Investigation of Fine Biomachining of Metals by Using Microbially Influenced Corrosion

为了将微生物腐蚀（MIC）应用于金属的精细生物加工，研究了pH值对一种铁氧化细菌氧化亚铁硫杆菌（ThiobacillusFerrooxidans）在9 K介质和培养液中的培养以及对低碳钢和铜的生物加工质量损失的影响。通过在9 K培养基和细菌培养液中的电化学测量和表面膜的观察，探讨了金属的生物加工机理，在pH1.5的9 K培养基中，细菌的数量随培养时间的延长而增加。2.0. 2.5和3.0。在除1.5外的其它pH条件下，在3 ~ 4 d时，酶活性达到最大值。低碳钢和铜在pH 1.5的菌液中的生物加工质量损失最大，在pH 2.5时达到最小值后，在pH 3.0时又有所增加。细菌培养产生的Fe_2（SO_4）_3作为氧化剂加速了铁和铜的生物机械质量损失 ...更多信息 分散剂在9 K介质和细菌培养液中，铁和铜的生物加工质量损失分别约为30 mm/y和6 mm/y，软钢的表面比铜的表面粗糙。在细菌培养液中进行生物加工后，低碳钢的表面粗糙度约为30 μm。另一方面，铜的粗糙度约为3 μm。低碳钢和铜一般都受到腐蚀。而在9 K介质和细菌培养液中，低倍观察到低碳钢表面组织出现局部点蚀。在所有的溶液中，铜通常受到攻击。铜的生物机械加工表面与低碳钢的生物机械加工表面的差别在于其具有非常精细的结构，在细菌培养液中，低碳钢的阴极极化曲线在-750 ~-900 mV zsSCE范围内有很大的去极化。这种由Fe^<3+> + e → Fe^<2+>还原反应引起的去极化加速了金属的溶解。在9 K介质中，FeSO_4膜阻止了碳钢和铜的溶解，而在细菌培养液中，由于细菌的作用，FeSO_4膜不形成，Fe^<3+>的氧化作用加速了溶解

In order to use microbially influenced corrosion (usually MIC) for the fine biomachining of metals, influence of pH on both culture of Thiobacillus Ferrooxidans of a kind iron oxidizing bacteria and biomachining mass loss of mild steel and copper in 9K medium and the and the bacteria-cultured solution has been investigated. Furthermore, the biomachining mechanism of metaks has been investigated both by electrochemical measurements in 9K medium and the bacteria-cultured solution and observations of the surface fils.The cells of bac-teria increased with culture time in 9k medium of pH 1.5. 2.0. 2.5 and 3.0. though they became maximum on 3 to 4 days at other pH except 1.5. The biomachining mass loss of mild steel and copper in the bacteria-cultured solution became larger at pH 1.5 than other pH and then after it became the least at pH 2.5, it increased again at pH 3.0. Fe_2 (SO_4)_3 whi-ch was produced through culture of bacteria accelerated biomachining mass loss of iron andcopper as oxi … More dizing agent. Biomachining mass loss of iron and copper were respectively about 30 mm/y and 6 mm/y of dissolution in 9K medium and the bacteria-cultured solution.The surface of mild steel was rougher than copper's in 9K medium and the bacteria-cultured solution. The surface roughness of mild steel was about 30 μm after biomachining in bacteria-cultured solution. On the other hand, the copper's roughness was about 3 μm. Both mild steel and copper were generally attacked. But localized pitting attacks were observed on the surface microstructures of mild steel through low magnification in 9K medium and the bacteria-cultured solution. In all solution, copper was generally attacked. The biomachined surface of copper differed from that of mild steel in the point of the very fine structures.Cathodic polarization curves of mild steel depolarized greatly in the region of -750 to -900 mV zs SCE in the bacteria-cultured solution. This depolarization caused by the reduction reaction of Fe^<3+> + e → Fe^<2+> accelerated the dissolution of metals. In 9K medium, the dissolution of mild steel and copper was prevented by FeSO_4 film, however, in the bacteria-cultured solution FeSO_4 film was not formed owing to the action of bacteria and the dissolution was accelerated by oxidizing effect of Fe^<3+> Less