| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1991: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
A final purpose of the present research is to develop nontraditional materials processing utilizing microbiogenic functions. As the first step for the purpose, general characteristics of microbial corrosion in the seawater were examined experimentally by the corrosion test for various metals, and from the results a few microbiogenic processings were attempted. Results obtained are as follows:
I. Study on General Characteristics of Microbial Corrosion (1) It was confirmed that a number of microorganisms gathered orientatively to all the tested metals, and inhavited their surfaces and corrosion products. (2) Microbiological effects on the corrosion of oxygen-free high-purity copper (OFHC) were clarified; aerobic bacteria acted to promote hydration of Cu oxide; pits were caused by action of anaerobic bacteria such as sulfate-reducing bacteria (SRB); resultant oxygen concentration cells assisted their formation. (3) Microoganisms preferred to corrode in-grain to grain boundary in the case of killed steels, and thus promotes markedly corrosion, compared with corrosion under a sterile condition.
II. Attempt of Microbiogenic Processing (1) A method to produce concave details on metal surface with the action of anaerobic bacterium, referred to as MBM concave process, was proposed by making artificial anaerobic environment, and was shown to be valid. (2) A principle to produce covex details on metal surface, referred to as MBM convex process, was attempted utilizing the combined action of crevice and microbial corrosions. Small letters were printed on the OFHC surface, although not satisfactory at present. (3) A process to make a metal crystal deposit and grow on the substrate, which was bioprocessed in advance, was presented, and called MBD process. Its validity was confermed by making copper crystals.
These results were presented at The JSME Tokai Branch Summer Conference (1992), and are to be reported at the International Seminar (IMM'93 Mie) held in 1993.
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