根据胜利油田的闸阀材料用金属调研结果发现,Cl-是造成电化学腐蚀的关键因素，通常采用喷涂、激光熔覆等表面处理工艺来提高闸阀材料的耐腐蚀性能。以闸阀阀板和阀杆常用12Cr13马氏体不锈钢(以下简称12Cr13)基材为研究对象,采用超音速火焰喷涂技术和大气等离子喷涂技术分别在其表面制备WCCoCr涂层和Ni60涂层,采用动电位极化曲线测试和电化学阻抗谱测试方法,研究12Cr13基材、WC-Co-Cr涂层和Ni60涂层在不同Cl-浓度环境中的腐蚀行为和电化学特性。结果表明:不同Cl-浓度下,12Cr13基材的耐腐蚀性能随Cl-浓度增加而降低；WCCoCr涂层和Ni60涂层在耐腐蚀性能上优于12Cr13基材,其一是因为涂层起到屏障作用,能够有效阻止Cl-进入基材表面发生腐蚀，其二是因为涂层中的Cr、Ni元素能够在涂层表面形成致密氧化膜,阻止腐蚀发生。可利用动电位极化曲线和电化学阻抗谱测试方法,对12Cr13基材用不同表面处理工艺制备涂层的耐腐蚀性进行快速评价,相较于传统长周期腐蚀模拟浸泡实验而言,通过电化学系列实验评价可缩短表面处理工艺耐腐蚀评价周期,提高闸阀阀板及阀杆耐腐蚀表面处理工艺优化效率,对闸阀材料表面处理工艺的应用有一定参考意义。

According to the investigation results of metal for gate valve materials in Shengli Oil and Gas Field, it is found that Cl- is the key factor causing electrochemical corrosion. Surface treatment processes such as spraying, laser cladding are usually used to improve the corrosion resistance of gate valve materials. In this paper, we select 12Cr13 substrate for valve plate and valve rod as candidate material, WC-Co-Cr coating and Ni60 coating were deposited on the surface of 12Cr13 by HVOF (High Velocity Oxygen Fuel) thermal spray and plasma spraying technology respectively. The corrosion behavior and electrochemical characteristics of the three materials were studied by means of potentiodynamic polarization curve test and electrochemical impedance spectroscopy test in different Cl- environment. The results show that under different Cl- environment, the corrosion resistance of 12Cr13 substrate decreases with the increase of Cl- concentration. The corrosion resistance of WC-Co-Cr coating and Ni60 coating is better than that of 12Cr13 substrate. The first reason is that the coating can effectively prevent Cl- from entering the surface of the substrate to cause corrosion. Secondly, Cr and Ni components in the coating can form a dense oxide film on the surface of the coating, thus preventing the occurrence of corrosion. The corrosion resistance of coatings on 12Cr13 prepared by different surface treatment processes was rapidly evaluated by potentiodynamic polarization and AC impedance testing methods. Compared with the traditional longperiod corrosion simulation immersion experiment, the corrosion resistance evaluation cycle of surface treatment process can be shortened by electrochemical experimental evaluation, so as to improve the optimization efficiency of corrosion resistant surface treatment process of valve plate and stem. This study provides certain reference for the application of surface treatment process of gate valve materials.