Application Of Alkylimidazoline Quaternary Ammonium Ionic Liquids In Metal Surface Pre-treatment Process

Due to the advantages of stability、designable and so on,ionic liquids are widely used in fields that organic synthesis、separation and purification、catalysis and electrochemical.As corrosion inhibitor which are added in acidic medium to inhibit or prevent corrosion of metallic materials, imidazoline and its derivatives exhibits excellent performance.Metal surface pre-treatment technology is the basis for metal protection technology and metal coating technology.In this paper,lauric acid,polyethylene polyamine and ethyl bromide,benzyl chloride were selected to synthesize two alkyl imidazoline ionic liquids.The structure of target product and their intermediates are characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy.Immersing Q215 steel with aqueous ionic liquids,as metal surface treatment agent,we got the two ionis liquids’ appropriate soaking time and the concentration by Tafel test and AC impedance test.In order to detect two ionic liquids’ stability in corrosive media,treating metal with ionic liquids under the optimum condition which were obtain by electrochemical method,then put these metals in corrosive media,the morphology of metal surface was observed by a scanning electron microscope.Selecting H2 Zr F6 For comparison treating agent,compare the different types of pre-treatment agents’ impact on the surface morphology of the metal in corrosive media.Detecting ionic liquids’ adhesion to metal surface with neutral salt spray test two former metal surface treatment agent,As additive,H2 Zr F6was add to ionic liquids for examine its effect on ionic liquids’ corrosion resistance and adhesion to the metal.Tafel results show that at the same concentration,corrosion current density of the substrates impregnated in ionic liquids has been reduced than that untreated substrate.When the product 1 and 2 impregnated substrate respectively 20 min and 25 min,the corrosion current density appear minimum income,however,under the same immersion time,the corrosion current density of substrates pretreated with product 2 are all less than thatpretreated with product 1.In the corresponding optimum processing time,with increasing concentration of the two treatment agent solution,the substrate surface took on maximum polarization resistance when product 1 and 2 respectively at the concentration of 2.0g/L and4.0g/L.Their is no further increase of the substrate polarization resistance but even has been reduced with increasing the two ionic liquids’ concentration.Thus as a pretreatment agent,the optimal conditions for the product 1 and product 2 are respectively 20 min,2.0g/L and25 min,4.0g/L.Tracking metals’ morphology in corrosive environments by scanning electron microscopy.At the beginning of the time,in addition to the adsorbed protective film, there is no other on surface of metals which were pretreated by two ionic liquids,and because of its acidity,many pitting corrosion produced in the H2 Zr F6 pretreated metal.With the time in corrosive media extending,protective film of metal pretreated by two ionic liquds were gradually damaged.After the metal were placed in corrosive media 30 min,two ionic liquids treated metal surface has a large area of severe corrosion,at the same time H2 Zr F6 treated metal surface changed little than the initial time.After painting,salt spray test were arranged for metal which were pretreated by two ionic liquids.Meanwhile,H2 Zr F6 were added to the solution of two ionic liquids for terms that investigate its role in improving two pre-treatment agent adhesion to the metal surface.After96 h,the surface of untreated model took on moderate corrosion.Metals pretreated by two ionic liquids have slight corrosion on the surface of the specimen.When H2 Zr F6 was added into ionic liquid,the corrosion extent of metals by the new pretreatment has reduced.