Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

Abstract

Cerium-vanadium (Ce-V) conversion coating was proposed as a new pretreatment for application of electroless NiP coating on AM60B magnesium alloy to replace the traditional chromium oxide pretreatment. Morphology and chemical composition of the conversion coating were investigated. The subsequent NiP coating deposited on the conversion coating was also characterized by morphology, chemical composition, microstructure, corrosion protection performance and micro-hardness. A uniform, compact and pore-free electroless coating with a moderate concentration of phosphorus (7.78 wt%) was obtained. The electroless coating showed a nobler opencircuit potential than that of the bare alloy during the first 13 h of immersion in 3.5 wt% NaCl solution. Also, the sample plated with the Ce-V conversion coating showed lower corrosion current density than the sample plated with traditional chromium oxide pretreatment. The micro-hardness of the bare alloy was significantly increased after electroless coating. The electroless coating is pore-free and there is suitable adhesion between the coating and alloy substrate.

Electroless Ni–B–MMT nanocomposite on magnesium alloy

“…The PDP parameters were extracted by a Tafel extrapolation technique. A comparison of the obtained results with those estimated for the bare AM60B magnesium alloy in our recent study [55] indicates a significant positive shift in the corrosion potential from about −1.54 to −0.33 V (with respect to the saturated silver-silver chloride reference electrode) and also remarkable decrement in the i corr from about 46.89 to 0.12 µA cm −2 . These facts clearly show that the plain nickel-boron layer improves the polarization resistance of the magnesium substrate.…”

Investigation of graphene-reinforced magnesium metal matrix composites processed through a solvent-based powder metallurgy route

“…Graphene has great potential to be used as a reinforcement material in polymers and metals and thus improves the performance of composites owing to its inherent strong mechanical properties, chemical inertness, thermal stability and good electrical properties [1][2][3][4]. Nowadays, magnesium (Mg)-based alloys are of great interest in industrial sectors due to their low density which supports weight reduction in the transport industry thereby increasing fuel efficiency [5][6][7][8][9]. Carbon nanomaterial has attracted attention as a positive reinforcement for Mg [10] and its alloys over the last two decades because of its capability of improving strength in structural applications [11].…”

The Influence of magnesium alloy surface roughness on Ce salt conversion film corrosion resistance

“…As a new type of green material in the 21st century, magnesium alloys have many excellent properties, such as low density, high specific strength and stiffness, good electromagnetic shielding performance, and has good application prospects in automobile, aerospace, military and communication electronics [1][2][3]. However, due to the low standard electrode potential and high electrochemical activity of magnesium alloys, the corrosion resistance of magnesium alloys is poor, which limits their application in industrial practice [4].…”