通过模拟环境中的电偶电流的跟踪测试,研究了P110钢表面腐蚀产物膜层/金属基体所构成的电偶电流随温度、时间和面积比等因素的变化规律.结果表明,40 ℃时,有膜层覆盖的P110钢电极作为阳极发生垢下阳极溶解,而裸露电极作为阴极反应;在60 ℃时,偶接初始阶段,有膜层覆盖的P110钢电极先发生垢下阳极溶解,但很快偶接电极之间会出现电流反转,裸露电极由阴极变成阳极而被腐蚀;不同面积比的裸露电极/膜层覆盖电极偶接时,电偶电位相差不大,随着阳/阴极面积比的增大而负移,电偶电流密度绝对值则随阳/阴极面积比的增大而减小.随着时间延长,稳态条件下,裸露电极/膜层覆盖电极的电偶电流密度趋近为零;而在动态变化条件下,则很可能会形成小阳极大阴极的情况,从而会导致难以极化,最终出现腐蚀穿孔的危险.

Through the simulation of galvanic current tracking test,the laws of the galvanic current between the corrosion film of P110 steel surface and the metal with temperature,time area ratio and other factors were studied.The results showed that the P110 electrode covered by film suffered anodic dissolution,the bare electrode acted as a cathode at 40 ℃.In the initial coupling stage at 60 ℃,P110 electrode covered by film suffered anodic dissolution,but current reversing between coupling electrodes happened quickly,and bare electrode corroded as an anode.At 60 ℃,the potentials of different electrodes with various ratios of bare electrode area / film covering electrode areas showed small diffrences,and the potentials moved in the negative direction and the absolute value of the galvanic current density decreased with the increase of the ratio of anodearea/cathode area.Under the steady conditions,the current density between bare electrode and film covered electrode was close to zero.Under the dynamic changing conditions,it was likely to form the situation of small anode and big cathode,which led to be hard for polarization and to be easy for corrosion perforation.