耦合多电极矩阵传感技术在埋地金属腐蚀监测中的应用

目的采用耦合多电极矩阵传感器(CMAS)测量不同状态下的埋地金属腐蚀速率。方法将腐蚀探头插入到含蒸馏水和3.5%模拟海水的饱和土壤中,通过将探头向上提升,测量金属在饱和土壤、水-空气界面、疏松土壤中的腐蚀速率。对两只腐蚀探头分别进行杂散电流干扰、阴极保护处理,一只探头处于自由电位状态,测量三只探头在土壤中的腐蚀速率。结果在含蒸馏水和3.5%模拟海水的饱和土壤中,测量的金属稳态腐蚀速率约为2~15μm/a,金属在含海水饱和土壤中的腐蚀速率并未高于含蒸馏水饱和土壤。在土壤中形成充满水的空间里,水-空气界面附近金属材料的腐蚀速率比饱和土壤中高2个数量级。杂散电流对埋地金属的腐蚀速率影响巨大,与自由状态下的埋地金属相比,受杂散电流干扰的埋地金属腐蚀速率提高2个数量级。在阴极保护电位为-0.9 V的情况下,腐蚀速率约为0.01μm/a,接近CMAS系统检测最低限。结论耦合多电极矩阵传感器(CMAS)能够有效测试埋地金属不同状态下的腐蚀速率。

Application of Coupled Multieletrode Array Sensors in Corrosion Monitoring of Metal Buried in Soil

The paper aims to measure the corrosion rate of carbon steel buried in the soil with a coupled multielectrode array sensor.The corrosion probe was inserted into the saturated soil containing distilled water and 3.5%simulated seawater.The probe was raised during the measurement to measure the corrosion rate of metal in the saturated soil,near the water-air interface,and loose soil.The two probes were affected by stray current and cathodic production.One probe was kept under free potential.Three probes were inserted into the soil to measure the corrosion rate.The measurement results showed that the steady state corrosion rate measured in saturated soil containing sea distilled water and 3.5%simulated seawater was found to be approximately 2 to15μm/a.The corrosion rate of metal in saturated soil containing sea eater was not higher than that of the saturated soil containing distilled water.However,the corrosion rate in a space filled with water was 2 orders of magnitude higher than those found in the densely packed soil saturated with water.It was demonstrated that the corrosion rate affected by stray current was increased by 2 magnitudes compared with the rate under free potential.Under the cathodic protection potential was-0.9 V,the corrosion rate was approximate to 0.01μm/a,which is close to the lowest limit of CMAS system detection.The coupled multielectrode sensor can measure the corrosion rate of buried metal under different conditions effectively.