The Research Of Ni-P Multilayer Coatings On Steel And Magnesium Alloy

It was found that the main factor in determining porosity was the thickness of the deposit. A dramatic reduction in porosity was found for deposits thicker than 12μm. A possibility for the improvement of corrosion resistance is the deposition interlayers and/or multilayered coatings. The use of mutilayers or hybrid techniques in surface engineering has often been cited as the way forward to improve the mechanical, tribological and electrochemical properties of coatings . A multilayer coating with layers having difference in corrosion potential has provided an effective solution to improve the corrosion resistance of the no-sacrificial coatings. In this paper, multilayer coatings consisting of different Ni–P and Ni layers were prepared by combining electrodeposition with electroless deposition. The microstructure and composition of the coatings was analyzed by scanning electron microscope (SEM) and X-ray diffractometer (XRD). The corrosion resistance of the coatings was estimated by electrochemical polarization measurements, acid solution immersion test and salt spray test.