Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

Abstract

Surface coatings formed by immersion in the ionic liquids (ILs) 1,3-dimethylimidazolium methylphosphonate (LMP101), 1-ethyl-3-methylimidazolium methylphosphonate (LMP102) and 1-ethyl-3-methylimidazolium ethylphosphonate (LEP102) on magnesium alloy AZ31B at 50 °C have been studied. The purpose of increasing the temperature was to reduce the immersion time, from 14 days at room temperature, to 48 hours at 50 °C. The abrasion resistance of the coated alloy was studied by microscratching under progressively increasing load, and compared with that of the uncoated material. The order of abrasion resistance as a function of the IL is LEP102 > LMP101 > LMP102, which is in agreement with the order obtained for the coatings grown at room temperature. The maximum reduction in penetration depth with respect to the uncovered alloy, of a 44.5%, is obtained for the sample treated with the ethylphosphonate LEP102. However, this reduction is lower than that obtained when the coating is grown at room temperature. This is attributed to the increased thickness and lower adhesion of the coatings obtained at 50 °C, particularly those obtained from methylphosphonate ionic liquids. The results are discussed from SEM-EDX and profilometry.

Surface Coating from Phosphonate Ionic Liquid Electrolyte for the Enhancement of the Tribological Performance of Magnesium Alloy

“…An attempt has been made to optimize the formation of protective coatings and reduce immersion times by increasing temperature to 50°C. 69 In all cases, the coatings formed by immersion in [EMIM][EtPO 3 H] presented the best tribological performance under scratching when compared with other alkylphosphonate alkylimidazolium ILs. The presence of other elements in the composition of magnesium alloys, such as Zn in EZ33A, prevents the formation of an abrasion protecting coating due to the low reactivity of Zn with ionic liquids.…”

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].…”

Estudio del comportamiento tribológico y de las interacciones de superficie de nuevos nanofluidos iónicos

“…Por ello, se está intentando desarrollar líquidos iónicos libres de halógenos y fósforo como aditivos de lubricantes eficientes y respetuosos con el medio ambiente [6,174,175,[209][210][211][212][213].…”

“…Como se ha visto, además de otras muchas aplicaciones científicas y tecnológicas, los líquidos iónicos están siendo estudiados como lubricantes de alto rendimiento para la ingeniería [2,17,22,23,28,29,[40][41][42][43][44] y precursores de recubrimientos protectores de superficies [210,222,223]. En ambos campos, la habilidad de las moléculas de IL para formar capas superficiales estables tiene mucha importancia.…”

“…Los aniones tetrafluoborato y hexafluorofosfato ya han sido estudiados como lubricantes [44,[48][49][50][51][52]255,256]. Los derivados del fosfonato están siendo estudiados como precursores de recubrimientos contra la abrasión [210,[221][222][223]. Los líquidos derivados del anión octilsulfato se consideran más respetuosos con el medio ambiente que los que contienen flúor [84].…”