Access to nanocrystalline, uniform, and fine-grained Ni-P coating with improved anticorrosive action through the growth of ZnO nanostructures before the plating process

Abstract In this work, the mild steel surface was modified by the growth of ZnO nanoflakes through a feasible and scalable procedure. The modified surface was used for the coating by the electroless nickel (EN) plating, and the influence of this modification on the morphology, surface roughness, uniformity, the corrosion behavior of Ni-P coating, and also on the deposition rate of EN plating was studied. The SEM micrographs, especially backscatter images, disclosed that the matrix of Ni-P coating with the underneath of ZnO NSs possesses smaller grain size with more uniform distribution compared to the specimen without ZnO NSs. The AFM analysis affirmed the lower surface roughness of this sample. The results of the EIS measurements and the Tafel extrapolation method indicated that the corrosion resistance of this sample is approximately two times higher than that of the sample without zinc oxide (Rp ≈ 35,000 Ω cm2). The role of ZnO NSs in increasing the active nucleation density and the formation of uniform, compact, and fine-grained Ni-P deposit was discussed. Besides, the effects of ZnO NSs on generating scattering centers, restricting the electron transfer, strengthening the Ni-P matrix, and the consequent corrosion behavior, were investigated.