Improving the Corrosion Resistance of Ni/SS Thin Films by Nitrogen Ion Implantation

Abstract

N + ions were incorporated into nickel-coated 316 stainless steel (SS) at room temperature using different energies (10, 20, and 50 keV) and a fluence of 5 × 10 17 N + cm −2. The microstructure, surface morphology, and corrosion inhibition of the obtained materials were investigated and compared with the properties of the untreated steel using several analytical techniques. The X-ray diffraction patterns indicated the formation of nickel nitride with the ion implantation process. The surface morphology of the samples was studied by atomic force microscopy and statistical and multifractal analytical methods. Moreover, the potentiodynamic polarization test in 3.5% NaCl solution was carried out to evaluate the corrosion properties of the samples. These studies revealed that the generalized fractal dimension, Dq, is dependent on the ion implantation energy and the symmetry of the multifractal singularity spectra, f (α), which is related to the uniformity of the sample. In this manner, the lowest value was obtained for the sample prepared with the maximum ion implantation energy. Also, the increment of the implantation energy yields to increase the corrosion resistance. The simultaneous decrease of the corrosion current density (Icorr) and the increase of the corrosion potential observed with the N + ion-implantation indicate that treated samples are more resistant to corrosion than the untreated steel, and the highest corrosion protection was observed for the maximum implantation energy (50 keV). The correlation between corrosion resistance, structural and surface morphology induced by implantation is discussed.

Influence of ion implantation on corrosion resistance of the nickel over steel

“…However, the choice of implanting energy is another parameter that is essential, Heat treatment at high temperatures can cause austenite to decompose near the grain boundaries and form carbides in these areas. Hence, this causes the discharge of chromium, which is a protective element, from the area around the carbides formed at the boundaries [16,[27][28][29]. Thus, these areas become more sensitive to corrosion.…”