Surface analysis and corrosion resistance of new nickel base thin film alloys

Abstract

Electroless Zn-Ni-P thin films were deposited on low carbon steel from an alkaline non-cyanide aqueous electrolyte. The newly developed ternary alloys structure and microstructure investigations were carried out via X-ray diffraction and SEM. Chemical composition of the coatings was investigated via energy dispersive spectroscopy. Polarization tests were used to study the corrosion properties of the coatings in a 3.5 wt.% NaCl solution. The results confirmed the high corrosion resistance of Zn-Ni-P alloy plated steel sheet. The surface analysis of the thin film samples before and after corrosion was performed by XPS. The incorporation of Zn in Ni-P thin film is proven for all initial samples to be as a mixture of zinc and zinc oxide, while nickel exists in +2 and +3 oxidized states. A passive film of a mixture of oxide and hydroxide of zinc and nickel forms on the surface and prevents the Zn-Ni-P thin films from corrosion.

Preparation of electrodeposited Zn–Ni–B alloy coatings

“…Zn-Ni-P alloys have been studied by many researchers, who have shown that Zn-Ni-P alloys have a higher corrosion resistance than Ni-P alloys. [7][8][9][10][11][12][13][14][15][16][17][18] However, these amorphous Zn-Ni-P alloys contain less Zn, and no high-Zn-content amorphous Zn-Ni-P coating has been investigated. Therefore, thus far, we have prepared amorphous Zn-Ni-P alloys with high Zn content.…”