NiW Alloys Electrodeposited under Super Gravity Field and Their Anti-Corrosion Properties in Alkaline Solutions

Abstract

NiW alloys were electrodeposited under a super gravity field. The effects of super gravity on the partial current density, W content, and cell voltage were studied. The surface morphologies of the NiW films were characterized by scanning electron microscopy (SEM). The anti-corrosion properties and stability of the NiW films in NaOH solution were also studied by Tafel, electrochemical impedance spectroscopy (EIS), and 144 h exposure test. The results indicate that the W content increases with the gravity coefficient (G) and no cracks are produced on the surface of the NiW alloys electrodeposited under the super gravity field. Compared with those electrodeposited under normal gravity conditions, the self-corrosion potentials of the NiW alloys electrodeposited under a super gravity field shifts in a positive direction and the self-corrosion current densities become smaller. Meanwhile, the corrosion resistance also increases from 865 to 2305 ohm.cm(2) with an increase in the G value from 1 to 256. After 144 h exposure in 10% (w) NaOH solution, no surface peeling or damage occur. We conclude that when the NiW alloy is electrodeposited under a super gravity field, both the anti-corrosion resistance and the stability of the NiW alloy in the NaOH solution are improved obviously.