Study On Microbial Corrosion Behavior Of 2024 Aluminum Alloy Based On Bioenergetics

Aluminum and its alloys are widely used in industry due to their superior physical properties,and the aluminum oxide passivation film on the surface will improve the corrosion resistance of the substrate.However,when the biofilm adheres to the aluminum alloy surface,it will destroy the aluminum oxide film and corrode the alloy matrix and cause pitting corrosion.Microbial corrosion will cause serious losses to industrial production operations and economic development,and bring unpredictable harm.The mechanism of biological cathode catalyzed sulfate reduction is based on the perspective of bioenergetics and biological electron transfer,which provides a new idea for studying the mechanism of microbial corrosion.From the perspective of bioenergetics,this paper conducts theoretical analysis from the thermodynamic point of SRB-induced aluminum alloy corrosion.Through experimental methods such as cell counting,electrochemical methods,and corrosion surface analysis techniques,the corrosion behavior of sulfate-reducing bacteria on 2024 aluminum alloy is carried out.A systematic study.Sulfate-reducing bacteria is a typical representative of anaerobic bacteria corroding metals,and the study of its corrosion mechanism has certain reference significance for the metal corrosion behavior of other anaerobic bacteria.At present,there is no report on the type of microbial corrosion caused by SRB metabolic activity on 2024 aluminum alloy.In this paper,we designed a carbon source starvation experiment to control the organic carbon source needed for the growth of SRB to study the effect of SRB on the corrosion behavior of 2024 aluminum alloy.The result found that the content of carbon source will affect the life activities such as cell division and reproduction.The diffusion of carbon sources and corrosive substances will affect the corrosion process and become a factor in controlling the corrosion reaction.In the low-carbon source medium,the starved SRB was more aggressive for survival than in the high-carbon source medium.The corrosion behavior of SRB on 2024 aluminum alloy is due to the fact that SRB metabolizes corrosive substances to destroy the aluminum oxide film to cause chemical corrosion and the bare aluminum alloy matrix provides electrons for SRB to carry out extracellular electron transfer and electrochemical corrosion combined.Since the proliferation of microorganisms in the aqueous solution at the bottom of the aircraft fuel tank poses a serious threat to the safe operation of the aircraft,the simulation experiment of microbial corrosion of the 2024 aluminum alloy at the bottom of the aircraft fuel tank is used to study the effects of a single strain of SRB and a mixed strain of SRB and IOB under different biofilm forms.Corrosion behavior of 2024 aluminum alloy.It was found that when SRB and IOB exist in the same environment,there will be growth inhibitory in the early stage（1d-3d）,which will increase a growth retardation period compared with the growth cycle of a single SRB.SRB and Cl^-are adsorption competition on the surface of aluminum alloy,and active SRB is the main step to control the corrosion rate.The hydroxyl groups generated by Cl^-and corrosion product Al（OH）₃ will adsorb on the surface of the alloy to make the corrosion morphology appear flower-like.During the experiment,the metabolic activity of SRB is different,and corrosion products with different morphologies are generated.After 15 days of experiment,the adsorption amount of mixed bacteria on the alloy surface was much greater than that of a single SRB.The pitting corrosion phenomenon under the action of mixed bacteria on the alloy surface was more significant.SRB and IOB had a synergistic effect on the corrosion of 2024 aluminum alloy.The corrosion behavior of mixed bacteria is closer to the effect of bacteria in the actual environment,which provides certain theoretical support for the prevention and control of microbial corrosion in aircraft fuel tanks.