Microbially influenced corrosion (MIC) of copper

摘要

Corrosion found in the heat exchanger pipes made of copper was estimated and found to bemicrobially influenced. Laboratory measurements by the use of the same environments were planed.Underground water from the same plant was transferred to laboratory and was used. Bacteria in thetest solution was activated by the addition of small nutrients in the underground water. Cu sampleswere exposed to the test solution. After 2 weeks, a lot of corrosion sites occurred on the surface aspitting cottosion. On the other hand, corrosion sites as pitting corrosion were not observed using asterilized test solution. Culturing of bacteria residing in the underground water revealed 7 different species of bacteria.It was become that some 4 species of bacteria were killed by microbicidal activity of Cu. The residual3 species were incubated separately in liquid culture. Next, this liquid culture was used as exposuretest solution. Formation of biofilm on the Cu sample surface was observed when the samples wereexposed in the test solution with the Staphylococcus sp. Under the biofilm, a lot of corrosion sites asa pitting occurred. It was become that the Staphylococcus sp. had an ability of proteinaceous fermentation. Thisfermentation produces ammonia. In conclusion, metallic Cu are corroded by the ammonia in the test solution. Corrosion path ofCu pipe by the underground water are discussed.