-ray mapping images of Ni-P/SiO2 showed that SiO2 particles were uniformly distributed in the deposit. Electrochemical impedance spectroscopy and polarization tests showed that addition of nano-SiO2 particles via sol solution increased corrosion resistance of Ni–P coatings in 3.5% NaCl aqueous solution from 2726 Ω to 6985 Ω.