Study on Biomachining of Metals Using Bacteria

本研究于1996年4月至1997年3月进行了为期2年的研究，目的是利用氧化亚铁硫杆菌这一化化营养细菌对金属进行精细加工。具体情况如下。在常规加工中，将物理或化学能集中到指定的点上，然后对指定的材料进行去除、变形或添加。然而，在本研究提出的生物机械加工中，生物能被用于金属的去除。第一年，首先建立了细菌纯培养方法，并在培养液中进行了加工实验。结果表明，该细菌基本具有加工金属的能力，去除率随加工时间的增加呈线性增加。此外，当低电压加到工件上时，去除料增加了一倍。第二年，对在实际应用中被认为是一大难题的侧蚀问题进行了实验研究。结果表明，刻蚀因子（凹槽深度与宽度之比）约为2，表明金属的去除深度优于凹槽宽度。此外，还尝试了向工件喷射培养液的方法。实验结果表明，该材料的去除率有较大的提高，侧蚀刻减少。今后，还需要进一步研究有效指定切削点的方法和开发加工装置。

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.