铜基片静态气液界面腐蚀规律的实验

Experimental study of the static air-liquid interface corrosion on copper

气液两相界面腐蚀广泛存在于日常工业中。因气液相界面存在不稳定特性,迄今对于相界面处腐蚀的研究多针对不断变化的界面位置附近,分析一段时间内的累积腐蚀效果。本文向液相内注入一定体积的气泡,维持气液界面在金属铜壁面的稳定以及气液相界面和液相主体浓度近似恒定;在含不同Cl^(−)浓度的溶液中,通过电化学方法对比有无相界面的腐蚀规律,并根据数据深入分析相界面处的腐蚀机理。结果表明:引入气液界面导致铜试样腐蚀电位升高、腐蚀电流增大,腐蚀更严重;气液界面处由于引入微观界面能差腐蚀、宏观氧浓差电池腐蚀的作用显著增大了试样的腐蚀电流,使得在整个溶液浓度范围内含界面的铜腐蚀电流均高于不含界面的腐蚀电流,同时在铜表面留下清晰的界面腐蚀线;通过对界面腐蚀电流的剥离,包含液相主体腐蚀部分时无论有无界面的铜腐蚀速率均随Cl^(−)浓度的升高呈现先增大后减小的趋势,而去除液相部分影响的单独界面腐蚀电流则随Cl^(−)浓度升高而增大。

The air-liquid interface corrosion widely exists in daily industries.Because of the instability of the air-liquid interface,most research on the interface corrosion is aimed at analyzing the cumulative corrosion effect near the changing interface position for a period of time.In experimenting,a fixed volume bubble was injected into the under surface of copper sample to maintain the stability of the air-liquid interface and the constant ion concentration.By comparing the corrosion data of interface/no-interface samples in different concentration of NaCl solution,the interface corrosion mechanism was proposed.The results show that the corrosion potential and corrosion current of the copper with air-liquid interface are increased.At the air-liquid interface,the corrosion current of the sample is significantly increased by the micro-interface energy difference corrosion and macro-oxygen concentration difference battery corrosion,and therefore the corrosion rates of samples with interface are bigger than those without interface in the whole concentration range.Meanwhile a clearly visible interface corrosion line on samples is left.The interface corrosion rate is extracted by the analysis of experimental data.The results show that the total corrosion rate increases firstly and then decreases,but the interface corrosion rate monotonically increases with the increase of solution concentration.