Corrosion Behavior And Inhibition Method Of 304 Stainless Steel By Corrosive Bacteria In Seawater Environment

The corrosion caused by microorganisms or affected by microorganisms is called microbial corrosion.Marine metal construction,shipping,marine defense and other fields have been seriously affected by microbial corrosion,causing huge losses to the national economy.Therefore,microbial corrosion and corrosion of steel in the marine environment have attracted widespread attention.Stainless steel(type 304)is a kind of material with good corrosion resistance,but under the action of microorganisms,it is also prone to localized corrosion,which greatly affects the application of stainless steel in the ocean.In order to study the mechanism of corrosion of stainless steel by microorganisms and to reduce the loss caused by corrosion,several strains of bacteria were screened out from the corroded steel rust layer soaked in seawater.The combination of Zobell 2216 E culture medium and 16 S r DNA analysis showed that the aerobic microorganisms in these rust layers were mainly Exiguobacterium,Halomonas,Fontibacter flavus,and Imtechella halotolerans.These bacteria were individually added to sterilized seawater impregnated with 304 stainless steel pieces.After 30 days of culture,according to the microscopic corrosion morp Hology of the surface of the steel sheet,the corrosion ability was as follows: Fontibacter flavus>Imtechella halotolerans> Exiguobacterium> Halomonas The Fontibacter flavus and Imtechella halotolerans were added into sterilized seawater to form a mixed bacteria system.The mixture was allowed to stand at 30° C.for 30 days.The analysis of atomic emission spectrometry(Atom Spectrometry)showed that the mixed system was average for 304 stainless steel.The corrosion rate is greater than the individual bacteria system.Further studies have found that iron bacteria belong to the family Cyclobacteriaceae and iron-reducing bacteria and are gram-negative bacilli that show exponential growth at 3-4 days of culture.The bacteria are widespread in natural seawater and are the main marine organisms that corrode stainless steel.The experimental results of suppressing steel corrosion show that Cu,Sb,Si C,Cu O and Sn all can significantly inhibit the growth of iron bacteria,and the inhibitory strength is Cu>Cu O>Sn>Sb>Si C.Applying these powders with epoxy resin to coat the surface of 304 stainless steel can prevent corrosion of 304 stainless steel by iron bacteria.Scanning electron microscopy was used to observe the microscopic morp Hology of the powder surface.Among them,Si C powders are sharp-edged crystals,which can wear stainless steel and increase corrosion,and are not suitable for stainless steel surface coating.This shows that the microscopic morp Hology of particles also affects steel corrosion.The Cu O powder with better performance and lower cost was analyzed and its application in the marine industrial environment was expected.