Study On Performance Of Corrosion Inhibitor Compound On Galvanic Corrosion Of Aluminum Alloy-Stainless Steel

With the process of modernization,high-speed rail has become one of the main means of travel.The connecting parts between the carriage and the base are often made of aluminum alloy and stainless steel.When these two metals are in contact with each other in harsh environments,a large potential difference is likely to be formed,causing severe galvanic corrosion and affecting the service life of components.In order to solve the problem of galvanic corrosion caused by aluminum alloy and stainless steel,the compound method of corrosion inhibitor was used to study the corrosion behavior of the A7N01 aluminum alloy and the 304 stainless steel phase contact components,adding organic and inorganic corrosion inhibitors,and discussed the corrosion inhibition mechanism in this paper.It provides a theoretical basis for the connection of dissimilar components to prevent or reduce the occurrence of galvanic corrosion.In this paper,galvanic corrosion and electrochemical corrosion tests were studied by using Galvanometer and Electrochemical test equipment,respectively,and the surface morphologies of the sample before and after corrosion process were observed and analysised through using metallographic microscope(OM),Effect of the corrosion inhibition on the couple pairs of the A7N01 aluminum alloy and the 304 stainless steel under the condition of acidic(p H=2)3.5%Na Cl solution was studied by adding the different contents of ammonium molybdate,the ammonium dihydrogen phosphate,the sodium tripolyphosphate,the sodium benzoate,the sodium gluconate and the lemon corrosion inhibitor in 3.5%Na Cl solution,respective,and the synergistic effect of these inhibitors has been investigated.The higher the concentration of corrosion inhibitor was,the higher the efficiency of slow release was.The corrosion inhibition efficiency in the corrosion solution of 10.0g/L ammonium molybdate was 87.35%and of 6.0g/L ammonium dihydrogen phosphate was 71.29%and of 3.0g/L sodium tripolyphosphate was 97.90%;adding sodium citrate 1.8g/L in the solution reached 98.48%,while adding 3.0g/L sodium benzoate and3.0g/L sodium gluconate were 89.25%and 86.90%,respectively.Except for sodium citrate and sodium tripolyphosphate,the corrosion inhibition efficiency of the other four corrosion inhibitors had yet to be perfected.By comparing the results,considering the synergistic effect of corrosion inhibitor compounding,ammonium molybdate was selected to compound ammonium dihydrogen phosphate and sodium tripolyphosphate,and sodium benzoate was compounded to sodium gluconate and sodium citrate.The experimental results of the corrosion inhibitor compound showed that the corrosion inhibition rate was 97.90%when the compound additive was 3.0g/L ammonium molybdate and 0.8g/L ammonium dihydrogen phosphate in the corrosion solution,and the corrosion inhibition effect of 0.8g/l sodium citrate and 0.4g/l benzene sodium formate compound reached 99.26%,1.8g/l sodium gluconate and 1.0g/l sodium benzoate compound reached 90.89%,0.8g/L sodium gluconate and 0.8g/L sodium benzoate and 0.8g/L sodium benzoate thiourea compound reached 99.36%.This result showed that the compounding of the corrosion inhibitor made the protective film formation on the metal surface more stable,and could fill the defects between the protective films,further increasing the coverage of the aluminum alloy surface,and thus improved the corrosion inhibition efficiency.After screening,sodium citrate,sodium tripolyphosphate,ammonium molybdate and sodium tripolyphosphate,sodium citrate and sodium benzoate,sodium gluconate and sodium benzoate and thiourea were selected.The SEM and EDAS tests showed that the five corrosion inhibitors had obvious slow release effect on the material,and the synergistic effect of the inorganic corrosion inhibitor was mainly through the formation of a precipitation film with metal ions and the competitive adsorption of Cl~-.The synergistic effect of organic corrosion inhibitor compounding was mainly through the formation of chelate complexes between oxygen elements on carboxyl groups and metals,and anions could combine with metal ions to form precipitations,which played a role in corrosion inhibition.