抗菌时效处理对含Cu双相不锈钢组织和性能的影响 Ⅱ.耐蚀及抗菌性能

EFFECTS OF ANTIBACTERIAL AGING TREATMENT ON MICROSTRUCTURE AND PROPERTIES OF COPPER-CONTAINING DUPLEX STAINLESS STEELⅡ.Corrosion Resistance and Antibacterial Properties

采用电化学方法分析了经抗菌时效处理后的含Cu双相不锈钢耐腐蚀性能,同时采用覆膜法测试了其广谱抗菌效果.极化曲线测试结果表明,材料表面存在的ε-Cu等富Cu相成为钝化膜中的薄弱点,粗大富Cu相的时效析出位置易成为点蚀形核源,析出粗大富Cu相所占比例增加使得材料耐点蚀性能减弱;阻抗谱测试显示钝化膜中存在的ε-Cu等富Cu相会降低整体电位及钝化膜电阻,使钝化膜稳定性下降;DL-EPR测试表明,在相界及晶间析出的ε-Cu等富Cu相会使晶间呈现阳极性,导致晶间发生选择性腐蚀,因富Cu相主要在铁素体上析出,与奥氏体相比,其耐晶间腐蚀性能下降严重.抗菌检测表明,富Cu相的相结构和体积分数是影响材料抗菌性能的关键因素,ε-Cu的抗菌效果最好,亚稳态富Cu相次之,固溶Cu最差.ε-Cu相数量越多,抗菌效果越好.

Effects of antibacterial aging treatment on the corrosion resistance of copper-bearing duplex stainless steels were investigated by electrochemical methods. The film-cover method was used to test the antibacterial effect of the materials. The polarization curve test results show ε-Cu and other copper-rich phases become the weak point of the passive film on the surface of the duplex stainless steel, and the sites where the coarse copper-rich phases are precipitated from the matrix are apt to become pitting nucleation source. The proportion of coarse copper-rich phase increases, which makes pitting resistance of the materials worse. EIS test reveals that the presence of ε-Cu and other copper-rich phases in passive film reduces the overall potential and passive film resistance, decreasing the stability of passive film. DL-EPR tests show that ε-Cu and other copper-rich phases in grain boundary makes it take on anode characteristic in corrosion process, leading to selectively intergranular corrosion. Compared with austenite, the intergranular corrosion resistance of ferrite decreases seriously because the copper-rich phases are mainly precipitated from ferrite matrix. Antibacterial tests show that the microstructure and volume fraction of copper-rich phases are the key factors affecting the antibacterial properties of the materials, ε-Cu displays the best antibacterial effect, followed by metastable copper-rich phase, solid solution copper is the worst. The more ε-Cu phases are, the more antibacterial effect is.