Study on Biomachining of Metals Using Bacteria

本研究从1996年4月至1997年3月进行了为期两年的利用化能无机营养菌氧化亚铁硫杆菌对金属进行微细加工的研究。详情如下。在传统的加工中，物理或化学能量被集中到指定的点，然后尖材料被去除，变形或添加。然而，在这项研究中提出的生物机械中，生物能源被用于去除金属。第一年，首次建立了细菌的纯培养方法，并在培养液中进行了加工实验。结果表明，该菌基本上具有金属切削能力，切削量随切削时间的增加而线性增加。此外，去除股票成为两倍时，低电压被添加到工件。第二年，对实际应用中的一个大难题--侧面腐蚀问题进行了实验研究。结果，作为槽的深度与宽度之比的蚀刻因子约为2，这表明金属去除的深度优于槽的宽度。此外，还尝试了向工件喷射培养液。实验结果表明，去除率有较大幅度的提高，侧蚀减少。今后，还需要进一步研究有效的去除点设计方法和加工装置的开发。

This study has done for 2 years from Apr.1996 to Mar.1997 in order to machine metals finely using Thiobacillus Ferroxidans which is a kind of chemolithotrophic bacteria. The details is as follows. In the conventional machining, physical or chemical energy is concentrated to the designated point, then the pointed material is removed, deformed or added. However in the biomachining proposed in this study, biological energy was used for the removal of metals. In the first year, the method of pure culture of bacteria was firstly established and the machining experiment was done in the cultured fluid. It was cleared that this bacteria hadbasically the ability of machining of metals and the removal stock increased linearly with the machining time. Furthermore, the removal stock became twice when the low voltage was added to the workpiece. In the second year, the problem of side etch which was consideted to be a big touble in practical use was experimentally investigated. As a result, etch factor which is the ratio of depth to width of groove was about 2, which indicates the depth of superior in metal removal to the width of groove. Moreover, the jet injection of cultured fluid towards the workpiece was tried. The experimental results pointed out that the removal rate increased by a large margin and the side etch decreased. From now on, further investigations of method of effective designation of removal point and the development of machining device are needed.