Creation Of New Copper/Aluminum Organic Corrosion Inhibitors And The Study Of Its Corrosion Inhibition/Failure Behavior

Copper/aluminum and its alloys are widely used in many fields of production and life.Inhibiting the corrosion of copper/aluminum and its alloys in relevant corrosive media has important practical significance.Inhibiting the corrosion of copper/aluminum and its alloys by adding corrosion inhibitors has the characteristics of simple process,good protection effect and strong applicability,so it has been widely concerned by researchers.Although there have been a large number of reports on the synthesis and application of corrosion inhibitors for copper/aluminum and its alloys in the literature,the following challenges are still faced.Firstly,the types and quantity of developed corrosion inhibitors for copper/aluminum and its alloy are inferior to those of carbon steel and other metal materials.Secondly,some common corrosion inhibitors have room for improvement in the corrosion inhibition performance in specific corrosion environments,and the chemical structures need to be redesigned to improve the corrosion inhibition performance.Finally,the lack of regularity research on the cracking of adsorption film and law of failure behavior hindered the in-depth understanding of the corrosion mechanism and the multi-faceted evaluation of the corrosion inhibitors.In response to the above problems,this paper has done the following work around the development of non-ferrous alloy copper/aluminum corrosion inhibitors:(1)Based on the excellent corrosion inhibition properties of imidazoline for iron-based alloys,amidino,S atom with good electron donating ability,pyrimidine and pyridine with good electron donating ability were introduced into the molecular structures to design and synthesize a new type of N-substituted-2-amidino-5-(2-mercaptopyrimidinyl)pyridine compounds.They are N-butyl-2-amidino-5-(2-mercaptopyrimidinyl)pyridine(P1),N-cyclo-hexyl-2-amidino-5-(2-mercaptopyrimidinyl)pyridine(P2),N-(2-aminoethyl)-2-amidino-5-(2-mercaptopyrimidinyl)pyridine(P3).The structures were proved correct by 1H-NMR,13C-NMR and HRMS.The corrosion inhibition behavior of brass in flowing 1 M HNO3 medium was studied,and the corrosion inhibition efficiency was as high as 98%under the condition that the usage amount was only 50 ppm.N-cyclohexyl-2-amidino-5-(2-mercapto-pyrimidinyl)pyridine still maintains good surface integrity after being soaked and washed for 12 hours and its excellent corrosion inhibition performance comes from the synergistic corrosion inhibition effect among the multi-groups containing N heterocycle,amidino group,S atom and so on.(2)Based on the structural characteristics of amide corrosion inhibitors,salicylic acid and Schiff base organometallic compounds,the electron-withdrawing group C?N group and the amide group with corrosion inhibition activity were introduced into salicylic acid by amidation reaction.A new type of N-cyano-salicylamide corrosion inhibitors with"amide-cyano" structural characteristics was designed and synthesized.The structures were proved correct by 1H-NMR,13C-NMR and HRMS.The corrosion inhibition behavior of N-cyano-salicylamide corrosion inhibitor in 5%NaHCO3 solution for pure copper was studied.The corrosion inhibition rate can reach about 90%under the condition of 300 ppm.Not only does it have high corrosion inhibition efficiency,but also the molecular stability and safety of this corrosion inhibitor are better than that of benzotriazole(BTA);The Cl-in the environment affects the corrosion inhibition efficiency of the corrosion inhibitor.The improvement of the corrosion inhibition efficiency of the corrosion inhibitor is attributed to the charge center "amide-cyano" structure formed in the molecule.(3)Based on the structural characteristics of mesotriazine and amino acid,the triazine ring with some N atoms was used as the parent group,and the methionine with S atoms and different organic amines were introduced respectively to design and synthesize a new kind of corrosion inhibitors in characteristics of "triazine-methionine":methionine-di-n-butylamine(T1),methionine-diethylamine(T2)and methionine-aniline(T3).The structures were proved correct by 1H-NMR,13C-NMR and HRMS.The corrosion inhibition behavior of 2024-T3 aluminum alloy in 1 M HCl medium was studied.When the usage amount is only 50 ppm,the corrosion inhibition efficiency can reach up to 99%,which solve the problem of large amount and poor performance when amino acids used alone for aluminum alloy protection,which solves the problem of amino acid used alone for aluminum alloy protection.When its concentration is greater than 200 ppm,it can effectively reduce the occurrence of local corrosion.The improved corrosion inhibition performance of the corrosion inhibitors is due to the synergistic corrosion inhibition effect between groups such as "triazine-methionine".