The Corrosion Inhibition And Mechanism Research Of Triethanolamine For Magnesium Alloy In Sodium Chloride Solution

Magnesium alloy is a kind of metal material that is the most rapidly used in modern industry,due to their advantages such as low density,high specific strength and specific stiffness,good machining and recycling ability and so on.But Mg alloy has a relatively poor corrosion resistance,it is easily corroded in corrosive medium.These have restricted the further application of magnesium alloys.Therefore,the appropriate surface treatment can enhance the corrosion resistance of the Mg alloy which has important practical significance.The corrosion inhibitors is a simple and effective method for inhibiting the corrosion of metals.Besides,the surface coatings have good protection,adornment and beautification for the metal substrate.Therefore,we systematically investigated the corrosion inhibition performance and the anti-corrosion mechanism of triethanolamine(TEA)and its composite coatings for AZ91 D magnesium alloy in 3.5 wt.% NaCl solution around the corrosion inhibitors and the surface coatings two anti-corrosion technology by immersion experiments,electrochemical measurements,surface analysis,and theoretical studies.It could obtain the following results:TEA as the mixed type inhibitor could effectively decrease the corrosion of Mg alloy in the NaCl solution.The adsorption behavior of TEA on the Mg alloy surface was found to follow the Langmuir adsorption isotherm,which was a spontaneous,exothermic process of increased entropy.And after the addition of TEA,the differential capacitance curve of Mg alloy appeared adsorption platform and the potential of zero charge(PZC)shifted to the positive direction.With the anodic polarization strengthened,surface coverage of TEA on magnesium alloy decreased,produced anodic desorption phenomenon.The results showed that TEA could adsorb on the Mg alloy surface by N,O impurity atoms,and decreased the corrosion of Mg alloy.In addition,TEA was respectively compounded with the sodium silicate(SS)and the glucose(GLC).The results showed that the two compound corrosion inhibitors could decrease the corrosion of Mg alloy in the NaCl solution,which showed good synergistic corrosion inhibition effect.When the concentrations of the TEA and the sodium silicate respectively were 3 ml/L and 7 g/L,the TEA/SS inhibitors had the best synergistic inhibition effect,and the best inhibition efficiency was 95.66 %.When the concentrations of the TEA and the glucose respectively were 3 ml/L and 500 mg/L,the TEA/GLC inhibitors had the best synergistic inhibition effect,and the best inhibition efficiency was 95.52 %.The SEM and XPS images suggested that TEA/SS compound corrosion inhibitors and TEA/GLC compound corrosion inhibitors could form a compact adsorption film on the Mg alloy,so it couldeffectively suppress the corrosion of Mg alloy in the NaCl solution.Besides,the triethanolamine/graphene oxide(TEA/GO)composite coatings were prepared by electrodeposition on the Mg alloy surface.The results indicated that the TEA/GO composite coatings were distributed evenly on the Mg alloy surface.It exhibited a good barrier between the substrate and corrosive medium to prevent the aggressive ions from the substrate surface.The composite coatings could improve availably the corrosion resistance of the magnesium alloy.