脉冲真空氮化油管钢的耐蚀性测试研究

Study on the Corrosive Endurance of Pulse Vacuum Nitriding Coating Oil Steel

通过电化学测试方法研究了脉冲真空渗氮防腐层及裸样的抗腐蚀性能。结果表明,氮化层试样的抗腐蚀性明显优于裸样:线性极化的试验数据表明了氮化层试样的腐蚀电流密度远小于裸样的腐蚀电流密度,腐蚀速率低于裸样;从极化曲线上看,尽管渗氮层和裸样两种试样的自腐蚀电位相近,但是极化曲线形状有很大的不同,氮化层试样在阳极极化过程中出现了较为明显的钝化区,减缓了腐蚀电流密度;同时,通过腐蚀失重的试验也进一步表明氮化层试样的耐蚀性优于裸样。在油田的试用效果表明,这种氮化层可使防腐性能提高4～5倍,而成本增加20 %～25 %。

The corrosive behavior of Pulse Vacuum Nitriding coating and plain sample were investigated by an apparatus of electrochemical measurement. The results showed that the resistance to corrosion of nitriding sample was better than that of plain sample obviously. The experimental data of linear polarization method showed that the corrosive current density of nitriding coating was much smaller than that of plain sample and the corrosion velocity was also smaller. According to the polarization curves, the open circuit potential of the Nitriding coating was the same as plain sample approximately, but the shapes of polarization curves were very different. During the anodic porlarization, the inactive area appeared obviously, the corrosion current density reduced slowly. In addition, the test results of the weight-loss method showed that the resistance to corrosion of the nitriding coating sample was superior to that of plain sample. The effect of probation in oil field showed that the oil pipe steel with nitriding coating could increase the resistance to corrosion to about 4～5 times, and the cost only enhanced 20 percent.