Improving corrosion resistance of AZ31B magnesium alloy via a conversion coating produced by a protic ammonium-phosphate ionic liquid

Abstract

Magnesium alloys are susceptible to corrosion because of their high reactivity and low electrode potential. The present work introduces a conversion coating using a protic ammonium-phosphate ionic liquid (IL). Initial results on the Mg AZ31B alloy have demonstrated substantially improved corrosion resistance for the IL treatment at 300 °C (IL_300C) compared to the treatment at room temperature. Potentiodynamic polarization analysis of the IL_300C treated Mg surface in a NaCl solution exhibited a strong passivation behavior. No pretreatment is needed and the treated surface morphology is well preserved. Cross-sectional nanostructure examination using transmission electron microscopy and element mapping using energy-dispersive X-ray spectroscopy have revealed the IL_300C conversion coating to be a 70-80 nm thick with a twolayer structure. Further surface chemical analysis using X-ray photoelectron spectroscopy suggested such an IL conversion coating possibly composed of metal oxides, metal phosphates, and carbonaceous compounds.

The ecotoxicity and tribological properties of choline monocarboxylate ionic liquid lubricants

“…From the SEM images, it can be seen that with the growth of the alkyl chain, more and more pittings are formed on the surface of the copper sheets. It can be concluded that for [Ch][MA] ILs, the longer the alkyl chain is, the more severe the corrosion . But the corrosion of all the [Ch][MA] ILs are much lower than that of L‐B104.…”

“…It can be concluded that for [Ch] [MA] ILs, the longer the alkyl chain is, the more severe the corrosion. 31 But the corrosion of all the [Ch][MA] ILs are much lower than that of L-B104. On the basis of the above analysis, it can be concluded that the corrosion resistance of [Ch][MA] ILs is superior to that of L-B104.…”

Preparation and corrosion resistance of Ni‐P bilayer on magnesium alloy

“…It is well known that magnesium alloys have been widely applied in automobile, aerospace, electronic communication and recreational industries due to their low density, high strength and excellent machinability . However, corrosion problems are often encountered for magnesium alloys when exposed in seawater, humid atmosphere with organic/inorganic acids and other salts because of their high chemical reactivity .…”

Magnesium and Aluminum Oxides Formation Via Conversion Coating of Magnesium Metal in Alcl3/Urea Room Temperature Ionic Liquid

“…They are generally nonvolatile, high thermal stability, wide and stable electrochemical window [15], nonflammable and can have a low toxicity, thus show promise as replacements for toxic molecular solvents [16]. Few works involved ILs treatment for corrosion protection of magnesium metal based on phosphates, for example trihexyl (tetradecyl) phosphonium bis (trifluoromethylsulfonyl) amide ([P 6,6,6,14 ] [17], ammonium phosphate IL [18] and halogen-free phosphonate ILs [19].…”