| Ni-Zn-P alloy coating was prepared on the surface of Q235 steel by alkaline electroless plating method. By means of optical microscope and SEM, the morphology of the coating was observed, and the composition of the coating was measured by EDS. The corrosion resistance of Ni-Zn-P alloy coating was analyzed by the method of total immersion test. The following conclusions were obtained.Electroless plating process of Ni-Zn-P alloy plating process is: the formation of the atomic group at the interface of the solid and liquid interface is higher. Ni, Zn, P three elements have a certain precipitation sequence, in the chemical plating Ni first priority and rapid deposition, followed by Ni and P deposition, the last is Ni, Zn, P three kinds of elements of a total deposition. Deposition mechanism of electroless Ni-Zn-P alloy plating on Q235 steel surface is the mechanism of induced reduction.In electroless plating process, with the increase of P content in the coating, the content of 2~25g/L in the range of the coating is uniform and dense, and the diameter of the cell body increases gradually, and the content of P in the coating gradually increases,the maximum amount of 18.27wt%. With the increase of P content in the coating, the corrosion resistance of electroless Ni-Zn-P alloy coating is improved.Ni-Zn-P alloy coating is more uniform and smooth, and the boundary of cell and cell is more continuous and dense than that of Ni-P coating. After corrosion of Ni-Zn-P alloy coating, the content of Zn decreased obviously, and a small amount of Fe and O, which showed that the corrosion process of the alloy coating was Zn first, and then the coating was corroded, and the corrosion of the substrate was corroded. The corrosion rate of NiZn-P coating was significantly lower than that of Ni-P coating, which is due to the corrosion resistance of the coating and substrate, which is due to the corrosion protection of the coating and substrate, which is due to Zn. |
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