The study of nickel addition effect on phosphate coating porosity

In this article, the effect of Ni2+ addition was studied on phosphate coating porosities. The phosphating bath in this research was included of 5gr/lit zinc oxide, 12 mlit/lit phosphoric acid and 2gr/lit sodium nitrate as an accelerator. Zero to 8gr/lit nickel nitrate was added to the phosphating bath and the effects were studied. All of the samples were phosphated at 55°C and 210 seconds conditions. Coating porosities were studied by an electrochemical linear polarization method, coating morphology was studied by Scanning Electron Microscopy (SEM) and coating phases were studied by X-Ray Diffraction (XRD). The results were shown that nickel content increasing, causes to porosities decreasing of phosphate coating.