高温高压氯离子环境对螺杆钻具硬铬镀层腐蚀行为的影响

发布时间：2018-02-20 03:56

本文关键词： 高温高压氯离子螺杆钻具硬铬镀层腐蚀行为电化学　出处：《表面技术》2017年10期 　论文类型：期刊论文

【摘要】：目的研究螺杆钻具表面硬铬镀层在高温高压氯离子环境下的腐蚀行为。方法利用高温高压反应釜模拟螺杆钻具的井下环境,对螺杆钻具表面硬铬镀层进行腐蚀和检测,通过正交实验法研究温度、压力和氯离子浓度对硬铬镀层腐蚀状态的影响。采用动电位扫描、腐蚀失重法,研究硬铬镀层的电化学参数及腐蚀特征。通过扫描电镜(SEM)和能谱(EDS),分析镀层腐蚀后的微观形貌和表面成分的变化。结果影响硬铬镀层腐蚀速率的最大因素是氯离子浓度,其次是温度,再次是压力。年腐蚀深度最严重为0.8925 mm/a,最大的腐蚀速率为1.9026 g/(m~2·h)。腐蚀速率随着氯离子浓度的升高而降低,随着温度和压力的升高而升高。结论推断在温度180℃、压力15 MPa和Na Cl质量浓度30 g/L的条件附近,硬铬镀层腐蚀最严重。氯离子是影响镀铬层腐蚀速率的主要因素,因为氯离子优先在敏感位置(钝化膜的薄弱点处,如裂纹)引发孔蚀核。在闭塞腐蚀电池催化作用下,镀层表面不断形成孔蚀,裂纹被加宽,最终导致少部分区域镀层剥落,影响镀层整体保护性能。
[Abstract]:Objective to study the corrosion behavior of hard chromium coating on screw drilling tool surface under high temperature and high pressure chloride ion environment. Methods the corrosion and detection of hard chromium coating on screw drill tool surface was carried out by using high temperature and high pressure reactor to simulate the underground environment of screw drill tool. The effects of temperature, pressure and chloride concentration on corrosion state of hard chromium coating were studied by orthogonal experiment. The electrochemical parameters and corrosion characteristics of hard chromium coating were studied. The changes of microstructure and surface composition of hard chromium coating after corrosion were analyzed by scanning electron microscopy (SEM) and EDS. The results showed that the concentration of chloride ion was the most important factor affecting the corrosion rate of hard chromium coating. The most serious corrosion depth is 0.8925 mm / a and the maximum corrosion rate is 1.9026 g / m ~ 2 路h ~ (-1) 路h ~ (-1). The corrosion rate decreases with the increase of chloride concentration and increases with the increase of temperature and pressure. Near the pressure of 15 MPa and the mass concentration of NaCl 30 g / L, the corrosion of hard chromium coating is the most serious. Chloride ion is the main factor affecting the corrosion rate of chromium plating layer, because chlorine ion preferentially lies in the sensitive position (weak spot of passivation film). Under the catalysis of occlusive corrosion battery, the surface of the coating is continuously formed pitting corrosion, and the crack is widened, resulting in a few areas of the coating peeling off, which affects the overall protection performance of the coating.
【作者单位】：重庆科技学院冶金与材料工程学院;德州联合石油机械有限公司;
【基金】：重庆科技学院校内科研基金资助项目(CK2015Z18);重庆科技学院研究生科技创新项目(YKJCX1620202) 重庆高校优秀成果转化项目(KJZH17136)~~
【分类号】：TE982;TG172.82

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