Study On The Electrochemical Behavior Of Corrosion Inhibitors Of Aluminium And Its Alloys In 3.5% NaCl Solution

Aluminium and its alloy material have excellent physical properties such as light quality, thermal conductivity,electrical conductivity and good process ability and high recovery performance and have been widely used in transportation,building decoration,aerospace,mechanical appliances, etc.Its production and use have become second only to the iron and steel metal material.Under natural conditions,aluminium can form a layer of surface oxide film.But this layer of membrane is very thin and is easily damaged.Therefore,its corrosion resistance is very poor,which results in the corrosion loss in various environments very amazing each year.In order to improve the corrosion resistance of aluminium material and make aluminium material being used effectively in various applications,domestic and foreign researchers have used a variety of methods to effectively improve its corrosion resistance.In this paper,pure aluminium and its alloys as anode materials were used as the study objects. and Tafel polarization curves and the equivalent circuit of electrochemical impedance spectroscopy were used to study the inhibition behavior of different corrosion inhibitors in 3.5%NaCl solution.The corrosion-resistant mechanism of different corrosion inhibitors was investigated.The main research works are as follows:1.Study on the corrosion inhibition of organic boric group for aluminiumIndustrial high-pure aluminium was self-assembled in a 4-mercaptophenyl-boronic acid solution,and the AC impedance method was then used to study corrosion behaviors of 4-mercaptophenyl-boronic acid on aluminium in 3.5%NaCl solution.The experimental results showed that the corrosion inhibition efficiency was different with the concentration of the 4-mercaptophenyl-boronic acid and assembly time.When the concentration of 4-mercaptophenyl-boronic acid was 3.2×10^-3 mol/L,and assembly time was 12 h,corrosion current was the smallest and the inhibition efficiency was the highest,up to 98%. 2.Study on the corrosion inhibition of melamine for 2024 aluminium alloyMelamine had corrosion inhibition for the 2024 aluminium alloy in 3.5%NaCl solution.When the concentration of melamine was 0.02 mol/L and pH was 5.48,the corrosion inhibition was the best and the efficiency of corrosion inhibition was as high as 97.79%.Melamine belongs to a mixed type inhibitor.3.Study on the corrosion inhibition of sodium benzoate for 6063 aluminium alloyThe experimental results of AC impedance technology and polarization curves showed that sodium benzoate had obvious inhibition of corrosion on the 6063 aluminium alloy in 3.5%NaCl solution.The efficiency of the corrosion inhibition increased with an increase in concentration of sodium benzoate in a certain concentration range.The corrosion inhibition was the best when the concentration of sodium benzoate was 0.4 mol/L.The corrosion inhibition efficiency was 73.37%. However,sodium benzoate is a corrosion inhibitor of anode type;therefore,the amount of its addition should be controlled carefully in the application process.4.Effect of sodium silicate post-processing on corrosion resistance of phosphated 6063 aluminium alloyThe phosphated 6063 aluminium alloy was post-processed with sodium silicate(water glass) solution to improve the corrosion resistance of phosphate coatings.AC impedance technology and polarization curves were used to study the effect of sodium silicate post-processing on corrosion resistance of phosphated 6063 aluminium alloy.The experimental results showed that the phosphated film treated closely with sodium silicate formed a better inhibition corrosion layer,and the corrosion resistance efficiency was related with pre-treatment phosphated time.When the concentration of sodium silicate solution was 10 g/L,closure time was 10 min and phosphating time was 10 min,the corrosion resistance efficiency of the film was the highest and was 97.33%.