Microelectrode investigation on the corrosion initiation at lead-brass galvanic interfaces in chlorinated drinking water.
Microelectrode investigation on the corrosion initiation at lead-brass galvanic interfaces in chlorinated drinking water.
复制标题
氯化饮用水中铅黄铜电偶界面腐蚀引发的微电极研究。
作者：
Xiangmeng Ma;D. Lytle;W. Lee
用微电极研究了腐蚀初期pH、溶解无机碳(DIC)和流量对铅-黄铜接头表面化学成分(pH、溶解氧和游离氯)变化的影响。表面测量表明，金属表面的水化学是高度不均匀的。在pH值为7时和水滞留期间，阳极(含铅焊料)和阴极(黄铜)区域之间的局部pH差异高达7.5个pH单位。在水流条件下，高DIC水的表面pH变化很小，而在低DIC水中，表面的pH范围为7.65.4(ΔpH 2.2)。在停滞状态下，铅黄铜表面附近的游离氯消耗量较大，而不考虑总体pH值。研究还发现，流动可以移动起源于阳极的低pH羽流。总体而言，这项研究提供了氯化饮用水环境中高度局部电偶腐蚀的直接证据。
In this study, the effects of pH, dissolved inorganic carbon (DIC), and flow on changes in surface chemistry (pH, dissolved oxygen, and free chlorine) of lead-brass joints at initial stages of corrosion were investigated using microelectrodes. Surface measurements showed that the water chemistry at the metal surfaces was highly heterogeneous. At pH 7 and during water stagnation, local pH difference between anodic (leaded solder) and cathodic (brass) regions differed by as much as 7.5 pH units. High DIC water under water flowing conditions showed minimal pH changes on the surface whereas in low DIC water, a pH range of 7.6-5.4 (ΔpH 2.2) was observed over the surface. Free chlorine consumption near the lead-brass surface was greater under stagnation regardless of bulk pH. It was also found that flow can move the low pH plume that originated at the anode. Overall, this study provides direct evidence for highly localized galvanic corrosion in a chlorinated drinking water environment.