Investigation On Preparation And Corrosion Inhibition Of Copper Surface Self-assembled Membrane

Copper and its alloys are widely used in Marine industry because of their excellent physical and chemical properties.However,Cl~-in seawater can easily corrode metals.In order to improve the corrosion resistance of copper,researchers have adopted a variety of methods to prevent accidents,such as adding corrosion inhibitor,coating and surface passivation.Organic corrosion inhibitors are widely used because of their low cost and small amount of additives.Especially containing N,P,S,O heterocyclic compounds,with multiple active adsorption sites,more easily adsorbed on the metal surface,the formation of complex,prevent corrosion intensification.In this paper,considering the direction of adding corrosion inhibitor,we aim to study the corrosion inhibitor with high performance.Self-assembly membrane(SAM)is a highly ordered and dense molecular membrane formed by corrosion inhibitor molecules consciously attached to the metal matrix through chemical bonds.Compared with the traditional corrosion inhibition technology,it has the characteristics of less consumption,high coverage and simple preparation.In this paper,under simulated seawater conditions,we seek for corrosion inhibitors with high performance from two aspects of synthesis and compound.The research contents are as follows:(1)SynthesisofheterocyclicSchiffbases:2-aminobenzimidazole-o-vanillin(ATOV),2-aminobenzimidazole-salicylaldehyde(AMOV).The electrochemical measurement results showed that the inhibition rates of the two inhibitors were 93.61 and 89.92%,respectively,when the concentration was 1.5 g/L and the assembly time was 10h.Corrosion inhibition performance:ATOV>AMOV.The results of surface analysis showed that the two corrosion inhibitors all formed dense protective film on the surface of the copper sheet.After corrosion,compared with AMOV,ATOV had no obvious corrosion phenomenon.(2)2-aminobenzothiazole and benzotriazole complex:when the total concentration of 20 mmol/L,each proportion of 50%,the inhibition rate can reach 99.67%.Two corrosion inhibitors exist physical adsorption(molecular inter-atomic forces)and chemical adsorption(lone pair electrons and metal empty track form coordination compound),and form a dense and orderly protective film on the copper surface,and at the same time,the ABT-BTA assembled on the surface of the Cu contact Angle is bigger,the surface roughness is small,ABT 50%,S=25.32,under this condition,strong synergy.(3)Synthesisofbenzimidazole-Schiffbases:2-aminobenzimidazole-benzaldehyde(AIBE),2-aminobenzimidazole-p-methylbenzaldehyde(AIDE).The electrochemical measurement results show that when the concentration is 15 mmol/L and the assembly time is 10 and 14h,the corrosion inhibition efficiency reaches 86.30and 99.89%,respectively.Corrosion inhibition performance:AIDE>AIBE.The results of surface analysis show that AIBE and AIDE form dense protective film on the copper surface,which can effectively inhibit the corrosion of the metal.Raman spectrum analysis shows that the two corrosion inhibitors adsorb vertically on the metal surface through the imidazole ring and the C=N bond in the Schiff base ligand.The measurement results of optical contact Angle and surface tension show that the hydrophobicity of AIDE is better than AIBE.(4)2-aminobenzimidazole and benzotriazole complex:the results show that the concentration of 20 mmol/L,the ratio of 50%,the inhibition rate of99.98%.The electrochemical measurement results showed that the corrosion current density decreased and the capacitive arc diameter increased compared with the single corrosion inhibitor,indicating that the two corrosion inhibitors had good synergistic effect.The surface analysis results show that when the inhibitor exists alone,the copper surface is covered with a dense and orderly protective layer.When the inhibitor exists together,the compound inhibitor is adsorbed on the metal surface,forming a multi-layer structure,which effectively avoids the shortcoming of incomplete film formation of the single inhibitor.