Naoki Washizu and Hiroyuki Masuda
National Research Institute for Metals, Tsukuba 305
It is known that iron-oxidizing bacteria (IOB) enhance corrosion of metals. But the influences of corrosion on IOB are still uncertain. The purpose of this study is to examine the effect of metal surface condition on the behavior of IOB.
The surfaces of Cu, Ni and SUS304 steel were observed by AFM (atomic force microscope) after 24 h immersion in water including IOB at pH 3. On the surfaces of Cu and Ni, corrosion was induced and many cells of IOB adhered. On the surface of SUS304 steel, corrosion was not induced and a few cells of IOB were observed.
The surfaces of SUS304 steel were observed by AFM after 48 h immersion in water including IOB at pH 2. Cells of IOB on the sites where no corrosion occurred did not segment. However, most of cells of IOB close to pits or intergranular corrosion sites segmented. Therefore, it seems that the corrosion activated IOB.
According to the above, the result is as follows:
1. IOB tend to adsorb on corrosion site.
2. IOB are activated by corrosion.
(Received November 15, 1996)
atomic force microscope, iron-oxidizing bacteria, corrosion, copper, nickel, SUS304 steel, adhesion, pit, intergranular corrosion, segmentation, activity
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